Cardiovascular system Flashcards
What is the function of the cardiovascular system?
To transport things around the boyd
What are the three components of any cardiovascular system?
1) A muscular pump (the heart) 2) A fluid (blood) 3) A series of conduits (blood vessels)
What are gastrovascular cavities?
Highly branched central cavities that bring the external environment into the organism.
Why do large and complex animals require a functional cardiovascular system?
Because they have to maintain their high metabolism
Circulatory systems can be:
-Open -Closed
Describe the characteristics of an open circulatory system:
The extracellular fluid is the circulatory fluid and is called hemolymph. Hemolymph leaves the vessels of circulatory system, percolate through the cells and tissues and then flow back into the vessels.
Describe the characteristics of a closed circulatory system:
It contains the circulatory fluid in a continous system of vessels so that blood cels and large molecules remains in the system while water and small molecules leak out the capillaries.
What are the two components of the extracellular fluid in closed circulatory system?
1) Blood plasma: fluid in the circulatory fluid 2) Interstitial fluid: Fluid around the cells
What are the advantages of a circulatory system?
-Fluid moves more rapidly and the diameter of blood vessels can be adjusted to control the flow to selected tissues. -Specialized cells and large molecules that aid transporting hormones and nutrients can be kept in the vessles.
What is the function of the valves between the chambers?
Prevent the backflow of blood between contraction and rilaxation.
What is the evolutionary tendency of closed circulatory systems?
is toward a separation between the oxygenated and deoxygenated blood and respective circuits.
What are the two types of circuits?
-Pulmonary circuit: blood is pumped from the heart to the lungs. -Systemic circuit: blood is pumped from the heart to the rest of the body.
What are the main characteristics of circulation in fishes?
Fishes have 4 chambers. -An atrium recevise blood from the body and pumps it into the ventricle -The ventriclule pumps blood to the gills where gases are exchanged. -Gasses are then collected in the aorta. -Unidirectional
What are the main characteristics of circulation in amphibians?
Amphibians have 3 chambers. -Pulmonary and systemic circulations are partially separated. -They have two atria, the left receives the oxygenated blood whereas the right receives the deoxygenated blood. -They can take oxygen from blood vessels in their skin.
What are the main characteristics of circulation in crocodilians?
-Two complete separated ventricle, they have two aortas. -When is breathing the resistance in pulmonary circulation is low and so all the blood flow in the pulmonary circuit. -When is not breathing polmunary vessles constrict and blood from the right ventricle flow from Aorta.
What are the main characteristics of circulation in birds and mammals?
They have four chambers with completely separated pulmonary and systemic circuits. -Oxygenated and deoxygenated blood cannot mix. -Respiratory gas exchange is maximised. -The two circuits can operate at different pressures.
What is the main function of the contraction of the heart?
It create a pressure gradient required to move blood along the vessels.
What is autorhythmicity?
The contraction of the heart is triggered by an action potential that generate itself.
What are the two types of cardiac cells (describe them)
1) Contractile cells: don’t initiate the action potential and they do the mechanical work of pumping the blood out. 2) Autorhythmic cells: don’t contract, they initiate and conduct the action potential and they display a peacemaker activity.
Describe the peacemaker activity:
The membrane potential slowly depolarize showing a peacemaker potential, until it reaches the threshold and an action potential is then generated.
What is a sinatrial node (SN)?
Is a cluster of autorhytmic cells located on the wall of the right atrium where the action potential is generated.
Where is the AP conducted once is generated?
-It is conducted across the atrium through using the interatrial pathway. -It is conduceted across the ventricles through th atriventricular line.
What happens when the AP leaves the atriventricular line?
It’s conducted down the bundle of His which goes down through the septum. The bundle of His then subdivide into Purkinje fibers that conduct the action potential to the ventricular muscle causing it to contract.
What is the effect of sympathetic stimulation of the heart?
The sympathetic nervous system speeds up heart rate by giving input at the AS node. Noradrenaline is release and cause an accelleration of activation of K channels and this decrease the K permeability. Thresholds is reached much quicker.
What is the effect of parasympatetric stimulation?
The heart rate decrease due to two effects: 1) Hyperpolarisation of the SA node. 2) Decrease the rate of spontaneous depolarisation
