BMS 302 Exam 3

Source of calcium in skeletal muscle is

sarcoplasmic reticulum

Source of calcium in cardiac muscle is

sarcoplasmic reticulum and extracellular sources

The means of excitation for skeletal muscle is

nervous system

The means of excitation for cardiac muscle is

inherent contractions initiated by pacemaker cells

Innervation of skeletal muscle is through

somatic nervous system

Innervation of cardiac muscle is through

autonomic nervous system

Length of refractory period in skeletal muscle is approximately

2-3 msec

The length of refractory period in cardiac muscle is approximately

200 msec or more

Which ion is responsible for the long plateau phase of the ventricular muscle action potential?

Ca++

The long plateau phase of the fast response action potential of cardiac muscle:

-is responsible for long refractory period seen in cardiac muscle

-prevents cardiac muscle from tetanizing

-allows the heart to serve as a pump because the ventricles have time to fill with blood before another contraction can be induced

-keeps the cardiac muscle in the depolarized state so another contraction cannot be initiated until the heart has had tome to contract and refill

During the cardiac cycle, an extra systole can be induced by electrical stimulation during

relative refractory period

Autoregulation is a result of

starlings law

Starling's Law

-is the result of the length-force relationship also observed in skeletal muscle

-states that, within physiological limits, the heart pumps blood that returns it within each cycle

-is observed in the absence of any nervous or hormonal control

-can also be described as autoregulation

-is the result of cardiac fiber length being proportional to end-diastolic volume

-is demonstrated by an increased force of contraction with increased stretch of cardiac muscle

-is demonstrated by a decreased force of contraction with decreased stretch of cardiac muscle.

-is demonstrated when an increased venous return results in an increased cardiac output.

Starling's Law of the heart holds that the _____, the greater the force of the contraction

- greater the venous return

- greater the end-diastolic volume

- greater the length of myocardial fibers

The SA node is innervated by

both parasympathetic and sympathetic nervous systems

AV node is innervated by

both parasympathetic and sympathetic nervous systems

The atria are innervated by:

both parasympathetic and sympathetic nervous systems

The ventricles are innervated by

sympathetic nervous system only

Parasympathetic nervous system

- uses acetylcholine as a neurotransmitter

- function can be altered by cholinergic agonists and antagonists

-reduces hear rate via stimulation of SA node

-increases K+ permeability of cells in SA node

-makes membrane potential in SA node more negative

-hyperpolarizes the membrane potential in SA node

-decreases prepotential slope of slow response cardiac action potentials

-causes membrane potential to take longer to reach threshold

Sympathetic Nervous System

-uses norepinephrine as neurotransmitter

-function can be altered by adrenergic agonists and antagonists

-increases heart rate via stimulation of SA node

-increases Ca++ permeability of cells in SA node

-makes membrane potential in SA node less negative

-increases prepotential slope of slow response cardiac action potentials

-causes membrane potential to reach threshold faster

-stimulates ventricular muscle cells by increasing the rate of force development, rate of relaxation, and maximal force developed

The ____ nervous system increases the intracellular Ca++, which permits and more rapid and forceful contraction, _____ the rate of reuptake of CA++ by sarcoplasmic reticulum following contraction which _____ plateau phase of ventricular fast response action potential or QT interval making it possible to cause a _____ heart rate

sympathetic, increases, shortens, faster

Decreasing the temperature of the fluid bathing the pacemaker caused a _____ rate of contraction and ______ stroke volume

decreased, increased

True or False: Altering only the temperature of the fluid bathing the heart does not affect overall metabolic needs of an organism.

True

True or False: If overall metabolic needs of an organism are not affected, there is no need for CO to increase or decrease.

True

Decreasing the temperature of the fluid bathing the sinus venosus

-decreases heart rate

-decreases rate of diffusion of ions across the membrane during the prepotential

-makes the prepotential slope more shallow

-follows Fick's law of diffusion

Increasing the temperature of the fluid bathing the sinus venosus

-increases heart rate

-increases rate of diffusion of ions across membrane during prepotential

-makes prepotential slope steeper

-affects Fick's law of diffusion

Vagal Tone

-is a tonic stimulation by Parasympathetic Nervous System of SA node

-reduces the inherent rate of contraction by about 20-30 beats/min in humans

-affects the heart rate during rest and response conditions

Cutting the right vagus nerve

eliminates vagal tone and causes the heart rate to increase

Stimulation of the right vagus nerve innervating the turtle heart

causes the heart rate to decrease

Vagal arrest is the result of

-continuing vagal stimulation until the heart stops beating

-continuing vagal stimulation that causes the prepotential slope of action potentials in the sinus venosus to approach zero

-binding of large quantities of acetylcholine to cholinergic receptors in the sinus venosus

Vagal stimulation following the addition of atropine results in

no change in the heart rate

The effect of atropine is the result of:

cholinergic receptors being blocked by the atropine so acetylcholine cannot alter heart function

With an injection of epinephrine into the heart, heart rate and force of contraction (stroke volume) both increase, leading to an increased cardiac output. This is because

-increased heart rate helps compensate for the decreased stroke volume that can be the result of an increased heart rate which decreases filling time.

