what do all animals do?
must eat to provide energy & build new molecules (they need essential vitamins & minerals)
what are the 4 stages of processing food?
ingestion
digestion
absorption
elimination
what happens in ingestion?
act of eating
what happens in digestion?
breaking down of food into molecules small enough for the body to absorb
what happens in absorption?
take-up of products of digestion, usually by cells lining digestive tract
what happens in elimination?
removal of undigested materials out of digestive tract
what makes up the alimentary canal?
mouth, anus, specialized regions associated with one-way flow of food
define peristalsis
alternating waves of contraction & relaxation by smooth muscle
where does mechanical and chemical digestion begin?
in the mouth
what is the purpose of chewing?
cuts, smashes, and grinds food (easier to swallow)
what do salivary glands do?
release a glycoprotein that moistens & lubricates food for easier swallowing
what is the purpose of salivary amylase?
(enzyme) begins hydrolysis of starch & antibacterial agents that kill some bacteria ingested w/food
what is the purpose of the epiglottis?
flap of elastic cartilage that prevents food from entering trachea
how much can the stomach hold?
can store up to 2L of food/drink
what is gastric juice comprised of?
mucus, protein-digesting enzyme, strong acid with pH of approx. 2
what is the importance of pepsin?
begins chemical digestion of proteins
what is the purpose of mucus in the stomach?
protects lining from acid (new cells produced every 3 days)
define acid reflux (heartburn)
chyme comes up to esophagus from stomach
define GERD (gastroesophageal reflux disease)
frequent acid reflux
what is the function of the small intestine?
site of most chemical digestion and where most nutrients absorbed
what is the function of the pancreas?
produces pancreatic juice containing mixture of digestive enzymes and alkaline solution rich in bicarbonate
what is the function of the liver?
produces bile stored in gallbladder until needed
what is the purpose of bile?
breaks up fats into smaller droplets that are more susceptible to attack by digestive enzymes
what is the function of villi and microvilli?
increase surface area for absorption in small intestine
what are lipoproteins?
transport fats/cholesterol to body cells, modifies substances absorbed in digestive tract into less toxic forms, & produces bile
what is the cecum?
pouch in large intestine near junction of small intestine
what does it mean when you have diarrhea?
too little water is reclaimed from contents of large intestine
what does it mean when you have constipation?
too much water is reclaimed in large intestine
what are the essential nutrients?
fatty acids
amino acids
vitamins
minerals
what is the function of fatty acids?
used to make phospholipids of cell membranes (found in seeds, grains, veggies)
what is the function of amino acids?
used to make proteins (found in meat, eggs, milk)
what is the function of vitamins?
act as coenzymes
what characteristics do vitamins display?
organic nutrients, water soluble (B & C), fat soluble (A, D, E, K)
what characterizes minerals?
inorganic nutrients
what is an important function of iron in the body?
produces hemoglobin on blood
what is the function of low-density lipoproteins (LDL)
contribute to blocked blood vessels and high BP
what is the function of high-density lipoproteins (HDL)
help to reduce blocked blood vessels
what are some examples of LDL/HDL
exercise increases HDL, smoking decreases HDL
trans fat in diet increases LDL, eating unsaturated fats decreases LDL