Structure of the heart Flashcards
Why don’t we just have oxygen diffusing through our body instead of having a cardiovascular system
Would be too slow
Lots of cells wouldn’t be able to be sustained
Would limit size of organism
Advantages of circulatory system
Organisms can be bigger
Can sustain a higher metabolic rate
Direct flow of substances between organs
Blood flow can regulate organ function
Drawbacks of a circulatory system
Circulatory failure can be fatal
High pressure and flow require control
High pressures place stress on vessels
Metabolically expensive
Functions of circulatory system
Transport to tissues
Remove waste products from tissues
Transport blood cells around the body
Regulate body temperature by transfer of heat
Things the circulation of blood transports
Oxygen
Nutrients
Hormomes
Growth factors
Cardiac output at rest
About 5L.min-1
Cardiac output during exercise
About 2-35L.min-1
Location of heart
Pericardium
Lining of the pericardial cavity
Pericardial cavity
Contains pericardial fluid
Acts as a lubricant, reducing friction as the heart beats
Visceral pericardium
Covers outer surface of the heart
Inner most layer of pericardium
Parietal pericardium
Lines inner surface (heart side) of the fibrous pericardium
Fibrous pericardium
Surrounds the heart
Dense network of collagen fibres
Stabilses the position of the heart in the mediastinum
What is the serous pericardium made up of
Visceral pericardium
Parietal pericardium
Order of pericardium starting closest to the heart
Visceral pericardium
Parietal pericardium
Fibrous pericardium
Another name for the fibrous pericardium
Pericardial sac
Right atrioventricular valve
Tricupsid valve
Seperates right atrium and the right ventricle
Has 3 fibrous flaps or cusps
Which valve in the heart doesn’t have 3 fibrous flaps
Left atrioventricular / bicuspid / mitral valve
Chordae tendinae
Tendinous connective tissue fibres
Attached to the free edges of the cusps in the valves of the heart
Stops the AV valves swinging loose and letting blood flow backwards
Originates from the papillary muscles
Which valve seperates the right ventricle and the pulmonary trunk
Pulmonary valve
Pulmonary valve
After right ventricle
Made of 3 semilunar cusps made of thick connective tissue
Stops blood flowing back into the right ventricle as it relaxes
Pupillary muscles
Conical muscular projections
Arise from the inner surface of the right ventricle
Where cordae tendinae originate
Which valve seperates the left atrium and left ventricle
Left AV / bicuspid valve / mitral valve
Left AV valve
Bicuspid / mitral valve
Has 2 cusps/fibrous flaps
Seperates left atrium and left ventricle
Aortic valve
Valve that blood passes through to leave left ventricle
3 semilunar cusps
Flow of blood from body into the heart and up to the lungs
- Superior/inferior vena cava
- Right atrium
- Trucuspid valve
- Right ventricle
- Pulmonary semilunar valves
- Pulmonary trunk
- Pulmonary arteries
Flow of blood from lungs, through heart and to the body
- Pulmonary veins
- Left atrium
- Bicuspid valve
- Left ventricle
- Aortic semilunar valve
- Aorta
Difference between right and left ventricles
Left ventricle wall is thicker
Left ventricle is spherical
Right ventricle resembles a pouch attached to the wall of the left ventricle
Which ventricle has the thicker wall
Why
Left
Requires more force to pump the blood around the body
Circuits of the circulatory system
Pulmonary
Systemic
Pulmonary system
Carries blood to the lungs
Systemic circuit
Carries blood to the rest of the body
Everything but lungs
What moves blood along
Elastic rebound
Blood pressure
Elastic rebound
Aorta is stretched by the blood pumped from the left ventricle
When the left ventricle relaxes no more blood is flows into the aorta
The pressure in the aorta declines
Walls of aorta recoil
This pushes the blood along
How does blood enter the coranary ateries
They originate from the base of the aorta
When the aorta recoils and pushes blood along some goes backwards and into the coranary arteries through the aortic sinus
Cardiac muscle cell
Wrapped in strong and flexible elastic sheath
Adjacent cells are tied together by fibrous cross links (struts)
These fibres are woven into sheets that seperate superficial and deep muscle layers
Cardiac muscle cells
Connective-tissue fibres roles
Provide physical support for cardiac muscle fibres, blood vessels and nerves of the myocardium
Help distribute the forces of contraction
Add strength and prevent over-expansion of heart
Provide elasticity and helps return the heart to it’s original size and shape after contraction
Myocardial infarction
Coranary circulation becomes blocked
Cardiac muscle cells affected die from lack of oxygen
Tissues degenerate and leads to a non-functional area (infarct)
Three layers of heart wall
Epicardium
Myocardium
Endocardium
Epicardium
Layer of heart wall
Is the visceral pericardium
Composed of exposed mesothelium and an underlying layer of loose connective tissue attached to the myocardium
Myocardium
Layer of heart wall
Muscular wall of heart
What does the myocardium consist of
Cardiac muscles
Blood vessesls
Nerves
Endocardium
Layer of heart
Covers the inner surfaces of the heart
Just a simple squamous epithelium
Features of cardiac muscle
Striated muscle
Branches cells
One or two nuclei in middle of cell
Intercalated discs
