preface - sapgrp.comsapgrp.com/shop/images/pdf/4418713_preface.pdf · discussed in the chapter....

iii

iii

c

The Synergy for Success in Science Series aims to enable students acquire in-depth knowledge and understanding of science concepts relevant to daily life, society, and the environment.

This series aims to develop students into lifelong learners having deep appreciation of scientific knowledge and processes, and equipped with scientific attitudes, skills, and values.

Each book in the series uses concrete examples and matches them with colorful visuals and language that is suited to the level of the students to whom the book is intended. This makes learning experience relevant, accessible, and meaningful to students regardless of their background and language skills.

This series makes science learning easier with the help of the following features:

Key Concept Important key words and concepts are defined, compared, and differentiated. This facilitates easy understanding of science concepts.

Know More This concept-related information enriches students knowledge and reinforces their understanding of science concepts, hence appreciate their applications.

Let’s Review These open-ended questions reinforce students understanding and mastery of science concepts in each lesson.

Let’s Do This These are simple classroom exercises that enable students to explore and apply science concepts in real-life experiences.

Chapter Summary This serves as a review guide for students.

Key Ideas summarizes important concepts at the end of each chapter.

Concept Map is a visual summary of the concepts presented in the chapter.

Chapter Test These multiple choice and structured questions enable students evaluate their knowledge, understanding, skills, and mastery of the concepts on their own.

Enrichment This contains suggested activities that students can do in relation to the topic in each chapter.

Making Connections This present practical application/s of the science concept discussed in the chapter.

PREFACE

iii

iv

Table of Contents

unit 1 Force, Motion, and Energy

Force and Motion Motion 3 Newton’s Laws of Motion 6 Uniform Circular Motion 18Chapter Summary 25Chapter Test 27Making Connections 30

Work, Power, and Energy Work 32 Power 36 Energy 40 Conservation of Energy 48Chapter Summary 53Chapter Test 55Making Connections 57

Sound The Nature of Sound 60 The Speed of Sound 65 Interactions of Sound 69 Applications of Sound 73Chapter Summary 75Chapter Test 77Making Connections 80

Light The Nature of Light 82 Interaction of Light Waves 86 Dispersion of Light 92 Scattering of Light 94

1.1

Chapter 1

1.2

1.3

Chapter 2

2.1

2.2

2.3

2.4

Chapter 3

3.1

3.2

3.3

3.4

4.1

Chapter 4

4.2

4.3

4.4

Preface iii

v

Chapter Summary 96Chapter Test 98Making Connections 100

Heat Temperature 102 Heat 105 Thermal Expansion 109Chapter Summary 112Chapter Test 114Making Connections 116

Electricity Electric Charges and Voltage 118 Electric Current 122 Electrical Resistance 126 Electric Power 129 Electric Circuit 134 Home Circuitry and Safety Devices 143Chapter Summary 146Chapter Test 148Making Connections 150

unit 2 Earth and Space

Earthquakes and Faults What Are Faults? 153 Seismic Waves 159 Damages Caused by Earthquakes 164 Earthquakes Preparedness 167Chapter Summary 170Chapter Test 172Making Connections 174

Chapter 5

5.1

5.2

5.3

Chapter 6

6.1

6.2

6.3

6.5

6.4

6.6

Chapter 7

7.1

7.2

7.3

7.4

vi

The Particulate Model of Matter What Is Matter Made Of? 213 States of Matter 216 Changes in States of Matter 223 Classification of Matter 231Chapter Summary 237Chapter Test 239Making Connections 242

The Atomic Structure The Discovery of Atomic Structure 244 Subatomic Particles 250Chapter Summary 254Chapter Test 256Making Connections 258

10.1

Chapter 10

10.2

10.3

10.4

Chapter 11

11.1

11.2

Typhoons Typhoons Are Intense Tropical Cyclones 176 Tracking a Typhoon 181 Effects of a Typhoon 186Chapter Summary 189Chapter Test 191Making Connections 194

Other Members of the Solar System Comets 196 Asteroids 200 Meteoroids, Meteors, and Meteorites 203Chapter Summary 206Chapter Test 208Making Connections 210

unit 3 Materials in the Environment

8.1

Chapter 8

8.2

8.3

9.1

9.2

9.3

Chapter 9

vii

The Periodic Table of Elements

Development of the Periodic Table 260

Representative Elements 268

Transition Elements 273

Periodic Trends 275

The Activity Series of Metals 278

Chapter Summary 281

Chapter Test 284

Making Connections 287

unit 4 Living Things and Their EnvironmentStructures and Functions of the Human Digestive System

Parts of the Human Digestive System and Their Functions 291

Changes in Food as It Undergoes Digestion 297

Diagnosis, Prevention, and Treatment of Digestive Disorders 304

Proper Nutrition and Overall Wellness 308

Chapter Summary 312

Chapter Test 314


Heredity: Inheritance and Variation

Cell Division 320

The Cell Cycle 323

Mendelian Genetics 330

Chapter Summary 340

Chapter Test 342


12.1

Chapter 12

12.2

12.3

12.4

12.5

Chapter 13

13.1

13.2

13.3

13.4

Chapter 14

14.1

14.2

14.3

viii

Biodiversity

What Is Biodiversity? 346

Classifying and Identifying Organisms 349

Kingdom Archaea 355

Kingdom Eubacteria 357

Kingdom Protista 359

Kingdom Fungi 362

Kingdom Plantae 367

Kingdom Animalia 374

Chapter Summary 389

Chapter Test 391


Ecosystems

Transfer of Energy in Trophic Levels 396

Cycling of Materials in the Ecosystems 402

Impact of Human Activities on Ecosystems 407

Chapter Summary 414

Chapter Test 416


Glossary 419Index 428

Chapter 15

15.1

15.5

15.2

15.6

15.3

15.7

15.4

15.8

Chapter 16

16.1

16.2

16.3

Living Things and Their Environment

Unit 4

Energy is an essential requirement of all life forms on Earth. Energy, which comes from sunlight or food, is needed to support all chemical processes within living things in order to maintain life. Also, essential nutrients from the environment are needed to support the continuous functioning of various living systems on Earth.

