chapter 12 anatomy

cardiovascular system includes

heart, blood vessels, blood

cardiovascular system function

transport gases , nutrients, hormones, wastes and heat

cardiovascular system protection

disease, fluid loss (clotting)

heart sits in a cavity called

mediastinum (= space between lungs within thoracic cavity)

pericardium

the double-walled membranous sac that encloses the heart

3 layers surrounding the heart

fibrous pericardium, pariental pericardium , visceral pericardium

fibrous pericardium

outermost layer = dense irregular CT anchors to surrounding structure eg diaphragm , great vessels

two parts of serous pericardium

parietal layer and visceral layer

pariental pericardium

fused to fibrous pericardium (fibrous pericardium + pariental pericardium = pericardial sac)

visceral pericardium

(epicardium) fused to heart surface so it is part of heart wall

between pericardial layers

pericardial cavity with serous fluid

3 parts of the heart wall

epicardium, myocardium and endocardium

epicardium

strat. squasha. epithelium and connective tissue

mysocardium

= cardiac muscle . arranged in spiral / circular pattern reinforced with connective tissue

endocardium

simple squamous epithelium and connective tissue

endothelium

epithelium lining the inner surface of heart and all blood vessels

right atrium contains

inferior and superior vena cava and coronary sinus (posterior)

left atrium contains

4 pulmonary veins

right ventricle contains

pulmonary trunk

pulmonary trunk

divides to form 2 pulmonary arteries

left ventricle

aorta

septa (separate chambers)

interatrial septum and inteventricular septum

interatrial septum

separates atria

interventricular septum

separates ventricles, deep to inter-ventricular sulcus (external)

sulcus

depression or groove in the surface

fibrous skeleton

- CT fibres around muscle fibres + CT rings between atria and ventricles at the coronary sulcus

fibrous skeleton allows

openings to remain open at all times (valves open and close)

fibrous skeleton provides

electrical insulation - prevents simultaneous contractions of chambers

types of valves

atrioventricular valves, semilunar valves

atrioventricular valves include

bicuspid (mitral) and tricuspid

bicuspid

left side 2 cusps

tricuspid

right side 3 cusps

chordae tendineae

connective tissue that attach AV cusps to papillary muscles (projections of myocardium)

What prevent eversion of cusps

chordae tendineae

semilunar valves

aortic and pulmonary (3 cusps each)

aortic

separates left ventricle and aorta

pulmonary

separates right ventricle and pulmonary trunk

cardiac muscle cells are from what system

both contractile myocardium and conduction system

similarities of cardiac muscle and skeletal muscle

striated (myofibrils with sarcomeres ) , has sarcoplasmic reticulum and T-tubules

differences of cardiac and skeletal muscle

branched (myofibrils with sarcomeres), uninucleated, intercalated discs (not on skeletal)

intercalated discs

region where 2 fibres meet contain anchoring and gap junctions

do cardiac muscle cells contract

no they produce and conduct electrical impulses

parts of the conduction system

1. Sinoatrial (SA) node
2. Atrioventricular (AV) node
3. AV bundle (Bundle of His)
4. AV bundle branches
5. Purkinje fibers

pacemaker

sinoatrial (SA) node

sinoatrical (SA) node location

right atrium at the base of the superior vena cava

sets pace - generates impulses the fastest

sinoatrial node (SA)

atrioventricualar (AV) node location

base of right atrium

atrioventricular bundle (bundle of his) location

superior part of inter ventricular septum, electrically connects atria to ventricles

AV bundle branches location

go to each ventricle

Purkinje fibers location

terminal fibers in ventricles only

electrical signal spreads from ___ to __ when they contract

conduction system to contractile cardiac cells

circulatory routes

Closed, double circulation.

closed circulation

blood confined to heart and blood vessels

double circulation

2 routes (pulmonary + systemic)

pulmonary circulation

right ventricle to lungs via pulmonary arteries (deoxy blood), pick up oxygen in lungs via capillaries, lungs to left atria via pulmonary veins (oxygenated blood)

systemic circulation

left ventricle to organs via aorta (oxygenated), organs remove oxygen via capillaries, organs to right atrium via superior and inferior vena cava (deoxy)

cerebral

brain

hepatic

liver

coronary

heart

fetal circulation

fetus gets O2, nutrients from and expensive wastes to mothers blood

where is exchange site for fetus and mother

placenta

baby and moms blood supply

close together but do not mix

Differences in Fetal and Adult Circulation

umbilical vein (towards fetal heart) and lungs and liver are basically non functional, umbilical arteries (away from fetal heart)

umbilical vein towards fetal heart

carries oxygen blood from placenta to vena cava

lungs and liver basically non fuctional

3 shunts to bypass (although some blood flow through these organs for nourishment / growth)

ductus venosus

connects the umbilical vein to the inferior vena cava, bypassing the liver. oxygenated and deoxy blood mix mixed blood enters fetal heart via inferior vena cava

foramen ovale

hole in interatrial septum. blood moves from right to left atrium (bypass lungs)

Ducts arteriosus

-connects pulmonary trunk to aorta (bypass lungs)

The umbilical arteries

returns mixed blood to placenta

general structure of blood vessels (except capillaries)

tunica externa, tunica media, tunica intima/interna, lumen

tunica externa

connective tissue

tunica media

smooth muscle and elastic fibers

tunica intima/interna

endothelium (simple squamous epithelium)

lumen

contains blood (not a layer of blood vessels)

arteries

carry blood away from the heart

two types of arteries

elastic and muscular

elastic arteries

elastic CT in all 3 layers, largest arteries (near heart) eg aorta

muscular arteries

a lot of smooth muscle, most arteries , eg coronary artery

arterioles

little arteries . regulate blood flow and blood pressure

cycle of blood vessels

heart, arteries, arterioles, capillaries, venues, veins

capillaries structure

only tunica intima - endothelium (one cell layer) + basement membrane

capillaries function

allow exchange of gases and nutrients , gaps allow limited fluid and solutes to leak out =ISF

Capillaries unite to form

venules

venules structure

intima, thin media, thin external

veins

large lumen, thin media (less smooth muscle) can collapse

valves in veins do what

prevent back flow of blood

characteristics of blood

higher viscosity then H2O, 37º C, pH 7.35-7.45,

how many litres of blood in a adult

4-6 L

composition of blood

plasma (fluid portion with solutes) and formed elements (cellular portion)

plasma is composed of

90% H2O, 8% proteins (albumin, fibrinogen, globulin) 2% other solutes (nutrients, hormones, wastes, electrolytes and gases)

albumin

control tissue water balance

fibrinogen

clot formation

globulin

antibodies

formed elements of blood

RBC, WBC, platelets

Erythrocytes (Red Blood Cells)

45% of blood volume, biconcave disc shape, anuncleate when mature

hematocrit

% of blood volume that is RBC (45%)

life span of RBC

120 days

RBC destroyed

in the liver and spleen

RBC contain

hemoglobin

hemoglobin parts

heme and globin