BIOL 252 Exam 2 Practice

A tumor has appeared on the hypothalamus of a seven-year-old boy, causing increased secretion of GHRH. The increase of GHRH has in turn increased GH and IGF levels. If left untreated, the young boy

a. will suffer from acromegaly, in which his bones will increase in girth, especially his head and facial bones

b. will suffer from gigantism since his epiphyseal plates have not closed.

c. will have a decreased amount of protein synthesis, decreasing muscle development and longitudinal bone growth

d. will suffer from pituitary dwarfism, where he will be short in stature.

b

A radiograph reveals epiphyseal lines in the long bones of a 12-year-old's hand. Which of the following statements is correct?

a. The epiphyseal plates have ossified, and further growth in length is not possible

b. Intramembranous ossification will enable continued growth in length

c. Administration of growth hormone will stimulate further bone growth in length

d. More growth will occur during the teenage years as sex hormones stimulate rebuilding of epiphyseal plates.

a

What stimulates the release of parathyroid hormone (PTH)?

low blood calcium ion levels

Which of the following is not one of the effects of the parathyroid hormone (PTH)?

a. increased blood calcium concentration

b. increased calcium storage in bones

c. increased calcium reabsorption in the kidneys

d. increased calcium absorption in the small intestine

b --> PTH stimulates osteoclasts to degrade bone and release calcium.

Bone, or osseous, tissue provides protection for our vital organs since the inorganic ground substance is:

calcium phosphate crystals

What accounts for the majority of bone (osseous) tissue matrix?

calcium salts

Osteoblasts are to bone deposition as:

osteoclasts are to bone resorption

T/F: Contractility is the ability of a muscle to shorten and create tension

True

If actin filaments were incapable of sliding past the myosin filaments.

Contraction would not occur, and tension would not be generated

A patient with myasthenia gravis, a disease that destroys acetylcholine receptors at the motor end plate, will display all the symptoms except:

a. Muscle weakness and partial or full paralysis

b. Muscle hypertrophy

c. Difficulty swallowing

d. Drooping eyelids and double vision

b

Troponin and tropomyosin are regulatory proteins that block the active sites of actin when the muscle is relaxed, and expose the active sites when the muscle is contracting. If troponin were unable to bind to tropomyosin...

a. troponin would be able to cover the active sites without the need for tropomyosin

b. tropomyosin would be able to move off the active sites without the need for troponin

c. they would not be able to turn on and off the process of muscle contraction

d. troponin would cover the active sites and tropomyosin would uncover the active sites of actin.

c

A pathway of ATP production that results in the formation of lactic acid is:

glycolytic catabolism

When trying to increase exercise performance, an athlete consumes large amounts of creatine phosphate. This supplement will provide..

a. Creatine phosphate is not involved in energy production

b. only a few seconds of energy because it metabolizes rapidly, even in excess

c. approximately an hour of extended energy before glycolytic catabolism takes over

d. hours of energy because it is part of the aerobic catabolism pathway.

b

Clostridium botulinum is a bacterium that produces botulinum toxin that inhibits the release of acetylcholine. Which description best fits how muscle cells will respond to a lack of acetylcholine?

a. Muscle cells will produce greater tension when there is a lack of acetylcholine

b. Muscle cells will become paralyzed when there is a lack of acetylcholine

c. Muscle cells will experienced fused or complete tetanus when there is a lack of acetylcholine

d. Muscle cells will produce sustained contractions without relaxation when there is a lack of acetylcholine

b

Latrotoxin, produced by the poisonous black widow spider, increases the release of acetylcholine. How do muscle cells respond?

a. Muscle cells will experience fused or complete tetanus when excess acetylcholine exists

b. Muscle cells will become paralyzed when excess acetylcholine exists

c. Muscle cells will experience a longer latent period when excess acetylcholine exists

d. Muscle cells will twitch irregularly when excess acetylcholine exists.

a

Resting muscles still have some degree of muscle tension produced by involuntary activation of motor units in the brain and spinal cord. This small amount of muscle tension is known as:

muscle tone

If GH hypersecretion occurs before closure of the epiphyseal plates, the result is

gigantism

osteoclasts

responsible for bone resorption during which they break down bone ECM

osteogenic cells

build bone

steps of endochondral ossification (5)

1.) Perichondrium is invaded by blood vessels

2.) Perichondrial cells differentiate into osteogenic cells then into osteoblasts

3.) Osteoblasts build the bone collar on the external surface of the bone.

