lec 10- nutrition

Question 1

what are the two requirements for animals when it comes to nutrition?

Answer 1

1. chemical energy for synthesizing ATP
2. carbon-containing compounds for building molecules

Question 2

what are the four processes needed to obtain energy from food?

Answer 2

ingestion- process of bringing food into digestive tract
digestion- is the breakdown of food
absorption- uptake of specific ions and molecules across the epithelium of the digestive tract
elimination- disposal of waste

Question 3

what are nutrients?

Answer 3

chemical energy and carbon-containing building blocks needed by the body

Question 4

what is food?

Answer 4

any material that contains nutrients

Question 5

what are essential nutrients?

Answer 5

nutrients that cant be synthesized and can only be obtained from diet

Question 6

what are vitamins?

Answer 6

organic compounds that are vital for health but are required only in minute amounts

Question 7

what are minerals?

Answer 7

are inorganic substances used as a component of enzyme cofactors, their ions act as electrolytes to the body

Question 8

why do canadians experience vitamin D deficiency?

Answer 8

because to make vitamin D, UV light is required which canadians experience less due to rainy weather and being inside

Question 9

how does light make vitamin D?

Answer 9

light strikes a molecule called
7-dehydrocholesterol and changes its shape so it can become vitamin D

Question 10

why is vitamin D needed by the body?

Answer 10

it helps absorb calcium in our small intestine

Question 11

do canadians experience insufficient amounts of UV light for most of the year?

Answer 11

yes

Question 12

how do canadians increase vitamin D?

Answer 12

by adding it into our milk

Question 13

how does vitamin D act in the cell?

Answer 13

like a steroid, it is membrane soluble, it attaches to a protein called VDR and turns on certain genes. The vitamin D-VDR complex attaches to vitamin D response element which turns on genes

Question 14

what are the two general designs of the digestive tract?

Answer 14

incomplete digestive tracts- one opening for both ingestion and elimination (eg. starfish)
complete digestive tracts- two openings, one for ingestion, other for elimination (humans)

Question 15

how does digestion begin?

Answer 15

-in the mouth where food is chewed, salivary amylase breaks down starch and glycogen (carbs)
-lingual lipase breaks lipids down
-salivary glands make it easy to swallow food with slimy substance called mucus

Question 16

how is food propelled down esophagus?

Answer 16

by muscle contractions called peristalsis

Question 17

what is the stomach and what does it do?

Answer 17

a tough, muscular pouch bracketed on both ends by ringlike muscles called sphincters, which control passage of material.
muscular contractions churn to mix and break down food, stomach also partially digests proteins

Question 18

what enzyme digests proteins?

Answer 18

pepsin

Question 19

what does chief and parietal cells do?

Answer 19

chief cells secrete pepsinogen which is a precursor to pepsin, the precursor turns into pepsin after interacting with HCL secreted from parietal cells.

Question 20

what do mucus cells do?

Answer 20

secrete mucus which lines the gastric epithelium and protects stomach from damage by HCL

Question 21

where does the food go after the stomach and what happens?

Answer 21

to the small intestine where the food is mixed with secretions from pancreas and liver and then move down the tube, small intestine absorbs food

Question 22

why does the small intestine have a large surface area?

Answer 22

to increase absorption

Question 23

what increases small intestine surface area?

Answer 23

multiple folds of villi which have microvillies

Question 24

what helps absorb nutrients quickly in the small intestine?

Answer 24

blood and lymphatic vessels called a lacteal in villus

Question 25

what enzyme is secreted by the pancreas and what do they travel through to get to the small intestine?

Answer 25

proteases that digest polypeptides to monomers and lipase that digest small globules of fat, they travel through the pancreatic duct

Question 26

what does enterokinase do and what occurs after?

Answer 26

enterokinase activates trypsinogen which turns into trypsin, trypsin then activates other enzymes when needed to prevent self harm

Question 27

what does pancreatic lipase do?

Answer 27

breaks lipids down even further so they are ready for digestion, emulsification occurs before

Question 28

what is the process of emulsification?

Answer 28

it is when liver creates bile which is stored in the gallbladder, then the bile enters the small intestine where pH is increased causing emulsification of fat into small globules, pancreatic lipase then digests the small globules

Question 29

how is water absorbed in the small intestine?

Answer 29

by osmosis through the pancreatic epithelium

Question 30

what does the large intestine do?

Answer 30

after mostly all water and nutrients have been absorbed in the small intestine, the large intestine turns the waste into feces in the colon which is the main section of the large intestine

Question 31

where is feces held?

Answer 31

in the rectum

Question 32

what is insulin?

Answer 32

a small hormone produced by the pancreas when glucose is high, muscle and fats have insulin receptors that activate the response from insulin, causing excess glucose to be imported for cellular respiration

Question 33

what happens with low and high levels of glucose?

Answer 33

low means the brain cant function well, high means decrease in blood pH which is bad for blood vessels, diabetes can occur

Question 34

what are the symptoms of diabetes?

Answer 34

increased thirst, slow healing, fatigue, blurred vision, frequent urination, unexplained weight loss

Question 35

what is type 1 and type 2 diabetes?

Answer 35

type 1- cant make insulin due to autoimmune system attacking insulin making cells, childhood type 2- cant respond to insulin, insulin sensitivity, middle age

Question 36

how does insulin release?

Answer 36

excess glucose causes closure of potassium ATP channels which cause depolarization, depolarization causes calcium release which triggers insulin to be released

Question 37

how does insulin let glucose enter the cell to be stored again?

Answer 37

insulin binds to receptor which sends a signal to vesicles with glucose transporters to attach to the cell membrane