pgy 206 uky exam 3 cardiac

three main functions of the circ system

transportation (respiratory, nutritive, excretory), regulation (hormonal, temperature), protection (blood clotting and immune)

the circulatory system is made up by the....

CV system and lymphatic system

CV system

blood, heart, bv

lymphatic system

- lymph vessels transport interstitial fluids

- lymph nodes cleanse lymph prior to return in venous blood

blood is made up of

formed elements and plasma

blood plasma

the liquid layer, straw colored

- consists of h2o and dissolved solutes

- Na+ is the major solute (ECF!)

plasma proteins

7-9% of plasma;

- albumin (produced in the liver) provides colloid osmotic pressure needed to draw water from isf to cc and MAINTAINS BP

- globulins: alpha and beta transport lipids and fat-soluble vitamins to liver, gamma antibodies function in immunity lymphocytes

- fibrinogen: clotting factor and converted to fibrin

formed elements are composed of

cellular components (includes rbcs, platelets, wbcs)

buffy coat

platelets and WBCs

rbcs (erythrocytes)

large surface area to promote the diffusion of gases; lack nuclei and mitochondria!!!!!, replaced every 3-4 months, Hb with iron (heme group that helps transport o2 from the lungs to the tissues)

wbcs (leukocytes)

- almost invisible so named after staining prop

- GRANULAR: help detox foreign substances

- AGRANULAR: produce antibodies

platelets

fragments of megakaryocytes

lack nuclei, BLOOD CLOTTING, release serotonin to vasoconstrict and reduce blood flow to areas needing clot, maintain the integrity of bv wall, short lived (5-9 days)

atria push blood to

ventricles

ventricles push blood to

the body

right AV valve aka

tricuspid valve

left AV valve aka

bicuspid valve

RV pushes to

lungs

LV pushes to

systemic circulation (tissues)

pulmonary circulation

path of blood from RV to lungs and back to LA

systemic circulation

oxygen rich blood pumped to all organ systems to supply nutrients

rate of blood flow through systemic circulation =

flow rate through pulmonary circulation

oxygenated blood

denoted as red, left side

deoxygenated blood

denoted as blue, right side

the heart generates the pressure to

push the blood around the body

what returns blood to the heart since lowered pressure

skeletal muscle pumps

what is the decreased pressure caused by (LV-large aa- small arterioles and aa-cc-venules-large vv)

resistance in bf

cardiac muscle cells

- sarcomeres contain actin and myosin to contract via sliding filament mech but ACTIVATED BY CALCIUM

- bifurcated (branches)

- joined by electrical synapses as gap junctions so cell-to-cell activity

- APs occur spontaneously

- cells behave as one unit (syncytium)

myocardial AP

- depolarization from gap junction

- rapid upshoot (VG Na channels open)

- PLATEAU PHASE (membrane stays depolarized, VG Ca open)

- rapid repolarization (VG K open slowly, rapid diffuse K out)

- long

myocardial resting membrane potential

maintained stable

EC coupling in heart

Ca increased in SR: Ca-release channels allow calcium binds and causes movement (conformational changes-->cross bridges) called calcium induced calcium release mechanism

repolarization

cytosolic Ca is transported into the ECF by Na-Ca exchangers into the SR by Ca-ATPases to relax cell

refractory periods

last almost as long as contraction (absolute almost through all repolarization, relative through the mid-end of repolarization)

tetanus in cardiac AP

no! does not stay contracted because just as long as refractory period

ec coupling and pumping

- cardaic depolorization starts in RA then to other atria

- passes to the ventricle then along walls of ventricle

- atria contract and push blood in ventricle

- ventricles contract to push blood up and out of large aa

ECG (electrocardiogram)

measures the electrical activity of the heart over time

- does not measure bf, contraction, or transmembrane potential difference (ie AP)

three major waves in ECG

P wave, QRS complex, T wave

p wave

atrial depolarization

QRS complex

ventricular depolarization (gen Q) and atrial repolarization

t wave

ventricular repolarization

systole

phase of contraction (LV)

diastole

phase of relaxation

end diastolic volume

total volume of the blood in the ventricles at the end of diastole (before blood ejects)

stroke volume

amount of blood ejected from ventricles during systole (EDV-ESV)

end systolic volume

amount of blood left in ventricles at end of systole

what sound does the heart make

lub dub

what causes heart sounds

closing of the AV and semilunar valves

lub

produced by closing of the AV valves during isovolumetric contraction

dub

produced by the closing of the semilunar valves when pressure in the ventricles falls below pressure in the aa

5 steps in the cardiac cycel

atrial systole, isovolumetric contraction, ejection, isovolumetric relaxation, rapid filling of ventricles

then repeat

atrial systole

atrial contraction; push 10-30% more blood into the ventricle

isovolumetric contraction

contraction of the ventricle causes ventricular pressure to rise above atrial pressure--> AV valve closes; ventricular pressure is less than aortic pressure--> semilunar valves are closed and volume of blood in the ventricle is EDV

ejection

- contraction of the ventricle causes ventricular pressure to rise above the aortic pressure and semilunar valves open so b from V can leave

