Module 5 Flashcards
Diffusion
cells constantly exchange oxygen and nutrients for carbon dioxide and waste
- diffusion becomes inefficient over long distances
Open circulatory systems
simple
easy to maintain
less energy and lower pressures
Closed circulatory systems
higher pressures
very demanding process
increased efficiency for meeting high metabolic demands
can deliver more blood to areas where blood demand is higher
Types of closed circulatory systems
single circulation
double circulation
Single circulation system in fish
there is a single circuit of blood flow from the heart
simple to maintain
achieved through gill capillaries and body capillaries
Double circulation in amphibians and mammals
blood comes to the heart, leaves the heart, and then travels back to the heart
- more energy required
- oxygen-poor blood returns to the heart foe exchange of oxygen red blood that leaves the heart
Pulmocutaneous circuit in amphibians
blood travels to the lung and skin capillaries to become loaded with oxygen
the systemic circuit is the oxygenated blood that is delivered to the rest of the body
Pulmonary circuit and systemic circuit in mammals
oxygen-poor blood returns to the heart for exchange of oxygen red blood that leaves the heart
The human cardiovascular system
double circulation
- right atrium receives deoxygenated blood from the posterior vena cava
- oxygenated blood returns to the left atrium and left ventricle to the rest of the body
Semilunar valve
creates pressure within the ventricles to allow blood to flow with enough force
Atrioventricular valve
found in the left ventricle
prevents the back flow of blood – closes once blood has passed
Cardiac cycle
- Atrial and ventricular diastole – all 4 chambers are relaxed and filling up with blood; AV valves are open; seminar valves are closed
ALL FOUR CHAMBERS ARE RELAXED - Atrial systole and ventricular diastole – contract to empty blood into respective ventricles; AV valves remain open; seminar valves remain closed
ATRIA CONTRACTS AND EMPTIES ALL BLOOD INTO THE VENTRICLES - Ventricular systole; atrial diastole – seminar valves are open; AV valves are closed
VENTRICLES CONTRACT AND PUSH BLOOD TO WHERE IT NEEDS TO GO
Systole and Diastole
systole - contraction/pumping
diastole - relaxation/filling
Cardiac output
Heart rate X Stroke volume
L/min
Muscle types
Skeletal - voluntary, striated
Cardiac - involuntary, striated
Smooth - non-striated
Maintaining the heart’s rhythm
some cardiac muscles are self-excitable
- they can contract without any signalling from the nervous system
Pacemaker cell
spontaneous action potential is induced by pacemaker potential
- action potential propagates to non-pacemaker cells
- gap junctions between all cells – pacemaker and non pacemaker cells – allows action potential to travel between all cells
Electric drive of the heart
impulses from the sinoatrial node travel to thee atrioventricular node
- here, the impulses are delayed
- the electric current then travels to the bundle of His and then to the Purkinje fibres
- this makes the ventricles contract
Sinoatrial node
known as the pacemaker region of the heart where the first group of pacemaker cells are found
- this master group of pacemaker cells control the rest of the pacemaker cells