Introduction to Physiology
Cellular Transport
Membrane and Action Potential
Skeletal Muscle Contraction & Excitation
Excitation & Contraction of smooth muscle
100
Disease is generally considered a state of disrupted homeostasis where homeostasis mechanisms are no longer operating in the body.
a. True
b. False
b. False
100
Which of the following is a correct statement about simple diffusion?
a. Substances flow against a concentration gradient
b. It is energy-consuming process
c. It does not utilizes any protein
c. it does not utilizes any protein
100
Which of the following is primarily responsible for the change in membrane potential between points B and D
a. Movement of Na+ into the cell
b. Movement of K+ into the cell
c. Movement of K+ out of the cell
d. Inhibition of the sodium potassium pump
e. Movement of Na+ out of the cell
a. Movement of Na+ into the cell
100
Which of the following decreases in length during the contraction of the skeletal muscle fiber?
a. I band of the sarcomere
b. A band of the sarcomere
c. Z disks of the sarcomere
d. Thin filaments
e. Thick filaments
a. I band of the sarcomere
100
Identify which of the following statements is INCORRECT
a. Smooth muscle contraction can be initiated by neurons
b. Smooth muscles, like skeletal muscles, make use of myosin and actin interactions
c. Smooth muscle lacks troponin and does not use Ca+
d. Smooth muscle can undergo extensive amounts of contraction
c. Smooth muscle lacks troponin and does not use Ca+
200
The following shows feedback control of blood temperature. From the image below and your understanding of homeostatic mechanisms, which of the following statements is true:
a. There is one effector in this system
b. Antagonistic effectors are not used
c. These processes are hormonally controlled
d. Extrinsic regulation is a feature of this system
e. None of the above are true
d. Extrinsic regulation is a feature of this system
200
All are characteristic of active transport EXCEPT one.
a. Particles travel against a concentration gradient
b. Primarily involves ion channels
c. Requires input of energy
d. Can be divided into primary or secondary active transport
b. primarily involves ion channels
200
Equilibrium potentials for Na+ and K+ are shown. Assume that a cell is permeable to these ions and has a resting membrane potential of −80 millivolts. Draw and/or explain the movement of the ions.
ENa+ = +70mV
EK+ = -95mV
Na+ ions will move in because it want to maintain equilibrium inside the cell
K+ ions will more out of the cell to repel and maintain equilibrium
200
In the context of a skeletal muscle contraction. Ca+2 binds which of the following
a. Myosin
b. Actin
c. Myosin light chain
d. Tropomyosin
e. Troponin
e. Troponin
200
Which of the following best represents the order of events in smooth muscle contraction?
a. Contraction, relaxation, MLC dephosphorylation, MLC phosphorylation
b. Contraction, MLC dephosphorylation, relaxation, MLC phosphorylation
c. MLC dephosphorylation, contraction, MLC phosphorylation, relaxation
d. MLC phosphorylation, contraction, MLC dephosphorylation, relaxation
d. MLC phosphorylation, contraction, MLC dephosphorylation, relaxation
300
Your sibling receives a glucose tolerance test at 26 weeks of pregnancy. They are asked to drink a sweet liquid and their blood is drawn 3hrs later. Their values climb to 150mg/dl from 100mg/dl. Results from a similar test taken at 12 weeks pregnancy saw their values climb to only 125mg/dl from 100mg/dl (normal). What is the feedback ‘gain’ of the system?
a. 0.0
b. -1.0
c. +1.0
d. +2.0
e. -2.0
b. -1.0
300
Simple and Facilitated diffusion share which of the following characteristics?
a. Can be blocked by specific inhibitors
b. Require transport protein
c. Do not require adenosine triphosphate (ATP)
d. Saturation kinetics
e. Transport solute against concentration gradient.
c. Do not require adenosine triphosphate (ATP)
300
Five Hypothetical nerve axons are shown in the image below. Axons A and B are myelinated, whereas axons C, D, and E are non-myelinated. Which axon is most likely to have the fastest conduction velocity for an action potential?
a. A
b. B
c. C
d. D
e. E
b. B
300
Order the following events in skeletal muscle contraction:
I - Myosin releases ADP and pulls on the thin filament
II - Calcium binds to Troponin, causing it to rotate
III - The myosin head binds the myosin binding domain of actin
IV - Electrical impulse travels down a nerve fiber
V - ACh binds muscle cell membrane and causes an impulse to be transmitted to the muscle.
a. IV, V, II, III, I
b. III, V, I, II, IV
c. IV, V, I, III, II
d. V, IV, III, II, I
e. V, IV, II, III, I
a. IV, V, II, III, I
300
Give two main differences between skeletal and smooth muscle physiology.
Difference:
1. skeletal muscle contraction is caused by CNS with neuron & A.P. While smooth occurs on ANS
2. In skeletal, we have troponin and tropomyosin protein, which does physical work, while smooth works with calmodulin protein.
