pulse - lab 7 - physiology

cardiac cycle

how the heart pumps blood in rhythmical sequence of both electrical and mechanical events

electrocardiogram (ECG)

initiates mechanical activity of the heart

• measured between successive R waves

• contraction and relaxation of atria and ventricles

• chambers contract → pump blood → next section of cardiovascular system

pulse

produced by the left ventricle when it pumps blood to the systemic circulatory system

ECG events

• QRS complex: ventricular systole contraction

• systole: begins at the time of R wave peak and ends at the end of the T wave

• T wave: ventricular repolarization

• diastole: relaxation of ventricles

blood flow

main force: arterial pressure

• contraction of ventricles (systole) pushes volume of blood (stroke volume) into arteries

• blood leaves left ventricle into aorta through the rest of the body

• each section of blood bumps neighboring section to facilitate flww

• aorta/arteries expand muscular walls to receive blood, hen elastic recoil of arteries help push thru system

arteries

carry blood away from the heart to other organs

• large, elastic

arterioles

smaller arteries that enter a tissue

capillaries

have thin walls for exchange of substances between the blood and body tissues

venules

groups of capillaries within a tissue reunite, which then merge into larger vessels

veins

blood vessels that convey blood from the tissues back to the heart

tunica interna

most innermost layer, adjacent to the lumen (interior opening) of the vessel

1) endothelium

2) basement membrane

endothelium

component of tunica interna where cells act as a barrier between the blood and the remainder of the vessel wall

• secrete chemical substances that change contractile properties of smooth muscle

• aid capillary permeability

basement membrane

component of the tunica interna that provides physical support base for overlying epithelial layer

• collagen fibers allows significant, tensile strength

• resilient for stretching and recoil

tunica media

has smooth muscle cells to extend circularly around the lumen, and regulate diameter of lumen wall

tunica externa

outer covering with elastic and collagen fibers, nerves, and smaller blood vessels that supply tissue of vessel wall

pressure wave

the pumping action of the ventricles initiates ____, transmitted via arterial walls

• increases with systole

• decreases with diastole

• stiffness of vessel helps transmit (stiffer=faster), but takes more work

blood volume

when a pressure wave is transmitted to periphery, there is a pulse of increased ______

• tissues and organs change in volume as blood vessels dilate/constrict and blood pulses

• changes brought by autonomic NS on cardio system, environmental factors, metabolic activity, etc.

temperature

regulation involves controlling blood flow to the skin

• need to conserve heat: minimize blood flow to the skin and vice versa

pressure speed

actual blood flow is slower than the transmission of pressure wave

• aorta has fastest blood flow

• traveling speed from heart to periphery due to heart ability to contract, bp, elasticity of arteries, and diameters of arteries/arterioles

• ex: increases with sympathetic influence and systole

plethysmography

study of blood volume changes within an organ by using volume displacement techniques

• ex: transducer shins beam of near-infrared light and can reflect capillary blood volume

• greater blood flow = greater signal amplitude