The circulatory system
heart, blood vessels and blood
transport O2 and nutrients to body cells
carries CO2 and metabolic waste away from cells
The heart
muscular, hollow organ
pump of the body
about the size of a closed fist
endocardium( inner layer ) lines inside of heart, allows for smooth flow of the blood
myocardium ( middle layer ) thick, muscular
pericardium ( double layered membrane ) sac that covers outside of the heart. Sac filled c pericardial fluid ( for lubrication ) to prevent friction and damage to heart as it beats/ contracts
septum… muscular dividing well, divides heart into R and L sides
heart is divided into 4 parts/chambers
atria- 2 upper chamber
ventricles- 2 lower chambers
R atrium- receives blood as it returns from body cells
R ventricles- receives blood from R atrium and pumps blood into pulmonary artery ( PA carries blood to lungs for O2)
L atrium- receives O2 blood from lungs
L ventricle- receives blood from L atrium and pumps blood into aorta for transport to body cells
valves
in chamber of heart ( also some in veins throughout the body)
one way, so blood flows in right direction
tricuspid valve- between RA and RV. Ensures that blood flows to lung, NOT back into RA
pulmonary semilunar valve- between RV and PA. Ensures that blood does not flow back into the RV
mitral/ bicuspid- between LA and LV. Ensures that blood goes into aorta, not back into LA
aortic semilunar valve- between LV and aorta. Ensures that blood flows into aorta, NOT back into LV
Cardiac cycle
L and R sides of heart work together in cyclic manner
systole- period of ventricular contraction ( atira are relaxing )
diastole- brief period of ventricular rest ( atria are contracting )
Blood in the right side of the heart: no O2, more CO2 to the lungs for release CO2 and pick up O2
Blood in left side of the heart : more O2, less CO2 to body for release O2 and pick up of CO2
Electrical impulses originating in heart cause cyclic contraction of muscle
Arrhythmias- abnormal heart rhythms, can be mild or life-threatening
Pacemaker- man- made machine( very small) that delivers electrical impulses to heart when hearts own conduction system not working properly.
Blood Vessels
heart and blood vessels form a closed system for the flow of blood
arteries
carry blood away for the heart
aorta= largest artery in the body
artery to the arterioles to the capillaries
stronger, more muscular and elastic than other other blood vessels.. b/c it receives blood as it is pumped from the heart
veins
carry’s blood back to the heart
vena cavae= largest veins in the body
superior vena cava ( comes from top part of the body/superior to the heart)
inferior vena cava ( comes from lower body/ inferior to the heart)
vein to the venue to the capillaries
thinner, less muscular walls than arteries
contains valves ( why? to prevent back flow of blood )
capillaries
connect aterioles c venules
thin walls, contain only one layer of cells… this is where nutrients and gas exchange take place
so narrow that erythrocytes must pass through in single file
O2 supply to heart muscle itself comes from coronary arteries
Blood
4-6 quarts( 16-24 cups) of blood in average adult… how much blood is collected from blood donor? 2 cups, or about 500ML… the fluid portion will be replaced within 48 hours; erythrocytes will be complete replaced within 4-8 weeks.
transports
O2, from lungs. - heat produced by various body parts
CO2, from body cells - nutrients, from digestive tract
hormones, from endocrine glands - metabolic waste products, from body cells
Blood
plasma( liquid ) formed/solid elements
water - erythrocyte
clotting factors - leukocytes
nutrients - thrombocytes (platelets)
erythrocytes (rbcs)- produced in the bone marrow.. contains Hgb( hemoglobin )… iron ,carry O2 to body’s cells and CO2 away.. lifespan.. 120 days
leukocytes (wbcs)- can pass through capillary walls and enter body tissue.. main function: to fight infection
thrombocytes (platelets)- very important in clotting process
blood vessel is cut- thrombocytes collect at the site to form a sticky plug- clot- scab
Disease and Abnormal Conditions
anemia
not enough rbcs, not enough Hgb, or both
cause: dietary insufficiency or hemorrhage
Sx: pallor(paleness), fatigue, dyspena, rapid heart rate
Tx: blood transfusion, iron supplements, increases intake of dietary iron
Genetic: sickle cell anemia.. abnormal , misshapen rbcs that break easily, carry less O2 and block blood vessels
Aneurysm
saclike formation ( balloning out) on arterial walls.. create weak spots
common sites: cerebral, aortal, abdominal arteries… if aneurysm ruptures- hemorrhage- can be fatal
Sx: most of the time, none… some may cause pain and/or pressures
Tx: remove damaged area of blood vessel and replace c plastic graft OR another blood vessel
Arteriosclerosis
hardening or thickening of arterial walls, results in decrease elasticity
causes: increases blood pressure (hypertension)
commonly occurs as a result of aging
atherosclerosis- fatty plaques(cholesterol) deposited on arterial walls - narrow arterial opening- reduce or eliminate blood flow.. if plaques break loose, they can circulate through blood stream as emboli
Tx: Low cholesterol diet, med, exercise
angioplasty
bypass surgery
Congestive heart failure
when heart muscles do not beat adequately to supply blood needs of body… can be either R or L sides of heart
chronic condition that gets progressively worse over time
there is no cure - eventually cause death
Embolus
foreign substance circulating in bloodstream: air,blood clot, bacterial clumps, fat globules, etc.
if emboules enters blood vessel too small to permit passage..BLOCKED BLOOD VESSEL… can cause death
Hemophilia
inherited disease almost completely…. ( women are carriers)
blood is unable to clot
Tx: blood transfusions, clotting factors
Hypertension
high bp… risk factors= race, family hx, obesity, stress, smoking, age, diet
NO CURE… but can be controlled c meds and lifestyle changes
if not treated, can cause permanent damage to the heart, blood vessels, kidneys
Myocardial infarction
heart attack… occurs when blockage in coronary arteries cuts off blood supply to heart
death may occur immediately
Sx: severe crushing pain that radiates to arm,neck, and jaw….. pressure in the chest:cold clammy skin: dyspena.. start cpr immediately if heart stops. call 911 and get to ER stat!
Phlebitis
inflammation of vein, frequently of vein, frequently in leg. IF thrombus or clot forms- thrombophlebitis
Sx: pain, edema, redness,discoloration
Tx: meds,pain meds,elevation of affected area.