In this unit, you will understand how living things obtain energy and essential nutrients from food and the environment, and use them to support various life processes, which are responsible for the continuity of life on Earth.

LEARNING GOALS

Chapter 13

Structures and Functions of the Human Digestive SystemFood such as bread, meat, and vegetables are made up of materials

which the body cannot directly use to provide energy, nourish, and build cells. They must be broken down into molecules of vitamins,

minerals, and other nutrients which the bloodstream can absorb and carry to various parts of the body.

The process in which food is transformed into substances which the body can use to maintain its various functions is called digestion. This chapter will help you understand the processes as well as the parts of the body involved in digestion.

• Describethecoordinatedfunctionsoftheorgansofthedigestivesystem.• Tracethepathoffoodasitisbeingdigested.• Explainhowenzymeshelpindigestionoffood.• Explainhownutrientsfromdigestedfoodareabsorbedthroughthevilliandcarriedthroughthebloodstreamtotheliver.

• Explainhowwastematerialsareeliminatedthroughtheexcretorysystem.• Illustratehowdiseasesofthedigestivesystemaredetected,prevented,andtreated.• Identifyhealthfulpracticesthataffectthedigestivesystem.• Discusscontemporaryhealthissuesthatpromotepropernutritionandoverallwellness.

Structures and Functions of the Human Digestive System 291

13.1 Parts of the Human Digestive System and Their Functions

The digestive system is a group of organs that works together to transform food into forms that cells in the body can absorb to provide energy for its various functions and to nourish and build new cells.

Food passes through a long tube called gastrointestinal tract inside the body. The gastrointestinal tract extends from the mouth to the anus and can be divided into two sections— the upper and lower gastrointestinal tract. The upper gastrointestinal tract consists of the mouth, pharynx, esophagus, and stomach. The lower gastrointestinal tract consists of the intestines, rectum, and anus.

In addition to the gastrointestinal tract, there are important accessory organs that help in the digestion of food. These accessory organs include the teeth, tongue, salivary glands, liver, gallbladder, and pancreas.

Organs of the Human Gastrointestinal Tract

Mouth

The mouth is the part of the digestive system that receives food. Inside the mouth are various accessory organs that help in the mechanical and chemical digestion of food—the tongue, teeth, and salivary glands. The teeth masticate or chew the food into smaller pieces (mechanical digestion). The salivary gland produces saliva, which moistens the food before the tongue and other muscles push the food into the pharynx and esophagus.

Pharynx

The pharynx, or throat, is a cone-shaped tube located at the back of the mouth. This part of the digestive system is lined with mucus membrane, and involved in passing chewed food from the mouth to the esophagus. It contains a flat, thin piece of tissue known as the epiglottis, which prevent chewed food from going down the trachea or windpipe to the lungs when swallowing.

Figure 13.1Organsofthehumangastrointestinaltract

mouthpharynx

esophagus

uppergastrointestinal

tract

lowergastrointestinal

tract

stomach

largeintestine

smallintestine

anusrectum

Know More!

Thesalivaryglandsproduceapproximately1.7litersofsalivaeachday.Theproductionofsalivaiscontrolledbytheautonomicnervoussystem;itoccursautomatically.Thisiswhypeoplesalivateatthesight,smelloreventhoughtoffood.

Figure 13.2Thepharynxandesophagus

pharynx

esophagus

292 Living Things and Their Environment

Esophagus

The esophagus, which is about 25 centimeters (10 inches) in length, is a muscular tube that connects the pharynx and the stomach. This organ receives masses of chewed food from the mouth through the pharynx and passes it to the stomach in a series of muscular contractions and relaxations known as peristalsis.

Figure 13.3Peristalsishelpfoodbolusmovethroughtheesophagustothestomach.

contraction

foodbolus

relaxation

esophagus

contractionrelaxation

stomach

The movement of food along the esophagus is controlled by two muscular sphincters—the upper and lower esophageal sphincter. The upper esophageal sphincter (UES), which is located at the upper end of the esophagus, keeps food and gastric or stomach contents from going down the trachea. The lower esophageal sphincter (LES), which is located at the lower end of the organ, prevents food and gastric contents from moving backward from the stomach.

Stomach

The stomach is a muscular sac-like organ located between the esophagus and the small intestine. This organ secretes hydrochloric acid (HCl) and digestive enzymes, which help break down food into soluble substances. The stomach acts as a receptacle for food, allowing the body to have enough time to digest food properly. Two sphincters—the esophageal sphincter and the pyloric sphincter—keep the contents of the stomach contained. The stomach has four sections: the cardia where the contents of the esophagus empty into the stomach, the fundus which formed the curvature of the organ, the corpus which is considered as the body or the main region, and the pylorus, which facilitates emptying of the contents into the small intestine.

