KIN 407 Flashcards
What is heart disease?
An umbrella term for a number of different diseases that affect the heart. Examples include CAD, CHD, cardiomyopathy, and heart failure.
What are other names for coronary artery disease?
Coronary heart disease and ischemic heart disease
What is the number one killer for heart disease?
Coronary Artery Disease
What is coronary artery disease?
Fatty deposits build up in blood vessel walls and narrow the passageway for the movement of blood. The resulting condition, called atheroscelerosis, often leads to eventual blockage of the coronary arteries, angina pectoris (chest pain), and myocardial infarction (heart attack)
Athersosceloris?
Some blood flow is still allowed`
Atherosceloris with a clot?
No blood flow
Spasm?
Occludes blood flow or completely blocks it
Ischemia?
Reduced blood flow
3 symptoms of coronary artery syndrome?
Reduced blood flow, chest pain (angina), and myocardial infarction (MI)
What is a hypoxic heart?
Low oxygen
What are the signs of a hypoxic heart?
Angina pectoris, arrhythmia, and heart failure
What is an anoxic heart?
No oxygen
What does an anoxic heart cause?
Infarction (death) of the tissue supplied by that artery
Primary prevention of heart disease is?
Health promotion and education
Secondary prevention of heart disease is?
Cardiac rehab
What is cardiac rehab?
The sum total of all interventions, physiological and behavioural, designed to favourably modify an individual’s lifestyle and enhance adherence and compliance with long-term behaviours compatible with minimizing disease progression
4 main parts of cardiac rehab?
- Medical evaluation 2. Physical activity and exercise 3. Lifestyle education (risk factor ducation) 4. Support
Ultimate purpose of the cardiovascular system?
Exchange gases, fluids, elextrolytes, large molecules, and heat
Where is the heart located?
Beneath the sternum, on the left of the body
Purpose of valves?
TO ensure one way flow
Where is the tricuspid valve located?
Between the right artium and right ventricle
Where is the mitral/bicuspid valve located?
Between the left atrium and left ventricle
Where are the semilunar valves located?
Between the ventricles and arteries (aorta and pulmonary)
Layers of the heart from superficial to deep?
Pericardium (fibrous and serous), pericardial cavity, epicardium, myocardium, endocardium
What is the purpose of the pericardium?
Prevents over-distension
What is the purpose of the pericardial cavity?
Contains a small amount of fluid to prevent friction when the heart beats
2 cell types to consider in the heart?
- myocyte…mature myocardial cell; contraction 2. autorhythmic cell…electrical activity
Differences in cardiac muscle versus skeletal muscle?
- Smaller, single nucleus 2. High density of mitochondria 3. Presence of intercalated discs to allow for quick transmission of action potential through the heart
What troponin isoforms are different in cardiac muscle?
TN-I and TN-T…TN-C is the same
Cells capable of electrical excitation in the heart?
Ventricular and atrial cells (normally not spontaneous), Purkinje fibres (specialized, rapidly conducting tissue), pacemakers (SA node, preferred. AV node, backup)
Resting membrane potential of ventricle?
-90 mV
RMO of Purkinje fibres?
-95 mV
RMP of SA node?
an unstable -60 mV
Ions move by…
- Diffusion, down their concentration gradients through specialized gates dependent on voltage 2. Active transport against their concentration gradient
Resting potential?
Electrical charge difference between inside and outside the cell
MP determined by?
- Concentration of ions on the inside and outside of the cell 2. The permeability of the cell membrane to those ions through specific ion channels 3. The activity of the pumps (Na+/K+ pump) that maintain hte ion concentrations across teh membrane
Steps in an action potential in a NON-PACEMAKER cell?
Phase 4: flat slope, Na+/K+ channels closed. Phase 0: Increase in Na+ conductance, the more + cell becomes, more Na+ channels open, at -70 mV (threshold potential) self-sustaining inward flux of Na+ leads to an action potential and stimulates the cells to contract. Phase 1: Na+ channels close, K+ and Cl- open, which starts repolarizing the cell. Phase 2: Ca2+ influx to stabilize cell (offset by K+ out), lengthens the depolarixed stage allowing Ca2+ to trigger Ca2+ in myocyte and to prevent another AP and contraction (want blood to completely empty). Phase 3: Rapid repolarization, K+ diffuses out, return to -90mV
Action potential in pacemaker cells?
Phase 4: the resting potential of a pacemaker cell (-60mV to -70mV) is caused by a continuous outflow or “leak” of potassium ions through ion channel proteins in the membrane that surrounds the cells. The difference is that this potassium permeability decreases as time goes on, partly causing the slow depolarization. As well as this, there is a slow inward flow of sodium, called the funny current, as well as an inward flow of calcium. This all serves to make the cell more positive.
This relatively slow depolarization continues until the threshold potential is reached. Threshold is between -40mV and -50mV. When threshold is reached, the cells enter phase 0. Phase 0: Though much faster than the depolarization caused by the funny current and decrease in potassium permeability above, the upstroke in a pacemaker cell is slow compared to that in an axon.
The SA and AV node do not have fast sodium channels like neurons, and the depolarization is mainly caused by a slow influx of calcium ions. (The funny current also increases). The calcium is let into the cell by voltage-sensitive calcium channels that open when the threshold is reached. Phase 3: The calcium channels are rapidly inactivated, soon after they open. Sodium permeability is also decreased. Potassium permeability is increased, and the efflux of potassium (loss of positive ions) slowly repolarises the cell.
Spread of depolarization in heart?
SA node–>across both atrium–>AV node–>AV node delay–>AV bundle/bundle of Hiss–>Left and Right bundle branches–>Purkinje fibres
P wave?
Atrial contraction
QRS complex?
ventricular contraction and atrial repolarization
T wave?
