Chapter 13: Blood, Heart, and Circulation

what is the circulatory system

organ system that transports molecules and other substances rapidly over long distances, between cells, tissues, and organs

what are the divisions of the cardiovascular system

cardiovascular and lymphatic

what is in the cardiovascular system

heart, vessels/vascular system, blood

heart (cardiovascular system)

pump of variable rate and strength

vessels/vascular system (cardiovascular system)

• pipes of variblae diameter

• interconnected system

blood (cardiovascular system)

• fluid (connective tissue) of variable volume and viscosity

• contains water, solutes, and cells

• averages 5.5L

what is a hematocrit

a rapid assessment of blood composition. it is the percent of blood volume that is composed of red blood cells (RBCs or erythrocytes)

what is hemaglobin

in RBCs carries O2 to tissues and CO2 away from tissues

what is plasma

the fluid portion of blood, includes water, ions, proteins, nutrients, gasses, hormones, wastes, etc.

what are white blood cells

(WBCs or leukocytes) for immunity

what are platelets

cell fragments for clotting

what does the red color indicate

blood is fully oxygenated due to its passing through the lungs

what does the blue color indicate

blood is partially oxygenated due to delivery of O2 to cells

what is the heart

it is a muscular pump that propels the blood thorugh the pulmonary (lung) circulation and systemic (other organs and tissues) circulation

what muscular organs does the heart contain

cardiac muscle and endothelial cells

what is myocardium

muscular tissue of heart

each cardiac muscle BLANK with a heart beat

contracts

what does pumping action of heart due to muscle contraction do

creates pressure to move blood quickly throughout the body

what are the right and left sides of the heart separated by

the septum

what is a ventricle

lower chamber of the heart, pumps blood into arteries

where does the right ventricle pump blood to

the lungs (via pulmonary arteries), pulmonary circulation

where does the left ventricle pump oxygenated blood to

the other tissues (via aorta), systemic circulation

what separates the two ventricles

the interventricular septum

what is the atrium

upper chamber of the heart, receives venous blood returning to heart

where does the right atrium receive blood from

the systemic circulation (via vena cava)

where does the left atrium recieve blood from

the pulmonary circulation (via pulmonary veins)

what are the atrium and ventricle separated by

connective tissue, fibrous skeleton

what is pulmonary circulation

circuit thorugh which partially oxygenated blood travels from the right ventricle of the heart via the pulmonary arteries to the lungs

there, the blood picks up O2 from inspiration and releases CO2 for expiration

this oxygenated blood travels back to the left atrium of the heart and enters via the pulmonary veins

what is systemic circulation

circuit thoruhg which oxygenated blood travels from the left ventricle of the heart via the aorta thorugh the organ systems.

there, the blood delivers O2 from inspiration and picks up CO2 for expiration

this partially oxygenated blood travels back to the right atrium o f the heart and enters via the superior vena cava and inferior vena cava

what is the atrioventricular valve between

atria and ventricles

what is the tricuspid valve (3 flaps; AV valve)

between right atrium and right ventricle

bicuspid (mitral) valve (2 flaps; AV valve)

between left atrium and left ventricle

how does the AV valve open and close

due to pressure difference across it, i.e. pressure can push a valve open or force it closed

what are papillary muscles (AV valve)

limit valve movement to prevent backflow of blood into atria

what are the two semilunar valves

pulmonary and aortic valves

pulmonary valve (SL valve)

between right ventricle and pulmonary trunk (right and left pulmonary arteries)

aortic valve (SL valve)

between left ventricle and aorta

what is diastole and systole

alternating contractings and relaxtions of atria and ventricles (apprx. 0.8s)

what is systole

period of ventricular contration and blood ejection, approx 0.3s

what is diastole

period of ventricular relaxation and blood filling, approx 0.5s

what is pressure

force exerted by blood (due to heart contraction) (mm Hg)

what is blood flow

is from region of higher pressure to region of lower pressure (volume/unit time such as L/min)

what are the two heart sounds heard through

a stethoscope

what is the first heart sound you hear when using a stethoscope

soft, low-pitched “LUB”

AV valve closure, at onset of systole

what is the second heart sound you hear when using a stethoscope

louder “DUB”

SL valve closure, at onset of diastole

Order of cardiac cycle: systole (1/5)

isovolumetric contraction: pressure in ventricles increases as ventricles begin contraction, causing AV valves to close (lub)

Order of cardiac cycle: systole (2/5)

ejection of blood into aorta and pulmonary trunk occurs when ventricular pressure (120 mmHg, systolic BP) exceeds aortic pressure so that SL valves open