Figure 13.4Partsoftheesophagusandstomach

esophagus

loweresophagealsphincter

pyloricsphincter duodenum

pylorus

fundus

stomach

cardia


Small Intestine

The small intestine is a long and narrow tube, about seven meters (23 feet) long in adults, located in the abdomen. This organ continues the process of digestion with the action of bile and enzymes secreted by the liver and the pancreas. The small intestine is divided into three sections: the duodenum, which is responsible for the digestion of food materials, and the jejunum and ileum, which are responsible for the absorption of nutrients into the bloodstream.

Large Intestine

The large intestine, also known as colon, is located in the lower abdomen of the body. This organ, which is about 1.5 meters (5 feet) in length and three inches in diameter, is shorter and wider compared to the small intestine. The primary function of this organ is to absorb water from the undigested food from the small intestine before sending it into the rectum as waste or feces, which are excreted out of the body through the anus. The large intestine contains many symbiotic bacteria that help break down wastes and produce some nutrients.

The large intestine is divided into three sections: the cecum, which receives food materials from the ileum; the colon, which is further divided into ascending colon, transverse colon, and descending colon; and the rectum where waste is removed from the body through defecation.

Rectum and Anus

The rectum is the end section of the large intestine before reaching the anus. The anus is the opening at the lower end of the gastrointestinal tract that controls the expulsion of feces.

Accessory Organs of the Digestive System

Teeth

Teeth are small, white, and hard organs located along the anterior and lateral sides of the mouth. These organs are used for cutting and grinding food into smaller pieces. They are made of a bone-like substance called dentin and covered in a layer of enamel. In addition, teeth contain blood vessels and nerves under the dentin in a soft region known as the pulp.

Figure 13.6Partsofthelargeintestine

transversecolon

descendingcolon

rectum

anus

ascendingcolon

appendix

Figure 13.5Partsofthesmallintestine

duodenum

jejunum

ileum

Figure 13.7Partsoftheteeth

premolarsmolars

enamel

rootrootcanal

gumtissue nerveandbloodvessels

crown

cement

incisors

canine

dentinpulpcavity neck

bone


There are four kinds of teeth in a set of permanent human adult teeth. The incisors are the four middlemost teeth on the upper and lower jaws. The canines are the pointed teeth outside the incisors. The premolars are the teeth between the canines and the molars. The molars are the flat teeth in the rear of the mouth.

Tongue

The tongue is a small muscular organ located at the lower portion of the mouth. The tongue is covered with mucus membrane—moist, thin layer of skin. The small bumps in the tongue, which give the tongue’s surface a rough texture, are called papillae. Papillae contain taste buds containing the receptors for taste. The tongue helps to taste and move food in the mouth while chewing and swallowing.

There are four types of taste receptors. Each of these taste receptors is concentrated in certain areas of the tongue's surface: sweet receptors on the tip of the tongue; sour receptors along the sides of the tongue; salty receptors in front of the tongue; bitter receptors at the back of the tongue.

Salivary Glands

The salivary glands are accessory organs located in and around the mouth and throat. These organs produce a watery secretion called saliva. Saliva helps moisten and lubricate food as it passes from the mouth through the pharynx and esophagus. Saliva contains the enzyme amylase that breaks down carbohydrates. Thus, chemical digestion of food begins within the mouth, even before food reaches the stomach.

The three major pairs of salivary glands are: parotid glands on the insides of the cheeks, submandibular glands at the floor of the mouth, and sublingual glands under the tongue.

Pancreas

The pancreas is a large glandular organ located deep in the abdomen behind the stomach. The pancreas is connected to the duodenum—the first section of the small intestine—through a small tube called the pancreatic duct. Pancreatic juice, which contains digestive enzymes secreted from the pancreas into the small intestine, helps complete the chemical digestion of carbohydrates, protein, and fat in chyme—partly digested food in the stomach mixed with stomach acid.

Figure 13.8Partsofthetongue

papillaebitter

receptors

saltyreceptors

sourreceptors

Figure 13.9Thesalivaryglands

parotidgland

submandibulargland

sublingualgland

Figure 13.10Thepancreasandpancreaticduct

bileduct

pancreaticduct

body

head

tail


Liver

The liver is a large reddish-brown organ located at the upper right-hand area of the abdominal cavity; below the diaphragm; and above the stomach, right kidney, and intestines. This organ consists of two large sections: the right and the left lobe.

The liver is a glandular organ that secretes bile—a substance that helps digest fats. Bile breaks down large droplets of fat into smaller ones. This process is known as emulsification. Also, the liver filters the blood coming from the gastrointestinal tract before passing through the blood vessels in various parts of the body.

Gallbladder

The gallbladder is a small pear-shaped organ located under the liver. This organ stores bile produced by the liver. As the stomach and intestines digest food, the gallbladder secretes bile into the small intestine through a small tube called bile duct. The duct connects the liver and the gallbladder to the small intestine.

Let’s Review1 What is the role of the digestive system in the

human body?2 What are the accessory organs of the human

digestive system?3 What is the function of each of the following

organs in the process of digestion?

a Esophagusb Large intestinec Mouth

d Rectume Small intestinef Stomach

Figure 13.11Partsoftheliver

rightlobeleftlobe

gallbladder

Figure 13.12Thegallbladder

gallbladder

pancreas

bileductliver


Let’s Do This!

PurposeCreate a three dimensional (3D) model of the digestive system using used household materials.

