Cardiovascular System Flashcards
1
Q
What is the Role of the Cardiovascular System?
A
- Primarily transport for cellular respiration
- Mediated by perfusion of around 40 billion capillaries
- supply cells with oxygen and nutrients
- removes waste e.g. CO2
- heat regulation
- endocrine hormonal transport
- immune function supply
- regulation of blood volume
2
Q
What is the cardiovascular system composed of?
A
- Heart
- Pulmonary circulation
- Systemic circulation
Supplies cells with nutrients and oxygen, matches demand output of pulmonary = input of systemic
3
Q
What is the circulatory system composed of?
A
- Heart pumps blood through two seperate circulatory systems
- systemic circulation = LH of body
- pulmonary circulation = RH of body
- both systems are interconnected so a problem with blood flow affects the other
- blood always moves in one direction (RH to pulmonary circulation to LH to systemic circulation and back to RH)
4
Q
Describe the anatomy of the heart?
A
- Situated obliquely in mediastinum
- anterior, thoracic cavity
- base superior, apex inferior
- left ventricle is thicker than right
5
Q
What are the 3 layers of the heart?
A
Pericardium
Myocardium
Endocardium
6
Q
What is the Pericardium?
A
- thin, external layer surrounding heart
- double walled membrane sac - parietal and visceral (epicardium) pericardium
Pathology
- pericardial tamponade
- pericarditis
7
Q
What is the function of the Pericardium?
A
- prevents displacement of heart
- barrier for infection and inflammation
- lubricant
8
Q
What is the Myocardium?
A
- cardiac muscle
- thick middle layer
- left is thicker than the right
- contracts in organised fashion
- damaged during myocardial infarction
9
Q
What is the function of the Myocardium?
A
Pumps blood around the body
10
Q
Describe the Pathology of Myocardium
A
- Myocardial infarction
- Myocarditis - inflammation infiltrate the heart muscle causing thickening or heart muscle gets dilated - this interferes with filling and pumping
- Myocardial Hypertrophy - develops from long standing HBP, thickened muscle wall makes it difficult for the heart chamber to fill
and muscle contraction become less effective, conduction system runs through muscle layers and gets “messed up” causing rhythm problem
11
Q
What is the Endocardium?
A
- Epithelial tissue that lines entire vasculture
- thin layer continuous and endothelium of arteries, veins and capillaries
- Prone to infection as it has direct contact with blood
12
Q
Describe the Atrioventricular valves
A
AV prevent entering atria from ventricle during systole
- Tricuspid - right atrium and right ventricle
- Mitral - left atrium and left ventricle
13
Q
Describe the Semi-lunar valves
A
Prevents blood entering ventricle from arterial tree during diastole
- Aortic - left ventricle + aorta
- Pulmonary - right ventricle + pulmonary artery
14
Q
What is Valve Regurgitation?
A
- blood flows back and forth across valve
- blood flows from the heart reduced
- poor cardiac output
15
Q
What is valve stenosis?
A
- blood trying to squeeze through narrow valve opening
- blood flow from the heart reduced
- poor cardiac output
16
Q
Describe the concept of coronary circulation
A
- heart requires high O2
- myocardial O2 consumption > skeletal muscle
- increased myocardial metabolic demand equals higher coronary blood flow
- local response and ANS
17
Q
What are the blood vessels associated with the heart?
A
- Vessels returning blood to the heart include the superior and inferior vena cava and right and left pulmonary veins
- Vessels conveying blood away from the heart include pulmonary trunk, which split into right and left pulmonary arteries and ascending aorta
18
Q
What the layers in the Vasculture?
A
- Lumen
- Tunica intima - endothelium, single layer of flattened cells
- Tunica intermedia - smooth muscle and elastic tissue regulated by SNS: controls vessel constriction and dilation
- Tunica Adventitia - fibrous connective tissue and collagen
19
Q
What is Cardiac Ouput?
A
amount of blood pumped by each ventricle in one minute
HR X SV = CO
20
Q
What is the Stroke Volume?
A
Amount of blood pumped out by a ventricle with each beat
21
Q
What is the preload?
A
Amount of ventricles are stretched by contained blood
- volume of blood that fills the ventricles during systole
- greater the venous return, the more the myocardial fibres will stretch
- preload decreased in hypervolemia
22
Q
What is afterload?
