Human Physiology Test Bank 3 Questions with Correct Answers

Human Physiology Test Bank 3
Questions with Correct Answers

(true/false) The "coupling" of skeletal muscle excitation and skeletal muscle shortening
isaccomplished by intracellular free Ca++ - ANSWERStrue

(one best answer) When Dr. Merriman talks about Ca++ "providing permission to slide",
she means that:
A) Ca++ influx from the ISF depolarizes the skeletal muscle cell, initiating contraction
B) Ca++ binding changes the shape of the myosin "hands" so they can grab the actin
C) Ca++ binding changes the shape of a protein that is blocking myosin's access to
actin - ANSWERSC) Ca++ binding changes the shape of a protein that is blocking
myosin's access to actin

one best answer) When skeletal muscle cells shorten, what actually gets shorter?
A) Actin filaments
B) Myosin filaments
C) Sarcomeres
D) Sarcoplasmic reticulum - ANSWERSC) Sarcomeres

(all that apply) What role(s) does ATP play in skeletal muscle contraction?
A) It powers AT Pase pumps that push Ca++ back into the sarcoplasmic reticulum
B) It powers AT Pase pumps that push Ca++ back into the interstitial fluid
C) It powers the pulling action of the myosin "hands" that in turn slides the actin filament
D) It enables the myosin "hands" to let go of actin and reposition themselves for another
slide - ANSWERSA) It powers ATPase pumps that push Ca++ back into the
sarcoplasmic reticulum
C) It powers the pulling action of the myosin "hands" that, in turn, slides the actin
filament

(one best answer) Which of the following is the best summary of the skeletal muscle
stretch reflex?
A) It ensures that skeletal muscle cells relax and lengthen enough that sarcomere
sliding filaments can no longer touch each other, saving the relaxing cell some ATP
B) It helps keep sarcomere sliding filaments overlapping just enough to be able to
shorten when commanded to do so by Ca++
C) It rapidly shortens sarcomere sliding filaments to the point that they completely
overlap and have generated maximal tension/force - ANSWERSB) It helps keep
sarcomere sliding filaments overlapping just enough to be able to shorten when
commanded to do so by Ca++

,What is the cytoplasmic molecule that skeletal muscle (and, as it turns out, cardiac
muscle) has that helps it have as good an oxygen supply as possible, even during
extreme physical exertion? ________________________________ -
ANSWERSmyoglobin

What is the cytoplasmic molecule that skeletal muscle (and, as it turns out,cardiac
muscle) has that helps it have as good a glucose supply as possible, even
duringextreme physical exertion? _____________________________ -
ANSWERSglycogen

Which of the following ATP-regenerating reactions within the muscle do NOT require O2
to occur?
A) Cori Cycle
B) Creatine phosphate dephosphorylation (loss of its phosphate)
C) Electron Transport Chain
D) Glycolysis
E) Krebs Cycle - ANSWERSB) Creatine phosphate dephosphorylation (loss of its
phosphate)
D) Glycolysis

all that apply) Which of the following are molecules found in abundance within skeletal
musclecytoplasm as adaptations to power contraction even in times of low plasma
pO2?
A) Cori Cycle
B) Creatine
C) Creatinine
D) Glycogen
E) Myoglobin
F) Triglycerides - ANSWERSD) Glycogen
E) Myoglobin

When skeletal muscle ismaximally active, the organ called the ________________
accepts lactate waste dumped intothe blood by the skeletal muscle, converts it back to
_____________________, and sends itback to the skeletal muscle by way of the
_______________________. This process is calledthe __________ __________. -
ANSWERSLiver
Glucose
Bloodstream
Cori Cycle

Creatine is a nitrogenous molecule made in the ___________________ and
transported to the skeletal muscle via the__________________. When taken up by
skeletal muscle cells, MOST creatine is converted to _______________________ that
then serves as a quick way to regenerate ATP by donating its phosphate group to
creatine. A TINY proportion of skeletal muscle creatine is converted to the waste form
known as ____________________ and lost in the urine - ANSWERSliver

, bloodstream
phosphocreatine (or creatine phosphate)
creatinine

WhatTWO (2) types of fuel molecules does skeletal muscle store for its own use? -
ANSWERSGlycogen, Triglycerides

(one best answer) As skeletal muscle's "oxygen debt" is repaid by re-establishing the
normalplasma pO2 and reloading O2-binding proteins with O2, which ONE of the
following ATP-regenerating pathways is "reactivated" FIRST?
A) Anaerobic fermentation in the cytoplasm
B) Creatine phosphate in the cytoplasm
C) Glycolysis in the cytoplasm
D) Krebs Cycle in the mitochondria
E) Electron transport chain in the mitochondria - ANSWERSB) Creatine phosphate in
the cytoplasm

(all that apply) Which are features of the action potential depolarization observed in
pacemaker cardiac muscle cells?
A) These APs are triggered by APs transferred by pacemaker or conduction system
cellswithin the heart
B) These APs arise spontaneously.
C) These APs depend on voltage-gated sodium channels.
D) These APs depend on voltage-gated potassium channels.
E) These APs depend on voltage-gated calcium channels.
F) These APs never truly return to Vrest - ANSWERSB) These APs arise spontaneously
E) These APs depend on voltage-gated calcium channels
A) These APs are triggered by APs transferred by pacemaker or conduction system
cells within the heart

all that apply) Which are features of the action potential depolarization observed in
contractilecardiac muscle cells?
A) These APs are triggered by APs transferred by pacemaker or conduction system
cellswithin the heart.
B) These APs arise spontaneously.
C) These APs depend on voltage-gated sodium channels.
D) These APs depend on voltage-gated potassium channels.
E) These APs depend on voltage-gated calcium channels.
F) These APs never truly return to Vrest - ANSWERSA) These APs are triggered by
APs transferred by pacemaker or conduction system cells within the heart
C) These APs depend on voltage-gated sodium channels
E) These APs depend on voltage-gated calcium channels

(one best answer) During the heartbeat, contractile atrial cells receive pacemaker action
potential excitation via:
A) Autonomic neurons