Cardiovascular system Anatomy & Physiology Flashcards
What is the main purpose of the CV system?
Ensures a continuous flow of blood to all cells to supply oxygen and nutrients and to extract tissue waste
Where does the heart lay?
Lies obliquely in the thoracic cavity in the mediastinum slight more to the left of the chest.
What is the mediastinum?
is the space in the thorax which lies between the lungs.
The heart has how many chambers and valves?
4 chambers and 4 valves
What are the two types of circulation?
The Systemic Circulation
The Pulmonary Circulation
What is The Pericardium?
(Outer layer - protecting the heart)
What is The Myocardium?
Inner layer responsible for the heart’s electrical signals
When an impulse is initiated contraction occurs.
Left ventricle thickest as it pumps blood around the body.
What is The Endocardium?
Lines the chambers and valves of the Heart, smooth membrane to ensure smooth flow of blood.
Briefly talk about the myocardium?
- specialised
- structure
This consists of specialised cells called cardiac myocytes
Large mitochondria, therefore have a high resistance to fatigue
Contracts as a result of an electrical impulse
Explain how the myocardium works?
Plasma membranes of adjacent cardiac cells are interlocked by intercalated discs, (tightly bound together, double membrane) which allow ions to pass from one cell to another to allow electrical current to move across the heart.
Plasma membranes of adjacent cardiac cells are interlocked by intercalated discs, (tightly bound together, double membrane) which allow ions to pass from one cell to another to allow electrical current to move across the heart.
The myocardial muscle contracts as a result of an electrical impulse which takes place momentarily before the contraction happens.
This impulse is generated by the exchange of ions (molecule with an electrical charge) including sodium and potassium across cell membranes of the myocytes and an influx of calcium.
So sodium and potassium as well as calcium are very important in the contraction of cardiac myocardial cells.
MYOCARDIUM
Automaticity?
Excitability?
Conductivity?
Contractility?
The ability to initiate a response spontaneously.
The ability to respond to a stimulus
The ability to transmit an impulse from one cell to another through the discs.
The ability to contract after an electrical stimulus
What is the SA node?
- where is it situated
- what is it a collection of
- depolarise/ repolarise
- how many bpm
situated in the right atrium
Collection of unstable/excitable cells. The instability leads them to discharge an electrical impulse (DEPOLARISE) regularly between 60 to 90 times a minute.
Then followed by recovery (REPOLARISATION). In 0.1 seconds impulse travels to
What is the AV node?
- where is it situated
- what does it generate
- how many bpm
2nd pacemaker if SA node fault) - situated at the atrial septum and close to the atrioventricular valves, generates electrical impulses from the atria through to the ventricles. 0.1 seconds 40-60 beats per minute.
What is the Atrioventricular bundle also known as?
Bundle of his
What is the bundle of his?
mass of fibrous ring separating the atria and ventricles, dividing into the left and right bundle branches.
Within the ventricular myocardium the branches break up into fine fibres called the ….?
Purkinje fibres.
How does the bundle of his work?
Electrical impulses are transmitted from the AV node to the apex of the myocardium causing ventricular contraction (upwards and outwards) to pump blood into the pulmonary artery and aorta.
When looking at an ECG, what does the:
P stand for
QRS?
T?
P - impulses from the SA node. (atrial depolarisation)
QRS - impulses from the AV node, through the bundle and Purkinje fibres. (ventricular depolarisation)
T - relaxation of the ventricle muscle (ventricular repolarisation)
What are arteries?
What are arterioles?
What are capillaries?
What do veins do?
Arteries and smaller branches -
arterioles carry blood away from the heart
Capillaries - enormous network of tiny exchange vessels, allowing nutrients, water and oxygen to diffuse into the tissues and cellular waste - carbon dioxide to diffuse into the bloodstream for excretion.
Small venules - Veins - carry blood back to the heart.
What are anastomoses and end arteries?
Arteries that form a link between the main arteries supplying an area e.g. palms of the hands and soles of the feet; the brain the joints and the heart muscle.
If an artery supplying the area is blocked, the anastomotic arteries supplies collateral circulation.
Sole source of blood to a tissue - end-artery if blocked then the tissue will die (retina of the eye, branches (circle of willis) in the brain.
What does the lymphatic system do?
Which helps to protect against infection and disease - immunity.
Assists movement of fluid back into the bloodstream - lymph maintaining homeostasis.
Transports plasma proteins back into the bloodstream, production and maturation of lymphocytes
What are the three types of blood vessel tissue?
Tunica Adventitia (Outer layer; fibrous tissue protects and supports vessels)
Tunica Media- (Middle layer contains variable smooth muscle)
Tunica Intima- (smooth lining layer only one layer thick, much thinner than arteries.)
Arteries:
Why are they so large?
Why are the walls thicker than veins?
Capillaries:
What do they link?
Why do they have large lumen?
Is blood flowing fast or slow?
Veins:
What sort of pressure of blood?
Are walls thin or thick, why?
How do they work?
Arteries - the largest (close to the heart) have more elastic tissue in the tunica media and less smooth - allowing more stretch to absorb the wave of pressure as it beats. Arteries branch many times through the body to smaller arteries then into arterioles where the tunica media contains more smooth muscle - enabling more control to regulate the internal pressure. . Arteriole walls are thicker than venous walls to withstand the high blood pressure in the arterial system.
Capillaries - link the smallest arterioles to the venules -single layer of endothelial cells extensive exchange of materials. In the liver and bone marrow, capillaries are wider and leakier than normal.The Capillaries are called sinusoid wall. Their walls are incomplete and larger lumen than usual (blood flows slowly, allowing much faster exchange of substances between blood and tissue) e.g. in the liver which regulates the composition of blood arriving from the Gastrointestinal Tract.
Veins - low pressure of blood, Venous walls are thinner than arterial wall (have three layers of tissue)
When cut vein collapse, whereas the artery remain open.
Veins (capacitance vessels) because they stretch. Therefore have the capacity to hold large proportion of the body’s blood.
In haemorrhage veins constrict preventing fall in blood pressure.
Some Veins possess valves prevents backflow of blood. (Valves are abundant in the lower limbs)
What happens during pulmonary and systemic circulations?
The right side of the heart pumps blood to the lungs (pulmonary circulation) where gaseous exchange occurs, oxygen collected by the blood from the air sacs, and excess carbon dioxide diffuses out into the air sacs for exhalation. The oxygenated blood then returns to the left side of the heart where it pumps to the remainder of the body (systemic circulation) - body cells extract oxygen and nutrients and remove waste.
