問題一覧
1
blood flows through a network of blood vessels that extend from the ? to the peripheral tissues
heart
2
blood is carried away from the heart by
arteries
3
capillaries are often called ? as their thin walls permit exchange of nutrients, dissolved gases and waste products between the blood and surrounding tissue
exchange vessels
4
how many muscular chambers does the heart contain
4
5
the right atrium passes blood to the right ventricle, which pumps blood into the
pulmonary circuit
6
the left atrium empties blood into the left ventricle, which pumps blood into the
systemic circuit
7
when the heart beats, the ventricles contract at the same time and the right ventricle ejects a ? amount of blood than the left ventricle
equal
8
the heart has a series of ? valves
one way
9
the right atrioventricular (AV) valve is known as the
tricuspid valve
10
semilunar valves include
aortic valves
11
blood from the systemic circuit flows through the venae cavae into the
right atrium
12
which type of cells control and co ordinate heartbeat
cells of the conducting system
13
each heartbeat begins with an action potential generated at a pacemaker called the
simpatico (SA) node
14
electrical events of the conducting system can be monitored from the surface of the body by means of an
electrocardiogram (ECG)
15
the arrival of an electrical impulse at a cardiac muscle cell membrane produces an ?, and this triggers the contraction of the cardiac muscle cells
action potential
16
the period between the start of one heartbeat and the start of the nest is called the
cardiac cycle
17
in contrast to skeletal muscle, cardiac muscle tissue contracts
on its own
18
the cardiac conduction system contains each of the following elements except
contractile cells
19
the conducting cells in the atria are found in
internodal pathways
20
each time the heart beats, a wave of depolarisation travels down the ventricular septum to the apex of the heart, from where it spreads through the ventricular
myocardium
21
the electrical activity of the heart can be monitored by means of a graphical recording, which gives information on performance off each of the following specific components except
neural
22
which appears as the ventricles depolarise
QRS complex
23
the P-R is the time from the start of ? to the start of the QRS complex and extension by even 0.2 sec can indicate damage to the conducting pathways or the atrioventricular (AV) node
atrial depolarisation
24
the Q-T interval indicates the time required for the ventricle to undergo a single cycle of depolarisation and repolarisation and extension may indicate all of the following
cardiovascular fitness
25
the action potential in a contractile cell is different than that observed in a skeletal muscle cell in that it has each of the following distinct steps except
synaptic phase
26
an action potential begins when the membrane of ventricular muscle cell reaches threshold (-75 mV) from the resting potential of -90mV l, this results in opening of
fast sodium (Na+) channels
27
the plateau phase of a cardiac action potential last for
175 sec
28
at the end of the plateau phase potassium (K+) channels open leading to a rapid repolarisation that restores
resting potential
29
In the cardiac cycle a phase of contraction is known as
systole
30
systole is followed by ? during which the chamber fills with blood
diastole
31
there are ? heart sounds
4
32
cardiodynamics is not dictated by which of the following factors
glomerular filtration rate (GFR)
33
cardiac output is an indication of blood flow through peripheral tissues and provides a useful indication of
ventricular efficiency
34
an increased heart rate is primarily caused by which one of the following
increased activity of sympathetic nerves to the heart
35
an increased stroke volume is primarily caused by
increased and end diastolic ventricular volume
36
? is calculated as the end diastolic volume (EDV, 135 ml) minus the ene systolic volume (ESV, 65 ml)
stroke volume
37
the wne systolic volume (ESV) is influenced by each of the following except
conductivity
38
pressure within the cardiovascular system, the circulatory pressure is often divided into each of the following components except
hydrostatic pressure
39
for circulation to occur the pressure gradient must be great enough to overcome the
total peripheral resistance
40
blood flow is determined by each of the following parameters except
vessel length
41
which features of arteries act to reduce the fluctuations in blood pressure caused by the heart beat
internal elastic membrane and smooth muscle
42
what mechanisms are responsible for movement of blood in the venous system of the lower limbs
one way valves and venous compression caused by skeletal muscle action
43
which chambers of the heart are directly connected? right atrium, right ventricle, left atrium or left ventricle
RA and RV; LA and LV
44
why is the left ventricle more muscular than the right ventricle
because the LV must overcome the total peripheral resistance of the much larger systemic circuit
45
what is the effect of neural inputs to the heart
change the rate of spontaneous contraction
46
what molecular mechanism is responsible for the plateau phase of the action potential in cardiac muscle
slow opening of Ca2+ channels
47
what molecular mechanism prevents tetanic contraction of cardiac muscle
the absolute refractory period is as long as the duration of contraction
48
which of the following will increase the heart rate
increased Na+ leakage
49
which structures ensure the rapid and accurate spread of excitation through cardiac muscle
the conducting system and gap junctions between individual cardiac muscle cells
50
what would be the effect on the heart of the vagus nerve were cut
heart rate will increase
51
the reduced oxygen level at high altitudes will have which effect on cardiac activity
general depression of cardiac activity
52
during heavy exercise, if the heart rate were to exceed ca. 180 bpm, the pumping action of the heart would become inefficient, why?
because there is not enough time for the cardiac chambers to fill with blood
53
what is the bainbridge reflex
increase in venous return stretches the nodal cells, which increases the heart rate
54
why does increased rigidity of blood vessels (atherosclerosis) increase blood pressure
increases total peripheral resistance
55
what May cause excessive turbulence in blood vessels
deformation of part of the blood vessels
56
which of the following may increase blood viscosity
dehydration
57
which of the folllwing responses to a change in blood volume directly involved the heart
increased venous return causes release of atrial natriuretic peptide (ANP), which reduces blood volume
58
beta blockers are drugs that reduce blood pressure. in the heart, they act as
antagonist of adrenaline and noadrenaline
59
during the fight or flight response, sympathetic activity changes the distribution of blood as follows
increased blood flow to skeletal muscle and brain, reduces flow to skin and internal organs
60
what molecular mechanisms is responsible to the spontaneous generation of action potentials in cardiac muscle
na+ leak channels