BIO 181 Animal Nutrition/Digestion

suspension feeders

filter/sift food particles from water; ex. clams, oysters, baleen whales

substrate feeders

live in the food source and eat as the burrow; ex. maggots, leaf miners

deposit feeders

type of substrate feeders that eat their way through dirt, picking up decayed organic material; ex. earthworms

fluid feeders

suck nutrient-rich fluids; from host, ex. mosquitos, aphids; from flowers, ex. bees, wasps, hummingbirds

bulk feeders

eat large pieces of food using adaptations such as claws, teeth, pincers, fangs, etc.

four stages of food processing

ingestion

digestion

absorption

elimination

what is absorption?

small nutrient molecules enter body cells

beneficial bacteria in the human digestive tract

- Escherichia coli, Acidophilus spp., and others

- produce methane, hydrogen sulfide, and other gases as they ferment their food

- secrete beneficial chemicals such as vitamin K, biotin, some amino acids; our main source of these nutrients

ruminants

organisms that have stomachs with 4 compartments (all herbivores)

rumen

processes swallowed plant material; contains bacteria, protists and chytrids which help digest tough plant material

reticulum

also houses microorganisms to contrive breakdown; where regurgitation occurs; after regurgitation, it chews its cud and re-swallows

omasum

water absorption

abomasum

secretes digestive enzymes to finalize stomach digestion

tongue

shapes food into a bolus

salivary glands

produce fluids that keep the mouth lubricated and prevents cavities

- parotid gland: salivary amylase

- sublingual gland: mucin (lubrication)

- submandibular gland: salivary amylase and mucin

mouth

- mastication (chewing) - mechanical digestion

- maceration (further breakdown of food by the mouth/teeth) - mechanical digestion

- carboydrate digestion starts

swallowing

bolus of food - masticated and minced with salivary fluids

pharynx - throat region; opens to esophagus and trachea

epiglottis - flap that can cover the trachea

larynx - moves up and tips the epiglottis

glottis - top of the trachea

swallowing is voluntary

peristalsis (action after swallowing) is involuntary

stomach opening is called

cardiac orifice (sphincter)

how much food can the stomach hold

2 liters (stretches)

what kinds of muscles does the stomach have?

longitudinal

circular/transverse

oblique

what mechanical digestion occurs in the stomach?

churning

the open area of the stomach is called

the lumen

what is rugae?

folds of epithelial tissue to increase surface area

what do mucus cells do?

secrete mucus that lubricates and protects cells of the stomach from acid

what do chief cells do?

secrete pepsinogen (inactive form of pepsin)

what is pepsin?

protease which digests protein

________ digestion starts in the stomach

protein

what do parietal cells do?

secrete HCl (activates pepsinogen to pepsin, neutralizes bad bacteria, helps breakdown cellulose material)

Helicobacter pylori

bacteria that eats at mucous secretions in stomach wall

how long does it take to clear a meal from the stomach? in what order?

2-6 hrs; carbs, proteins, fats

____% absorption of ______, absorption of ________, and some _______ takes place in the stomach

10; water; alcohol; drugs

what is acid chyme?

predigested material that goes into the small intestine

what are the 3 parts of the small intestine?

duodenum, jejunum, ileum

what occurs at each part of the small intestine?

duodenum - digestion

jejunum - absorption

ileum - absorption

what are the accessory organs for intestinal digestion in the duodenum?

liver, gallbladder, pancreas

what does the liver do?

produces bile for fat digestion

what does the gallbladder do?

stores bile until needed

pancreas secretions

bicarbonate - neutralizes acid chyme

pancreatic amylase - continues carb breakdown

proteases - breakdown proteins further

lipase - fat breakdown (starts and ends; w/ help of bile)

what proteases does the pancreas secrete?

chymotrypsinogn (inactive); chymotrypsin (active)

trypsinogen (inactive)

incomplete vs complete digestion

- incomplete (hydra) - only one opening for ingesting and excreting; cavity is lined with endothelial cells which secrete digestive enzymes to help the organism process its food (usually small crustaceans like brine shrimp)