-ejection fraction increases when the ventricles are stimulated by the SANS and that helps keep stroke volume from falling due to the increased heart rate.

Which of the following statements are true for both increasing the temperature of the fluid surrounding the sinus venosus and stimulating the heart with epinephrine?

-heart rate increases

-filling time decreases

Systole

contraction phase of the cardiac cycle

Diastole

relaxation phase of cardiac cycle

Extra-extole

contraction induced by a stimulus applied during the relative refractory period of the cardiac cycle

relative refractory period

phase of cardiac cycle when supra-threshold stimulus can induce contraction

Non refractory

muscle is in polarized state with resting membrane potential of -85 mV

The compensatory pause is seen because

the wave of depolarization from the sinus venosus reaches the ventricular muscle during the absolute refractory period of the extra-systole

You are given a turtle heart preparation with the Stannius Ligatures I and II tied properly. You count the ventricular rate and find it tterm-42o be 12 beats per minute. Based on what you've learned, what rates might you expect to find for sinus venosus and atria, respectively?

20 beats/min, 15 beats/min

Stannius Ligature I

between sinus venosus and atria

Stannius Ligature II

between atria and ventricle

When Stannius Ligatures I and II are tied on a turtle heart, the ______ the lowest (shallowest) prepotential slope, the ______ an intermediate prepotential slope and the ______ the greatest (steepest) prepotential slope.

ventricles have, atria have, sinus venosus has

When taking a blood pressure, the first sound that you hear represents the _____, and is the pressure that is generated during _____.

systolic reading, contraction of the ventricles

Mean arterial pressure must be homeostatically maintained to

-insure adequate perfusion of all vascular beds and sufficient pressure so that the forces of gravity can be overcome

-to prevent one from passing out if the brain is insufficiently perfused

-to allow one to change positions such as going from reclining to standing without feeling faint

-through the baroreceptor reflex

As the heart to brain distance becomes greater, the MAP at the level of the heart _____ , while the MAP at brain level _____ when compared with different species.

increases, remains about the same

Mean arterial pressure =

(cardiac output)(peripheral resistance)

(stroke volume)(heart rate)(peripheral resistance)

(systolic pressure-diastolic pressure)/3 + diastolic pressure

Your subject has the following experimental data:

(1) heart rate of 69 beats per minute,

(2) a stroke volume of 72 milliliters per beat, and

(3) a peripheral resistance of 22 mm Hg . minute per liter.

Calculate their mean arterial pressure.

109

Given a systolic pressure of 110 mm Hg and a diastolic pressure of 71 mm Hg, calculate the mean arterial pressure (MAP) for a subject. Record your answer to the nearest whole number. Also include the units for MAP. HINT: If you do not know where to find the formula to answer this question, refer to the Experiment #10 index in your Lab Manual.

You Answered

84

Systolic blood pressure is reflected or influenced by _____, whereas diastolic pressure is reflected by _____.

cardiac output, peripheral resistance

You are measuring the blood pressure in a patient using a sphygmomanometer. You could detect an increase in venoconstriction by observing _____________, and you could detect an increase in vasoconstriction of the arterioles by observing ______________.

an increase in systolic pressure, an increase in diastolic pressure

If heart rate doubles and stroke volume doubles, cardiac output will

quadruple

Your subject has the following experimental data: (1) heart rate of 71 beats per minute (2) stroke volume of 71 ml /beat. Calculate his/her cardiac output in liters/minute. Record your answer to the nearest 1/10.

5

What factors can affect stroke volume

-end diastolic volume

-venous return

-heart rate

-ejection fraction

-ventilation

-exercise

-sympathetic stimulation

Venous valves

-prevent blood from pooling in the extremeities

-assist in reducing the effect of hydrostatic pressure

-when impaired are the cause of varicose veins

3 Mechanisms for the return of blood to heart form extremities

1. skeletal muscle pump

2. thoracic pump

3. venoconstriction

What facilitates venous return?

