heart Flashcards
Functions of the Cardiovascular System (3)
- maintain homeostasis
- transport of: metabolites/wastes, hormones/signal molecules, dissolved gasses, immune/inflammatory cells
- regulation of body temperature
Components (4)
- Pump - the heart
- Conducting Vessels - arteries/veins
- Sites for exchange with tissues - capillaries
- Drainage System for Excess tissue fluids - lymphatic vessels
Arteries vs. Veins
Arteries: away from heart. Veins: back to heart
Two Circuits?
- Pulmonary circuit: to lungs
- Systemic Circuit: to rest of body
Pulmonary vs. Systemic Circuit Diagram
Location of heart ?
- heart resides in the mediastinum (middle of sternum)
- mediastinum: region of the thorax between the lungs/pleural cavities - contains heart, esophagus, trachea, thymus gland and large blood vessels
Pericardium
- heart is contained within the pericardial cavity
- pericardial cavity is formed by pericardial sac
Heart valves - occur between? insure?
- atria and ventricles (so blood only flows from atria to ventricles)
- ventricles and outflow vessels: pulmonary artery, artery
- valves insure: one way flow of blood - open to allow blood through, close to prevent backflow
Blood Flow and Heart Valves (3)
- Tricuspid valve: right atrium and right ventricle
- Bicuspid/Mitral Valve: Left atrium/ventricle
- semilunar valves: pulmonary artery and aorta
Cardiac cycle - def? what happens?
- all the events associated with one heartbeat
- the two atria contract while ventricles relax
- two ventricles contract whil atria relax
Diastole vs Systole?
- diastole: relaxation phase
- Systole: contraction phase
Blood Vessels - names of the three layers?
- tunica interna
- tunica media
- tunica externa
Tunica Interna (blood vessel)
composed of simple squamous epithelium (endothelium) and thin layer of CT
Tunica media composition
thickest layer, composed of elastic fibers (to allow vessles to expand when ventricle contract and increase blood pressure) and smooth muscle (to control diameter of blood vessel)
Tunica Externa - composition? attachment?
composed of connective tissue, attaches vessel to surrounding connective tissue = anchors blood vessel in place
Elastic (Conducting) Arteries - properties? tunica media? function?
- largest diameter arteries (closest to the heart, like the aorta)
- tunica media contains high density of elastic fibers
- stretch and recoil in response to pumping of heart - even out pressure surges (so not a lot of pressure change in capillary beds)
Muscular (Distributing) Arteries - size? function? tunica media? able to?
- medium sized arteries
- distribute blood to skeletal muscles and internal organs (by contracting and relaxing)
- tunic media: contains predominantly smooth muscle
- able to vasoconstrict (close) and vasdilate (open)
Arterioles - size? layers? function?
- small to microscopic vessels
- poorly defined tunica externa (so small, don’t need much to anchor them) and media composed of few smooth muscle cells
- deliver blood to capillaries - change in luminal diameter regulates blood pressure
Capillaries - size? function?
- smalles blood vessels
- connect arterioles to venules: mediate exchange between blood and surrounding tissues
Control of Blood flow In Capillary Bed (2)
- precapillary sphincters: control blood flow through capillaries
- metarterioles: shunt blood through capillary bed when sphincters closed
Veins - direction?
collect blood from organs and tissues - return it to heart
Venules - function? wall?
- collec blood from capillaries
- wall composed of primarily tunica interna
- are like wide capillaries
Medium/Large Veins - properties of layers?
- tunica externa: thickest layer
- lots of connective tissue, but not so much smooth muscle ( so small medium)
Valves - found where? purpose?
- found in walls of veins (not found in arteries) for uppoer/lower extremities
- prevent backflow of blood since blood has to travel against gravity
- venous compression caused by contraction of adjacent muscle aids in maintaining blood flow
Fluid Loss to Tissues?
- blood from capillaires to tissues: filtration from plasma into interstitial fluid
- interstial fluid flows into lymphatic vessels - goes to veins back to heart
Lymphatic Vessels - pressure? vessels? cell?
- lymphatic system at extremely low pressure
- vessels very thin
- endothelial cells discontinuous
Lymph Flow vs. Blood Flow
- blood: actively pumped through vessels by heart
- Lymph: flows passively along a pressure gradient, no pump
Lymphatic Valves - number? purpose?
- large number of valves
- prevent back flow of lymph
