case 2 Flashcards
1
Q
right side heart
A
receives oxygen-poor blood.
blood vessels carry blood to/from the lungs –> pulmonary circuit
2
Q
left side heart
A
receives oxygenated blood.
blood vessels that carry blood to/from body tissue –> systemic circuit
3
Q
heart bigger structures
A
left + right atrium
left + right ventricles
enclosed within mediastinum
4
Q
pericardium
A
double walled sac enclosing the heart
5
Q
fibrous pericardium
A
loosely fitted superficial part
- protect, anchor and prevent overfilling
6
Q
serous pericardium
A
two layer membrane, froms sac around heart
- parietal layer: lines internal surface of fibrous. attaches to large arteries and turn inferiorly and continues
- -> visceral layer (epicardium). essential part.
7
Q
pericardial cavity
A
between parietal and visceral layer. contains serous fluid.
8
Q
epicardium
A
superficial, visceral layer of pericardium.
–> infiltrated with fat
9
Q
myocardium
A
middle layer.
- -> cardiac muscle, biggest part
- -> contracts, spiral of circular bundles.
10
Q
cardiac skeleton ( myocardium)
A
connective tissue fibers –> strengthens myocardium + anchors muscle fibers.
limits spread of action potentials
11
Q
endocardium
A
inside layer, white squamous epithelium.
- -> resting on connective tissue + covers fibrous skeleton of valves.
- continuous
12
Q
Chambers
A
- 2 atria
- 2 ventricles
- -> separation longitudinally: interatrial septum (separates atria)
- -> interventricular septum (separates ventricles)
13
Q
Grooves that indicate boundaries –> sulcus
A
- coronary sulcus: encricles junction of atria + ventricles.
- anterior interventricular sulcus: cradling the anteror interventricular artery –> continues as posterior.
14
Q
Right atrium
A
two parts: - smooth walled: posterior - anterior, muscle forms ridges --> pectinate muscles regions separated by crista terminalis --> C-shaped ridges
15
Q
Left atrium
A
- mostly smooth.
interatrial septum bears shallow despression –> fossa ovalis. (opening fetal heart)
16
Q
function atria
A
receive blood returning to heart. thin walled.
17
Q
right atrium blood vessels
A
- superior vena cava –> above diaphragm
- inferior vena cava –> below
- coronary sinus –> myocardium
18
Q
Left ventricle
A
dominates posteroinferior surface
19
Q
Trabeculae carneae
A
irregular ridges of muscle, mark walls of ventricles
20
Q
papillary muscles
A
play a role in valve function
21
Q
right ventricle
A
pumps blood into pulmonary trunk
22
Q
left ventricle
A
pumps blood into aorta
23
Q
atrioventricular (AV) valves
A
located at atrial-ventricular junction
function: prevent backflow into atria.
- -> chordae tendinae (collagen cords) attached to flap. anchor susps to papillary muscles
24
Q
right AV
A
tricuspid valve
–> 3 flexible cusps
25
left AV
```
mitral valve (bicuspid)
--> two flexible cusps
```
26
How do AV valves work?
relaxed: AV flaps hang into ventricles.
| - -> contraction ventricles: pressure rises forcing blood superiorly against valves. flaps close.
27
semilunar (SL) valves
aortic and pulmonary valves.
| function: prevent backflow.
28
How do SL valves work?
ventricles contract --> pressure rises above aorta and pulmonary trunk.
valves are forced open.
ventricles relax --> cusps filled and valves closed.
29
coronary arteries
left + right coronary arteries, encircle heart in coronary sulcus.
30
left coronary artery
two branches:
- anterior interventricular artery: follows sulcus and supplies to septum and anterior walls of ventricles
- circumflex artery: supplies left atrium + posterior walls ventricles
31
right coronary artery
two branches:
- right marginal artery: serves myocardium lateral side
- posterior interventricular artery: heart apex and supplies posterior ventricles. merges with anterior interventricular artery
32
coronary veins
after myocardium blood is here collected.
| veins join to enlarged vessel: coronary sinus.
33
coronary sinus
```
3 tributaries:
- great cardiac vein
- middle cardiac vein
- small cardiac vein
several anterior cardiac veins empty directly into atrium
```
34
cardiac muscle cells
self-excitable.
can initate depolarization + rest of the heart in sponaneous and rhythmic way
--> autmaticity
1% is autorhythmic
35
myogenic
functions in ordered rhythmic fashion because of inherent properties of cardiac muscle rather than specific neural stimuli
36
contraction heart general
either all fibers contract of nothing.
| --> gap junctions
37
how does contraction happen?
triggered by action potentials.
| heart muscle does not depend on NS.
38
cardiac pacemaker cells
make up intrinsic conduction system. unstable resting potential
- -> continuously depolarizing.
