Week 5 - Cardiovascular System Flashcards
Describe the purpose of the cardiorespiratory system
Transport O2 and nutrients to tissues
Removal of CO2 wastes from tissues
Regulation of body temperature
What are the two major adjustments of blood flow during exercise
Increased cardiac output
Redistribution of blood flow from inactive organs to active muscle
What are the main aspects of the circulatory system
Heart: creates pressure to pump blood
Arteries & arterioles: carry blood away from heart
Capillaries: Exchange of O2, CO2, and nutrients with tissues
Veins and venules: carry blood towards the heart
What is the difference between the pulmonary circuit and systemic circuit
Pulmonary circuit is the right side of the heart. Pumps deoxygenated blood to the lungs via pulmonary arteries. Returns oxygenated blood to the left side of the heart via pulmonary veins
Systemic circuit is the left side of the heart. Pumps oxygenated blood to the whole body via arteries. Returns deoxygenated blood to right side of heart via veins
What are some wall components of blood vessels
Smooth muscle
Collagen
Elastin
Endothelium
Define resistance to flow
Resistance = measure of hinderance or opposition to blood flow through a vessel caused by friction between the blood in the vessel wall
What factors affects blood flow
Directly proportional to the pressure difference between the two ends of the system
Inversely proportional to resistance
Blood flow = changes in pressure / resistance
What factors influence resistance
Length of vessel
Viscosity of the blood
radius of the vessel (greatest influence)
Define arterivenous difference
Amount of O2 that is taken up from 100ml of blood
Increases during exercise due to increased O2 uptake in tissues
What is Ficks equation
VO2 = cardiac output x a-vO2 difference
How does the central command affect the cardiovascular system
Initial signal to drive cardiovascular system comes from higher brain centres
Fine-tuned by afferent feedback from receptors (from mechanoreceptors of heart and muscle)
Exercise pressor reflex (feedback to medulla oblongata to amend CV response to exercise)
Why is there a continued increased in systolic BP with exercise when baroreceptors work to maintAIN BP homeostasis
The baroreflex is reset during exercise. Central command and exercise pressor reflex both play an active role in resetting baroreflex.
Define myocardial infarction
Blockage in coronary blood flow results in cell damage
Exercise training protects against heart damage during an MI
What are the consecutive layers in the heart
Epicardium (lubricative outer covering)
Myocardium (muscular contractions)
Endocardium (protective inner layer)
What factors affect the electrical stimulation of the myocardium
Sinoatrial node
Atrioventricular node
Bundle Branches
Purkinje fibres
Describe the conduction system of the heart
- Action potentials originate in the sinoatrial node and travel across the wall of the atrium from the SA node to the atrioventricular node
- Action potentials pass through the AV node and along the atrioventricular bundle, which extends from the AV node, through the fibrous skeleton, into the interventricular septum
- The AV bundle divides into right and left bundle branches, and action potentials descend to the apex of each ventricle along the bundle branches
- Action potentials are carried by the Purkinje fibres from the bundle branches to the ventricular walls
What are the main aspects of the electrocardiogram (ECG)
P wave: Atrial depolarisation
QRS complex: Ventricular depolarisation and atrial repolarisation
T wave: Ventricular repolarisation
Define atherosclerosis
Fatty plaque that narrows coronary arteries.
Reduces blood flow to myocardium
How does exercise training protect the heart
Reduces heart attacks
Improves heart’s antioxidants capacity
Improves function of ATP sensitive potassium channels
Define the terms chronotropic and inotropic
Chronotropic: Heart rate increases
Inotropic: Contractility increases
What is the main metabolic vasodilator in coronary blood vessels
Adenosine, also beta-adrenergic vasodilation
What is the process during conduction system of the heart
- Action potentials originate in the sinoatrial (SA) node and travels across the wall of the atrium from the SA node to the atrioventricular (AV) node
- Action potentials pass through the AV node and along the atrioventricular (AV) bundle, which extends from the AV node, through the fibrous skeleton, into the interventricular septum
- The AV bundle divides into right and left bundle branches, and action potentials descend to the apex of each ventricle along the bundle branches
- Action potentials are carried by the Purkinje fibres from the bundle branches to the ventricular walls
How is heart rate regulated during exercise
Parasympathetic nervous system:
- via vagus nerve which slows HR by inhibiting SA and AV node
Sympathetic nervous system:
- via cardiac accelerator nerves which increases HR by stimulating SA and AV nodes
What are the main valves in the heart located
Atrioventricular valves
Tricuspid (Right atrium & right ventricle)
Mitral (left atrium & left ventricle)
Semilunar Valves:
1. Pulmonary (right ventricle & pulmonary artery)
2. Aortic (left ventricle & aorta)
What does a segment in S-T ECG diagram indicate
Myocardial ischemia
