Physiology of the Cardiovascular System Flashcards
CVS - transport
- body cells need a constant supply of oxygen and nutrients, removal of waste products
- circulating fluid is required for transport
- exchange between blood, cells, extracellular fluid
Pulmonary Circulation
Gas exchange in lungs
Deoxygenated blood enters right atrium, flows into right ventricle
Exits heart through pulmonary trunk
Pulmonary trunk divides into left and right pulmonary arteries
Blood travels to right and left lung (gas exchange)
Oxygenated blood travels in left or right pulmonary veins and enters left atrium
Systemic circulation
Capillary exchange in cells
Oxygenated blood enters left atrium, flows into left ventricle
Left ventricle contracts, pushes blood out of heart through aorta
Aorta branches into ascending aorta, aortic arch, descending aorta
Blood is delivered to all cells and tissues for gas/nutrient/fluid exchange
Travels back to the heart, reenters right atrium through vena cava
Cycle and control
Contraction of heart produces pressure
Blood moves through system from high to low pressure
Cardiac cycle - repetitive contraction (systole) and relaxation (diastole) of heart chambers - moves blood through body
Blood flow is proportion to metabolic needs of tissues;
Brain, kidney, liver, exercising skeletal muscle - high blood flow
Cardiac Output= Heart Rate x Stroke Volume
Nervous system interaction
- maintains blood pressure, blood flow - rerouting blood flow
eg. increase BP with excercise, reroute blood flow away from skin and viscera towards brain and cardiac muscle in response to blood loss/injury
Hormonal control
epinephrine from adrenal gland - increase HR and SV; vasoconstriction in respinse to stress
Conducting system
Heart generates own action potential
Auto-rhythmicity - repetitive contractions
Sinoatrial node (SA) - “pacemaker”
Atroventricular node (AV)
Action potentials spread through the conducting system of heart to all cardiac muscle cells - cardiac muscles contract
Capillary exchange
The movement of substances into and out of capillaries - cells receive nutrients, wastes are removed
Diffusion - substances move from high concentration in capillary to low concentration in interstitial fluid (oxygen, hormones, nutrients)
Lipid soluble - diffuse through plasma membrane of endothelial cells (oxygen, carbon dioxide, steroid hormones, fatty acids)
Water soluble - diffuse through intercellular spaces or through fenestrations of capillaries (glucose, amino acids)
Lymphatic system
Fluid moves out of capillaries into interstitial space, returns to capillaries
Fluid remaining in tissues enters lymphatic system, returns to venous circulation
Edema
swelling caused by excess fluid accumulation in body tissues
- lymphatic space exhausted
Causes of enema
- problems with capillaries, heart failure, kidney disease, liver problems, pregnancy, problems with lymphatic system, standing/walking in hot weather, excess salt consumption