400
A friend exhibits syncope (fainting) when getting up from lying down. Which of the following is likely
a. baroreceptors not firing a sufficient number of action potentials on the effector cardiac muscle
b. decreased hormonal output from the integrating center
c. depressed serum K+ levels in medulla oblongata neurons of the integrating center
d. All of the above are possible
c. depressed serum K+ levels in medulla oblongata neurons of the integrating center
400
A clinical study is conducted to determine the actions of an unknown test solution on red blood cell volume. One milliliter of heparinized human blood is pipetted into 100 milliliters of the test solution and mixed. Samples are taken and analyzed immediately before and at 1-second intervals after mixing. The results show that red blood cells placed into the test solution immediately swell and burst. Which of the following best describes the tonicity and osmolarity of the test solution?
a. Hypertonic; could be hyperosmotic, hypo-osmotic, or iso-osmotic
b. Hypertonic; must be hyperosmotic, hypo-osmotic
c. Hypertonic; must be iso-osmotic
d. Hypotonic; could be hyperosmotic, hypo-osmotic, or iso-osmotic
e. Hypotonic; must be hyperosmotic, hypo-osmotic
f. Hypotonic; must be iso-osmotic
d. Hypotonic; could be hyperosmotic, hypo-osmotic, or iso-osmotic
400
Which of the following diseases are linked when voltage-gated sodium channels are mutated?
a. Epilepsy
b. Cardiac arrhythmias
c. Chronic pain syndrome
d. All of the above
d. All of the above
(because these channels play a role in regulating neuronal excitability and electrical impulse transmission in the heart and nervous system)
400
A patient with skeletal muscle contraction undergoes a series of electrophysiological studies, revealing strong end-plate potentials and action potentials within myocytes/muscle cells but weak contraction. The problem could be:
a. Defects in the DHP or RyR receptors
b. Changes to the Ach receptors, causing them to fail
c. problem with the VG Na+m channels needed for muscle action potentials
d. A and B
e. B and C
a. Defects in the DHP or RyR receptors
400
Which of the following is not likely to cause dilation of smooth muscle in a typical (non-lung) tissue?
a. eNOS (endothelial nitric oxide synthase)
b. Bradykinin
c. Increased O2
d. Increased CO2
e. Increased temperature
b. Bradykinin
500
The function of the blood coagulation pathway is to maintain hemostasis, resulting in the blockage of bleeding or hemorrhage. An important step of this process is the formation of a temporary platelet plug. When a vessel is injured, platelets will bind to collagen exposed in injured areas, and release TXA and ADP, which draws more platelets to the injured site, activating those platelets and the release of more TXA and ADP. A plug eventually forms in healthy individuals. What type of feedback regulation is present here and is this control intrinsic or extrinsic?
a. Negative feedback; Intrinsic
b. Positive feedback; Extrinsic
c. Negative feedback; Extrinsic
d. Positive feedback; Intrinsic
d. Positive feedback; Intrinsic
500
The diagram shows a model cell that transports substance X across the cell membrane. The cell is equipped with a Na+-K+-ATPase pump, as shown. Substance X enters the cell by a transport mechanism and exits the cell by carrier-mediated diffusion. Treatment with a substance that inhibits the Na+-K+-ATPase pump inhibits the transport of X by which of the following mechanisms?
a. Decreased intracellular Na+ concentration
b. Increased intracellular Na+ concentration
c. Decreased intracellular K+ concentration
d. Increased intracellular K+ concentration
b. Increased intracellular Na+ concentration
500
Provide a paragraph (or draw with an explanation) that explains either the generation, maintenance or resolution of an action potential. Use five of the following terms: Stimulus, depolarization, repolarization, after hyperpolarization, subthreshold stimulus, threshold stimulus, resting membrane potential, activation gates, inactivation gates, mechanical stimulation, hyperpolarization, axon hillock or trigger zone, cable properties, myelin, all or none response, absolute refractory period, relative refractory period.
500
Which of the following statements about BOTOX is true?
a. it binds irreversibly to acetylcholine and causes decreased end-plate-potentials
b. it causes decreased acetylcholine in the synapse
c. it targets structures in the subneural cleft
d. it binds irreversibly to the choline transporter and causes decreased end-plate-potentials
e. it causes muscle contraction at low levels but makes muscle unresponsive at high levels
b. it causes decreased acetylcholine in the synapse
500
Explain how smooth muscle is contracted by initiating the signaling step (starting at Ca+2 influx).
In smooth muscle contraction, there is an increase in Ca2+ concentration from (primarily) extracellular fluid & a bit from S.R. Ca2+ ions bind to calmodulin. The complex will activate myosin light-chain kinase protein (MLCK). Then, the MLCK will phosphorylate the myosin heads, basically activating myosin head ATPase activity. which will cause actin to bind, forming a cross-bridge, and contraction occurs.
