32.1 Nutrients and Homeostasis
The six types of nutrients are water, carbohydrates, proteins, fats, minerals, and vitamins.
• Water makes up 55% to 60% of your body. – involved in nearly every cell and body process– need 2 liters (8 cups) a day to replace fluid lost
32.1 Nutrients and Homeostasis
• Carbohydrates are the main source of energy for the body.– simple and complex carbohydrates supply glucose– fiber from plant foods helps elimination
Simple and Complex Carbohydrates
32.1 Nutrients and Homeostasis
• Proteins are necessary for growth and repair of the body’s cells.– body makes 12 out of 20 amino
acids – other eight essential amino acids
come from food• Fats provide energy and key
building components.– fats are saturated and
unsaturated – essential fatty acids come from
food
Proteins and Fats
32.1 Nutrients and Homeostasis
• Minerals are inorganic materials.– help to build or repair tissues– replenished by eating variety of foods
32.1 Nutrients and Homeostasis
• Vitamins are organic molecules that work with enzymes.– vitamins are fat-soluble and water-soluble – regulate cell functions, growth, development – replenished by eating variety of foods
32.1 Nutrients and Homeostasis
Meeting nutritional needs supports good health.
• During puberty, you require more nutrients and Calories.– One Calorie equals one
kilocalorie, or 1000 calories. – 1g of protein or carbohydrate
equals 4 Calories. – 1g of fat equals 9 Calories.
32.1 Nutrients and Homeostasis
• A balanced diet of whole foods provides the best nutrients and Calories.
• Food and physical activity also need to be balanced. MALES
FEMALES
32.1 Nutrients and Homeostasis
KEY CONCEPTThe digestive system breaks down food into simpler molecules.
32.1 Nutrients and Homeostasis
mouth
esophagus
liver
gallbladder
large intestine
small intestine
rectum/anus
Several digestive organs work together to break down food.
• The digestive system breaks down food into energy cells can use.
• After digestion is complete, nutrients are absorbed and transported to all cells.
• Undigested materials are eliminated as liquid and solid wastes.
32.1 Nutrients and Homeostasis
Digestion begins in the mouth and continues in the stomach.
• Mechanical and chemical digestion break down food. • Peristalsis moves food through the organs.
esophagus
muscles contract
muscles relax
food
stomach
32.1 Nutrients and Homeostasis
• Digestion of carbohydrates begins in the mouth.
• Digestion of proteins occurs in the stomach. • Digestion of fats and sugars occur in the
small intestine.
32.1 Nutrients and Homeostasis
Digestion is completed in part of the small intestine.
• Most digestion takes place in the duodenum. • The pancreas, liver, and gallbladder aid in digestion.
– pancreas helps digest fat and protein – bile from the liver/gallbladder helps digest fats
liver
bile
bile
gallbladder
duodenum
pancreas
enzymes
chyme
stomach
32.1 Nutrients and Homeostasis
KEY CONCEPTNutrients are absorbed and solid wastes eliminated after digestion.
32.1 Nutrients and Homeostasis
Most absorption of nutrients occurs in the small intestine.
• Three structures in the small intestine help absorb nutrients. – folded lining: adds surface area, slows food– villi: absorb nutrients– microvilli: cover villi, absorb nutrients
32.1 Nutrients and Homeostasis
• Duodenum, jejunum, and ileum absorb different nutrients.
• Nutrients enter the circulatory or lymphatic systems. • Liver stores excess glucose for future use.
liver
small intestine
32.1 Nutrients and Homeostasis
Water is absorbed and solid wastes are eliminated from the large intestine.
• The colon helps to maintain the body’s fluid balance.• Undigested material forms the solid feces.
– stored in rectum – eliminated through anus
large intestine
rectum/anus
32.1 Nutrients and Homeostasis
• The large intestine contains many bacteria.– some synthesize important vitamins– Some, like E. coli, can cause illness
32.1 Nutrients and Homeostasis
KEY CONCEPTThe excretory system removes wastes and helps maintain homeostasis.
32.1 Nutrients and Homeostasis
The excretory system eliminates nonsolid wastes from the body.
• Nonsolid wastes are eliminated through lungs, skin, and kidneys.
• Lungs exhale carbon dioxide and water vapor.
• Sweat glands in skin release excess water and salts.
• Kidneys filter and clean the blood to produce urine.
skin
lungs
kidneys
ureters
urinary bladderurethra
32.1 Nutrients and Homeostasis
The kidneys help to maintain homeostasis by filtering the blood.
• Kidneys are a pair of bean-shaped organs.– two layers: medulla and
cortex– filtering units called
nephrons – renal artery and renal
vein
cortex
medulla
renal artery
renal vein
ureter
(to bladder)
32.1 Nutrients and Homeostasis
• Kidneys have three basic functions in maintaining homeostasis.– remove waste from blood– help to maintain electrolyte, pH, and fluid balances – release key hormones
32.1 Nutrients and Homeostasis
Nephrons clean the blood and produce urine.
• Nephrons are the filtering units in the kidneys.• They clean and rebalance the blood to produce urine.
from body
to body
to body
from other nephrons
loop of Henle
32.1 Nutrients and Homeostasis
• Nephrons clean the blood in a three-step process.• The first step is filtration of the blood.
FILTRATION
Water,electrolytes,aminoacids,glucose,urea, and other small molecules diffuse out of the blood,creating the filtrate.
1
Glomerulus
Bowman’s capsule
32.1 Nutrients and Homeostasis
• The first step is filtration of the blood. • The second step is reabsorption of materials.• The third step is excretion of materials.
from body
to body
collecting duct
from other nephrons
loop of Henle
REABSORPTION
As the filtrate enters the rest of the tubule ,most of the materials are reabsorbed into the blood.Materials not reabsorbed make up the urine,which flows into the loop of Henle.
2
EXCRETION
In the loop of Henle,water can be reabsorbed one final time to reduce the volume of urine.The remaining urine flows into a collecting duct that leads to the ureter.
3
32.1 Nutrients and Homeostasis
Injury and disease can damage kidney functions.
• A kidney transplant can replaced damaged kidney. – recipient and donor tissue must match – drugs prevent tissue rejection
The daughter and son in this photo donated a kidney and liver tissue to their mother.