BMS1054 Previous Questions

L-type calcium channels in the cardiac ventricular muscle

- They are open during the plateau phase of the action potential - They allow calcium entry that triggers sarcoplasmic reticulum calcium release - They are found in the T-tubule membrane

How do the valves keep blood moving in one direction?

- vents contract and pressure rises in the vents - natural tendency for block to backflow/regurg to the atria - papillary muscles contract, placing tension on the chordae tendineae, which holds the AV valves in place to prevent the valves from prolapsing and being forced back into the atria/ - Semilunar valves lack chordae tendineae and papillary muscles, but do not face the same pressure gradients as do the AV valves. - Vents relax and pressure drops within the vents, there is tendency for blood to flow backward. - But the valves (made from endothelium and connective tissue)_ fill with blood and seal off the opening preventing the return of blood.

How many lobes if the left lung made of?

2

Cardiac muscle cells, what percentage of cytoplasmic Ca2+ required for the contraction is released from the extracellular fluid?

20%

How many lobes if the right lung made of?

3

The right AV valve has how many cusps?

3

In a resting person, what % of total blood volume can be found in all capillaries?

5%

In a resting person, what % of total blood volume can be found in the venous system?

65%

Cardiac muscle cells, what percentage of cytoplasmic Ca2+ required for the contraction is released from the sarcoplasmic reticulum?

80%

The region within the sarcomere unit, representing the length of the thick filaments

A band

During the process of excitation-contraction coupling in cardiac muscle, calcium is released from the sarcoplasmic reticulum primarily by...

An increase in intracellular Ca2+ conc

The one-way valve that separates the LV from the aorta

Aortic valve

Which septum normally has openings in the adult?

Atrioventricular septum

Which conductive fibres of the heart originate in the AV node and pass through the cardiac skeleton

Bundle of His

What ionic influxes are most responsible for a decreased HR and decrease in myocardial fibre contractility?

Calcium influx

How do cardiac muscles differ from skeletal muscles?

Cardiac have intercalated discs

Cells are known as the primary pacemakers of the heart

Cells of the SA node

Conductive tissues of the heart, only these cells can directly stimulate cardiac myocytes to contract

Cells of the SA node

Which ligaments prevent the eversion of AV valves during ventricular systole

Chordae tendineae

1. Which of the following is not important in preventing backflow of blood? - chordae tendineae - papillary muscles - AV valves - endocardium

Endo cardium

Which layer of the heart secretes chemicals that help to regulate ionic environments and strength of contraction and serve as powerful vasoconstrictors?

Endocardium

True or False: smooth muscle consists of regular arrangement of actin and myosin

F

Atrial myocytes are electrically coupled via what?

Gap junction channels

Inactivation of the sodium-potassium pump will cause what in cardiac muscle

Inactivation of the Na/Ca exchanger

What hormonal changes occur from blood loss?

Increased angiotensin II

The channel responsible for the initiation of the spontaneous depolarisation in phase 4 of the SA nodal cells exhibits what property

It is primarily permeable to Na+

Where is the myocardium thickest?

LV

The highest hydrostatic BP is found in the

LV during atrial systole

What is the pulse pressure in the ascending aorta directly proportional to?

LV stroke volume

Cardiac valve separates the LA from the LV

Left AV valve/Bicuspid valve/Mitral valve

Hilus of the lung is on which aspect of the lung?

Medial

Which valve separates the LA from LV?

Mitral/bicuspid

Pacemaker potentials of the heart result from

Na+ influx, opening of the If channels

The spike phase of the action potential of the SA node pacemaker cells of the heart is caused by:

Opening of voltage gated Ca2+ channels

Fast response cardiac- describe the 4/5 phases#/ What ion channels are permeable during each phase?

Phase 4: resting potential (K+ open)

During a cardiac myocyte contraction, some Ca2+ comes from the extracellular fluid. During relaxation, Ca2+ will have to be extruded from the cell.. Most of the Ca2+ is removed from the cell due to the activity of the...

Plasma membrane MA+/Ca2+ exchanger

The upstroke of the SA nodal action potential is produced by opening of a channel that is

Primarily permeable to Ca2+

Blood oxygen content is lower in the pulmonary artery or the pulmonary vein?

