Biol 125 exam 1

Define threshold voltage

The membrane voltage that an excitable cell needs to reach to trigger an action potential

What is the definition of CAP and max amplitude?

CAP = summed electrical signal record from a group of nerve or muscle fibers acting together

Max cap = the highest possible recorded electrical response

Which way did the solution go in the thistle tube and why did it move that way so fast?

The 30% sucrose solution went up the thistle tube because the inside of the bag has high solute concentration and saline outside the bag was a permeable membrane to solution 

What happens when you mix sheep’s blood with 0.2% saline solution?

solution becomes isotonic because solution wouldn’t change and there is no net movement of water

tetanus

Sustained contraction caused by very frequent stimuli with no relaxation phase

Summation

Where multiple graded potential combine to see if reaches the threshold needed to trigger and action potential 

Explain what happens during a refractory period

Na+ channels close and K+ channels open, allowing K+ to leave the cell and repolarize the membrane before the channels rest

explain relaxation

Where nerve signals stop, calcium is reabsorbed, and muscle fibers lengthen and soften

Ach release

It stimulates muscle which realseas Ca2+ and makes actin and myosin interact leading to contraction 

which ways neuron (sensory and motor) enters and leaves 

Sensory neurons enter though the dorsal root and motor neurons exit through the ventral root 

how would heart change if someone just held their breath instead of face immersion 

Mild bradycardia, heart rate would drop slower then if doing face immersion

thicker nerve require ___voltage than muscle  

less

what determines rate of osmosis 

i= amount of particles

what decreases cardiac sympathic activity 

cardio-accelerator

what is something that doesn’t happen in mammals during dive response?

increased heart rate

where is blind spot?

all of the above (cornea and retina…)

Eating a couple of bananas and some oranges could prove fatal to a person whose kidneys are not functioning properly due to the resultant

high plasma [K+]

shine light in left eye what do both eyes do

 (constrict, constrict)

What were two ways that nerve stimulus was tested

by changing stimulus strength/voltage and by changing the time interval between two stimuli, either directly through the muscle or indirectly through the sciatic nerve

For the dive reflex what were the two purposes of vasoconstriction

to conserve heat by reducing blood flow to the limbs and to help maintain blood to the heart and other important organs

physiological mechanism of dive response (two nerves stimulus)

cold water activates the trigeminal nerve, which signals the brain to increase vagus nerve activity, slowing the heart, while sympathetic activity decreases, causing vasoconstriction

physiological and experimental mechanism

The nerve needs less voltage because it is smaller and propagates action potentials, while direct muscle stimulation spreads through tissue, and maximum force occurs at the optimal sarcomere length for the most cross-bridges.