Chapter 6 Flashcards
Functions of the Circulatory System
– Transports oxygen and food to the cells of the body
– Removes waste products from cells to the excretory organs
– Aids in coagulation
– Assists in defending the body against disease
– Helps regulate body temperature
Circulatory system main components
Cardiovascular: heart, blood vessels, & blood
Lymphatic: lymph vessels, lymph nodes, & lymph
Heart structure
Muscular organ surrounded by a fluid-filled sac called the pericardium
Consists of two upper chambers called atria (singular atrium) and two lower chambers called ventricles
Has three layers* Epicardium – thin outer layer* Myocardium – muscular middle layer* Endocardium – thin inner layer
Coronary circulation
*Coronary arteries, right & left which carries oxygentated blood from the aorta to the heart muscle
* Damage or blockage of the coronary arteries can lead to ischemia (lack of oxygen) and myocardial infarction (“heart attack”)
coronary veins
Returns oxygen-poor blood from the heart muscle back to the heart
Cardiac cycle
One complete contraction (systole) & relaxation (diastole) of heart
Electrical conduction system
Specialized cells that initiate & distribute electrical impulses throughout the myocardium to coordinate cardiac cycle
Electrocardiogram
Graphic recording of the heart’s electrical activity during the cardiac cycle
Origin of heart sounds
First sound is heard as the atrioventricular valves close as ventricles contract
Second sound is heard as the semilunar valves close as the ventricles relax
Heart rate
Number of beats per minute
Cardiac output
volume of blood pumped by the heart in one minute. Averages five litres per minute
pulse
palpable rhythmic throbbing caused by expansion and contraction of an artery as blood passes through it
Blood pressure
the force exerted by the blood on the walls of the blood vessels.
Usually measured in brachial artery of arm using sphygmomanometer
Measured in mm of mercury
Systolic and diastolic
Systolic
pressure in arteries during contraction of the ventricle
diastolic
pressure in the arteries during relaxation of the ventricles
Pulmonary circulation
- Carries unoxygenated blood from the right ventricle to the lungs to remove carbon dioxide and pick up oxygen via the pulmonary artery
- Returns oxygenated blood to the left atrium via the pulmonary vein
Systemic circulation
- Arteries carry oxygenated blood and nutrients from the left ventricle to the rest of the body
- Veins return blood carrying carbon dioxide and other waste products to the right atrium
Arteries
conveys blood. aorta is largest
Arterioles
arteries branch into small arterioles which eventually junction with capillaries
capillaries
forms the junction between arterioles and venules; microscopic, one cell thick allowing for gaseous exchange
venules
forms a junction between capillaries and larger veins
veins
largest is the vena cavae; longest is the great saphenous vein in the leg
Tunica adventitia
outer layer of blood vessel; made up of connective tissue; thicker in arteries
Tunica media
middle layer of blood vessel; made of smooth muscle; much thicker in arteries
Tunica intima
inner layer or lining of blood vessel; single layer of endothelial cells with an underlying basement membrane, connective tissue layer, and an elastic internal membrane
Lumen
Internal opening through which blood flows
valves
thin, membranous leaflets composed of epithelium. Valves keep blood flowing toward the heart in one direction.
antecubital fossa
the bend of the arm
Best veins to draw from if the patient has H-shaped antecubital veins
Medial cubital vein
cephalic vein
basilic vein
Best veins to draw from if the patient has M-shaped antecubital veins
Median vein (intermediate antebrachial vein being best)
median cephalic vein
median basilic vein
Should veins from the underside of the wrist be drawn from?
No, they need to be avoided due to vasculature and enervation of the area
Blood composition
Plasma which consists of* 90% water* Gases (O2, CO2, N)* Minerals (Na, K, Ca, Mg)* Carbs & lipids* Proteins* Waste products* Vitamins, hormones, drugs
Formed elements consisting of erythrocytes, leukocytes, and thrombocytes
Blood type is determined by
presence or absence of antigens on surface of red blood cells
Rh factor
based on “D” antigen
Compatibility test/cross-match
Test that determines whether donor blood and recipient blood are compatible (suitable to be mixed together)
Blood specimens
Serum, plasma, whole blood
hemostasis
arrest or stoppage of bleeding
Hemostasis process
- Vasoconstriction
- Formation of a primary platelet plug
- Progression to a stable blood clot
- Fibrinolysis (dissolving of clot)
Coagulation factors
Named with Roman numerals in order of discovery
* Enzyme precursors
* Cofactors
* Substrates – Fibrinogen is most important
Coagulation extrinsic pathway
Requires an external source (trauma) to be activated
Coagulation intrinsic pathway
Involves coagulation factors circulating within the body thatare activated when they come in contact with surfaces ofcertain cells
Thrombin role
– Enzyme that plays the major role in coagulation
– Generated at injured site from prothrombin
– Converts fibrinogen to soluble fibrin
– Amplifies coagulation
– Supports platelet plug formation
Lymphatic system functions
– Returns tissue fluid to the bloodstream
– Protects the body by removing microorganisms
– Processes lymphocytes
– Delivers fates absorbed from the small intestine to the bloodstream
Lympathic system structures and functions
– Lymphatic vessel and ducts: transports lymph through the body
– Lymph nodes: mass of lymphatic tissue
Lymph flow
- Excess tissue fluid that filters into lymphatic capillaries
- Lymph is moved by skeletal muscle contraction
- Lymph passes through lymph nodes that filter out impurities