Pulmonary artery

Which one-way valve separates the RV from the pulmonary artery

Pulmonary semilunar

Cardiac valve separates the RA from RV

Right AV valve/ tricuspid valve

Sequence of action potential conduction along the conductive tissues of the heart

SA, AV, BoH, Bundle Branches, Purkinje

What action do the ventricular myocytes do when the ventricle contracts?

Simultaneous single twitches

How are skeletal muscle cells and cardiomyocyte different in their nervous systems?

Skeletal muscles are individually innervated, whereas cardiomyocytes aren't

Why is pressure in the pulmonary circulation lower than in the systemic circulation?

The pulmonary circuit consists of blood flowing to and from the lungs, whereas systemic circuit carries blood to and from the entire body. - Systemic more extensive, more vessel and greater resistance to the flow of blood, so heart generates higher pressure to overcome this resistance. - Seen in the thickness of the myocardium in the vents.

Ca2+ binds with this molecule, leading to exposure of cross-bridge binding sites

Troponin

The sarcomere: the thin filament of muscle fibres are made of what protein?

actin

In SA node, phase 4 depolarisation is attributable to

an increase in Na+ conductance

Turbulent blood flow is...

audible

when we inhale

both alveolar pressure and intrapleural pressure decrease

how are cardiac and skeletal muscles similar?

both have striations

Which element is important in directly triggering contraction?

calcium

the sliding filament model states that binding sited on actin open when?

calcium ion levels rise

Muscle relaxation occurs when

calcium ions are actively transported into the sarcoplasmic reticulum

which muscles consist of intercalated discs?

cardiac

Function of smooth muscle

contract relatively slowly in a controlled manner

during which phase of a twitch in a muscle fibre is tension the greatest?

contraction phase

during internal and external respiration, gases move by

diffusion

muscle fatigue is caused by

exhaustion of energy reserves and buildup of lactic acid levels

volume of air that can be exhaled after normal exhalation

expiratory reserve volume

Correct order smallest to largest unit of organisation in muscle tissue

filament, myofibril, muscle fibre, fascicle

Ventricular myocytes are electrically coupled via what?

gap junction channels

During the plateau phase of the cardiac action potential, membrane permeability to K+ is....

higher than its resting value

The bronchi enter the lungs at the ________

hilus

exchange of gas between blood and cells is called

internal respiration

Venous blood is referred to deoxygenated blood because...

its O2 content is lower than the O2 content of arterial blood

smooth muscles differ from skeletal and cardiac muscles in that they

lack myofibrils

What affects LV diastolic filling?

mitral stenosis- rheumatic heart disease

Thin and thick filaments are organized into functional units called ________.

myofilaments

the thick filaments of muscle fibres are made of which protein?

myosin

Which part of the respiratory tract does the eustachian tube open?

nasopharynx

Parasympathetic stimulation of the heart has a

negative chronotropic effect

In atrial systole, the AV valves are...

open

Ventricular diastole, AV valves are...

open

The plateau phase of the cardiac action potential is due to __________.

opening of voltage-gated Ca2+ channels

What membranous sac encloses the heart?

pericardium

correct order of structures in the respiratory passageway

pharynx, larynx, trachea, bronchi, bronchioles

Sympathetic stimulation of the heart has a

positive inotropic effect

Which structure is the most common site of impaction of an aspirated foreign body due to its anatomical predilectation?

right main bronchus

Cell membrane of a muscle fibre

sarcolemma

Laminar blood flow is...

silent

If cardiac muscle cells were prevented from undergoing aerobic metabolism, they ultimately would ________.

stop contracting

What is the ultimate result if cardiomyocytes were prevented from undergoing aerobic metabolism?

stop contracting

Depolarisation of the sarcolemma means...

the inside of the membrane has become less negative as sodium ions accumulate

When the diaphragm and external intercostal muscles contract

the intrapleural pressure increases

Valve pathway of blood from the vena cava

tricuspid, pulmonary valve, mitral, aortic

In relaxed muscle, Myosin-binding site on actin is blocked by

tropomyosin

Nose functions

warms, cleanses, and humidifies air acts as a passageway for air movement