Ventricular relaxation
Excitation-contraction coupling?
o Action potential enters from adjacent cell via gap junctions in the intercalated disk
o Voltage-gated Ca2+ channels open, and Ca2+ enters the cell
o Ca2+ induces Ca2+ release through ryanodine receptor-channels (RyR)
o Local release causes a Ca2+ spark
o Summed Ca2+ sparks create a Ca2+ signal
o Ca2+ ions bind toTN-C, which allows TN-I t move out of the way, thus exposing the active site on actin for myosin to bind, this initiates contraction
o Relaxation occurs when Ca2+ unbinds from TN-C
o Ca2+ is pumped back into the SR for storage
o Ca2+ is exchanged with N1+ by the NCX antiporter
o Na+ gradient is maintained by the Na+/K+ ATPase
Path of blood flow through the heart?
SVC and IVC to right atrium through tricuspid valve to right ventricle through the pulmonary semilunar valve to the pulmonary trunk to the lungs through the pulmonary veins to the left atrium through the mitral/bicuspid valve to the left ventricle through the aorta valve to the aorta to the rest of the body
3 main coronary arteries?
Right coronary artery, left anterior descending artery, and left circumflex artery
When do the coronary arteries and heart muscles receive blood?
During diastole (when the aortic valve is closed)
If the right coronary artery is blocked, where will an MI occur?
Inferior and posterior right heart heart
If the left anterior descending coronary artery is blocked, where will an MI most likely occur?
Left ventricular anterior wall, anterior septal wall, anterior right ventricular wall
Is the left circumflex artery is blocked, where will an MI most likely occur?
Lateral and posterior left ventricle
Systole?
Contraction of heart
Diastole?
Relaxation of heart
ESV?
blood remaining in left ventricle following contraction
EDV?
blood remaining during ventricular relaxation
Stroke VOlume?
EDV-SV
Preload?
pressure (force) on the left ventricle prior to contraction
Afterload?
pressure (force) against which the left ventricle is working during contraction (measured as the pressure in the aorta during contraction)
Cardiac output?
total amount of blood ejected from ventricle in 1 min… = HR x SV
Normal resting CO (Q) value?
5 L
Normal CO (Q) value during exercise?
25 L
Spontaneous rate of SA node?
100-115 bpm
Why is RHR lower than the spontaneous rate in the SA node?
PNS stimulation of Ach on muscarinic receptors via the vagua nerve lowers it to 60-8- bpm
How is HR increased during exercise?
Remove PNS stimulation, then SNS stimulation and increased catecholamines increases it above 100-115 bpm
How does the SNS increase HR?
Releases NE from sympthathetic neurons that act on Beta-2 receptors, which increases Na+ and Ca2+ influx, causing earlier depolarization, and thus an increased HR. E from the adrenal medulla works the same way.
How does the PNS slow HR?
Releases Ach onto muscarinic receptors, which increases K+ efflux and Ca2+ influx, so hyperpolarizes cell, slowing the rate of depolarization, which decreases HR
Mechanisms that increase EDV by increasing venous return?
Venoconstriciton, respiratory pump, muscle pump, and increased blood volume
What is the Frank-Starling mechanism?
states that 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. The increased volume of blood stretches the ventricular wall, causing cardiac muscle to contract more forcefully (the so-called Frank-Starling mechanisms
How do neuronal and hormonal mechanisms increase SV?
NE and E decrease ESV by increasing the force of contraction by letting in more Ca2+ for the myocardial muscle cell to use
How does afterload affect SV?
It decreases it!
Ejection fraction?
Amount of blood ejected from the left ventricle as a % of total volume of blood in left ventricle prior to contraction… SV / EDV x 100%
Normal ejection fractioN?
50-70%
Ejection fraction that may confirm diagnosis of systolic heart failure?
35-40%
Ejection fraction that may cause a person to be at risk for life-threatening irregular heart beats?
<35%
Systolic BP?
Pressure in arteries during contraction…110-120 mmHg
Diastolic BP?
Pressure during relaxation…80 mmHG
Pulse pressure?
Systolic - Diastolic pressure. pressure that is felt when feeling the pulse
Mean arterial pressure?
average blood pressure in an individual. t is defined as the average arterial pressure during a single cardiac cycle. [2 DBP + SBP] / 3
The 3 things that regulate BP?
- Autonomic nervous system 2. Hormonal responses 3. Local control
How does the autonomic nervous system regulate blood pressure?
By its action on HR and SV and through the constriction of blood vessels by NE working on alpha1-adrenergic receptors
How do hormones regulate BP?
E works on beta receptors in the heart to cause vasodilation?
What does angiotensin II do?
Has both direct and indirect effects. Causes adrenal cortex to secrete aldosterone, the brain to release vasopressin, and stimulates thirst all of which increase Na+ and water retention. Also vasoconstricts the veins. All of these things increase/restore BP
What is vasopressin?
It is an anti-diuretic hormone that senses low blood volume and then causes smooth muscle constriction and reabsoprtion of water
Atrial natriuretic factor?
Released in atria when stretch via an increase in blood volume. Acts to reduce blood volume via inhibiting renin (no ANG II produced) and causing direct vasodilation
How does the local control system regulate BP?
Vasodilation in arterioles through changing [CO2], [H+], [K+], adenosine, and nitric oxide. Endothelin causes vasoconstriction, and so do oxygen.
KNOW SUMMARY OF BP CONTROL! (draw it out)
fdasoifh oa
What is oxygen uptake (VO2)?
Energy expended by the body in meeting the demands to perform work
Maximal oxygen uptake (mVO2)?
the maximal energy expenditure of the body…how much oxygen the body can take in and use
Myocardial oxygen uptake (mVO2)?
the demands placed on the heart to perform work