KINS 4630 EXAM 2 CHAPTER 7

Cardiovascular System Major Functions

• deliver O2 and nutrients

• remove CO2 and other waste products

• transport hormones and other molecules

• maintain acid base balance

• support temperature balance and control fluid regulation

• regulate immune function

pump component of cardiovascular system

heart

heart pump function

generates pressure to drive blood through vessels

channels or tubes component of cardiovascular system

blood vessels

blood vessel function

flow must meet metabolic demands

fluid medium component of cardiovascular system

blood

prevailing determinant of cardiovascular adjustment is

maintenance of blood

right and left atria

receiving chambers

right and left ventricle

pumping chambers

right side of heart function

pumps deoxygenated blood from the body to the lungs

left side of heart function

pumps oxygenated blood from the lungs to the body

features of myocardium

striated

single nucleus

intercalated discs

contraction is involuntary

fiber type of myocardium

only one fiber type

high capillary density

high # of mitochondria

calcium induced calcium release steps

1. AP spreads rapidly along myocardial sarcolemma via gap juntions

2. AP enters cells via T-tubules

3. Ca2+ enters cell via L-type Ca2+ channels

release of Ca2+ via L-type Ca2+ channels stimulates

release of more Ca2+ from sarcoplasmic reticulum via RY receptors

functional synctium

individual cells work with adjacent cells for coordinated action

spontaneous rhytmicity

special heart cells generate and spread electrical signal

intrinsic HR

100 bpm

electrical signal is spread by

gap junctions

cardiac conduction steps

1. SA node spontaneously depolarizes at 100 bpm

2. signal travels through RA and LA, atria contract

3. AV node receives signal from SA node

4. interventricular septum carries impulse to right and left side of heart

5. purkinjie fibers: allows all parts of ventricle to contract simultaneously

AV node function

receives signal from SA node

induces short delay before relaying signal to ventricles

allows maximal ventricular filling

purkinjie fibers function

conduct impulse through ventricles 6x faster than the rest of the system

allows all part of ventricle to contract simultaneously

parasympathetic extrinsic control of heart activity

innervates heart via vagus nerve

carries impulses to SA and AV nodes

decrease HR below intrinsic HR

vagal tone

how effectively the vagus nerve helps your body shift from stress into a calm, resting state

primary neurotransmitter of parasympathetic

ACh

Heart rate at rest

60-100 bpm

sympathetic nervous system control of heart activity

opposite effects of parasympathetic

carries impulses to SA and AV nodes

increase HR above intrinsic HR

maximal possible HR

250 bpm

primary neurotransmitter of sympathetic NS

norepinephrine

electrocardiogram

electrical signals can be mapped as they travel through the heart

P wave section

Atrial depolarization

QRS complex

ventricular depolarization

atrial repolarization

ST segment

ventricular repolarization 1

T wave

ventricular repolarization 2

PR interval

includes AV delay

QT interval

ventricular depolarization and repolarization

1 cardiac cycle =

one systole and diastole

cardiac output

Q

total amount of blood pumped out of the heart each minute

cardiac output equation

Q = HR x SV

stroke volume equation

SV = EDV - ESV

stroke volume definition

volume of blood pumped out of the heart in one beat

blood that was pumped out of left ventricle

end of diastole volume EDV

blood in left ventricle before contraction

end systolic volume

blood in left ventricle after contraction

ejection fraction

percent of EDV pumped out of the heart

EF = SV / EDV

distribution of cardiac output at rest

brain 14%

heart 4%

liver + digestive tract 27%

kidneys 20%

skeletal muscle 21%

skin 5%

bone and other tissues 9%

average total blood volume

~5 L

arteries function

carry blood away from the heart

arteries structure/anatomy

distribution vessels

more smooth muscle

elastic

high pressure

low volume

arterioles function

control blood flow

abilities to increase vascular resistance

feed capillaries resistance vessel

capillaries

site of nutrient and waste exchange

exchange vessel

venules

collect blood from capillaries

veins function

carry blood from venules back to heart

capable of storing larger volumes of blood than arteries

capacitance vessel

veins structure/anatomy

less smooth muscle

one way valves

low pressure

high volume

windkessel effect

how the large arteries smooth out the pulsing, stop and go pumping of the heart into a steady, continuous flow of blood to organs

blood flow

required by all tissues

blood pressure

the force that drives blood flow

provided by contraction of ventricles

resistance

force that opposes flow

provided by the physical properties of vessels

equation of resistance

R = (8nL / pi r^4)

N in equation of resistance

= blood viscosity, how thick the blood is

blood viscosity effect on resistance

more thick = harder to push forward = more resistance

L in equation of resistance

= vessel length

vessel length effect on resistance

longer = more resistance

r in equation of resistance

= radius

most important/influential factor

radius effect on resistance

more influential due to ^4

larger radius = less resistance

systolic blood pressure (SBP)

highest pressure in artery

top number

diastolic blood pressure (DBP)

lowest pressure in artery

bottom number

mean arterial pressure

average pressure over entire cardiac cycle

mean arterial pressure equation

MAP = 2/3 DBP + 1/3 SBP

because diastole is 2x longer as systole

hemodynamics

easiest way to change blood flow is to change resistance

why are vasoconstriction and vasodilation used in hemodynamics

used because change in radius is most influential to change resistance

Blood flow equation

change in pressure / resistance

where do hemodynamics occur

at resistance vessels

responsible for 70-80% of drop in pressure from LV to RA

intrinsic control of blood flow

alteration of regional flow based on need

metabolic mechanisms

endothelial mechanisms

myogenic mechanisms

metabolic mechanisms

buildup of local metabolic by products

endothelial mechanisms

substances secreted by vascular endothelium

nitric oxide, prostagandins

myogenic mechanisms

local pressure changes causing vasoconstriction or vasodilation

increases stretch causes contraction

integrative control of BP

BP maintain by autonomic reflexes

simple cardiovascular control centers

initiates appropriate reflex to correct

baroreceptors function

detect changes in arterial pressure

located in aorta and carotid arteries

chemoreceptors and mechanoreceptors

helpful in monitoring chemical environment and length/tension of muscle

local control of muscle blood flow

increase of blood flow to exercising muscle to match its metabolic demand

functional sympatholysis

inhibition of sympathetic vasoconstriction by reducing vascular responsiveness to a-adrenergic receptor activation

upright position

makes venous return to heart more difficult

venous return is assisted by 3 mechanisms

one way venous valves

muscle pump

respiratory pump

blood three major functions

transportation

temperature regulation

acid-base (pH) balance

blood viscosity definition

thickness of blood (due to red blood cells)

viscosity increases as

hematocrit increase

hematocrit definition

percentage of your blood volume that is made up of red blood cells

plasma volume must increase as

red blood cells increase

occurs in athletes after training, heat acclimation

hematocrit and viscosity remain stable

otherwise blood flow or O2 transport may suffer

men blood volume

women blood volume

hemoglobin

O2 transporting protein in red blood cells

how many O2 per hemoglobin

4

how many hemoglobin per red blood cell

250 million