A
Resistance against which the ventricles have to overcomes to eject blood into the large arteries
- controlled by SNS
23
Q
What is Contractility?
A
Ability of myocardium to contract when no change in preload or afterload
Cardiac cell contractile force –> calcium ions, actin and myosin binding
2 factors change contractility
- changes in stretching of myocardium caused by changes in preload
- alterations in SNS e.g. B adrenergic receptors are stimulated by noradrenaline
24
Q
What is chronic heart failure?
A
- defined as cardiac impairment with inability to fill or eject blood volume
- common causes are HTN, coronary heart disease and congestive heart failure (left ventricular failure)
25
What is Ischemic heart disease?
- narrowed arteries leading to impaired oxygen to tissues in heart ---> HA
26
Systole vs Diastole
Systole - contraction of heart muscle
| Diastole - relaxation of heart muscle
27
Describe Atrial Contraction
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SA node (primary pacemaker)
- Sends electrical signals which are propagated throughout the entire atria via gap junctions in the intercalated disc (this in response allows cardiac muscle to contract simultaneously)
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- SA node sends electrical signal to atrial myocardium, this causes the atria to contract and blood is forced into the ventricles
28
Describe Ventricular contraction
- SA node sends signal to AV node
- signals are sent down the septum via the Bundle of His which triggers a network of fibres called Purkinje fibres in the walls of the ventricles which causes ventricular contraction and blood is force out the arteries
29
Sinus Rhythms
- P wave represents atrial depolarisation
- QRS - represents ventricular depolarisation
- T wave - represents ventricular repolarisation
30
Control of the heart - SNS
- Fight or flight response
- stimulation of beta 1 and 2 receptors increase
- increases rate of SA node
- increases conduction through AV node
- increases speed of contraction of atria & ventricles
- coronary vasodilation
31
Control of the heart - PNS
- rest and digest response
| - reduced HR and force of myocardial contraction - blocks B2 receptors (lower HR, Contractility and Automaticity)
32
Sinus Node and Ageing
- Sinus node activity is correlated with age
- lengthing of time sino atrial node to recover and conduct and progressive lengthening of sinus cycle length
- Progressive decrease of Parasympathetic activity with increasing age
- parasympathetic activity predominate in younger ppl
- sympathetic and parasympathetic tine becomes equal
33
Causes of Sinus Node Dysfunction
- inflammatory cardiac disease
- cardiomyopathy
- sclerodegenerative processes - replacement of normal organ-specific tissue with connective tissue
34
Causes of AV node diseases
- Coronary artery disease
- rheumatic artery disease
- inflammatory disease
- connective tissue disorders
35
What is Calcification?
Hardening of tissue or other material by the deposition of conversion to calcium carbonate or other insoluble calcium compounds
36
Poor conduction equals poor preload- explain this concept
- preload is the volume of blood that fills the ventricles during systole
- influenced by atrial kick ( P wave?)
- influenced by AV synchrony ( are P waves followed closely by QRS waves?)
The greater the venous return, the more the myocardial fibres will stretch
37
What is the problem with scar tissues?
usually from old infarcts may predipose to ventricular arrhythmia
38
What are potential causes of slow rhythms?
- medications e.g. digoxin and beta blockers
- natural degeneration of the SA or AV nodes
- surgery or disease of the aortic or mitral valve
- threatened blood supply to the SA or AV nodes
39
What are sinus pauses?
- sinus node not firing reliably
| - absence of P wave at the time it is expected
40
What is Asystole?
- no electrical activity, cardiac arrest
- not shockable - CPR
- check leads/connections
41
What are some causes of fast rhythms?
- re-entry circuits
- myocardial irritability
- poor blood supply
- poor oxygen supply
- AF from pneumonia
- myocardial scarring
42
What is Atrial Fibrillation?
- No p waves
- usually has normal QRS
- irregular heart beat
43
What is Ventricular Tachycardia?
- HR of greater than 100
- can cause cardiac arrest
- CPR and defrillate
- have wide QRS
44
What is Ventricular Fibrillation?
- no orderly QRS complexes
- irregular ventricular complexes
- always a cardiac arrest - shockable/CPR
