Gross And Cellular Structure Of The Heart Flashcards
What is the positioning of the heart in the body ?
Behind the sternum for protection
Extends from 2nd to 5th rib
Angled in the chest cavity
What are the roles of cardiac muscle ?
1- supply oxygenated blood containing nutrients to major organs
2- remove waste products formed during metabolism
Describe the pulmonary circulation ?
Pulmonary artery which carries deoxygenated blood to the lungs
Pulmonary veins which carries oxygenated blood to the heart
Important for taking blood to the lungs for re-oxygenation
Describe the coronary circulation ?
Is provides oxygenated blood to the heart
Coronary arteries branch from the base of the aorta
Left coronary artery splits into the the anterior inter ventricular artery and supplies mainly the wall of left ventricle
Right splits into marginal artery and supplies the free right ventricular wall and goes around to the posterior aspect of the heart
The venous blood drains into the coronary sinus
What mirrors the marginal artery in the coronary vessels ?
Small cardiac vein
What vessel mirrors then terror interventricular artery ?
Great cardiac vein
Describe the systemic circulation ?
Provides oxygenated blood to the organs and tissues of the body
Served by the left side of the heart
What arteries of the systemic circulation supply the head and brain ?
Vertebral and carotid arteries
What the 1st vessel to branch from the aorta ?
brachiocephalic trunk
What arteries of the systemic circulation supply blood to the arms ?
Subclavian arteries, they run under the clavicles
What artery supplies blood to the upper part of the digestive tract ?
Superior mesenteric
Which artery supplies the lower part of the digestive tract?
Inferior mesenteric
What arteries supply blood to the pelvis and legs ?
The common iliac and internal iliac feed into the external iliac and deep femoral
What is the outer layer of the heart called ?
Fibrous pericardium
- protects the heart
- anchors the heart to adjacent structures
- it’s indistensible so it prevents overfilling
What is the inner layer of the heart called ?
Serous pericardium
- secretes fluid into the pericardial cavity to aid the twisting of the heart during pumping
What is the epicardium?
It surrounds the outside of the muscular surface of the heart
What is the endocardium ?
It surrounds the inner face of the heart
What is pericarditis ?
It is the inflammation of the pericardial membranes
- causes sharp chest pains
- with a stethoscope you can hear the membrane rubbing against one another
What is the right AV valves called ?
Tricuspid valve cos it has 3 cusps
What is the right AV valve called ?
It’s the biscuspid valve or mitral valve with 2 cusps
How many cusps do the semi-lunar valves have ?
3
Why do valves open and close ?
It is a passive movement based upon the pressure gradients across them
When do valves open ?
They open when the pressure gradient is greater behind the valves
When are valves shut ?
They are shut when the pressure gradient is greater in front of the valves
What is the role of the papillary muscles ?
They are used to close the AV valves
When the ventricles contract the pressure is greater in the ventricles than in the atria so the valves shut. This occurs because the papillary muscles also contract when the ventricles contract and they pull on chordae tendinae to prevent the valves eventing into the atria
What are the dimensions of muscles cells of the ventricles ?
120 micrometers long
30 micrometers wide
How do cardiac muscle cells join together ?
They are joined together by intercalated discs which tend to join end to end
What are the 2 roles of the intercalated discs ?
1- they act by firmly binding together the adjacent cells allowing mechanically coupling
2- this also enables electrical coupling
What are gap junctions ?
They are proteins made up of connexins which create ion channels so small ions can pass between cells
Allow electrical coupling so aps can pass between cells easily and quickly
Enables heart to function as functional syncytium
What is the flow of arteries for the upper chest and arms ?
Subclavian - axialllary - brachial arteries
Where does venous blood from the coronary circulation drain into ?
Coronary sinus then into right atrium.
What is the double walled sac of the heart called ?
Pericardium
When do valves open ?
When pressure behind them is greater
When do valves close ?
When pressure is greater in front of them
What size of the gap between adjacent cardiac cells ?
0.02 micrometers - filled with connective tissue
What causes the membranes of adjacent cardiac cells to be joined together more strongly at certain points ?
Desmosomes
