Cardiovascular & lymphatic systems Flashcards
Cardiovascular system: components and function
Components
- Blood, heart and blood vessels
Function
- Blood pumped through vessels via the heart
- Oxygen and nutrients carried to cells via the blood.
- Carbon dioxide and waste carried away from cells via blood
- Aids in the regulation of
- acid/base balance
- Temperature
- water content of body fluids
- blood components help defend against disease and repair damaged blood vessels.
Location of the heart
- In the anterior aspect of the thoracic cavity
- Posterior to the sternum
- Normally slightly towards the left
- middle mediastinum a subdivision of the inferior mediastinum.
- Located between the pleural membrane of the left and right lung
- Superior to the diaphragm
Chambers of the heart
-Right atrium
-left atrium
-right ventricle
-left ventricle
-septum
Left ventricle has much larger muscle- thicker muscles indicate strength, it is responsible for pumping blood around the body (systemic circulation).
Right responsible for lungs (pulmonary circulation).
cardiac valves
-pulmonary arteries
-tricuspid valve
-aortic valve
-bicuspid valve
-left ventricular outflow tract
Systematic and pulmonary circulation process
1) deoxygenated blood returns from the body in the vena cava and enters the right atrium.
2) the blood then passes via atrioventricular valve (tricuspid) into the right ventricle and out, via semilunar valve, into the pulmonary artery.
3) The blood now passes through the lungs and returns to the left atrium via the pulmonary vein.
4) the blood passes through a second AV valve (bicuspid) into left ventricle and then through semi lunar valve into the aorta and then body tissues.
Functions of circulatory system
- deliver nutrients and oxygen to tissues
- remove waste products of cellular metabolism (e.g.CO2)
- transport hormones & drugs
- acid base balance
- blood clotting (haemostasis)
- distribution of heat
- immune response
Describe the aorta
- oxygenated blood from the heart is distributed from the aorta to all parts of the body
- systemic circulation
- divided into ascending aorta, aortic arch and descending aorta.
- large diameter, relatively thin walled and highly elastic
- stretches to receive ejected blood from left ventricle
describe the Arteries
- often called distributing arteries
- relatively greater amount of smooth muscle with some elastic fibres
- transport blood over long distances with little drop in blood pressure
- take blood away from the heart
Arterioles
- transition between artery and capillary
- thick muscular wall
- regulate blood flow within tissues
- important role in regulation of arterial blood pressure (called resistance vessels)
Capillariesries:
- form interweaving networks called capillary beds
- microscopic vessels
- form large cross sectional area (13.57 m2)
- exceedingly thin consisting only of tunica intima - single endothelial cell.
- site for diffusion of solutes
Veins
- relatively thin walled with large lumen
- largely non-muscular and elastic
- very distensible and easily collapse
- low pressure vessels
- capacitance vessels: 67% of blood volume contained in veins (Berne & Levy 1998)
- take blood to the heart
Venules
- are the smallest veins
- located at the convergence of capillaries and return blood to veins
Lymphatic and immune system: components and functions
Components
- Lymphatic fluid and vessels;
- Spleen, thymus, lymph nodes and tonsils
Function
- Returns proteins and fluid to blood;
- carries lipids from gastrointestinal tract to blood;
- includes structures where lymphocytes mature and proliferate.
Functions
Immunity
- Production and maturation of white blood cells (lymphocytes and macrophages)
- 90% of immune cells within lymphatic tissue
- Organs/tissue supported by network of vessels
Tissue drainage (homeostasis)
- 21 litres of interstitial fluid diffuses from bloodstream each day
- Most returns to bloodstream directly
- Excess fluid (3-4 litres) drained through lymphatic system
- Maintains pressure and volume of interstitial fluid and blood
Absorption of fat/fat-soluble nutrients/fatty acids
- Into central lymphatic vessels (lacteals) in villi of small bowel
Interstitial fluid and Lymph- Overview
- Interstitial fluid in extra-cellular matrix between cells diffuses freely from bloodstream through permeable capillary walls
- Most diffuses back into bloodstream through venous capillaries
- Remaining fluid diffuses through more permeable lymph capillaries; called lymph
- Passes through lymph vessels though lymph nodes before diffusing back into blood
- Low pressure system parallel (but separate to blood circulation)
- Follows pressure gradient; High in blood capillaries, Low in large veins where terminates
Organs/components in the lymphatic system
- Lymph
- Lymph vessels
- Lymph nodes
- lymph organs: Spleen, thymus
- Diffuse lymphoid tissue: Mucosa-associated lymphoid tissue (MALT) – Tonsils, Gut-associated lymphoid tissue (GALT) PEYER’S PATCHES
- Bone marrow