Circulatory System Flashcards
What is the elastic layer like on arteries?
Thicker than veins to help maintain blood pressure. Walls can stretch and recoil in response to the heart beat
What is the smooth muscle layer like on arteries?
Thicker than veins so that constrictions and dilation can occur to control the volume of blood.
What it the collagen layer like in the arteries
Collagen outer layer to provide structural support
What is the function of arteries
Adapted to carrying blood away from the heart to the rest of the body
Thick walled to withstand high blood pressure
Elastic tissue to stretch and recoil
Smooth endothelium to reduce friction
What is the function of arterioles
Branch off arteries
Have thinner and less muscular walls
They feed blood into capillaries
What is the function of capillaries
Smallest blood vessels
Site of metabolic exchange,
One cell thick for fast exchange of substances
What is the function of venues
Larger than capillaries but smaller than veins
What is the function of veins
Carry blood from the body to the heart
Wide lumen to maximise volume of blood carried to the heart
Thin walled as blood is under low pressure
Valves to prevent backflow of blood
What is hydrostatic pressure created/ present
When blood is pumped along the arteries, into arterioles and then capillaries. This pressure forces blood fluid out of the capillaries.
What is a heart
Organ. Made up of cardiac muscle, responsible for pumping the blood around the blood vessels
What does it mean when the cardiac muscle is referred to as ‘myogenic’
Means it automatically contracts and relaxes, and it never fatigues
What does the coronary arteries supply and why is this helpful
Coronary arteries supply the cardiac muscle with oxygenated blood for aerobic respiration. This is helpful because it provides ATP so that the cardiac muscle can continually contract and relax
What is pericardial membrane
These are inelastic membranes which surround the heart which prevents the heart from filling and swelling with blood
How does blood transport around the body, simplest terms
Deoxygenated blood comes into the RA from the body and then into the RV. Then blood pushed into the pulmonary arteries in the lungs. Now u have oxygenated blood which travels back to the heart through pulmonary veins into the LA to the LV and out the body’s tissues
Why does the left ventricle have a thicker muscular wall ?
So that it can contract with more force and pump the blood at a higher pressure. This is needed so that the blood will flow all the way around the body
Why does the right ventricle have a thinner muscular wall?
This is because the right ventricle only pumps blood to the lungs which is much closer and requires blood to flow slowly to allow time for gas exchange.
The cardiac cycle is split into 3 stages, name them
Diastole
Atrial systole
Ventricular systole
What happens in the diastole stage in the cardiac cycle
The atria and ventricular muscles are relaxed. This is when blood will enter the atria via the vena cava and the pulmonary vein. The blood flowing into the atria increases the pressure and the atrioventricular valves open so blood can begin to flow into the ventricles
What happens during atrial systole in the cardiac cycle
The atria muscular walls contract, increasing the pressure further. This causes the blood to flow into the ventricles, through the open atrioventricular valves. The ventricular muscular walls are relaxed
What happens during the ventricular systole in the cardiac cycle
After a short delay, the ventricle muscular walls contract, increasing the pressure beyond that of the atria. This causes the atrioventricular valves to close and the semi-lunar valves to open. The blood is pushed out of the ventricles into the arteries
What is the formula for the cardiac output
Cardiac output = heart rate x stroke volume
What is the rate of contraction controlled by?
It is controlled by wave of electrical activity
Where does the electrical excitation/activity begin?
Begins in the pacemaker area called the sino-atrial node (SAN)
Where is the atrioventricular node (AVN) located
Near the border of the right and left ventricle.