What You Needused household materials cardboardscissors or cutterglue or adhesive tapemarker

What You Need to Do1 Collect used household materials like aspirator bulbs, balloons,

plastic bottles, cups, funnels, hosepipes, plastic valves, styropor, etc.2 Create a 3D model of the digestive system using the materials you

collected. 3 Clearly label the organs represented by the household materials

and write their functions.4 Present the model to the class.

Guide Questions1 In which parts of the human body does mechanical digestion

occurs?2 Which parts of the digestive system produce enzymes for the

digestion of food?3 What is the function of the small and large intestines in the chemical

digestion of food?4 In which part of the digestive system is waste excreted?


13.2: Changes in Food as It Undergoes Digestion

Digestion isaprocessinwhichfoodisbrokendownintosubstanceswhichthebodycanusetoprovideenergytoitsvariousfunctionsandtonourishandbuildnewcells.

Digestion involves two processes: mechanical digestion and chemical digestion.

Mechanical digestion is the process of breaking down food into smaller pieces which can be swallowed. This involves cutting and chewing of food in the mouth by the action of the teeth and tongue. Muscular contractions and relaxations of the muscles in the esophagus and stomach also help in the mechanical digestion of food.

On the other hand, chemical digestion is a process in which large molecules in food like carbohydrates, proteins, and fats are broken down into smaller molecules that can be absorbed by the cells in the body. This involves the action of digestive enzymes.

Enzymesareproteinsthatactascatalysts,speedingupchemicalreactionsinthebody.

Generally, there are three types of enzymes responsible for chemical digestion: proteases help break down proteins, carbohydrases break down carbohydrates, and lipases break down fats.

Digestion of food begins in the mouth as food is broken down into smaller pieces that can be swallowed. In the mouth, food is masticated by the action of the teeth and mixed with saliva with the help of the tongue, turning it into a bolus. Saliva is a watery substance secreted by the salivary glands in the mouth. Saliva contains an enzyme called salivary amylase, which help digest starch into smaller molecules, maltose, a disaccharide.

Know More!

Fulldigestion—fromthetimefoodentersyourmouthuntilwastematerialsareeliminated—takes24-72hours.Thetotaltimedependsuponthecontentofthefood,physicalactivity,medicationyoumaybetaking,sickness,andyouremotions.

tongue

esophagus

foodbolus

Figure 13.14 Mechanicaldigestionoffoodbeginsinthemouth


Figure 13.13Thethreetypesofenzymesresponsibleforthechemicaldigestionoffood

Aproteinmoleculeismadeupofmanydifferentaminoacids

Astarchmoleculeismadeupofmanyglucosemolecules

Proteasesbreakdownproteinmolecules

Shorterpolypeptides

Dipeptides

Carbohydrasesbreakdowncarbohydratemolecules

Maltose

Lipasesbreakdownfatmolecules FattyAcids Glycerol

Glucose

Aminoacids

Afatmoleculeismadeupoffattyacidsandglycerolmolecules

acts on breaks into

Amylase

Starch Maltose

Once food is masticated and mixed with saliva, it turns into a bolus and passes through the pharynx into the esophagus with the help of the tongue and palate. In the esophagus, the bolus moves down into the stomach by means of peristalsis, or the involuntary movement of the muscles in the stomach.

When the bolus approaches the stomach, the lower esophageal sphincter relaxes and allow the bolus to pass into the stomach. In the stomach the bolus is mixed with gastric juice secreted by the glands that line the wall of the stomach. Gastric juice is a mixture of various substances such as hydrochloric acid, mucus, a protease known as pepsinogen, and other digestive enzymes. Hydrochloric acid activates pepsinogen into pepsin, which breaks down proteins into polypeptides.

Figure 13.15Peristalsisinthestomach


HCl

Pepsinogen Pepsin

Proteins Polypeptides

activates converted into

acts onbreak into

Also, hydrochloric acid inhibits the growth of harmful bacteria from the food in the stomach. Mucus prevents the stomach wall from being digested by its own enzymes or from being burnt by the hydrochloric acid.

Churned by the muscular wall of the stomach and degraded by the gastric juices, the bolus turns into a semifluid and creamy mixture called chyme. The chyme passes the pyloric sphincter and move into the first section of the small intestine, known as the duodenum. The pyloric sphincter releases only about 4 cubic centimeters (eight of an ounce) of chyme at a time. The rest is held back for more mixing in the stomach.

In the small intestine the chyme is acted upon by more digestive enzymes from the gallbladder, liver, and pancreas. Enzymes that help digest carbohydrates include pancreatic amylase (for starch) maltase (for maltose), sucrase (for sucrose), and lactase (for lactose).

Maltase

Maltose Glucose + Glucose

Lactase

Lactose Glucose + Galactose

Sucrase

Sucrose Glucose + Fructose

acts on

acts on

acts on

breaks into

breaks into

breaks into


The initial and final digestion of fats occur in the small intestine. However, before fats can be digested into fatty acids and glycerol by the enzyme lipase, large globules of fats must be broken down into smaller droplets with the action of bile from the gallbladder. This process is called emulsification. Bile is a mixture of bile salts, cholesterol, water, and other substances. It is produced in the liver and stored in the gallbladder.

Bile Lipase

Big fat globules Small fat globules

acts on acts onbreak into smaller

break into

Fatty Acids + Glycerol

Digestion of protein is completed in the small intestine by various enzymes. Polypeptides from the stomach are broken down into peptides. Polypeptides are then acted upon by peptidases and broken down into amino acids. Likewise, undigested proteins from the stomach are also processed in the small intestine. Enterokinase is the enzyme secreted by the small intestine in the duodenum that activates trypsinogen into trypsin. Protein molecules are acted upon by trypsin, an activated form of the pancreatic enzyme trypsinogen, and are broken down into peptides.

