1.1 The Cardiovascular System

The cardiovascular system
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interventricular septum
Divides the right and left chambers of the heart
Atria
The two upper chambers of the heart. They push blood towards the ventricles. They have thinner muscular walls.
Why do the ventricles have thicker walls than the atria?
They have to contract with greater force in order to push blood out of the heart.
Why is the left side of the heart bigger?
Blood needs to be pumped all around the body
vena cava
a large vein carrying deoxygenated blood into the right atrium. One is superior one is inferior.
Valves
Flap of tissue in the heart and large veins that prevents blood from flowing backwards.
4 chambers of the heart
right atrium, right ventricle, left atrium, left ventricle
tricuspid valve
valve between the right atrium and the right ventricle
bicuspid valve
valve between the left atrium and the left ventricle.
semilunar valves
pulmonary valve and aortic valve
Right and left ventricle
cardiac conduction system
A system of specialized muscle tissues/cells located in the wall of the heart which sends electrical impulses to the cardiac muscle that stimulate the heart to beat.
Myogenic
Describes muscle tissue (heart muscle) that generates its own contractions.
(SAN)
Means sinoatrial node
sinoatrial node
A small mass of cardiac muscle found in the wall of the right atrium that generates the heart beat. Can be called a pacemaker.
chordae tendineae
thin bands of fibrous tissue that attach to the valves in the heart and prevent them from inverting.
(AVN) or AV node
atrioventricular node
atrioventricular node
This node relays the impulse between the upper and lower sections of the heart
Role of the AVN
Found in the atrioventricular septum. The AVN delays the transmission of cardiac impulses for approximately 0.1 seconds to enable atria to fully contract before ventricular systole begins.
Systole
Contraction of the heart
How is the bundle of his formed
Electrical impulses are passed down through some specialised fibres
Where is the Bundle of His located?
interventricular septum
Purkinje fibers
The bundle of his branches out into two bundle branches and then moves into smaller bundles called purkinje fibres which spread throughout the ventricles causing them to contract
Conduction system route
-SAN
-Atrial Systole
-AVN
-Bundle of his
-Purkinje fibres
-Ventricular Systole
sympathetic nervous system
Stimulates the heart to beat faster
Parasympathetic system
Returns the heart to its resting level
What two parts are the CNS Made up from
Spinal chord and the brain
Medulla Oblongata
The most important part of the brain as it regulates processes that keep us alive such as breathing and heart rate
Where is the cardiac control centre located
Medulla Oblangata
What stimulates the cardiac control centre
Chemoreceptors, Baroreceptor, Proprioreceptors
Where are chemoreceptors found?
carotid bodies and aortic arch
What do chemoreceptors sense?
Chemical changes
An increase in what is important because it can control the heart rate?
carbon dioxide
Where are baroreceptors
aortic arch and carotid sinus
What are baroreceptors and what do they contains?
Nerve endings that respond to the stretching of the arterial wall caused by changes in blood pressure.
When does the baroreceptor send signals to the medulla in the brain?
If there is an increase above or a decrease below a set point.
A decrease in heart rate is due to
An increase in arterial pressure causes an increase in the stretch of the barorecptor sensors
An increase in heart rate is due to
A decrease in arterial pressure causes a decrease in the stretch of the barorecptors
Where are proprioceptors located?
muscles, tendons, and joints
What do proprioceptors do?
Sensory nerve endings that provide information about movement and body position.
Hormonal Control
The release of energy during exercise
What nerves is adrenaline released
A stress hormone released by the sympathetic and cardiac nerve during exercise
Diastole phase
When the heart relaxes to fill with blood
ejection fraction
percentage of blood pumped out by the left ventricle per beat.
=Ejection Fraction
Stroke volume/ (volume of blood in the ventricles at rest)
Bradycardia
A decrease in resting heart rate to below 60 beats per minutes.
=max heart rate
220-age
Stroke volume increases when
Intenisty of exercise increases
Atherosclerosis
Occurs when arteries harden and narrow as they become clogged up by fatty deposits
Atheroma
A fatty deposit found in the inner lining of an artery
Angina
Chest pain that occurs when the blood supply through the coronary arteries to the muscles of the heart is restricted
CHD
coronary heart disease
LDL
low-density lipoprotein
HDL
high-density lipoprotein
What are the two types of cholesterol
LDL and HDL
What is classed as bad cholesterol
Low density lipoproteins transport cholestrol in the blood to the tissues.
Which type of cholesterol is linked to an increased risk of heart disease.
LDL
What is classed as good cholesterol
High density cholesterol transports excess cholesterol in the blood back to the liver where it is broken down
Which type of cholesterol reduce the risk of developing heart diseases.
HDL
Stroke
A stroke occurs when the blood supply to the brain is cut off
Two types of stroke
ischemic and hemorrhagic
Which is the most common form of stroke
Ischaemic
Ischaemic strokes
Occurs when a blod clot stops the blod supply
Haemorrhagic stroke
Occurs when a weakened blood vessel supplying the brain bursts.
Two types of circulation
Pulmonary and Systemic
Pulmonary Circuit
Deoxygenated blood from the heart to the lungs and oxygenated blood back to the heart
systemic circulation
Oxygenated blood to the body from the heart and then the return of deoxygenated blood from the body to the heart.
blood pressure
the pressure that is exerted by the blood against the walls of blood vessels
=blood pressure
blood flow X resistance
systolic pressure
When the heart contracts it forces blood out under high pressure. also known as pressure of contraction
Diastolic Pressure
The lower pressure as the ventricles relax is called the diastolic pressure
Where is blood pressure measured
brachial artery in the upper arm
venous return
The return of blood to the right side of the heart via the vena cava
Factors that aid venous return
-Thin layer of smooth muscle in the walls of the veins
-Suction pump action of the heart
When systolic blood pressure increases
There is an increase in venous return
When systolic blood pressure decreases
There is a decrease in venous return
The heart contracts with more force
If venous return increases
Pressure gradient
(venous pressure(Pv)-Right atrial pressure(Pra)) / Venous vascular resistance (Rv)
How much oxygen diffuses into the plasma
3%
Plasma
Fluid portion of blood that surrounds blood cells and transports them.
Haemoglobin
Found in red blood cells, transports oxygen to body tissue
Myoglobin
An oxygen-storing, pigmented protein in muscle cells.
Mitochondria
Powerhouse of the cell as respiration and energy production occur there.
Bohr Shift
Increase in blood co2 and a decrease in pH results in reduction of the affinity of haemoglobin for oxygen
pH
a measure of how acidic or basic a solution is
Vascular shunt mechanism
The redistribution of cardiac output
Why is redistribution of blood so important
-Increase the supply of oxygen to the working muscle
-Removes waste products from muscles
-Ensures more blood gets too the skin
-Directs more blood to the heart
Arterio-venous difference
The difference between the oxygen content of the arterial blood arriving at the muscles and the venous blood leaving the muscles
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