- complete (earthworms, grasshoppers, birds) - two openings, one for ingesting and one for excreting; organs help break down food

digestive tract of herbivores vs. carnivores

- herbivore cecum is much larger than carnivore cecum

- herbivore intestinal length is usually longer

coprophagia

voluntarily ingesting its own feces; to acquire as many nutrients as possible from plant material; ex. rabbits

insectivore

type of carnivore (insect-eating organism)

frugivore

type of herbivore (fruit-eating organism)

three basic nutrients

carbohydrates

proteins

fats (lipids)

carbohydrates

monosaccharides (one sugar); glucose

polysaccharides (many sugars); starch, glycogen, cellulose

carbohydrate primary functions

major fuel molecules that provide the raw "carbon skeletons" used in the synthesis of important molecules

protein primary function

mostly used for structure or specific functions such as enzymatic reactions and regulation

difference between incomplete and complete protein sources (plant and animal)

incomplete - does not contain all the essential amino acids (mostly plants)

complete - does contain all the essential amino acids (mostly meat)

difference between fat-soluble and water-soluble vitamins

Water-soluble: dissolve in water (ex. B Vitamins, Vitamin C, Biotin)

Fat-soluble: do not dissolve in water; more easily absorbed when they are eaten with fat (ex. Vitamin A, D, E, K)

what are minerals?

simple inorganic nutrients found in food that are used by the body (like calcium, phosphorus, etc.)

functions of water

essential to life:

- helps in the transport of nutrients and waste by blood

- keeps cells from shriveling (maintains cell turgidity)

- cushions and lubricates joints

- regulates body temperature due to its high specific heat, high thermal conductivity, and capability for evaporation

malnorishment

occurs when one or more essential nutrients are missing; can have enough calories, but be malnourished if you are missing essential components of your diet

Kwashiorkor

protein deficiency; leads to 'edema' (accumulation of fluids in tissue); common swollen areas - feet and legs; distended stomach not uncommon

children w/ kwashiorkor may not necessarily lose weight, and instead may appear fat/swollen despite being malnourished

Marasmus

lack protein calories, and can develop earlier (before 6 months old) than kwashiorkor; marasmus can cause thinness, but not edema: type of malnourishment

ED: anorexia

maintaining a body weight well under that of the normal weight for their age and height; incredibly high amount of fear of gaining weight even while underweight

ED: bulimia

frequently eating large amounts of food, feeling not in control of this behavior, and then frequently trying to "fix" it by self-induced vomiting, laxatives or diuretic abuse, fasting, etc.; people w/ bulimia are obsessively concerned with body weight/shape

ED: binge eating disorder

regularly eating large amounts of food in short periods of time and feeling like you are not in control of your eating actions, leading to feeling ashamed or disgusted by doing so; may also eat when not hungry or in secret

what is obesity and how does it happen?

occurs when there is an excessively high amount of body fat or adipose tissue in relation to lean body mass; affects nearly 1/3 of the adult American population

what role does genetics play in obesity (specifically leptin and ob gene)?

in some individuals, the gene that regulates leptin is defective and appetite is not properly suppressed. (image of genetically obese mouse w/ defective copy of the "ob" gene) "ob" gene codes for leptin

mild to morbid obesity

- mild obesity: weight is 20-40% over ideal weight as based on gender, body frame, and height, treated with diet

- moderate: in between (41-100% over), treated with either surgery or diet.

- morbid: greater than 100% over, treated with surgery

leptin

influence long term energy balance and inhibit hunger; an be useful with weight loss

PYY

secreted in the small intestine, it helps regulate and reduce appetite as well as inhibiting food intake; makes people feel full after eating

ghrelin

also thought to play a role in energy balance; stimulates appetite, causing increased food intake, and increased fat storage; a part in controlling the release of insulin

difference between insulin and glucagon in maintaining blood glucose levels

- blood sugar is too high, more insulin is secreted by the pancreas (insulin helps cells absorb glucose, lowering blood sugar)

- blood sugar drops, glucagon is released (also by the pancreas) to raise it; causes the liver to discharge stored glucose, leading to higher blood sugar

types of diabetes

Type I diabetes (insulin-dependent diabetes): requires insulin or other medication to be taken daily, often diagnosed in children/young adults (can be diagnosed at any age); those with a family history of this are at greater risk; chronic.