Peptidases

Polypeptides Amino Acids

Enterokinase

Trypsinogen Trypsin

Protein Polypeptides

act on

activates

acts on

break into

break into

turns into

The small intestine consists of three sections. The first section is the duodenum. This is where the final digestion of food occurs. The next two sections are the jejunum and ileum. These sections are responsible for the absorption of nutrients from the processed food into the bloodstream through the

Figure 13.16Bilefromthegallbladderemulsifyfats.

bilesalts

bigfatglobule

smallfatglobules

Let’s Do This!


walls of the intestine. On the walls of the small intestine are finger-like projections that help in absorption of nutrients into the bloodstream. These projections are called villi.

Once digestion is completed in the small intestine, waste materials from digestion moves into the large intestine. In the large intestine, water from waste materials are absorbed and waste materials are solidified into feces or stool. Waste materials are stored in the rectum and eliminated through the anus.

Let’s Review

4 What are the two processes of digestion?5 What is the role of enzymes in the digestion of

food?6 In which parts of the digestive system does

chemical digestion of food occurs?

Figure 13.17Villionthewallsofthesmallintestine

mucosa

villi

villus

veinartery

PurposeSimulate mechanical and chemical digestion of food in the digestive tract.

What You NeedActivity 1: Two pieces of unsalted soda crackers, timerActivity 2: Two small marshmallows, 250 mL beaker, timerActivity 3: Two plastic sandwich bags, 2 crackers,

120 mL vinegarActivity 4: Two 250 mL beakers, 100 mL graduated cylinder, 4 paper

towels

What You Need to DoActivity 11 Chew the crackers for two minutes. 2 Take note of the physical and chemical changes that you noticed on

the crackers. Describe the taste as you chew the crackers. Record your observations.

Activity 21 Unwrap the marshmallows. Put one in your mouth and place the

other in a 250-mL beaker half full of water. Set the beaker aside.

Let’s Do This!


2 Keeping your mouth closed, you may suck on but not chew the marshmallow. Record in the table the time it takes for the marshmallow to completely dissolve in your mouth and in water from start to finish.

3 Compute the total amount of time it took for the marshmallows to dissolve in the mouth and in water.

Initial Time Final Time Total Time

Marshmallow dissolved in the mouth

Marshmallow dissolved in water

Activity 3

1 Place one cracker in each sandwich bag. Carefully pour 60 mL of vinegar into each bag.

2 Label one bag as Bag A to represent No Muscular Action and the other bag as Bag B to represent With Muscular Action.

3 Take note of the time and observe the contents of Bag A. Record in the table your initial observations under No Muscular Action in the table. Set the bag aside and record observations again after five minutes. Try not to move the bag too much as you make your observations.

4 Take Bag B and gently squeeze the bag six times being sure not to rip or accidently open the bag.

5 Record in the table your initial observation under With Muscular Action. Squeeze the bag six times. After five minutes, squeeze the bag again six times. Record your observations.

Set UpUpon Addition

of VinegarAfter 5 minutes

Bag A: No Muscular Action

Bag B: With Muscular Action


Activity 4

1 Using the graduated cylinder, pour 100 mL of water into each beaker.

2 In the first beaker, dip one folded paper towel. In the second beaker, dip three folded paper towels

3 Wait for 30 seconds. Using a graduated cylinder, record the volume of the remaining water in the cup.

Set UpInitial Amount

of WaterAmount of

Water after 30 s

One paper towel

Three paper towels

Guide Questions:1 What are the physical and chemical changes in the crackers in

Activity 1?2 In Activity 2, which marshmallow dissolved first? What causes the

marshmallow to “disappear”?3 In Activity 3, why did we add vinegar in two bags? Which bag did a

better job of digesting the crackers? Why?4 In Activity 4, which paper towel had the largest surface area? Which

cup had the least amount of water remaining? Why?5 How are the paper towels similar to villi in our

small intestine?


13.3: Diagnosis, Prevention, and Treatment of Digestive Disorders

The proper functioning of the digestive system can be disrupted by diet, disease, and even emotional stress. Some common disorders of the digestive system are as follows:

Liver Cirrhosis

Cirrhosis is a condition characterized by irreversible scarring of the liver and loss of liver cells, which eventually prevents the organ from functioning properly. The main causes of cirrhosis are excessive alcohol consumption, viral Hepatitis B and C, and fatty liver. Other causes include parasitic infections, reactions to medication, and prolonged exposure to environmental pollutants.

People who have cirrhosis sometimes do not have symptoms until damage in the liver is severe. Symptoms and complications of cirrhosis include abdominal discomfort or pain, bleeding and bruising easily, nausea and vomiting, itching, loss of appetite, redness of the palms, weakness, hair and weight loss, and yellowing of the skin or jaundice.

Diagnosis of cirrhosis can be suggested by the person’s medical history, blood tests, liver biopsy, physical examination, and image scanning—computed tomography (CT) scan, magnetic resonance imaging (MRI), or ultrasound scan.

Treatment of cirrhosis prevent severe damage and complications to the liver. Liver transplant is an important option to treat patients with advanced cirrhosis.

Peptic Ulcer

Peptic ulcer is a painful sore on the linings of the stomach or duodenum. This may be caused by the regular use of painkillers called nonsteroidal anti-inflammatory drugs (NSAIDs) like aspirin, ibuprofen, and naproxen. Smoking and drinking alcohol may also cause ulcer. In addition, ulcer may be caused by an infection of the bacterium Helicobacter pyroli.

