lec 10- nutrition Flashcards
what are the two requirements for animals when it comes to nutrition?
- chemical energy for synthesizing ATP
- carbon-containing compounds for building molecules
what are the four processes needed to obtain energy from food?
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
what are nutrients?
chemical energy and carbon-containing building blocks needed by the body
what is food?
any material that contains nutrients
what are essential nutrients?
nutrients that cant be synthesized and can only be obtained from diet
what are vitamins?
organic compounds that are vital for health but are required only in minute amounts
what are minerals?
are inorganic substances used as a component of enzyme cofactors, their ions act as electrolytes to the body
why do canadians experience vitamin D deficiency?
because to make vitamin D, UV light is required which canadians experience less due to rainy weather and being inside
how does light make vitamin D?
light strikes a molecule called
7-dehydrocholesterol and changes its shape so it can become vitamin D
why is vitamin D needed by the body?
it helps absorb calcium in our small intestine
do canadians experience insufficient amounts of UV light for most of the year?
yes
how do canadians increase vitamin D?
by adding it into our milk
how does vitamin D act in the cell?
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
what are the two general designs of the digestive tract?
incomplete digestive tracts- one opening for both ingestion and elimination (eg. starfish)
complete digestive tracts- two openings, one for ingestion, other for elimination (humans)
how does digestion begin?
-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
how is food propelled down esophagus?
by muscle contractions called peristalsis
what is the stomach and what does it do?
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
what enzyme digests proteins?
pepsin
what does chief and parietal cells do?
chief cells secrete pepsinogen which is a precursor to pepsin, the precursor turns into pepsin after interacting with HCL secreted from parietal cells.
what do mucus cells do?
secrete mucus which lines the gastric epithelium and protects stomach from damage by HCL
where does the food go after the stomach and what happens?
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
why does the small intestine have a large surface area?
to increase absorption
what increases small intestine surface area?
multiple folds of villi which have microvillies
what helps absorb nutrients quickly in the small intestine?
blood and lymphatic vessels called a lacteal in villus
what enzyme is secreted by the pancreas and what do they travel through to get to the small intestine?
proteases that digest polypeptides to monomers and lipase that digest small globules of fat, they travel through the pancreatic duct
what does enterokinase do and what occurs after?
enterokinase activates trypsinogen which turns into trypsin, trypsin then activates other enzymes when needed to prevent self harm
what does pancreatic lipase do?
breaks lipids down even further so they are ready for digestion, emulsification occurs before
what is the process of emulsification?
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
how is water absorbed in the small intestine?
by osmosis through the pancreatic epithelium
what does the large intestine do?
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
where is feces held?
in the rectum
what is insulin?
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
what happens with low and high levels of glucose?
low means the brain cant function well, high means decrease in blood pH which is bad for blood vessels, diabetes can occur
what are the symptoms of diabetes?
increased thirst, slow healing, fatigue, blurred vision, frequent urination, unexplained weight loss
what is type 1 and type 2 diabetes?
type 1- cant make insulin due to autoimmune system attacking insulin making cells, childhood
type 2- cant respond to insulin, insulin sensitivity, middle age
how does insulin release?
excess glucose causes closure of potassium ATP channels which cause depolarization, depolarization causes calcium release which triggers insulin to be released
how does insulin let glucose enter the cell to be stored again?
insulin binds to receptor which sends a signal to vesicles with glucose transporters to attach to the cell membrane
