Cardiovascular System Flashcards
What is the structure of the heart?
What is the structure and function of cardiac muscle
Cardiac muscle cells are joined by intercalated discs, with gap junctions to allow action potential propagation between cells.
All right and left atrium myocytes depolarise and contract together, and are separated from the ventricles by CT. A bit later, all right and left ventricular myocytes depolarise and contract together.
Describe the process of the generation of an action potential in cardiac muscle and draw a diagram of an action potential.
In cardiac muscle, action potentials last about 200-300 msec, compared to 2-5 msec in skeletal muscle. Contraction lasts about 200-300 msec, compared to 50msec in a skeletal muscle twitch.
Depolarisation occurs when sodium channels open, and there is a net movement of Na+ into the cell. The change in voltage causes repolarisation, in which potassium channels open which causes a net movement of potassium out of the cell. While potassium is leaking out of the cell, voltage gated calcium channels open and allows calcium to move into the cell counteracting the activity of one another causing a ‘plateau’. The calcium channels then close, causing depolarisation to continue.
Describe the movement of blood around the body.
Oxygenated blood travels from the capillary beds of the lungs through the pulmonary veins into the left atrium and left ventricle of the heart, from here, it is pumped through the aorta to the aortic branches and the capillary beds of all body tissue, where it becomes deoxygenated. It then travels from the capillaries through the venous system to the inferior/superior vena cava and into the right atrium, the right ventricle and the pulmonary artery to the capillary bed of the lungs.
What is the structure of the lymphatic system?
The lymphatic system is dispersed throughout the body, with various glands and nodes spread around the body. Generally, lymph vessels accompany veins, and nerves and thus form part of a nervous bundle. At various location in the body, lymph enters lymph nodes via afferent lymph vessels, where it flows pas a large number of lymphocytes and then leaves the lymph nodes via efferent lymph vessels.
Lymph eventually returns to the blood, usually after filtering through several lymph nodes via the thoracic duct (most of the body) to the left subclavian vein or left brachiocephalic via the right lymphatic duct (from the right head and neck, right upper limb and right thorax) to the subclavian vein or the right brachiocephalic vein.
Illustrate the main blood vessles