Figure 13.18Scarringoftheliverwithcirrhosis

liver

Figure 13.19Ulcersintheliningsofthestomachandduodenum

ulcerintheduodenum

ulcerinthestomach

Know More!

Gastroenterologyisthebranchofmedicinefocusedonstudyingandtreatingdigestivesystemdisorders.Physicianspracticingthisspecialtyarecalledgastroenterologists.


The most common symptoms of peptic ulcer are burning pain in the middle or upper stomach between meals or at night, gas pain, bloating of the stomach, heart burn, nausea, and vomiting.

In order to diagnose peptic ulcer, medical experts may recommend several diagnostic examinations and procedures such as Helicobacter pyroli test, upper gastrointestinal endoscopy, and X-ray. Upper gastrointestinal endoscopy involves inserting an endoscope—a small, flexible tube equipped with a camera—down the throat, into the esophagus, stomach, and small intestine to look for ulcers. This procedure is done to patients with severe symptoms of ulcers.

Figure 13.20Uppergastrointestinalendoscopy

pharynx

monitor

esophagus

endoscope

duodenum

stomach

There are several ways in which peptic ulcer may be prevented or treated. These include having a healthy lifestyle, taking medication, and undergoing surgery.

Gallstones

Gallstones may develop when cholesterol and other substances in the bile form crystals that become hard stones in the gallbladder or bile duct. Gallstones can be smaller than a grain of sand or as large as a golf ball. Several factors may contribute to the formation of gallstones in the gallbladder. These include diet, body weight, and genetics.

Generally, people with gallstones have no symptoms. However, when gallstones move out of the gallbladder into the bile duct where they can get stuck, symptoms

Figure 13.21Gallstonesinthegallbladderandbileduct

gallbladder

gallstonesinthebileductpancreas

gallstonesinthegallbladder

duodenum


begin to manifest. Symptoms may include severe upper abdominal pain, which may spread to the back and shoulder and last for several hours; nausea and vomiting; and high fever.

Gallstones are commonly diagnosed through blood and urine examinations, MRI scan, and ultrasound scan. Treatment includes medications to dissolve gallstones and surgery to remove the gallbladder (cholecystectomy).

The chance of developing gallstones may be reduced by having a healthy diet and maintaining an ideal body weight for a particular age and height.

Constipation

A person suffering from constipation has less than three bowel movements a week and stools that are dry, hard, and difficult or painful to pass. Constipation is commonly caused by not drinking enough fluids; not eating enough fiber, such as cereals, fruits, and vegetables; a sudden change in ones lifestyle, such as a change in eating habits, not having regular exercise, and travelling; resisting the urge to pass stool; side effects of certain medication; overuse of laxatives; and anxiety or depression, and stress.

The most common symptoms of constipation are irregular bowel movement, difficult and/or painful bowel movement, swollen abdomen and/or abdominal pain, and vomiting.

Diagnosis is commonly based on ones medical history and the symptoms that one is having. The following procedures may also help diagnose severe complications caused by constipation.

•physical examination of the rectum; •blood and/or stool examination; and• lower gastrointestinal endoscopy.

Apersonsufferingfromconstipationhasstoolsthataredry,hard,anddifficulttopass.

Figure 13.22Lowergastrointestinalendoscopy

endoscope

colon


An oral laxative—medication that help empty the bowels—is commonly prescribed to treat constipation. However, to prevent constipation one should drink at least eight glasses of water a day, eat lots of fiber, exercise regularly, and go to the bathroom when there is an urge to have bowel movement.

Let’s Review

1 What are the symptoms of cirrhosis of the liver?2 What kind of drug causes peptic ulcer?3 How do gallstones develop?4 What causes constipation?5 How can digestive disorders be avoided?


13.4 Proper Nutrition and Overall Wellness

Nowadays, many people enjoy the convenience of take-away foods, low fiber diets, and foods with high sugar and preservatives. Due to unhealthy diet, many people experience symptoms of digestion disorders such as constipation, diarrhea, indigestion, and others. These may not be serious disorders but these may lead to something severe if disregarded.

It is important, as part of one's overall wellness, to keep the digestive system in optimum condition. The following recommendations can help boost digestive health:

1 Eat food rich in fiber.Fiber enhances proper bowel function, prevents constipation, and diverticulosis—a condition that develops when pouches form in the wall of the large intestine or colon. Fruits, vegetables, and whole grain food products contain more fiber than any other food group. These food also contain essential vitamins, minerals, and nutrients that enhance digestive health and help reduce the risk of cardiovascular disease and some cancers.

2 Drink enough water daily.Healthy digestion requires adequate water intake. The recommendation is to drink at least eight glasses of water daily. Water helps break down the food in the stomach, helps in dissolving nutrients, and prevents constipation. Also, water helps to keep the gastrointestinal tract clean and healthy.

3 Exercise at least thirty minutes a day.Cardiovascular exercise increases blood flow in the digestive organs and activates the muscles in the gastrointestinal tract to move digestive contents through the system. These help the organs work more efficiently and improve digestion. Common cardiovascular exercises include walking, running, swimming, cycling, or any activity that increases the heart rate.

Figure 13.23 Divertula form inthe colonor inotherpartsofthegastrointestinaltractwhenincreasedpressurepushesthewall of the colon outward atcertainweakpoints.

largeintestine(colon)

pouches(diverticula)

Joggingisagreatcardiovascularexercise.


