physiology Flashcards
(103 cards)
1
Q
define the ‘mean arterial pressure’
A
average arterial blood pressure over the entire cardiac cycle
2
Q
normal PH range
A
7.35-7.45
3
Q
factors that locally increase TPR
A
vasoconstrictors: angiotensin 2, adrenaline, sympathetic stimulation, endothelin-1, ADH
4
Q
factors that locally decrease TPR
A
vasodilators: hypoxia, atrial natriuretic peptide, H+, NO
5
Q
how to calculate stroke volume
A
end diastolic col - end systolic col
6
Q
how to calculate cardiac output (L/min)
A
stroke volume x heart rate
7
Q
What is the frank starling law
A
the stroke volume of the heart increases in response to an increase in the volume of blood filling the heart (the end diastolic volume) when all other factors remain constant.
8
Q
what is epinephrine
A
adrenaline: a hormone that stimulates the fight/flight response
9
Q
what does viscosity mean
A
thickness and stickiness of blood
10
Q
summarise the depolarisation of the heart
A
depolarisation initiated the SAN. spreads across atria causing atrial systole. depolarisation delayed at the AV node in order for full atrial contraction to occur. depolarisation spreads down bundle of his and its branches. purkinje fibres distribute the impulse to the work cells in the endocardium. impulse spreads to epicardium to depolarise whole ventricles.
11
Q
what causes the first heart sound
A
closure of the AV valves
12
Q
what causes the second heart sound
A
closure of semilunar valves
13
Q
what is stenosis?
A
stiff heart valves, values fail to open enough so limited blood flow
14
Q
what is incompetence?
A
valves do not close properly so blood leaks back. called regurgitant flow
15
Q
what does the P wave represent and how long does it take
A
atrial depolarisation - 0.08-0.1 s (P)
16
Q
what does the QRS complex represent?
A
ventricular depolarisation - 0.06-0.1 s
17
Q
what does the T wave represent?
A
repolarisation of the ventricles
18
Q
how long does the P-R interval take?
A
0.12-0.2 s
19
Q
sympathetic innervation of the heart and its neurotransmitters
A
spinal cord - ACh and noradrenaline
20
Q
parasympathetic innervation of the and its neurotransmitters
A
vagus - ACh and ACh
21
Q
what are inotropes and chronotropes
A
inotrope - and agent that affects the force of contraction. chronotrope - affects heart rate
22
Q
examples of inotropes
A
adrenaline, noradrenaline, dopamine
23
Q
examples of chronotropes
A
acetylcholine, veramapril, metoprolol
24
Q
what is preload?
A
the stretch of the sarcomeres just prior to the initiation of contraction. greater the stretch, the greater the contract due to higher availability for actin/myosin cross bridges
25
what is afterload?
tension/stress developed in the wall of the left ventricle during ejection. or the 'load' the heart is having to eject against.
26
What are arterial baroreceptors and where are the found?
They detect blood pressure and relay this info to the brain. they are either in the carotid sinus or the aortic arch.
27
how do baroreceptors work?
Baroreceptors are located in the aortic arch and carotid sinuses. They detect stretch in the arterial walls and send impulses to the CV centre in the medulla oblongata which regulates bp.
28
how do chemorecptors work and where are they located\?
They are in the carotid and aortic bodies. They detect changes in O2/CO2 and send signals so that sympathetic/parasympathetic innervation of the heart takes place accordingly.
29
short/long term control of bp.
short term = baroreceptors. long term = kidneys and RAAS system.
30
describe the sympathetic innervation of the heart
innervation is via the spinal nerves. They act on beta-adrinergic receptors in the cardiac muscle
31
describe the parasympathetic innervation of the heart
parasympathetic fibres terminate in the cells of the atria. they release ACh which acts on muscarinic receptors
32
what is the function of capillaries?
exchange of substances required for metabolism. uptake of 02 and nutrients and expulsion of CO2 and waste products
33
name some plasma proteins and their functions?
albumin - retains oncotic pressure so that water stays in blood vessels and blood pressure is retained. immunoglobins (antibodies) and produced by white blood cells and recognise specific antigens on bacteria/viruses. critical part of immune response.
34
phases of electrical conduction in the heart.