4.) Chondrocytes die

5.) In the primary ossification center, osteoblasts replace calcified cartilage with early spongy bone

muscle hypertrophy

increase in skeletal muscle due to strength training

High-pressured blood in the ventricles ________.

forces the semilunar valves open

Which of the following events is the first part of the cardiac cycle?

a. atrial contraction phase

b. ventricular filling phase

c. isovolumetric relaxation phase

d. isovolumetric contraction phase

a. atrial contraction phase

Which chamber generates the highest pressure during systole?

left ventricle

What percentage of atria blood flows passively into the ventricles?

80%

Which of the following factors would increase cardiac output to the greatest extent?

a. increased heart rate and decrease stroke volume

b. decrease heart rate and increase stroke volume

c. decrease heart rate and stroke volume

d. increase heart rate and increase stroke volume

d

The degree of stretch experienced by the sarcomeres in the ventricle cells before they contract is called __________.

preload

Which of the following chemical messengers decreases heart rate?

a. glucagon

b. acetylcholine

c. norepinephrine

d. epinephrine

b. acetylcholine

Approximately how much blood is pumped from each ventricle during the ventricular ejection phase?

70 mL

the parasympathetic nervous system innervates the heart by what nerves?

right and left vagus nerves (CN X)

how does the nervous system decrease HR?

-parasympathic nervous system releases acetylcholine when stimulated

-acetycholine primarily affects the SA node, decreasing its rate of AP generation

the neurons of the sympathetic nervous system releases which neurotransmitter?

norepinephrine

how does norepinephrine increase heart rate?

-norepinephrine released from sympathetic nerve terminals

-causes G-protein/cAMP/Kinase phosphorylation pathway, to phosphorylate HCN channels that create funny current (If)

-increase of If and slowed Ca2+ inward current —> increases slope of phase 4 —> quicker threshold voltage reached —> faster heartbeat

the adrenal medulla is activated by what nervous system?

a. sympathetic

b. parasympathetic

a

preload

-the degree of stretch experienced by the sarcomeres in the ventricle cells before they contact

-refers to the length or degree of stretch of the sarcomeres in the ventricular cells before they contract

degree of preload is largely determined by

end-diastolic volume (EDV)

EDV

the amount of blood that has drained into the ventricle by the end of the filling phase

as blood fills the ventricle,

is stretches the muscle cells, which also stretches their sarcomeres

stroke volume

amount of blood pumped in one heartbeat

3 factors that influence the stroke volume

1. preload imposed on heart before it contracts

2. hearts contractility, or ability to generate tension

3. after load against which the heart pumps as it contracts

contractility of heart

its in intrinsic pumping ability, or ability to generate tension

afterload

refers to the force that the right and left ventricles must overcome to eject blood into their respective arteries

isovolumetric contraction phase

-the beginning of the ventricular systole

-pressure in ventricles rises rapidly as the ventricles began to contract

-high pressure closes the AV valves

-ventricular pressure is not yet high enough to push open the semilunar valves, so both valves are closed, and the ventricular pressure does not change

4 phases of cardiac cycle

1. ventricular filling

2. isovolumetric contraction

3. ventricular ejection

4. isovolumetric relaxation

at the beginning of the ventricular filling phase, the atria are in

diastole

stroke volume =

EDV-ESV

cardiac output =

heart rate x stroke volume

ESV

amount of blood remaining in a ventricle after contraction

what is the average ESV?

50 mL

What two values are needed to calculate cardiac output (CO) for a ventricle?

stroke volume (SV) and heart rate (HR)

What largely determines preload?

End-diastolic volume (EDV)

According to the Frank-Starling law, a bigger preload will result in __________.

a stronger contraction

Which of the following paths does an action potential in the heart normally take?

a. SA node —> atrial contractile cells —> AV node where it is delayed —> AV bundle —> right and left bundle branches —> Purkinje fibers —> ventricular contractile cells

b. Purkinje fibers —> ventricular contractile cells —> SA node —> atrial contractile cells —> AV bundle —> AV node where it is delayed —> right and left bundle branches

c. AV bundle —> AV node where it is delayed —> right and left bundle branches —> Purkinje fibers —> ventricular contractile cells —> SA node —> atrial contractile cells

d. SA node —> AV bundle —> right and left bundle branches —> atrial contractile cells —> AV node where it is delayed —> Purkinje fibers —> ventricular contractile cells

a

why is not all the blood ejected?

the beginning of the ventricular ejection phase is marked by rapid outflow of blood from the ventricles. However, as this phase continues, the pressure in the pulmonary trunk and aorta approaches that in the ventricles --> at this point, ejection of blood into the vessels decreases considerably

Which of the following terms refers to the force the ventricles must overcome to eject blood into their respective arteries?

after load

Calculate the end-systolic volume (ESV) if the end-diastolic volume (EDV) in a resting heart is 110 ml and stroke volume (SV) is 70 ml.

