Week 12- Digestive system Flashcards
Describe processes and purposes of digestion (mechanical vs. chemical) and absorption.
Mechanical
Starts in mouth-primarily Chewing
Physical breakdown of larger food into smaller components
Describe processes and purposes of digestion (mechanical vs. chemical) and absorption.
Chemical
Requires digestive enzymes
will chemically break down food into the smallest molecules so absorption can occur
Absorption
When molecules move from gi tract into blood or lymph
What happens to ingested material that cannot be digested and absorbed?
will move to large intestine and will become feces to be eliminated
Briefly describe 4 layers of GI tract—describe how absorption occurs in specific layers.
mucosa
innermost layer
where food will touch gi tract-must go through its epithelial cells in order to enter blood or lymph
Briefly describe 4 layers of GI tract—describe how absorption occurs in specific layers.
submucosa
second innermost layer
will connect mucosa to larger armies, veins and lymph vessels
Briefly describe 4 layers of GI tract—describe how absorption occurs in specific layers.
musculares externa
smooth muscle layer
will help in movement of food down gi tract
help in peristalsis and segmentation
Briefly describe 4 layers of GI tract—describe how absorption occurs in specific layers.
serosa
Protective outer layer
What is peristalsis (aka gastric motility)? Which layer is responsible for peristalsis
alternating contraction and relaxation of smooth muscle so food can move through digestive tract
musculares externa
Briefly describe swallowing (voluntary versus involuntary processes)
Voluntary
mouth will chew food and form bolus
then tongue will move bolus to back of throat
moves food to pharynx (line between voluntary and involuntary)
Briefly describe swallowing (voluntary versus involuntary processes)
involuntary
after bolus gets moved into pharynx-
will move bolus from pharynx into esophagus
bolus then pushed into stomach
what brain structure controls swallowing?
medulla oblongata
Know the enzymes secreted from the salivary glands and give their general functions (what do they break down?
Salivary amylase- Carbohydrates
Know the enzymes secreted from the tongue and give their general functions (what do they break down?
Lingual lipase- lipids/fats
Know the enzymes secreted from stomach, and give their general functions (what do they break down?
Pepsin- protein
gastric lipase- lipids/fats
Know the enzymes secreted from the pancreas and give their general functions (what do they break down?
Pancreatic amylase- carbohydrates
trypsin- proteins
chymotrypsin- proteins
pancreatic lipase- lipids/fats
Know the enzymes secreted from small intestine and give their general functions (what do they break down?
Maltase/sucrase/lactase- carbohydrates
peptidase- proteins
Where does chemical digestion BEGIN for each of these molecules: Carbohydrates
in the mouth
because salivary amylase breaks down carbs
Where does chemical digestion BEGIN for each of these molecules: lipids,?
in the mouth
because lingual lipase breaks down lipids/fats
Where does chemical digestion BEGIN for each of these molecules: proteins?
stomach
because pepsin breaks down proteins
Where will the pancreas secrete substances?
Small intestine
specifically duodenum
Where will the gallbladder secrete substances?
small intestine
What will ingested carbohydrates , lipids and proteins get chemically broken down into so that they can be absorbed?
C- Glucose
P-amino acids
L-Fatty acids
How are ingested carbohydrates and proteins absorbed?
go straight into intestinal cells
then go straight into venous side of capillaries
will filter into hepatic system- so liver, then heart, then cells
How will ingested carbohydrates and proteins nutrients be used in the body?
C- broken down into glucose , so it cam be made into ATP
P-broken down into amino acids, so the body can make the proteins that it needs
Describe storage of carbohydrates (glucose) in the body
Stored as glycogen in liver
if changed into fat, stored in adipose tissues
Describe storage of amino acids in the body
used in cells to make proteins
DO NOT STORE
Describe storage of lipids in the body
Stored in adipose tissues/cells
Know function of bile and where it is produced/stored
Helps in absorption of fats
produced/stored in liver
Know functions of HCl secreted from stomach
convert pepsin from pepsinogen
kill microbes that accidentally got ingested
Know functions of intrinsic factor secreted from stomach
goes into small intestine
will help absorb vitamin B12 into system
(B12 is necessary to help produce RBC)
Know functions of mucus secreted from stomach
will prevent HCL from destroying lining of GI tract
What is the main function of the small intestine?
absorption of most of nutrients
How is the small intestine structurally adapted for its functions?
Describe the purpose of the hepatic portal system (also–where does the blood come from and where does it go to?)
nutrients from GI tract will enter blood, and enter hepatic portal vein- will bring to liver
in liver- nutrients can be modified, detoxified and liver can give its own nutrients
will end up in vena cava, in heart, then in cells
Describe a micelle and chylomicron and their role in getting fats we eat into our blood
Micelle- will cover the fat in bile, will get fats into intestinal cells- and leaves bile behind
C-New protein coat after it gets in intestinal tract- will take it to lymph capillaries, where it can enter subclavian vein
Describe these lipoproteins and their primary function
VLDL
Very low density lipoprotein
created in liver- will deliver fat to cells
Describe these lipoproteins and their primary function
LDL
low density lipoprotein
when VLDL drops off its fat, gets converted into LDL
will deliver cholesterol to cell
if it runs out of places to deliver cholesterol, it can accumulate in blood= bad
Describe these lipoproteins and their primary function
HDL
High density lipoprotein
Will go to blood, and collect excess cholesterol that LDL dropped off and bring back to liver
if not enough HDL to balance our LDL, high cholesterol can occur
How does the nervous system control the GI tract?
Can promote or inhibit digestive activities based on if PNS or SNS are activated
What is the enteric nervous system?
can promote local digestion
How do the parasympathetic nervous systems affect the digestive system?
Will promote digestion
How do the sympathetic nervous systems affect the digestive system?
will inhibit digestion
Describe defecation reflex.
Parasympathetic nervous system-can only control smooth muscle
In rectum- stretch receptors will detect that it is full of feces
anal sphincters will open so you can defecate
major functions of the following hormones: gastrin
promote digestion in stomach and secrete gastric acids and enzymes in stomach
major functions of the following hormones:, secretin
promote secretion of bile and buffers from pancreas
inhibits gastric activity
major functions of the following hormones:
CCK
promote secretion of bile and buffers from pancreas
inhibits gastric activity
What types of molecules can the liver produce?
Bile
glycogens
cholesterol
clotting proteins/plasma proteins
VLDL, LDL and HDL
