bio module 10 - circulatory system

function of circulatory system

transportation, defense, homeostasis

major organs and tissues

blood, heart, blood vessels

blood

cells and plasma

heart

pumps blood to drive circulation

blood vessels

arteries, veins, capillaries

artieries

carry blood away from the heart

veins

carry blood to heart

plasma

liquid in which cellular elements are suspended

erythrocytes

red blood cells; biconcave disaces, high surface area to volume ratio, loaded with hemoglobin

leukocytes

white blood cells

platelets

cell fragments

plasma composition

92% water, 7% plasma proteins, 1% other

hematopoiesis

formation of blood cells; occurs in red bone marrow; formed from hematopoietic stem cells

anemia

low erythrocyte count; low or faulty production; sickle cell anemia, iron deficiency, vitamin deficiency

heart chambers

4; left and right atria, left and right ventricles

cardiac output (CO)

the amount of blood pumped by each ventricle in 1 minute; average = 5.25 L/min

stroke volume (SV)

quantity of blood pumped out of ventricles, related to blood pressure

heart rate (HR)

number of cardiac cycles per minute; CO = SV x HR

pressure gradient

increased pressure in one area will move blood to another area; move from high to low

myocardium

cardiac muscle cells surrounded by collagenous fibers, blood vessels, and nerve fibers regulate the heart; thicker on the left side

systole

contraction

diastole

relaxation

pumping of blood

cycles of systole and diastole

septa

extensions of the myocardium that divide chambers

interatrial septum

divides atria

interventricular septum

divides ventricles

atrioventricular septum

divides atria and ventricles

atrioventricular valves

tricuspid and mitral (bicuspid)

semilunar valves

pulmonary and aortic

tricuspid valve

right valve; 3 flaps

bicuspid valve

left, mitral, 2 flaps

heart sound 1

lub, AV valves closing

heart sound 2

dub, SL valves closing

murmur

sounds othecr than “lub, dub";” might indicate heart function

coronary arteries

supply heart with oxygen

myocardial infarction

blockage of coronary artery usually by plaque or blood clot, lack of oxygen to the heart; cells die and cannot be replaced, so scar tissue is built in place

myocardial contractile cells

pump blood, similar to skeletal muscle; 99% of cells in atria and ventricles

myocardial conducting cells

trigger contraction

sinoatrial (SA) node

specialized cells in the right atrium that initiate the sinus rhythm; electric

sinus rhythm

electrical pattern that causes contraction

atrioventricular (AV) node

specialized cells in right atrium (inferior) that cause a pause

AV Bundle (Bundle of His)

carries signal to ventricles and papillary muscles; split into bundle branches

purkinje fibers

conductive fibers that extend throughout the myocardium

electrical activity in heart **

electrical signal spread from SA to atrial myocardial contractile cells and the AV node; interatrial band conducts electrical activity from SA node to left atrium; electrical activity triggers muscle contraction; critical pause before the AV node transmits the impulse to the AV bundle (allows the atrial cardiomyocytes to complete their contraction before signal is transmitted to the ventricle)

arteries - systemic circulation blood

oxygenated

arteries - pulmonary circulation blood

dexoygenated

veins - systemic circulation blood

deoxygenated

veins - pulmonary circulation blood

oxygenated

systolic

pressure in arteries when heart is in ventricular systole

diastolic

pressure in arteries when heart is in ventricular diastole

pulse

when blood is pumped from the heart, the arteries expand and recoil

measuring blood pressure

use of a sphygmomanometer and stethoscope

regulation of capillary blood flow

sphincters guard the entrance to individual capillaries

relaxed sphincters

accommodate blood flow

contracted sphincters

block blood flow

capillary blood pressure

pressure starts high and drops lower as it enters venules

bulk flow in capillaries

fluid moves from high pressure to low pressure

venous blood pressure

steady throughout the cardiac cycle; need help to bring blood back to heart because of gravity

respiratory pump

inhalation compresses abdomen and creates high pressure, chest expands and creates low pressure

skeletal muscle pumps

creates pressure gradients

neural regulation of blood pressure

the brain responds to changes in pressure and CO2

baroreceptors

on the walls of large arteries; stimulus: increased BP stretches receptor, response: vasodilation of arteries and veins, effect: reduce resistance, BP and CO

chemoreceptors

stimulus: drop in pH due to increased CO2, making blood more acidic; response: increased heart rate and vasoconstriction, effect: increased CO and blood flow viscosity; opposite for increase in pH

short term effect of exercise on vascular homeostasis

CO increases from 5L/min to 20L/min; BP increases 120/80 to 185/75; blood distribution changes

long term effect of exercise on vascular homeostasis

heart size increase; lowered cholesterol and decreased plaque formation, decreases BP