my digestive

8/9/2019 My Digestive

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DIGESTIVESYSTEM and

BODY

METABOLISM

Alyssa Ashley R.


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y y

THE DIGESTIVE SYSTEM

AND BODY METABOLISM Digestion

Breakdown of ingested food

Absorption

Passage of nutrients into theblood

Metabolism

Production of cellular energy

(ATP)


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ORGANS OF THE

DIGESTIVE SYSTEM Two main groups

1. Alimentary canal

- continuous coiled

hollow tube

2. Accessory digestive organs


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CANAL

Mouth Pharynx

Esophagus Stomach

Small intestine Large intestine

Anus


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ANATOMY

Lips (labia) protect the anterioropening

Cheeks form the lateral walls

Hard palate forms the anteriorroof

Soft palate forms the posteriorroof

Uvula fleshy projection of the

soft palate


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ANATOMY


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ANATOMY

Vestibule space between lipsexternally and teeth and gumsinternally

Oral cavity area contained bythe teeth

Tongue attached at hyoid andstyloid processes of the skull,

and by the lingual frenulum


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ANATOMY


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ANATOMY Tonsils

Palatine

tonsil

Lingualtonsil


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MOUTH Mastication (chewing) of food

Mixing masticated food with

saliva Initiation of swallowing by the

tongue Allowing for the sense of taste


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PHARYNX ANATOMY

Nasopharynx not part of the digestive system

Oropharynx posterior to oralcavity

Laryngopharynx below the

oropharynx and connected tothe esophagus


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PHARYNXANATOMY


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PHARYNX FUNCTIONS

Serves as a passageway for air andfood

Food is propelled to the esophagus by

two muscle layersLongitudinal inner layer

Circular outer layer

Food movement is by alternating

contractions of the muscle layers

(peristalsis)


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ESOPHAGUS

Runs from pharynx tostomach through the

diaphragm Conducts food by peristalsis

(slow rhythmic squeezing)

Passageway for food only

(respiratory system branches


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LAYERS OF ALIMENTARY

CANAL ORGANS1. Mucosa

Innermost layer

Moist membrane

Surface epithelium

Small amount of connectivetissue (lamina propria)

Small smooth muscle layer


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LAYERS OF ALIMENTARY

CANAL ORGANS2. Submucosa

Just beneath the mucosaSoft connective tissue with

blood vessels, nerve endings,

and lymphatics


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ORGANS

3. Muscularis externa smoothmuscle

Inner circular layer

Outer longitudinal layer4. Serosa

Outermost layer visceralperitoneum

Layer of serous fluid-producing

cells


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STOMACH ANATOMY

Located on the left side ofthe abdominal cavity

Food enters at thecardioesophageal sphincter


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STOMACH ANATOMY

Regions of the stomachCardiac region near the heart

Fundus

Body

Pylorus funnel-shaped terminal

end

Food empties into the small

intestine at the pyloric sphincter


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STOMACH ANATOMY

Rugae internal folds of themucosa

External regions

Lesser curvature

Greater curvature


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STOMACH ANATOMY

Layers of peritoneum attached tothe stomach

Lesser omentum attaches the

liver to the lesser curvatureGreater omentum attaches the

greater curvature to the posteriorbody wall

Contains fat to insulate, cushion,

and protect abdominal organs


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STOMACH ANATOMY


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STOMACH FUNCTIONS

Acts as a storage tank forfood

Site of food breakdown Chemical breakdown of

protein begins Delivers chyme (processed

food) to the small intestine


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(STOMACH) Simple columnar epitheliumMucous neck cells produce a

sticky alkaline mucus

Gastric glands secrete gastricjuice

Chief cells produce protein-

digesting enzymes(pepsinogens)

Parietal cells produce

hydrochloric acid


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STRUCTURE

Gastric pits formed byfolded mucosa

Glands and specializedcells are in the gastric gland

region


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STRUCTURE


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SMALL INTESTINE

The bodys major digestive organ Site of nutrient absorption into the

blood

Muscular tube extending from the

pyloric sphincter to the ileocecal

valve Suspended from the posterior

abdominal wall by the mesentery


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SUBDIVISIONSDOGS JUST ITCH! DuodenumAttached to the stomachCurves around the head of the

pancreas JejunumAttaches anteriorly to the

duodenum IleumExtends from jejunum to large

intestine


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CHEMICAL DIGESTION

(SMALL INSTESTINE) Source of enzymes that are

mixed with chymeIntestinal cells

Pancreas Bile enters from the gall

bladder


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CHEMICAL DIGESTION


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VILLI OF THE SMALL

INTESTINE Fingerlike structures formed

by the mucosa Give the small intestine

more surface area


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INTESTINE


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MICROVILLI OF THE

SMALL INTESTINE Small

projections ofthe plasma

membrane

Found on

absorptive


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IN ABSORPTION OF

NUTRIENTS Absorptivecells

Bloodcapillaries

Lacteals(specialized

lymphatic


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FOLDS OF THE SMALL

INTESTINE Called circular folds Deep folds of the mucosa and

submucosa Do not disappear when filled

with food

The submucosa has Peyerspatches (collections of

lymphatic tissue)


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INTESTINE Enzymes from the brush border

Break double sugars into simplesugars

Complete some protein digestion

Pancreatic enzymes play themajor digestive function

Help complete digestion ofstarch (pancreatic amylase)

Carry out about half of all protein

digestion (trypsin, etc.)