Type II diabetes: most common form; usually diagnosed in adults (although increasing in children/young adults); risk factors include obesity and physical inactivity; can develop when your body creates an "insulin resistance" and cannot fully use the insulin made, or when the pancreas steadily loses its ability to produce insulin

types of cholesterol and their roles

LDL - moves cholesterol from the liver to cells throughout the body

HDL - transports excess cholesterol back to the liver where it can be used to create bile salts

what happens when you have too much LDL?

higher risk of heart disease

how can fiber help control cholesterol levels?

becomes a gel-like substance that picks up bile salts, cholesterol, etc.

what is the normal range for total cholesterol in the blood?

target: less than 200mg/dL

what is peristalsis?

muscular contractions that move food along the tubular structures of the digestive tract, such as the esophagus and intestines

what is segmentation?

specific peristaltic movement in the intestines

chemical digestion

enzymatic secretions throughout the digestive tract

what happens to the esophageal sphincter before and when swallowing?

before - contracted

when - relaxed

what happens to the epiglottis before and during swallowing?

before - epiglottis up

when - epiglottis down

what are the epithelial cells in the stomach?

mucus cells, chief cells, parietal cells

villi and microvilli in the small intestine

villi - finger-like projections to increase surface area (jejunum and ileum)

microvilli - brush border, also increases surface area

capillary system in villi

once fatty acids cross the epithelium, they recoalesce and are too big to fit into the capillary bed, so they enter the lacteal

lacteal in small intestine

inside the villus and is part of the lymphatic system; eventually gets to the blood system

where does digestion of carbs, proteins and fats start?

carbs - mouth

proteins - stomach

fats - small intestine

where is digestion of carbs, proteins and fats completed?

small intestine

what does bile do to fat?

emulsifies it

how does bile make it easier for lipase to digest fat?

attach to fat globules to break them down and expose them to lipase; coats the fat globules

hydrophilic and hydrophobic ends

bile salts get into the small intestine via

bile duct

what is the mechanical action of the duodenum?

segmentation (peristalsis that occurs in various segments simultaneously

primary role of the large intestine

water absorption

what do peptidases (SI) do?

breakdown proteins into amino acids

what are the essential amino acids?

histidine

isoleucine

leucine

lysine

methionine

phenylalanine

threonine

tryptophan

valine

what common hepatic duct do?

carries bile to the gallbladder

what does the common bile duct do?

carries bile to small intestine

what does the pancreatic duct do?

carries enzymes and HCO3- to small intestine

_____% of all absorption happens in the jejunum and ileum

90

________ _______ and ________ ___________ cross the epithelial lining straight into the capillary bed

simple sugars; amino acids

food molecule movement in small intestine

from lumen --> through epithelial cells --> into capillaries and lacteals

what is the cecum?

a pouch that houses bacteria to finish breakdown of food materials

what is the ileocecal valve?

connects large intestine and ileum of small intestine

you find a skull while walking in the woods. it appears to have forward facing eyes, a large zygomatic arch, and overlapping molars. what sort of diet might this animal have?

carnivore because the teeth are suited for catching prey and shearing meat

what are the characteristics of the digestive system belonging to an animal like a wolf?

a short digestive tract because its food is relatively simple to digest

you have been fasting for the past twelve hours. in terms of insulin and glycogen what is currently happening in your liver?

glucagon levels are increasing resulting in the breakdown of glycogen

you have a friend who eats constantly but complains of always being hungry. what could be a possible cause for your friend's condition?

he does not produce enough leptin