4 Avoid smoking and excessive drinking of alcohol. Smoking can harm the digestive system, causing serious diseases such as, cirrhosis of the liver, colon cancer, gallstones, and peptic ulcers. Likewise, excessive alcohol intake can lead to cirrhosis of the liver. Also, it can inflame the lining of the stomach and cause symptoms of heartburn.

5 Practice good eating habits.Eating in a rush and in large portions will put the digestive system under stress. Eat slowly and chew each bite of the food well.

6 Limit eating sweets and fatty food.High-fat and high sugar diet can increase the risk for some kinds of cancer, diabetes, heart disease, and obesity. Examples of foods that are high in fat and sugar are cakes, chips, cookies, doughnuts, and fast food products. Eat meat that are low in fat such as chicken and lean cuts of pork. Consume non-fat dairy products and use vegetable oil instead of butter or margarine.

7 Avoid eating processed food products.Processed food products contain large amounts of saturated fats and preservatives, which prevent proper digestion. Examples of processed food products are canned foods, breakfast cereals, and processed meats such as ham, hotdogs, and sausages. These foods have less nutritional value.

8 Manage daily stress. Stress can cause direct negative effects on the digestive system and affects proper food digestion. Stress can slow down or speed up the movement of food through the digestive system, which can cause abdominal pain or loose bowel movement. The digestive muscles may exert less effort and digestive enzymes may be secreted in smaller amounts. Stress can worsen symptoms of digestive conditions such as bloating, constipation, and peptic ulcer. Caring for your emotional well-being is important for your physical well-being. Manage stress daily by doing relaxing activities.

Doingrelaxingactivitylikeyogacanhelpreducesdailystress.

Let’s Do This!


9 Take probiotics food and supplements.Probiotics are microorganisms, commonly bacteria, that are identical to the beneficial microorganisms found in human stomach. These good bacteria are available in food and supplements. They help reduce or prevent conditions that affect the gastrointestinal tract. Also, they regulate the amount of healthy bacteria in the digestive system and normalize bowel movements. Probiotic food and supplements include dark chocolate, fermented tea, kimchi, milk, miso soup, olives, pickles, soy milk, and yogurt.

Let’s Review

1 What are some advantages of maintaining a high fiber diet?

2 How many glasses of water should one drink every day?

3 What are probiotics?4 What food contain probiotics?

PurposePerform a simple meditation exercise to help reduce stress.

Materialssitting mat or chairwatch

What You Need To DoA Warm Up

1 Record your heart rate.2 Begin by sitting comfortably, balanced, and relaxed. Breathe easy

and from the abdomen. 3 Practice a few deep breaths with the group. 4 Rotate your head in easy, slow circles. Change direction and rotate

in slow, easy circles. 5 Look up by tilting your head way back. Look down by placing

your chin on your chest.


6 Drop your arms and hands to the side and shake them gently and easily.

7 Raise your feet off the floor and gently shake the knees. 8 Straighten your spine while meditating.

B Meditate 1 This exercise is done silently: Close your eyes for two minutes.

Once your eyes are closed, relax and clear your mind of any thought. Slowly, your mind will clear and relax.

2 Open your eyes. Sit straight up, relaxed, and balanced. 3 Repeat steps 1 to 2 twice.4 Record your heart rate and compare it to the heart rate before

meditation.5 Compare the result with those of your classmates.

Guide Questions1 What is your heart rate before the meditation? After the

meditation?2 Do you find it easy to relax your mind and clear it from any

thoughts?3 What is your feelings before the meditation? After the meditation?


Chap t er Summary

Key Ideas

1 The digestive system has important functions, which include the breaking down of food, the absorption of nutrients, and elimination of waste.

2 The main organs of the digestive system include the mouth, esophagus, pharynx, stomach, small intestine, large intestine, rectum, and anus. Also, the digestive system consists of accessory organs, which include the teeth, tongue, salivary glands, liver, gallbladder, and pancreas.

3 Digestion of food involves mechanical and chemical processes. Chewing, peristalsis, and the churning of the stomach carry out the mechanical process of digestion. The chemical process of digestion involves the action of enzymes on food substances.

4 Proper functioning of the digestive system may be affected by diet, disease, daily stress, and other factors.

5 Proper diet and healthful practices promote overall wellness of the human body.


Chap t er Summary

Concept Map

Accessory Organs

Large Intestine

Rectum

Anus

Small Intestine

Esophagus

Stomach

Mouth

Pancreas

Gallbladder

Liver

Teeth

Tongue

Salivary Glands

Absorption of nutrients

Elimination of waste materials

Breaking down of food

Digestive System

Chemical

Mechanicalcould be

functions for

is composed of

such as includes

found in the

Gastrointestinal Tract


Chap t er Tes t

I Multiple Choice Questions Choose the correct answer.

1 Which set includes only accessory digestive organs?A Salivary glands, small intestine,

pancreas, liverB Stomach, duodenum, pancreas,

gallbladderC Gallbladder, liver, pancreas,

salivary glandsD Liver, esophagus, gallbladder,

anus

2 Which digestive organ mechanically and chemically transforms bolus into chyme?A EsophagusB MouthC Small intestineD Stomach

3 What is the function of the villi in the small intestine?A To decrease the amount of

exposed surfaceB To facilitate enzyme retention

and actionC To increase the surface area for

absorption of nutrientsD To sweep particles across the

surface with wavelike actions

4 Which organ produces bile?A GallbladderB LiverC PancreasD Small intestine

5 Which is not a carbohydrase?A AmylaseB LactaseC MaltaseD Pepsin

6 Which form of food molecule cannot be used directly by body cells?A Amino acidsB Fatty acidsC FructoseD Polypeptides

7 What happens when food reaches the stomach?A No digestion occurs in the

stomach.B The food moves quickly into the

small intestine.C Gastric juices mix with the food

and stomach muscles squeeze it.D The food is completely digested

and is absorbed by tiny blood vessels in the walls of the stomach.