• amount of blood ejected is the stroke volume; around 2/3 of the blood in the ventricles

Order of cardiac cycle: diastole (3/5)

isovolumetric relaxation: pressure in ventricles decreases, causing SL valves to close (dub)

• aortic pressure is 80 mmHg (diastolic BP)

Order of cardiac cycle: diastole (4/5)

when pressire in ventricles falls below atrial pressure, AV valves open and there is rapid filling of the ventricles (blood in atria → ventricles)

Order of cardiac cycle: diastole (5/5)

atrial contraction delivers final amount of blood into ventricles just prior to #1 occuring again

• volume of blood in ventricles at end of diastole is the end-diastolic volume (EDV)

what can the cardiac cycle be measured by

using an ECG to measure systolic and diastolic arterial BP

where does pressure and volume change during the cardiac cycle

in the left ventricle

• similar changes occur in the right ventricle, but the pressures are lower

what does depolarizarion in the sinoatrial (SA) node do

initiates APs that spread to the rest of the cardiac cells, leading to contraction

what are some functions of the SA node

• small group of cardiac muscles in right atrium of heart

• hearts pacemaker

• cells depolarize spontaneously and quickly

• excitation causes contraction

• APs spread through cells of atria via gap junctions, electrical synapses

what does the atrioventricular (AV) node do

carries APs from right atrium

how do APs travel to ventricles

bundle of His

• slow conduction in AV node, so ventricular contraction occurs after atrial contraction has ended

what does an ECG/EKG do

detects electrical activity in the heart via electrodes on the surface of the skin

what do electrodes record (ECG/EKG)

current conducted through fluid around heart, caused by simultaneous APs in myocardial cells

what are the 3 distince ECG/EKG waves

P, QRS, and T

what is the P wave

results from the spread of atrial depolarization

what is the QRS wave

results from the spread of depolzarization into the ventricles

what is the T wave

results from repolarization of the ventricles

what is the structure of blood vessels

connective tissue, smooth muscle, and epithelial tissues

• capillaries only have epithelial

what do blood vessels do

distribute blood to tissues, regulate BP

what is a closed loop (blood vessels)

blood pumped from the heard in arteries returns to the heart in veins

what do ateries branch into

arterioles, vessels between arteries and capillaries

what are capillaries

smallest blood vessels; there is exchange of substances between cells and vessels, such as nutrients and waste

what do capillaries merge to form

venule, vessles between capillaries and veins

what do venules merge into

veins

what are arteries

have strong, thick elastic walls that resist flow

• high pressure/low volume

what are veins

have weaker walls and a wider lumen and fill more easily

• low pressure/high volume

  • act as volume reserves (54% of total volume)

what are aterioles

have the greates pressure drop

what do arterioles vessels serve as

controllers of flow into capillary beds

what does vasoconstriction of arterioles cause

(contraction of their smooth muscle layer to decrease diameter) decreases blood flow

what does vasodilation of aterioles cause

(relaxation of smooth muscle layer to increase diameter) increases blood flow

what do capillaries mediate the exchange of

substances with ISF

where are capillaries located

in every tissue except cornea

what kind of layer do capillaries have

single layer of epithelium which allows rapid exchange of substances

• gas exchange (O2, CO2)

• nutrient and waste exchange

  • cell secretions

what do veins have

greatest total blood volume and can expand with greater blood volume

what kind of pressure do veins have

low pressure, but blood flows back to the heart due to the skeletal muscle pump (skeletal muscle contraction), and the direction of flow is one-way due to venous valves in peripheral veins

what happens when muscles contract in veins

they are partially compressed → diameter reduction, venous pressure increase and increased volume of blood returning to the heart

what is coronary artery disease (CAD)

insifficient blood flow (ischemia) due to change in coronary arteries (arteries that nourish heart)

what can coronary artery disease cause

heart attack (myocardial infarcation (aka MI))

what is the primary cause of coronary artery disease

atherosclerosis in coronary arteries, which is thickeing of arterial wall with plaques that include cholesterol and fat deposits

what are some risk factors of coronary artery disease

HTN, stress, smoking, obesity, sedentary lifestyle, diabetes, high cholesterol

what what the lymphatic system transport

• excess ISF that filtered out of blood vessels back to the blood

  • fat absorbed from the small intestine into the blood

what do lymphocytes defend against (lymphatic system)

disease-causing agents

what do lymph nodes do

filter lymph to remove pathogens before the fluid is returned to the blood