internal heart Flashcards
pericardium
Fibrous
- tough & inelastic
- rests on/attached to diaphragm
- open end fused with great vessels
Serous
- Parietal layer fused to fibrous pericardium
- Visceral layer continuous/part of epicardium
- Pericardial cavity space between parietal
and visceral layers contains pericardial fluid
heart wall
Outer – Epicardium - visceral serous pericardium
Middle – Myocardium - cardiac muscle
Inner – Endocardium - continuous with endothelium of large vessels of heart
heart chambers
Right atrium (RA):
Receives deoxygenated blood from vena cavae and coronary sinus.
Right ventricle (RV):
Pumps deoxygenated blood to lungs (pulmonary circulation)
Left atrium (LA):
Receives oxygenated blood from lungs via pulmonary veins.
Left ventricle (LV):
Pumps oxygenated blood into aorta (systemic circulation)
internal structure of right atrium
Openings:
SVC & IVC – deoxygenated blood from body
Coronary sinus – deoxygenated blood from heart walls
Crista terminalis – Boundary
– smooth wall sinus venarum posteriorly
– rough wall pectinate muscles anteriorly
Fossa ovalis – remnant of opening between L and R atria
- allowing blood to bypass lungs during embryonic development
internal structure of right ventricle
Tricuspid valve – prevents backflow of blood into R. Atrium during systole
Chordae tendineae – attaches cusps to papillary muscles
Papillary muscles – contract to prevent cusps reverting into atria during systole
Pulmonary valve – prevents backflow of blood into right ventricle during diastole
Trabeculae carneae – muscular ridges in wall of ventricle
internal structure of left ventricle
Mitral (bicuspid) valve – prevents backflow of blood into L. Atrium during systole
Chordae tendineae – attaches cusps to papillary muscles
Papillary muscles – contract to prevent cusps reverting into atria during systole
Aortic valve– prevents backflow of blood into left ventricle during diastole
Trabeculae carneae – muscular
valves of the heart
Semilunar valves:
-Aortic and pulmonary
-3 cusps
-No chordae tendineae
-Prevent backflow during diastole
Atrioventricular valves:
-Tricuspid and mitral (bicuspid)
-Chordae tendineae attached to papillary muscles
-Prevents backflow during systole
foetal circulation
1) Oxygenated blood enters through the umbilical vein
2) Some blood enters the liver and the rest enters the ductus venosus to bypass the liver and enter the inferior vena cava
3) The IVC enters the right atrium and most of the blood passes through the foramen ovale to the left atrium, left ventricle and aorta
4) Blood entering the right atrium from the superior vena cava is poorly oxygenated as is blood returning from the lungs
5) This passes through the ductus arteriosus and reduces the oxygenation of the blood in the aorta (purple)
parasympathetic- vagus nerve, conduction
Vagal motor nuclei in brainstem (medulla) – vagus nerve
Right side – SA node
Left side - AV node
NT = Acetylcholine
Binds to muscarinic
receptors
Decreases rate of SA node depolarization
by making membranes hyperpolarized
(more negative)
sympathetic nerve- conduction
Cardiac sympathetic fibres
exit SC at T1-T5
Long nerve fibres that run
along the great vessels
Right supply atria
Left supply ventricles
NT = Noradrenalin
B1 adrenoreceptors
Increase AV conduction velocity (i.e. <0.1sec)
2) Decrease myocyte AP length
Increase rate of relaxation
Increase contractile force (increase SV)