Chap t er Tes t

8 Digestion takes place in a long tube-like canal called gastrointestinal tract. Food travels through the various organs of the gastrointestinal tract in the following order:A Mouth, esophagus, stomach,

small intestine, large intestine, and anus

B Mouth, esophagus, stomach, large intestine, small intestine, and anus

C Mouth, stomach, esophagus, small intestine, large intestine, and anus

D Mouth, stomach, small intestine, esophagus, large intestine, and anus

9 Which of the following best describes the role of the esophagus in digestion?A Serves a minor role in the

chemical digestion of fatsB Digestive enzymes are secreted

as food passes from the C esophagus to the stomachD Mucus is secreted to protect

the esophagus from the gastric enzymes

E Connects the mouth to the stomach and has no function in chemical digestion

10 Which combination of organs is chemical digestion of proteins confined?A Mouth, stomach, and small

intestineB Stomach and small intestineC Stomach, esophagus, and small

intestineD Mouth and large intestine


Chap t er Tes t

II Structured Questions

1 Name the parts of the human digestive system.

2 Draw an arrow pointing to the organs where mechanical digestion occurs. 3 Place the symbols below on the organs

where chemical digestion of the following substances occurs:

for digestion of protein for digestion of carbohydrates for digestions of lipids

3 Name the organ where absorption of nutrients occurs.

4 Name the organ where most water is absorbed.

5 Why is absorption of water important?Humandigestivesystem

Enrichment

1 Compose a short story, narrating the journey of food in the human digestive system. Also, create a map following the movement of food in the gastrointestinal tract.

2 Imagine the digestive system as an amusement park. Design a brochure promoting the park to visitors by providing relevant information about each location or attraction in the park. Use your creativity to describe or explain exciting events in each location in the park.

3 Compose a rap song describing the process of digestion from the mastication of food in the mouth to the absorption of nutrients in the small intestines and the elimination of waste via the anus.

4 Interview the school physician or nurse regarding the most common digestive disorder experienced by students in the school. Find out the common causes, symptoms, and cure of the disorder. Solicit your physicians recommendation on how the disorder may be prevented, and make a poster about it. Display the poster in five different locations in the school.

5 Watch the documentary film, “Super Size Me” and write a single-page reflection paper on fast food consumption and how it affects proper nutrition and general wellness of individuals.


Making Connections

Technology

Exercise and diet alone often fail to treat people with obesity. Another option is available for those who are having serious health problems caused by obesity—the weight loss surgery, also called bariatric surgery. Bariatric surgery includes variety of procedures performed on people who are suffering from obesity. The basic principle of bariatric surgery is to control food intake and reduce the absorption of food nutrients in the stomach and intestines. This can be achieved by reducing the size of the stomach using a gastric band, removing a portion of the stomach, or by resecting and re-routing the small intestines to a small stomach pouch.

Bariatric surgery alters the usual digestion process—the food is not broken down and absorbed the usual way—hence, the regulated amount of nutrients and calories absorbed enables patients to lose weight and ultimately decrease the risk of obesity-related health disorders.

Weight loss surgery may be performed using an “open” approach, which involves cutting open the abdomen or by means of laparoscopy, in which surgical instruments are guided into the abdomen through small half-inch incisions. Today, most bariatric surgery is laparoscopic since it requires less extensive cuts, causes minimal tissue damage, leads to fewer post-operative complications and allows for earlier hospital discharge.

Bariatricsurgeryprocedures:(a)verticalbandedgastroplasty(b)laparoscopicadjustablegastricband(c)Roux-enYgastricbypass

gastricband

(a) (b) (c)


Making Connections

Health

Eating disorders are conditions characterized by abnormal eating habits, which may involve either insufficient or excessive food intake causing harm to an individual’s physical and mental health. Bulimia nervosa and anorexia nervosa are the most common forms of eating disorder.

Bulimia nervosa is an eating disorder characterized by recurrent and frequent episodes of eating, usually large amounts of food (binge eating) followed by behaviors such as purging (self-induced vomiting and excessive use of laxatives, diuretics, and diet pills), over exercising, and fasting. Usually, bulimic behavior is done secretly. It is often accompanied by feelings of disgust or shame.

People with anorexia nervosa, on the other hand, have an intense fear of gaining weight. They severely limit the amount of food they eat and can become dangerously thin. They perceive themselves fat though they are already very thin. Untreated anorexia can lead to starvation and serious health problems such as bone thinning, kidney damage, and heart problems. This eating disorder is life threatening.

According to experts, occurrence of eating disorders may be caused by several contributing factors. It may be due to a mix of family history, social, interpersonal, and psychological disorders. People with these disorders have coexisting illnesses such as depression, anxiety, obsessive-compulsive disorder, post-traumatic stress disorder, and sometimes with substance abuse problems.

Apersonsufferingfromeatingdisorder

preface - sapgrp.comsapgrp.com/shop/images/pdf/4418713_preface.pdf · discussed in the chapter....

Documents