0 - rapid depolarisation (Na in), 1 - initial repolarisation (CL- and K+ in) 2 - plateau stage prevents depolarisation happening too quickly (Ca2+ in, K+ out), 3 - main stage of repolarisation (K+ out), 4 - quiet phase
35
what does troponin-I do
holds the troponin-tropomyosin complex in place
36
what does troponin-C do
binds to ca2+ which deforms the configuration of troponin-I which consequently breaks off of actin
37
what does troponin-T do
binds to tropomyosin to create a tropomyosin-troponin complex
38
where is ca2+ released from during contraction
sarcolemma and t-tubules
39
describe what is happening during muscle contraction
a wave of depolarisation arrives at the cell. ca2+ diffuses into the t-tubules to go into the cell. sarcoplasmic reticulum released ca2+. ca2+ released into the sarcolemma by t-tubules (unique to heart) and sarcoplasmic reticulum. ca2+ diffuses into myofibrils and binds to troponin C, making the myosin binding site open. actin heads bind to myosin sites to create cross bridges, and contraction begins. ATP used to 're-cock' heads.
40
what is Ohm's law?
flow(Q) = pressure gradient(triangleP)/resistance(R)
41
what is Poiseuille's law?
Q=r squared. volume flowrate is given by the pressure difference divided by the viscous resistance.
42
what is the equation for pulse pressure?
pulse pressure = systolic - diastolic pressure
43
what is the equation for BP?
CO x TPR.
44
what is contractility?
the force of contraction for a given lengths fibre
45
what is compliance
the ability of a vessel or organ to distend and increase volume
46
how long is diastole and how long is systole? (normal heart rate)
0.5 s and 0.3 s
47
how is CO2 carries in the body?
bound to haemoglobin, dissolved in plasma, as carbonic acid
48
what does phospholamban do
regulares Ca2+ pump in cardiac and skeletal cells
49
if you are blood group O, what antibodies do you have?
A and B, so cannot accept these blood groups in transfusions
50
What does Rhesus blood group mean?
You can also have an Rhs antigen on your blood cells. if you are Rhs positive, it means that you do not have Rhs antibodies, and cal accept Rhs positive blood. If you are Rhs negative, you cannot accept Rhs positive blood.
51
what are type 1 and type 2a and 2b fibres.
type one are slow twitch. they use oxygen as a source for energy so they are darker due to the higher number of blood vessels running through them, they are fatigue resistant. type 2a are moderately fast, they use oxygen and glycogen as energy, and are moderately fatigue resistant. type 2b are fast twitch fibres and are susceptible to fatigue as they use a lot of energy very quickly from glycogen stores. they are pale.
52
what are herring bodies?
they mark the terminal end of the axons from the hypothalamus and hormones are temporarily stored here
53
what are the 3 layers of the heart wall? what is each of their functions?
epicardium = serosa lining the outer layer of the heart. secrete fluid into the pericardial cavity. myocardium = cardiac muscle surrounding heart. endocardium = lines valves, tendons, papillary muscles, similar to endothelium of blood vessels.
54
what are the functions of the CV system?
rapid transport of nutrients, removal of waste products, hormonal control, temperature regulation, reproduction (erection of the penis), host defence.
55
how is the movement of blood aided in veins?
one way valves.
56
what does the superior/inferior compartment of the mediastinum contain?
superior = anteriorly, the thymus. posteriorly, the great vessels, oesophagus, trachea and thoracic duct. inferior = anteriorly, the thymus. posteriorly = heart, oesophagus,
57
what does the thymus do?
training and development of T cells.
58
what is the base of the pericardium fused to?
the central tendon of the diaphragm.
59
what is the base of the heart formed by?
left atrium
60
what is the sternocostal surface formed by?
right ventricle.
61
what is the diaphragmic surface formed by?
right ventricle and left ventricle.
62
what is the pulmonary surface formed by?
left ventricle.
63
when does the heart begin to pump?
week 4.
64
when do the 4 chambers form?
week 5-8
65
where does the heart derive from?
mesoderm
66
how much pericardial fluid is there? what is its function?
50ml. prevents friction, shock absorption.
67
where is ANP from?
atrial myocardium.
68
what are the 3 layers of the endocardium?
outer most layer of connective tissue and nerves etc. middle layer of connective tissue and innermost layer of endothelial cells.
