the cardiovascular system Flashcards
what does myogenic mean?
the capacity of the heart to generate its own impulses. heart muscle is described as being myogenic.
Describe the cardiac control system
this is a group of specialised cells located in the wall of the heart which send electrical impulses to the cardiac muscles causing it to contract. the beat starts in the heart itself with an electrical signal in the SINOATRIAL NODE (SAN). the impulse spreads through the walls of the atria and then passes through the ATRIOVENTRICULAR NODE (AVN). the AVN delays the transmission for 0.1 seconds to enable the atria to fully contract before ventricular systole begins. the impulse the passes down through some specialised fibres which form the BUNDLE OF HIS. this branches out into two bundle branches and then moves into smaller bundles called PURKINJE FIBRES which spread throughout ventricles causing them to contract.
What’s the difference between the sympathetic and the parasympathetic system\/
They are both part of the autonomic nervous system and the sympathetic speeds up heart rate while para sympathetic slows down heart rate.
Name the three receptors and state what they do?
CHEMORECEPTORS- tiny structures that detect changes in blood acidity caused by an increase or decrease in the concentration of carbon dioxide.
BARRORECEPTORS- special sensors in tissues that respond to changes in blood pressure to either increase or decrease heart rate.
PROPRIOCEPTORS- sensory nerve endings in the muscles, tendons and joints that detect changes in muscle movement.
define stroke volume
the volume of blood pumped out by the heart ventricles in each contraction
describe the diastole phase
when the heart relaxes to fill with blood
Describe adrenaline
Adrenaline is a stress hormone that is released by the sympathetic nerves and cardiac nerves during exercise which causes an increase in heart rate. this results in more blood being pumped to the working muscles so they can receive more oxygen for the energy they need.
describe what venous return is?
venous return is the volume of blood returning to the heart via the vena cava. if venous returns increases then stroke volume will also increase. (the more blood that enters the heart the more blood that goes out)
What is starlings law?
this states that the stroke volume of the left ventricle as the left ventricular volume increases.
What is cardiac output?
the volume of blood pumped out by the heart ventricles per minute
How do you calculate cardiac output
Cardiac output (Q) = Stroke Volume (SV) x Heart Rate (HR)
How do you calculate maximum heart rate?
220 - age of athlete = Max heart rate
Describe the terms cardiac hypertrophy and bradycardia
cardiac hypertrophy- the thickening of the muscular wall of the heart so it becomes bigger and stronger, also can mean a larger ventricular cavity
Bradycardia- a decrease in resting heartrate below 60 beats per minute
what is cardiovascular drift?
a progressive decrease in stroke volume and arterial blood pressure together with a progressive rise in heart rate.
when and why?
- occurs after prolonged exercise (10mins)
- in a warm environment
reduce CVD by maintaining high fluid
define blood pressure and describe the difference between systolic and diastolic pressure
blood pressure is the force exerted by the blood against the blood vessel walls
systolic pressure is the pressure when contracting and diastolic is the pressure when ventricles are relaxing
describe the difference between pulmonary and systemic circulation
Pulmonary- deoxygenated blood from the heart to the lungs and oxygenated blood back to the heart.
systemic- oxygenated blood to the body from the heart and then the return of de-oxygenated blood from the body to the heart
state the path of the vascular system
heart- arteries- arterioles- capilaries- venules- veins- heart
name and describe the three venous return mechanisms
skeletal muscle pump: when muscles contract and relax- change shape- means muscles press on nearby veins causing pumping effect squeezing blood towards heart.
The respiratory pump- when muscles contract and relax during breathing in pressure changes in the chest and stomach- these pressure compress the nearby veins to squeeze blood to heart
Pocket Valves: important valves present so blood only flows one direction. close up after path through to prevent backflow
what is the bohr shift?
when an increase in blood carbon dioxide and a decrease in PH results in a reduction of haemoglobin for oxygen.
what are the factors for bohr shift?
- increase in blood temperature
- partial pressure of carbon dioxide increases
- ph
describe the difference between vasoconstriction and vasodilation
vasodilation is the widening of the blood vessels to increase blood flow into capillaries where as vasoconstriction is the narrowing of blood vessels to reduce blood flow into the capilaries
define vascular shunt
the redistribution of cardiac output
