Cardiovascular System

system function

1. circulation

2. temperature regulation

3. removing carbon dioxide and waste

heart

pumps blood to lungs and body

arteries

1. carry oxygenated blood to body cells

2. strong, elastic, thick

3. high pressure

veins

1. carry deoxygenated blood back to heart

2. thinner, not as elastic

3. lower pressure

4. contain 1-way valves

capillaries

tiny tubes where nutrients, gas, and waste are exchanged

what is a pulse

a surge of blood through your arteries that gives vital information about health

where is the pulse felt in adults

neck or wrist

where is the pulse felt in infants

arm (brachial artery)

pulmonary circuit

carries deoxygenated blood to lungs to pick up oxygen and unload carbon dioxide

• veins

systemic circuit

sends oxygenated blood and nutrients from heart to all body cells and removes waste

• arteries

structure of the heart

1. hollow, cone-shaped, muscular pump

2. located in the thoracic cavity within mediastinum

3. rests on top of the diaphragm

4. distal end extends to the left

5. encased in a parietal pericardium

6. average adult heart is 14 cm long, 9 cm wide, and weights 10-12 oz

epicardium

• outer layer of the walls of the heart

• serous membrane (contains fluid)

• protects heart by reducing friction

myocardium

• middle layer of the walls of the heart

• thick

• mostly cardiac tissue that pumps blood out of the heart

endocardium

• inner layer of the walls of the heart

• epithelial and connective tissue

• lines inner chambers of the heart

atria

upper chambers of heart that recieve blood returning to the heart

ventricles

lower chambers of heart that recieve blood from atria and force blood into arteries

septum

separates left and right halves so blood doesn’t mix

atrioventricular (AV) valves

separate atria and ventricles to prevent backflow of blood

tricuspid

right side of heart

bicuspid

left side of heart

semilunar valves

prevent backflow into the ventricles

pulmonary valve

allows blood to leave right ventricle and enter pulmonary trunk, prevents backflow

aortic valve

allows blood to leave left ventricle and enter aorta, preventing backflow

regurgitation abnormality

valve doesn’t close properly and blood regurgitates back into atrium

mitral valve prolapse

valve bulges back into left atrium

aortic stenosis

not enough blood passes through valvesvess

vasoconstriction

vessels shrink to retain heat

vasodilation

vessels expand to retain heat

coronary arteries

first two branches of aorta that supply oxygenated blood to the heart tissue

cardiac veins

bring deoxygenated blood from heart tissue to right atrium

angina pectoris

coronary arteries becomes partially blocked or narrowed, depriving myocardial cells of oxygen and causing pain

• usually occurs during physical activity, lessens with rest

myocardial infarction

1. blockage that completely obstructs coronary arteries, killing part of the heart

   1. heart attack

angiogram

allows doctor to get image of the blockage in coronary arteries

angioplasty

catheterization of coronary arteries with balloon

bypass surgery

reroutes the blood in coronary arteries around the blockage

thrombosis

blood clot

embolism

blockage in a vessel caused by thrombosis or cholesterol

aneurysm

“outpouching” of a blood vessel that can hemmorrhage

systole

phase of heart cycle where heart contracts, pumping blood out of the heart

• atrial systole = ventricular diastole

• ventricular systole = atrial diastole

• both relax briefly after ventricular systole

diastole

heart is relaxed and ventricles fill with blood

what is an EKG

machine that measures electrical activity and impulses generated by the heart

P-wave

atrial depolarization/systole

QRS complex

ventricular depolarization/systole

T-wave

ventricular repolarization

1500 / # of small boxes

more accurate way of determining heart rate from an EKG

count the # of R-R intervals and multiply by 10

way of determining heart rate from an EKG

EKG irregularities

1. no defined P wave

2. no defined QRS

3. different lengths of time between segments

4. “dropped” beats - murmur

ventricular fibrillation (v-fib)

heart beats with rapid, erratic impulses; ventricles quiver uselessly

sinus bradycardia

slower than normal heart rate (< 50 bpm)

sinus tachycardia

faster than normal heart rate (> 100 bpm)

atrial fibrillation (a-fib)

atria beat chaotically and irregularly, out of coordination with ventricles

atrial flutter

atria beat too quickly, but more organized and less chaotic than a-fib

asystole

cardiac arrest, no electrical activity (flatined)

steps of the cardiac cycle

1. pressure is low during ventricular diastole, opening the AV valves

2. ventricles fill with blood and atrial systole occurs

3. AV valves close when ventricular pressure exceeds atrial pressure

   1. papillary muscles pull on the chordae tendinae to prevent valves from bulging back into atria

4. atrial pressure is low (atrial diastole) and they begin to fill up again to start the next cycle

5. ventricular pressure rises, opening the semilunar valves and forcing blood into the pulmonary trunk and aortic arch (ventricular systole)

6. pressure drops in ventricles after contraction and the semilunar valves close

heart sounds

“lubb-pupp”

lubb - AV valves closing during ventricular contraction

pupp - semilunar valves closing during ventricular relaxation

blood pressure

the force blood exerts against the intter walls of blood vessels

• the human heart creates enough pressure to squirt blood 30 feet

systolic pressure

maximum blood pressure during ventricular systole (top #)

diastole pressure

maximum blood pressure during ventricular diastole (bottom #)

physiological factors affecting blood pressure

• heart action

• blood volume

• preipheral resistance

• blood viscosity

cardiac conduction system

coordinates the events of the cardiac cycle

cardiac muscle fibers

form bands of muscle that wind around the heart and work together as a unit called a “function syncytium”

cardiac conduction system

1. sinoatrial (SA) node

2. AV node

3. bundle of his

4. right and left bundle branches

5. purkinje fibers

sinoatrial (SA) node

• “pace maker”

• specialized cardiac muscle tissue

• can depolarize on its own

• generates impulses (70-80 per min)

AV node

delays ventricular excitation

bundle of his

transmits signal from AV node to purkinje fibers

purkinje fibers

cause myocardial tissue to contract