Human Anatomy- Circulation & Blood

heart location

mediastinum of the thorax resting on the diaphragm

heart general structure

hollow cone-shaped muscular pump

heart function

pump blood throughout the body

pericardium

covering enclosing the heart and the proximal ends of the large blood vessels it attaches to

layers of the cardiac wall

• epicardium

• myocardium

• endocardium

blood through coronary circulation

• first branches of the aorta

  • coronary arteries

• blood through capillaries of myocardium

• drained by cardiac veins that join in coronary sinuns

• empties into right atrium

cardiac cycle

• low pressure in ventricles

• AV valve opens

• ventricles fill

• atria contract

• rest of bld forced to ventricles

• when ventricular pressure abv atrial pressure AV valves close

• AV valve pressure low bld flows from vein to atria

• ventricles contract

• when pressure in ventricle > p in aorta & pulm. trunk pulm & aortic valves open

• blood out of ventricle into arteries

• when p in ventricle < p in arteries valves close

• ventricles relax

• when v p < a p AV valves open ventricles refill

origin of heart sounds

1st part(Lubb)- AV valves closing

2nd part(dupp)- pulmonary & aortic valves closing

cardiac conduction system

cardiac musscle tissue that initiate & distribute impulses throughout the heart

cardiac conduction system controlling heart

• SA node initiates impulse

• atria contract

• AV note recieves impulse

• goes into AV bundle

• purkinje fibers carry impulse to myocardium

• ventricle contracts

control of vasoconstriction & vasodilation

vasomotor fibers - vasoconstriction

inhibition of vasomotor impulses- vasodilation

capillary structure

walls are endothelium (1 layer simp squam cells)

capillary function

diffusion- substances in bld for substances in body

control of blood flow through a capillary

• muscles at cap entrances

  • precapillary sphincters

• respond to needs of cell

  • low neutrients/O up bld flow

  • got enough down bld flow

how diffusion functions

through cap wall high concentration to low concentration

factors that influence bld pressure

• heart action

• bld volume

• resistance to flow

• bld viscosity

heart action effect bld pressure

• blood forced into arteries by heart

  • bld presser up

• determines how much bld enters arterial system w/ each ventricle contraction

bld volume effect on bp

directly proportional to bld pressure

change in bld volume = change in bp

peripheral resistance effect on bp

force that hinders bld flow

bp must overcome force so bld can flow

change in peripheral resistance → change in bp

viscosity effect on bp

changes how much bld resistance

up bld resistance → up bp

factors that promote the flow of venous bld

• heart action

• skeletal muscle contraction

• breathing movements

• vasoconstriction of veins

pulmonary circuit

bld from heart 2 lungs & back

systemic circuit

bld from heart to all parts of body & back

why don’t alveoli fill with fluid

• epithelial cells tightly joined

• ions & molecules can’t get in

• high osmatic pressure in interstitial fluid

• osmosis moves water away

major components of bld

• rbc

• wbc

• bld platelets

hematocrit

the percentage of bld volume that is rb cells in a blood sample

erythropoietin

hormone that controls the rate of rbc formation

biliverdin

• greenish pigment

• converted to bilirubin

bilirubin

orange pigment

types of leukocytes

• neutrophils

• eosinophils

• basophils

• monocytes

• lymphocytes

neutrophils function

phagocytize bacteria fungi and some viruses

eosinophils function

moderate allergic reactions & defend against parasitic worm infestation

basophils function

release histamine- inflammation

heparin- inhibits bld clotting

increase bld flow to injured tissues

monocytes function

phagocytize bacteria dead cells & other debris

lymphocytes function

produce antibodies

bld vessel spasm after an injury

• cut or broken vessel

• smooth muscle in wall contracts

• lessens bld loss

• opportunity for platelet plug to form

platelet plug formation

• platelets attach to ends of injured bld vessels

• attach to eachother

• form plug

steps to bld clot

• coagulation

• extrinsic clotting mechanism

• intrinsic clotting mechanism

extrinsic clotting

• bld contacts damaged bld vessels

• chemicals released

• clot forms

intrinsic clotting

• triggered when bld exposed to a forgien surface

• chemicals released

• blood clot forms

fibrinogen

soluble plasma protein fibers

fibrin

insoluble protein fibers

positive feedback system

extrinsic clotting

thrombin causes prothrombin to form more thrombin, promotes more blood clotting

thrombus

blood clot abdormally formed in vessel

embolus

disloged piece/whole part of thrombus swept away