chapter 20: the heart

pericardium

the membrane around the heart, fibrous sac, opaque (not see-through)

2 layers of pericardium

• fibrous sac (outside)

• serous lining

fibrous sac

• outer layer of pericardium - cannot stretch

• so if pericardial space fills with fluid, the heart will squeeze

serous lining

• second layer of pericardium - serum

• produced all the little serous exudate → helps hear beat with no interruption

• pericardial shape should have a little fluid, just enough to make it moist

heart layers

• epicardium

• myocardium

• endocardium

epicardium (epi=outside)

• thin membrane under the visceral layer of the pericardium

  • thin, flexible, not super protective

• outermost layer

myocardium (myo=muscle)

• bulk/mass of heart; cardiac muscle (striated)

• thicker on left side (side that produces blood to body)

endocardium (endo=inner)

• line heart chambers

• forms valves of the heart

• inner lining of heart

• thickens in heart disease/infection

  → continuous with endothelium (lining of BVs)

  • platelet plugs in hemostasis stick to this (endothelium)

blood vessels are either

arteries or veins

why is the top of the heart thicker

where blood goes in and out

arteries

• take blood away from the heart

• thicker walled

veins

• return blood to the heart

• some goes to lungs to be oxygenated

sinus

a space

superior vena cava

brings blood from head/neck (any tissues above neck), dumps into RA

inferior vena cava

brings blood from body parts below heart, dumps into RA

is the heart an organ?

yes

cardiac veins

• go to coronary sinous

• all venous blood in heart collects in cardiac veins, dumps into coronary sinus (at the entrace to RA)

• “3rd vein” → 3rd source of blood coming into the RA

4 pulmonary veins

• bring blood from lungs, go to LA → base of heart

• have high O2 b/c just picked it up from lungs to be pumped to the body

  • still return to heart despite having high )2

aorta

• biggest artery

• exits on left side of heart

• when it comes out it branches (aortic arch) to supply high O2 blood to body

• sends arterial blood to all tissues

• opposite of vena cavas

pulmonary trunk/artery

• leave the heart to go to the lungs

• start deep in the heart, comes up

  • splits to R/L arteries after leaving heart

  • comes out RIGHT side to go to lungs

coronary arteries

go to heart muscle

valves

• keep blood going in one direction so nothing leaves going in the wrong direction

  • chambers close as soon as blood is done pumping

semilunar valve

• tiny flaps, look like a cup (not solid)

• made of endocardium → should see right through them

• pused open, heart relaxes, fall back down to collect blood

• 2 types

  • aortic __

  • pulmonic

aortic semilunar valve

• in BV heart, keep blood on its way

pumonary semilunar valve

leaving the pulmonary trunk

atrioventricular

as venous comes into the heart, thin endocardium, but have 2 structures attached to them

• chordae tendinae

• papillary muscles: inside heart chamber

• Left AV valve (bicuspid) (mitral)

• right AV valve (tricuspid)

left AV valve

• mitral valve/bicuspid

• when blood comes through pulmonary veins, comes through this

auricles

extra pouches on the outside of the heart - involved with heart conditions; not involved with the direction of flow

chordae tendinae

• anchor the AV valves to ventricular papillary muscles and keep the AV valves closed during ventricular systole to prevent the backflow of blood into the atria

papillary muscles

contract and pull the chordae tendinae and help prevent the prolapsing of the AV valves

apex

• only on left side of the heart

atria

• 2 top chambers

• more blood comes through the RA

ventricles

• LV biggest; pushes blood up and out of the heart

• RV pushes blood to lungs