3 mechanisms, increase in venous tone, postural changes such as lying down with feet elevated, fainting

skeletal muscle pump

muscle contraction squeezes veins forcing blood back toward the heart past one way valves

thoracic pump

negative pressure in chest "pulls" blood into the thorax (and heart) with each inhalation

venoconstriction

smooth muscle in the elastic venous vessels contracts forcing blood from the venous system back toward the heart

What branch of the autonomic nervous system innervates the veins?

sympathetic

What autonomic output leads to venoconstriction?

increased sympathetic

What is the effect of venoconstriction on venous return?

increases

What autonomic output leads to venodilation?

Decreased sympathetic

What is the effect of venodilation on venous return?

decreases

Increased sympathetic activity stimulates the smooth muscle (effector) in the wall of the veins to ________ and therefore ______ the diameter of the vessel.

contract, decrease

3 factors that alter peripheral resistance

viscosity, length, diameter

What vessels play the most important role in altering peripheral resistance?

arterioles

Decreased sympathetic activity stimulates the smooth muscle (effector) in the wall of the veins to ________ and therefore ______ the diameter of the vessel.

relax, increase

Vasoconstriction of arterioles leads to

-increased mean arterial blood pressure

-increased peripheral resistance

-decreased diameter of blood vessels

-decreased blood flow "downstream" from the vasoconstriction

-increased diastolic pressure

What branch of the autonomic nervous system innervates the arterioles?

sympathetic

What is the effect of arteriolar vasoconstriction on peripheral resistance

increases

What autonomic output leads to arteriolar vasoconstriction?

increased sympathetic

What autonomic output leads to arteriolar vasodilation?

decreased sympathetic

What is the effect of arteriolar vasodilation on peripheral resistance?

decreases

Increased sympathetic activity stimulates the smooth muscle (effector) in the wall of the arterioles to ________ and therefore ______ the diameter of the vessel.

contract, decrease

Decreased sympathetic activity stimulates the smooth muscle (effector) in the wall of the arterioles to ________ and therefore ______ the diameter of the vessel.

relax, increase

Veins and arterioles are in a partially contracted state under rest and repose conditions.

-This state is called sympathetic tone.

-The partially contracted state is the result of a tonic sympathetic stimulation of the smooth muscle in the walls of the vessels.

Under Fight or Flight conditions:

-Increased Sympathetic Nervous System stimulation causes arterioles controlling blood flow to visceral organs to constrict.

-Blood flow to visceral organs decreases.

-Metabolic by-products from contracting skeletal muscle causes a local vasodilation of arterioles in skeletal muscle.

-Blood flow to active skeletal muscle increases.

During moderate exercise, systolic pressure increases because cardiac output _____ and diastolic pressure is maintained close to resting levels or decreases as blood flow to exercising skeletal muscle _____, and blood flow to the digestive tract _____.

increases, increases, decreases

Hypertension

-refers to high blood pressure

-can be diagnosed with repeated blood pressure measurements using a sphygmomanometer and stethoscope

-is diagnosed when blood pressure readings exceed 140/90

-can be treated with medication and life style changes, but not permanently cured

-has no symptoms in the early stages of development and goes unnoticed until damage to the cardiovascular system has occurred

Total Lung Capacity

IRV + TV + ERV + RV

Vital Capacity

IRV + TV + ERV

Functional Residual Capacity

ERV + RV

Inspiratory Capacity

TV + IRV

Tidal volume

amount of air inhaled per breath during normal breathing

Inspiratory reserve volume

amount of air that can be inspired above and beyond that inspired during a normal quiet inspiration

Expiratory Reserve volume

maximal amount of air that can be expired following a normal quiet expiration

Residual Volume

amount of air left in the lungs after a maximal expiratory effort

Tital volume at rest

0.5 liters

Total lung capacity in men

6.0 liters

Total lung capacity in women

4.6 liters

FEV3

>97%

BTPS refers to

body temperature, ambient pressure, saturated gas

A subject exhales 7.8 liters in one minute. The BTPS factor for the room temperature is 1.04. What is the subject's ventilation corrected for BTPS? Round your answer to the nearest 1/10.

8.1

Your subject has a forced vital capacity of 5.9 liters and a predicted vital capacity based on age, height and gender of 5 liters. What is their percent of predicted vital capacity? Record your answer to the nearest percent.

118

Calculate the volume in liters that a subject exhaled in one second if their vital capacity is 5.2 liters and their FEV 1 is 93 percent. Calculate to the nearest 1/10 liter.

4.8

Composition of room air

is 20.93% O2, 0.04% CO2, and 79% N2

Your subject has a total expired volume of air of 22 liters over 3 minutes (liters/3 minutes). You determine their breath rate to be 15 breaths per minute. Calculate his tidal volume in liters per breath. Record answer to the nearest 1/10 unit.

0.5