69
why is important to know that the valves are avascular?
no fight against bacterial infection.
70
what are the 3 types of myocyte?
work myocytes = main contractile cell. nodal = generate cardiac impulses. conduction = fast conduction of action potentials.
71
what are the relative concentrations of Na, K and Cl in the ECF and ICF?
ECF = 140, 5, 120 mmol/L. ICF = 5, 140, 30 mmol/L
72
why do we need the cardiac myocyte plateau phase?
retain contraction so that maximum blood volume is squeezed out of the heart.
73
how is the wave of depolarisation halted at the AV node? how much by? and why?
0.1 s. the depolarisation of nodal cells is due to L-type calcium channels which are slower to depolarise than Na channels. therefore, the depolarisation's halted to allow full contraction of the atria and filling of the ventricles.
74
how long are all the phases of the ECG?
P wave = 0.08-0.1s. QRS = 0.06-0.1s. PR = 0.12-0.2. Q-T = 0.4
75
what are the two types of Calcium channel?
L- type long lasting. and T type transient.
76
what is isovolumetric contraction?
the phase at the start of systole where the ventricles are contracting but both values are shut so ventricular pressure rises and focus the AL valves to open.
77
what is isovolumetric relaxation?
the phase at the start of diastole where the ventricles are relaxing but both valves are shut and the low pressure of the ventricles forces the AV valves open.
78
how much is end systolic vol? why?
50%. allows for higher stroke vol if needed.
79
what are the 5 phases of the cardia cycle?
ventricular filling during atrial systole. isovolumetric contraction. ejection. isovolumetric relaxation. passive ventricular filling
80
when does the mitral valve close?
at the start of isovolumetric contraction.
81
when does the aortic valve open?
at the end of isovolumetric contraction.
82
when does the aortic valve close?
at the end of ejection and start of isovolumetric relaxation.
83
when does the mitral valve open?
at the end of isovolumetric relaxation.
84
explain the physiology behind nodal myocyte depolarisation?
the resting pressure is unstable. it is gradually depolarisating due to open Na+ channels and T-type Ca channels. once is reaches threshold at -40mV, Ca L-type channels open and depolarisation occurs slower than myocyte. K+ channels then open at 0mV and depolarisation occurs. the unstable resting potential causes this to repeat and gives the SAN and AVN automaticity.
85
what is automaticity?
cells ability to produce spontaneous and rhymic self-generating action potentials.
86
what is a chronotrope/isotrope?
C = increases/decreases HR. I = increases/decreases force of contraction.
87
give examples of positive inotropes.
the increase cytosolic Ca2+ levels. e.g. noradrenaline activates more Ca2+ channels.
88
give examples of negative inotropes.
inhibit Na/K+ ATPase so slows Ca/Na exchange.
89
what is excitation-contraction coupling?
converting an electrical stimulus into a mechanical response.
90
what are the 4 heart sounds?
closure of AV valves. closure of SL valves. rapid flow of blood into ventricles passively during diastole. rapid flow of blood into ventricles during atria systole.
91
what is preload?
the end diastolic pressure. pressure inside the left ventricle prior to the initiation of ejection.
92
what is afterload?
the force against which flood is ejected form the left ventricle.
93
what is the septomarginal trabeculum?
contains the right bundle so allows depolarisation to spread across to the other side of the atria. allows contraction of the anterior papillary muscles.
94
what is MAP?
diastolic pressure + 1/3 pulse pressure.
95
how does blood stay liquid?
clotting factors staying inactive. endothelial cells are a natural anticoagulant.
96
what is myogenic?
smooth muscle in blood vessels respond to changed in blood pressure.
97
where is lead 1?
right sternal 4th intercostal
98
V1 and V2
inversed QRS.
99
AVr
everything is flipped.
100
describe the stages of a platelet plug.
break in the endothelium. collagen is exposed.
101
elasticity?
the ability of tissue to recoil.
102
what is ryanodine?
Ca2+ comes in from depolarisation and then goes into the t-tubules to the sarcoplasmic reticulum and binds to the ryanodine receptor on the membrane which causes an flux of Ca2+ into the cell.
103
elastic fibres in the sarcoplasmic reticulum?
titin.