- -> pacemaker potentials
39
places where pacemaker cells are found
1. sinoatrial node
2. atrioventricular node
3. atrioventricular bundle
4. right + left bundle branches
5. subendocardial conducting network
40
sinoatrial (SA) node
located in right atrial wall. genrates 75 impulses/min.
sets pace for the heart. no other region has a faster depolarization rate.
--> hearts pacemaker + sinus rhythm.
41
atrioventricular (AV) node
depolarization spreads via internodal pathway to AV node.
location: in inferior portion of interatrial spetum (above tricuspid)
- impulses delayed for 0.1 s --> atria can complete contraction.
42
atrioventricular (AV) bundle
impulse sweeps to AV bundle (bundle of His).
| location: superior part of interventricular septum
43
bundle of his branches
right and left bundle branches
44
subendocardial conducting network
long strand cells with few myofibrils --> Purkinje fibers.
through interventricular septum.
total time: 0.22 s
45
cardioinhibitory center
sends impulses to parasympathetic dorsal vagus nuclues --> medulla.
sends inhibitory impulses to heart via vagus nerves
46
cardiac cycle
all evetns associated with blood flow through the heart during one complete heartbeat
- artrial systole + diastole + ventricular systole + diastole
47
ventricular filling: mid-to-late diastole
blood flows passively through atria and open AV valves into ventricles.
--> atria contract: rise in pressure, proprels blood ouf tof atria into ventricles
48
ventricular systole
ventricles contract, walls close in on blood. pressures rises --> closing AV valves. split second ventricles are closed chambers. --> isovolumetric contraction phase
49
isovolumetric relaxation: early diastole
ventricles relax. end systolic volume (ESV) no longer compressed, pressure drops and blood in aorta and pulmonary trunk flow back--> closing SL valves
50
heart sounds
1st: tricuspid + mitral
2nd: pulmonary and aortic valves
heart sound: phonocardiogram
51
pressure volume curve:
stroke volume: EDV (end diastolic volume - ESV ( end systolic volume)
52
stroke volume factors:
contractility
preload
afterload
53
contractility (stroke volume)
inotropy --> ability of heart muscle to contract.
increasing: though influx of Ca2+ or maintaning Ca2+ levels.
increases slope and shifts ESV to the left
--> permits ventricles to generate more pressure. also increases ejection velocity --> increase stroke volume.
54
preload (stroke volume)
left ventricular wall stress at ED.
increase: increase in stroke volume, cardiac output + arterial pressure.
--> increasing end-systolic volume
increased afterload reduces velocity of fiber shortening and ejection velocity.
55
afterload (stroke volume)
pressure required to open aortic valve. , stroke volume is reduces and ESV increased. if afterload is decreased --> stroke volume increases and EDV decreases
56
Blood volume
determined by water + sodium.
| mainly regulated by kidneys
57
increase blood volume
- increases central venous pressure
increases right atrial pressure + right vetricular EDV and volume.
--> increase in ventricular preload increases stroke volume by Frank-Starling mechanism.
- increase in right ventricular stroke volume: increase in pulmonary venous bloof flow to left ventricle, increasing left ventricular preload + stroke volume --> decrease cardiac output + arterial blood pressure
58
ANS influence on the heart
- emotional/physical stress --> activate SNS --> norepinephrine: binds to B1-adrenergic receptors. SA node fires more rapidly
- enhances contractility + speed relaxation. enhancing Ca2+ movement.
movement in contractile cells lower ESV.
- parasympathetic: mediated by acetylcholine, hyperpolarizes membrane via opening K+ channels.
- rest: autonomic divisions send impulses to SA node, dominant influence is inhibitory. the heart is vagal tone, heart rate is generally slower.
59
nicotinic acetylcholine receptors
respond to acetylcholine, drugs --> nicotine. primary receptor in muscle for motor nerve-muscle communication that controls contraction.
activation --> depolarization of plasma membrane. leads to regulation of genes or release of neurotransmitters
60
muscarinic acetylcholine receptor
work with G-proteins
act as main end-receptor stimulated by acetylcholine . more sensitive to muscarine than to nicotine. activation: resulsts in inhibiting/ exciting of postsynaptic neurons
--> parasympathetic nervous system.
61
adrenergic receptors
alfa + beta. targets of noradrenaline + adrenaline. stimulate SNS.
alfa: vasoconstriction + descreased motility of smooth muscle in GI
beta 1: increase cardiac output via increasing heart rate, conductiong velocity, stroke volume + rate of relaxation, by increacing Ca2+ concentration.
62
dobutamine
drug used in treatment of heart failure. direct stimulation of B1-adrenergic receptors of SNS, causing threshold to be reached faster. increase in heart rate + cardiac output.
