AAMC QP Biology 2 Flashcards
kidney functions
acid-base balance, blood pressure, water balance, and removal of nitrogen wastes
what happens when you block reuptake of a neurotransmitter
it remains in the synaptic cleft and continues to elicit its function, often resulting in “spazzy” behavior or an increased sympathetic response
what happens during starvation
the body uses up its stores of carbohydrate and lipids, and then begins to break down body proteins for metabolic energy. A byproduct of the metabolism of the amino acids from protein is nitrogen.
when do divisions occur in the oocytes
mitotic divisions (form primary oocytes) occur before birth
the first meiotic division (forms secondary oocyte) occurs during ovulation; second will be initiated at this time but the secondary oocyte will be arrested in metaphase II
after fertilization, secondary oocyte will finish its second meiotic division, forming the ovum that combines w the sperm to form a zygote
watson and crick model of DNA
the nitrogenous bases form hydrogen bonds with each other in a 1:1 ratio: guanine pairs with cytosine, and adenine pairs with thymine
BASE PAIRING RULES
what tissues are exposed to the external environment
Tissues that are exposed to the external environment have mucosal membranes.
These include the lining of the reproductive tract, the GI tract, and the respiratory tract.
antidiuretic hormone function
ADH or vasopressin
increase to enhance the permeability of the distal tubules and collecting ducts of the kidney to promote water reabsorption and excretion of more concentrated urine
magnitude of blood pressure, greatest to least
arteries > arterioles > capillaries > venules > veins
organs of the digestive tract and their functions (4)
Mouth: chewing; saliva contains amylase, mucin, lipase, antibodies, and lysozyme
Stomach: churning; release of protease (pepsin), more lipases, and HCl
Small intestine: peristalsis through the duodenum, jejunum, ileum; release of amylase, protease, lipase, (assisted by bile), nuclease → nutrient and water absorption
Large intestine: aka colon; feces formation → water absorption; production of vitamin K
- cecum + ascending > transverse > descending > sigmoidal > rectum
Secretions of the digestive tract and their functions (6)
Amylase: breaks down polysaccharides → found in mouth and small intestine
Antibodies + lysozyme: kill pathogens → found in mouth
Mucin: protein that lubricates the bolus (chewed up food ball) → found in mouth
Pepsin: protease that becomes activated in acidic environments; cleaves peptide bonds → found in stomach and small intestine
Nuclease: breakdown of nucleic acids → found in small intestine
Lipase: breakdown of fats → found in mouth and small intestine
adaptive radiation
Adaptive radiation involves the divergence of one species into multiple species over time, which can occur when subgroups of the original species are separated or isolated in different environments so that these subgroups evolve independently of one another.
where is filtrate formed?
Filtrate is formed as fluid passes from the glomerular capillaries through the glomerular membrane into the Bowman’s capsule.
This region of the nephron is known as the glomerulus.
what is phagocytosis? what structure does it require?
Phagocytosis requires that the cell change shape dramatically as it surrounds and engulfs large extracellular particles.
Microtubules are one of the cytoskeletal elements that help determine cell shape. This function relies on the ability of the microtubules to disassemble and reorganize.
what happens upon disruption of the mitotic spindle
disruption of the mitotic spindle (or of the microtubules that comprise it) prevents the proper segregation of chromosomes into the daughter cells and usually results in unequal numbers being distributed to the two daughter cells
what gates are open when during an action potential
When the plasma membrane is at its resting potential, the voltage-gated K+ channels and the voltage-gated Na+ channels are closed.
As triggering events bring the membrane up to its threshold potential, the voltage-gated Na+ channels open and cause further depolarization of the membrane by allowing Na+ to flow into the cell.
The voltage-gated K+ channels are closed during the depolarization phase of an action potential.
After the membrane reaches its peak potential, the voltage-gated K+ channels open, allowing K+ to flow out of the cell and repolarize the membrane by returning the membrane to near its resting potential; the voltage-gated Na+ channels are closed.
