1. Nutrition and Digestion
Chapter 21
Nutrition and Digestion

2. Humpback whale
Can eat up to 2 tons of krill and fish in a day which allows them to harvest much more energy than they need
In cold weather they migrate to breed in warmer waters
They do not need to eat or hardly eat during these 4 months

3. Ways of ingesting food for animals

4. Ways of ingesting food for animals continued
Suspension feeders: extract food from particles in fluid/ examples: humpback whale, clams, oysters
Substrate feeders: live in or on their food source and eat their way through it/ example: earthworm
Fluid feeders: obtain food by sucking nutient-rich fluids from a living host/ ex. mosquitoes
Bulk feeders: ingest their food in large pieces/ example: grey heron

5. Food processing ingestion: the act of eating
Digestion: breaking down food into smaller pieces (physical and chemical)
Absorption: the take up of the products of digestion
Elimination: undigested materials exit the digestive tract

6. Specialized compartments of digestion
Gastrovascular cavity: just a mouth
Alimentary canal: mouth and an anus
Pharynx: throat
Esophagus: tube that channels food
Crop: softens and stores food
Stomach: churn and grind food
Gizzard: churn and grind food
Intestine: chemical digestion and nutrient absorption
Anus: expels undigested food

7. Human digestion: the oral cavity
Saliva is released before a bite is even taken
Salivary glands release more than a liter of saliva a day
A glycoprotein protects the soft lining of the mouth and lubricates food for easier swallowing
Saliva contains salivary amylase which begins to breakdown the carbs the food
Buffers neutralize the food to prevent tooth decay
Mechanical and chemical digestion occur here
Tongue: muscular organ that is covered in taste buds and pushes the bolus of food to the back of the oral cavity and into the pharynx

8. Oral cavity Blade like incisors (2): Used for biting
Single pointed canine: used to rip apart food
Premolars (2): grind and crush food
Molars (3): grind and crush food

9. Food path continued
Oral cavitybolus to the back of the oral cavity bolus down the pharynx down the esophagus by way of peristalsis

10. Stomach
Secretes gastric juices made up of mucous, enzymes and strong acids/ pH of 2/ breaks apart the particles of food
Pepsin begins the chem. Digestion of proteins/ breaks down large polypeptides into smaller polypeptides
The stomach takes about 2-6 hours to empty after a meal

11. Small Intestine The rest of chemical digestion occurs here
More than 6 m in length
Sources of digestive enzymes in the sm intestine: pancreas, liver, gallbladder
First 25 cm of sm intestine is the duodemnum

12. Digestion in the small intestine
Starch (pancreatic amylase)maltose (maltase)monosaccharides
Polypeptides (trypsin, chymotrypsin) smaller polypeptides (aminopeptidase, carboxypeptidase, dipeptidase) amino acids
DNA and RNA (nucleases)nucleotides (other enzymes)N-bases, sugars and phosphates
Fat (bile salts)fat droplets (lipase)fatty acids and glycerol

13. Absorption in the small intestine
Use microvilli which are finger-like projections that increase surface area for absorption
Some materials are absorbed through simple diffusion

14. Liver
Hepatic portal vein: the large vessel that transport nutrients absorbed from the small intestine right into the liver
Regulates the amount of glucose released into the blood
Plays a large role in the body’s metabolism
Aids in the digestion of fats
Detoxifies and modifies substances

15. Large Intestine AKA colon Reabsorbs water from undigested foods
As water is absorbed the remaining undigested materials remains a solid (feces)
Feces is eliminated through the rectum