The Cardiac System Flashcards
Sympathetic nervous system
- increased HR by releasing adrenaline
- adrenaline increases the strength of ventricular contraction
- increased metabolic activity increases the release of CO2 which is detected by chemoreceptors and informs the sympathetic centre to flush ou the excess CO2
Parasympathetic system
- Releases acetylcholine which slows the spread of impulses throughout the heart .
- lowers HR
sympathetic nerves (fight or flight)
- dilate pupils
- inhibit salivation
- inhibit stomachs activity
- inhibit bladder and intestine function
Parasympathetic nerves (rest and digest)
- Constrict pupils
- stimulate stomachs activity
- stimulate intestine activity
- inhibit release of glucose and stimulate gallbladder
What is the cardiac control centre stimulated by?
Chemoreceptors- senses the increase in CO2- increases HR
Baroreceptors- senses blood pressure -decreases HR
Proprioceptors-senses and increase in joint and muscle movement-stimulated higher HR
Diastole
The term used to describe the relaxation phase of the cardiac cycle.
The heart ventricle are reloaded and fill with blood
Systole
The term used to describe the contraction phase of the cardiac cycle - the ventricles contract and pump blood tho the arteries
( right ventricle to the pulmonary artery and lungs, left ventricle to the aorta and the body)
Stroke Volume
The volume of blood that leaves the heart in each contraction
health
A state of complete physical, emotional and social well being and not merely the absence of disease and infirmity
Fitness
The ability to meet and cope with the demands of the environment
Physical activity
Being active and taking part in exercise - can directly benefit your physical health and wellbeing
Anticipatory rise
Slight increase of heart rate usually before activity starts due to the expectation of the exercise.
cardiac output
The amount of blood the heart pumps out in 1 min. Measures in litres per minute (L/M)
Name the parts of the heart
- left and right ventricle, left and right atrium
- tricuspid valve
- bicuspid valve
- chordae tendinae
- interventricular septum
- semi lunar valve
sate the order electrical impulse travels through the heart
- SAN
(0. 1 seconds delay) - atrial systole
- Av node
- bundle of His
- bundle branches
- purkinje fibres
- ventricular systole
Myogenic
Creates its own electrical impulses e.g. the heart
Vascular shunt mechanism
The redistribution of blood through vasoconstriction and vasodilation
Myoglobin
Main function to transport oxygen from the muscle cell membrane to the mitochondria
Serves as an extra reserve of oxygen to help exercising muscle maintain activity for longer
Venous return
- def
- 6 mechanisms
- the return of blood to the right side of the heart via vena cava
1 - skeletal muscle pump
2 - the respiratory pump
3 - pocket valves
4 - smooth muscle walls of veins
5 - gravity
6 - the suction pump action of the heart, pressure gradient , negative pressure in the right atrium
What is the Bohr shift
When and increase in blood carbon dioxide and a decrease in PH results in a reduction of the affinity of haemoglobin for oxygen.
What is cardio vascular drift
Cardiovascular drift occurs during prolonged exercise and is the result of an increasing heart rate and decreasing stroke volume. Cardiovascular drift results from a decrease in blood volume and sympathetic nervous system triggered increase in heart rate.
Stages of cardiovascular drift (8)
- cardiovascular drift occurs 10 mins into exercise and in a hot environment
- HR increases
- stroke volume decreases
- fluid is lost in sweat
- this reduces plasma volume
- this reduces venous return
- cardiac output increases Due to higher energy demands
Arterio venous difference
The difference between the oxygen content of the arteriolar blood arriving at the muscles and venous blood leaving the muscles.
At rest arterio venous difference is low because…
Not much oxygen is required in the muscles
Training can increase arterio venous difference because…
Trained performers can extract more oxygen from the blood
Name mechanisms of venous return
- gravity
- skeletal pumps
- pocket valves
- the respiratory pump.
What is starlings law
Starling’s Law states that the greater venous return, the greater stroke volume is. As venous return increases the walls of the ventricles are stretched further. Results in a more powerful contraction. Increases the amount of blood pumped around the body during exercise.
Medulla oblongata
- The most important part of the brain
- regulates processes that keep us alive
E.g. breathing, HR
What receptor detects an increase in CO2 in the blood
Chemoreceptors
What receptor detects blood pressure
Baroreceptors
- and therefore decrease HR
What receptor monitors joint movement
Proprioceptors
What happens to the oxyhemoglobin curve during exercise (Bohr shift)
It shifts to the right
