Cardiovascular and respiratory systems Flashcards
Define the pulmonary and systemic circuit
Pulmonary - carries deoxygenated blood through the pulmonary artery to the lungs and pulmonary vein back to the heart (right side)
Systemic - carries oxygenated blood through the aorta to the body and vena cava back to the heart (left side)
Explain the conduction system
1) Sino atrial node - Generates the electrical impulse and fires it through the atria walls causing them to contract
2) Atrio ventricle node - Collects the impulse and delays it for 0.1 secs, to allow the atria to finish contracting. Then releases the impulse to the bundle of his
3) Bundle of his - Splits the impulse into 2, to be distributed through each separate ventricle
4) Bundle branches - Carry the impulse to the base of each ventricle
5) Purkyne fibres - Distributes the impulse through the ventricle walls causing contraction
Define myogenic
Capacity of the heart to generate its own electrical impulse, using cardiac muscle to contract.
what are the 3 phases in the cardiac cycle
Diastole - Relaxation phase. As the atria and ventricles relax, they expand drawing in blood into the atria. The pressure in the atria increases opening AV valves, blood enters ventricles. SL valves close to prevent back flow of blood.
Atrial systole - atria contracts, forcing remaining blood into the ventricles
Ventricular systole - ventricles contract, increasing the pressure closing AV valves to prevent back flow into the atria. SL valves are forced open as blood is ejected from the ventricles into the aorta and pulmonary artery.
Define heart rate and how to calculate the maximal HR
Number of times the heart beats per min
220 - age
Define stroke volume
Volume of blood ejected from the left ventricle per beat
approximately be 70ml
Define cardiac output and how to calculate Q
Volume of blood ejected from the left ventricle per min
HR x SV
Define bradycardia
A resting HR below 60 bpm
What is venous return
Return of the blood to the right atria though the veins.
State a few HR responses to exercise
Rapid increase in HR will increase blood flow and oxygen delivery.
Release of hormone adrenaline
Oxygen supply meets demand
Decrease in HR as recovery enters
State a few stroke volume responses to exercise
Increase venous return
Frank starling mechanism
Increased HR towards maximal intensities
What is the Fank starling mechanism
Increased venous return leads to an increased stroke volume, due to increased stretch of the ventricle and force of contraction
what is the ccc
cardiac control centre
Receives information from the sensory nerves and sends direction through motor nerves to change HR
What are the control mechanisms in the CCC
1) Neural control :
chemoreceptors - detects chemical changes in the blood stream
Proprioceptors - informs ccc of motor activity
Baroreceptors - inform ccc of increased blood pressure
2) Intrinsic control :
Temperature changes will affect the viscosity of blood and speed of nerve impulse transmissions
Venous return affects the stretch in ventricle walls, contractions and SV
3) Hormonal control :
Adrenaline and noradrenaline are released increasing SV and electrical activity (HR)
what is the sympathetic nervous system
responsible for increasing HR during exercise
what is parasympathetic nervous system
responsible for decreasing HR during recovery
what is the vascular system
Dense work of blood vessels and blood. Ensures oxygen and nutrients are delivered to all cells for energy production and waste is removed.
Vascular system is of blood vessels. Explain the 3 main types of blood vessels
1) Arteries - smooth muscle and elastic tissue to smooth pulsating blood flow.
Arterioles - smooth muscle allowing vessels to vasodilate and vasoconstrict to regulate blood flow and blood pressure.
2) Capillaries - bring the blood slowly into close contact with muscle and organ cells for gaseous exchange.
3) Veins and venues - small layer of smooth muscle allowing them to ventilate and venoconstrict to maintain slow flow of blood. Veins have a one way pocket valves
What are the mechanism of venous return
1) Pocket valves - one way valves in veins
2) Smooth muscle - venoconstricts to aid the movement of blood
3) Gravity
4) Muscle pump - skeletal muscle contract compressing veins to squeeze blood back to the heart
5) Respiratory pump - During inspiration and expiration, a pressure difference between thoracic and abdominal cavity is created, squeezing blood back to the heart.
After exercise we may feel light headed - blood pooling - accumulation of blood in veins due to gravitational pull and lack of venous return.
What is vascular shunt mechanism
redistribution of cardiac output around the body from rest to exercise, increasing blood flow to skeletal muscles by the vasodilation and vasoconstriction of arterioles and precapillary sphincters dilating and constricting.
Explain the vasomotor control centre
Is located in the medulla oblongata and is responsible for the distribution of cardiac output. Receives information from chemoreceptors and baroreceptors.
At rest - arterioles and pre capillary sphincters are stimulated to vasoconstrict, listing blood flow to muscle cell. During exercise, they vasodilate to increase blood flow
At maximal intensities, up to 88% of cardia output is redistributed.
Define alveoli
Clusters of tiny air sacs covered in a dense network of capillaries which together serve as the external site for gaseous exchange.
Define gaseous exchange
Movement of oxygen from the alveoli into the blood stream and carbon dioxide form the blood stream into the alveoli.
Define breathing rate
Number of inspirations or expirations per min (approx 12-15 breaths/min)
Define tidal volume
Volume of air inspired or expired per breath (approx 500 ml)
What is haemoglobin
Ion rich protein in red blood cells which can chemically combine with 4 oxygen molecules to form oxyhemoglobin
Define minute ventilation and how is it calculated
The volume of air inspired or expired per min
TV x breathing rate
Explain the mechanics of inspiration at rest
External intercostals contract lifting the rib cage and sternum up. The diaphragm separates the thoracic and abdominal cavity, contracts and flattens.
Explain the mechanics of inspiration during exercise
In addition to the mechanics at rest. The sternocleidomastoid and pectorals minor are recruited to give a larger force of contraction. Creating a greater up and outward movement, increasing volume and decreases pressure inside thoracic cavity. Increases depth of breathing
Explain the mechanics of expiration at rest
External intercostals relax, lowering rib cage and sternum down and in. The diagram relaxes and returns to its dome shape.
Explain the mechanics of expiration during exercise
Internal intercostals and rectus abdominis are recruited. creating a greater down and inward movement of the rib cage and sternum.
Define partial pressure
Pressure exerted by an individual gas held in a mixture of gases
Define diffusion
The movement of gases across a membrane down a gradient from an area of high pressure to low pressure
Define diffusion gradient
The difference in areas of pressure from one side of a membrane to the other
What is the oxyhemoglobin dissociation curve
A graph showing the relationship between pO2 and percentage saturation of haemoglobin.
Define Bohr shift
A move in the oxyhemoglobin dissociation curve to the right caused by increased acidity in the blood stream.