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INTESTINE

Pancreatic enzymes play themajor digestive function

(continued)

Responsible for fat digestion(lipase)

Digest nucleic acids(nucleases)

Alkaline content neutralizes


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INTESTINE Water is absorbed along the length of

the small intestine

End products of digestion

Most substances are absorbed byactive transport through cellmembranes

Lipids are absorbed by diffusion Substances are transported to theliver by the hepatic portal vein or

lymph


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INTESTINE

Peristalsis is the major meansof moving food

Segmental movements

Mix chyme with digestive

juices

Aid in propelling food


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LARGE INTESTINE

Larger in diameter, butshorter than the small

intestine Frames the internal

abdomen


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LARGE INTESTINE


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FUNCTIONS Absorption of water Eliminates indigestible food

from the body as feces Does not participate in

digestion of food

Goblet cells produce mucus to

act as a lubricant


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STRUCTURES

Cecum saclike first part of thelarge intestine

Appendix

Accumulation of lymphatic tissue

that sometimes becomes

inflamed (appendicitis)Hangs from the cecum


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STRUCTURES

ColonAscending Colon

Transverse ColonDescending Colon

S-shaped sigmoidal Colon

Rectum

Anus external body opening


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ABSORPTION IN THE LARGE

INTESTINE No digestive enzymes areproduced

Resident bacteria digest remainingnutrientsProduce some vitamin K and B

Release gases Water and vitamins K and B areabsorbed

Remaining materials are


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INTESTINE Sluggish peristalsis

Mass movementsSlow, powerful movementsOccur three to four times per day

Presence of feces in the rectumcauses a defecation reflexInternal anal sphincter is relaxed

Defecation occurs withrelaxation of the voluntary(external) anal sphincter


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ORGANS

Salivary glands Teeth

Pancreas Liver

Gall bladder


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SALIVA

Mixture of mucus and serousfluids

Helps to form a food bolus Contains salivary amylase to

begin starch digestion

Dissolves chemicals so they

can be tasted


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TEETH

The role is to masticate (chew)food

Humans have two sets of teethDeciduous (baby or milk)

teeth

20 teeth are fully formed by

age two


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TEETH

Permanent teethReplace deciduous teeth

beginning between theages of 6 to 12

A full set is 32 teeth, butsome people do not have

wisdom teeth


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CLASSIFICATION Incisors Canines

Premolars

Molars


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CLASSIFICATION


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TOOTH REGIONS Crown exposed part

Outer enamelDentinPulp cavity

NeckRegion in contact with the gumConnects crown to root

RootPeriodontal membrane attached tothe bone

Root canal carrying blood vessels

and nerves


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TOOTH REGIONS


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PANCREAS Produces a wide spectrum of

digestive enzymes that breakdown all categories of food

Enzymes are secreted into theduodenum

Alkaline fluid introduced withenzymes neutralizes acidic chyme

Endocrine products of pancreas

Insulin

Glucagons


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LIVER Largest gland in the body

Located on the right side of thebody under the diaphragm

Consists of four lobessuspended from the diaphragmand abdominal wall by the

falciform ligament Connected to the gall bladder

via the common hepatic duct


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BILE Produced by cells in the liver

Composition

Bile salts

Bile pigment (mostly bilirubinfrom the breakdown ofhemoglobin)

CholesterolPhospholipids

Electrolytes


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METABOLISM

Several roles in digestion Detoxifies drugs and alcohol

Degrades hormones

Produce cholesterol, bloodproteins (albumin and clotting

proteins) Plays a central role in

metabolism

GALLBLADDER


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GALLBLADDER

Sac found in hollow fossa ofliver

Stores bile from the liver by

way of the cystic duct

Bile is introduced into the

duodenum in the presence offatty food

Gallstones can cause

PROCESSES OF


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PROCESSES OF

DIGESTIVE SYSTEM Ingestion getting food into themouth

Propulsion moving foods fromone region of the digestive systemto another

Peristalsis alternating waves ofcontraction

Segmentation moving materials

back and forth to aid in mixing

PROCESSES OF


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PROCESSES OF

DIGESTIVE SYSTEM

PROCESSES OF


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PROCESSES OF

DIGESTIVE SYSTEM Mechanical digestion

Mixing of food in the mouth bythe tongue

Churning of food in the

stomachSegmentation in the small

intestine

PROCESSES OF


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PROCESSES OF

DIGESTIVE SYSTEM Chemical DigestionEnzymes break down food

molecules into their building blocks

Each major food group usesdifferent enzymesCarbohydrates are broken to

simple sugarsProteins are broken to aminoacids

Fats are broken to fatty acids and

PROCESSES OF


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PROCESSES OF

DIGESTIVE SYSTEM AbsorptionEnd products of digestion are

absorbed in the blood or lymphFood must enter mucosal cellsand then into blood or lymphcapillaries

Defecation

Elimination of indigestible

substances as feces


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CONTROL OF DIGESTIVE


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ACTIVITY Mostly controlled by reflexesvia the parasympathetic

division

Chemical and mechanical

receptors are located in organwalls that trigger reflexes



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ACTIVITY Stimuli include:Stretch of the organ

pH of the contentsPresence of breakdown products

Reflexes include:

Activation or inhibition ofglandular secretions

Smooth muscle activity

NUTRITION


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NUTRITION Nutrient substance used by the

body for growth, maintenance, andrepair Categories of nutrients

Carbohydrates: simple sugars,starches, fiberLipids: triglycerides, phospholipids,

fatty acids

Proteins: amino acidsVitaminsMineral

BODY ENERGY BALANCE


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BODY ENERGY BALANCE Energy intake = total energy

output (heat + work + energystorage)

Energy intake is liberatedduring food oxidation

Energy output

Heat is usually about 60%Storage energy is in theform of fat or glycogen

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