40 mL

What is the volume of blood pumped out by one ventricle per heart beat?

stroke volume (SV)

Which wave on the electrocardiogram (ECG) corresponds with the ventricular filling phase of the cardiac cycle?

P wave

P wave

atrial contraction → ventricle filling

what occurs during the ventricular filling phase?

the SA node fires an AP, which is propagated through the atria and delayed at the AV node

what does the R and S waves of ECG represent?

isovolumetric contraction phase

S-T segment of ECG

represents the plateau phase (the normal baseline) of the ventricular action potential. Heart's ventricles are contracted and pumping blood, with minimal electrical voltage gradient across the myocardium

isovolumetric contraction phase

the depolarization spreads through the AV node to the ventricles

What is initiated by a rapid influx of sodium ions into contractile cells creating a positive membrane potential inside the cell?

rapid depolarization phase

The P wave on an electrocardiogram (ECG) represents the depolarization of cells in the __________.

atria

Which of the following cell populations does not spontaneously generate action potentials in the cardiac conduction system?

a. sinoatrial node

b. Purkinje fibers

c. contractile cells

d. AV node

c. contractile cells

Which wave on the electrocardiogram (ECG) represents ventricular depolarization?

QRS complex

What provides a graphic representation of all the action potentials occurring in the heart?

electrocardiogram (ECG)

What part of an electrocardiogram (ECG) represents ventricular repolarization?

T wave

What allows the atria and ventricles to depolarize and contract separately?

atrioventricular (AV) node delay

Which of the following pacemaker cell populations has the slowest intrinsic rate of depolarization at about 20 times per minute?

Purkinje fiber system

QRS complex of ECG

represents ventricular depolarization

Q wave

is the first downward deflection after the P wave

R wave

large upward deflection

S wave

second downward deflection

the SA node generates an AP which speeds to

atrial cells and the AV node

after the AV node delay,

the AP is conducted to the AV bundle and then to the right and left bundle branches

the AP spreads from the bundle branches along the

Purkinje fibers to the contractile cells fo the ventricles

pacemaker cells

rhythmically and spontaneously generate Action potentials that trigger the other type of muscle cell, known as contractile cells, to also have action potentials

3 population of cells in heart that are capable of spontaneously generating action potentials and setting the pace of the heart

SA node

AV node

Purkiinje fibers

atrioventricular (AV) node delay

allows the atria and ventricles to depolarize and contract separately

when the impulse reaches the AV node, conduction slows considerably as a result of 2 conditions:

1. the lower number of gap junctions between AV nodal cells

2. the presence of the nonconducting fibrous skeleton that surrounds the AV node

AV node delay lasts for about

0.13 sec

the AV node delay allows for

-the atria to depolarize and contact before the ventricles, gibing the ventricles time to fill with blood

-also helps to prevent current from flowing backward into atria

what is the normal pacemaker of the heart

SA node

sinus rhythm

electrical rhythms generated and maintained by the SA node

plateau phase occurs when

depolarization is sustained at about 0 mV

refractory period

time during which an excitable cell cannot be stimulated to contract again

plateau phase is mostly because of

-the slow opening calcium ion channels and the resulting influx of calcium ions

-as the calcium ions enter, K+ ions leave so there is little net change in membrane potential

-the calcium ion channels are also slow to close, which allows the plateau phase to last much longer than the initial depolarization phase

depolarization phase of the heart occurs when

both the sodium and calcium ions return to their resting states and most of the K+ channels open (leaky at equilibrium)

3 components to Purkinje fiber system

1. AV bundle

2. right and left bundle branches

3. terminal branches of Purkinje fibers

the SA node is located in the

right atrium

Autorhythmicity in the heart is a function of ________.

cardiac pacemaker cells

What normally serves as the pacemaker of the entire heart?

SA node

Which of the following cardiac dysrhythmias is immediately life-threatening and manifests on the electrocardiogram (ECG) with chaotic activity?

a. atrial fibrillation

b. heart block

c. tachycardia

d. ventricular fibrillation

d. ventricular fibrillation

What obscures atrial repolarization on an electrocardiogram (ECG)?

QRS complex

which of the following structural components is only found in cardiac muscles?

a. sarcoplasmic reticulum

b. transverse tubules

c. striations

d. intercalated discs

d. intercalated discs

What is a contractile cell with a membrane potential of 0 mV experiencing?

plateau phase

Which of the following statements describes the total refractory period of cardiac muscle?

a. It is longer than the contraction of cardiac muscle.

b. It is longer than the total refractory period for skeletal muscle.

c. it is about the same as the total refractory period for skeletal muscle.

d. It is shorter than the total refractory period for skeletal muscle.

b. It is longer than the total refractory period for skeletal muscle.

The right and left atria depolarize and contract following the arrival of the action potential from the __________.

SA node