module 1: absorption in the small intestines videos Flashcards
when transporting nutrients across the cell membrane, the bigger the nutrients, the bigger the _______
transporter
describe the potassium leak channel
due to the high concentration of potassium inside the cell, potassium will flow down its concentration gradient to exit the cell
what kind of transport is the K+ leak channel?
passive transport (facilitated diffusion)
what is passive transport?
transport that doesn’t require energy
what are the types of passive transport and describe them
diffusion- movement of solutes in space
osmosis- movement of water
filtration- as occurs in the kidneys
facilitated diffusion- utilizes help of protein channel
why is there a lot of potassium inside the cell and lot of sodium outside the cell?
because of the energy used to set up the ion gradient
what is the Na+/K+ ATPase pump?
moves Na+ against its gradient to exit the cell and import K+ into the cell while utilizing ATP using active transport (primary)
what is primary active transport? example?
directly uses ATP
Na+/K+ ATPase
what are enterocytes
cells of the GI tract
what are symports?
transport both molecules in the same direction
what is secondary active transport? example
transport that uses energy indirectly, uses a gradient setup using energy
ex. Na+ transport with glucose via symport
after Na+ and glucose are absorbed into the intestine (enterocytes), where must they go?
bloodstream
how does glucose exit the cell to enter the capillary?
antiport- two molecules moving in the opposite direction
ex. glucose exiting cell and Na+ entering cell down its concentration gradient (secondary active transport)
what is a vesicle?
small pocket of cell membrane that surrounding “cargo” (ex. amino acids, etc.)
describe how proteins can enter the cell via endocytosis
vesicles when it gets close enough to the membrane, it fuses which creates an opening inside of the vesicle connecting it to the inside of the cell and the protein can enter inside
true or false: endocytosis does not utilize energy
false
describe how acetylcholine can exit the cell via exocytosis
once vesicle is made with ACH, from the golgi apparatus it floats towards cell membrane and fuses, allowing ACH to exit the cell
true or false: exocytosis does not use energy
false
why is it important to know how things are transported across the cell membrane?
helps us understand and combat infectious diseases
how are amino acids shuttled into cells?
via primary active transport
how do sugar monosaccharides enter the cell?
secondary active transport
what mechanism do the nucleoside and base use?
primary active transport
what is special about fat and its absorption in the small intestine?
- nonpolar tail allows for diffusion across the membrane
- once inside enterocyte, all fatty acids are reorganized into chylomicrons
- chylomicrons are too big to enter capillary
where are chylomicrons abosrbed into?
lymphatic capillary where are they are broken down and end up in veins, sending the digested fat into the heart and eventually arteries
true or false: the duodenum is where most of the digestion occurs in the GI tract
true
where does the most absorption occur in the GI tract?
jejunum