- ventircular pressure is greater than atrial pressure so AV closed and volume of blood ejects: SV

isovolumetric relaxation

ventricular pressure drops below aortic pressure and back pressure causes semilunar valves to close--> AV still closed and volume of blood in ventricle is ESV

rapid filling of ventricle

ventricular pressure decreases below atrial pressure--> AV valves open so rapid filling of ventricles occur

bv

aa, aterioles, cc, venules, vv

arteries

bring blood away from the heart; PRESSURE

veins

carry blood to the heart; VOLUME

capillaries

exchange vessels, smallest bv with one endothelial cell thick; EXCHANGE

arteries and veins three layers

tunica externas, tunica medias, tunica internas

tunica externas

outer layer of CT

tunica media

middle layer of smooth muscle

tunica interna

innermost simple endothelial cell layer

arteries gas

high oxygen, low co2

veins gas

low oxygen (out), high co2 (in)

arteries large to small

elastic aa, muscular aa, arterioles

elastic aa

help store stressure, numerous layers of elastin fibers between SM

- expand when pressure of blood rises and act as recoil system when ventricles relax

muscular aa

less elastic and have a thicker layer of smooth muscle; diameter changes slightly as BP rises and falls

arterioles

contain the highest % of SM; greatest pressure drop and greatest resistance to flow!

relax for increased bf (like exercise)

three types of capillaries

continuous, fenestrated, sinusoids

continuous cc

adjacent endothelial cells tightly joined together

- intercellular channels that permit passage of molecules other than proteins between capillary blood and tissue fluid

- MUSCLE, LUNGS, ADIPOSE TISSUE

fenestrated cc

wide intercellular pores to provide greater permeability

- KIDNEYS, ENDOCRINE GLANDS, INTESTINES

discontinuous (sinusoidal) cc

larger and leaky cc

- LIVER, SPLEEN, BONE MARROW

exchange of fluid between cc and tissues

- capillary hydrostatic pressure

- colloid osmotic pressure

capillary hydrostatic pressure

blood pressure exerted against the inner capillary wall; promotes movement of fluid into tissues (filtration out)

colloid osmotic pressure

exerted by plasma proteins (liquid portion); promotes fluid reabsorption into circulatory system

- back into cc

Pcap =

BP/capillary hydrostatic pressure

most of the blood volume (2/3rds) is contained where

in the venous system

venules

formeed when cc unite

veins contain

little smooth muscle or elastin-- capacitance vessels (blood reservoirs)

- one way valves to ensure blood flows to the heart

mean arteriole pressure (MAP)

Diastolic + 1/3 of pulse pressure.

- depends on CO and diameter of arterioles

auscultation

listening-- indirect method of correlating BP and arterial sounds

laminar flow

normal bf; blood in central axial stream moves faster than blood flowing closer to artery wall (smooth and silent)

turbulent flow

vibrations produced in the artery when cuff pressure is greater than diastolic pressure and lower than systolic pressure

measure MAP: BP cuff

inflated above systolic pressure, pressure lowered so blood flows when systolic pressure is above cuff pressure producing SOUNDS OF KOROTKAFF, sounds heard until cuff pressure quals diastolic pressure

average arterial BP

120/80

average pulmonary BP

22/8 (RV has not much resistance and distance so lower pressure to lungs)

pulse pressure

the expansion of the artery in response to the volume of blood ejected by LV

pulse pressure = systolic P - diastolic P

MAP formula

MAP = diastolic pressure + 1/3 pulse pressure

MAP calculation meaning

represents the average arterial pressure during the cardiac cycle (closer to the diastolic pressure as the period of diastole is longer than the period of systole)

cardiac output formula

CO = HR x SV

cardiac output

volume of the blood pumped each minute by the ventricles

- each ventricle pumps the equivalent of the total blood volume each minute at resting conditions

regulation of the HR

the SA node

- bundles of His, AV is the backup node

SA node initiates

AP of heart

sinoatrial node

demonstrates automaticity (functions as pacemaker), no VG Na channels,

- spontaneous depolarization-- If channels

If channels

open in response to repolarization to allow in diffusion fo Na

- funny-- weird dip then up in graph

SA node cells resting membrane potential

cells do not maintain a stable RMP

pacemaker APs

depolarization: VG Ca open to diffuse in

repolarization: VG K channels open to K out

- spread APs by gap junctions

regulation of CO by autonomic control

s and ps nn innervate SA node; NE and Epi increase AP frequency while AcH decreases AP frequency (frequency=HR)

- cardiac control center/medulla oblongata coordinates activity of autonomic innervation

2 ways to increase resting HR

- pull back on ps

- activate s

regulation of stroke volume

- EDV

- contractility