cardiovascular system Flashcards
function of arteries
they carry oxygenated blood away from the heart and to the body at high pressure
structure of arteries
thin, elastic walls
function of veins
carries deoxygenated blood towards the heart at low blood pressure
structure of capillaries
they have thin walls that allow for exchange of molecules between the blood and tissues
what are naturally occurring substances in blood
water, red blood cells, white blood cells, antibodies, platelets, waste, nutrients, plasma proteins and hormones
what are foreign substances in blood
drugs, toxins and pathogens
what are the 4 blood components and their percentages
plasma 55%, white blood cells and platelets 1%, red blood cells 45%
structure of plasma
clear, straw colour liquid fluid matrix in the blood
function of plasma
soluble molecules transported such as carbon dioxide, nutrients, waste products and hormones
structure of platelets
cell fragments with surface proteins that stick together
function of platelets
clot in areas of bleeding to prevent blood loss
structure of red blood cells
bio concave disc shape to maximise surface area for oxygen absorption. They are small and flexible so they can go through narrow capillaries
function of red blood cells
contains haemoglobin which carries oxygen from lungs to tissues. Carries waste gases. They don’t have a nucleus which allows for more haemoglobin.
how has blood got its colour
haemoglobin contains iron which when combined with oxygen creates the red colour
structure of white blood cells
they have granular cytoplasm and characteristic shaped lobed nuclei
function of white blood cells
defend against disease
different types of white blood cells
lymphocytes, basophils, eosinophil, monocyte, neutrophil
explain the double circulatory system
right side of the heart takes in deoxygenated blood and pumps to the lungs. Left side of the heart receives oxygenated blood from the lungs and circulated to the body.
what is the diastole cardiac cycle
relaxation phase, during this stage the blood pressure is the lowest when the chambers are filling with blood.
what is the systole cardiac cycle
contraction phase and the blood pressure is at its highest
1st step of the cardiac cycle
- blood drains into the left atrium from the lungs along the pulmonary artery
- raising of the blood pressure in the left atrium forces the left bicuspid valve open
- contraction of the left atrial muscle/systole forces more blood through the valve
- as soon as left systole is over, the walls of the ventricle starts to contract. This is called ventricular systoles
- this forces the left bicuspid valve to close and opens the valve in the mouth of the aorta. Blood leaves the left ventricle along the aorta.
function of the sinoatrial mode (pacemaker)
this causes an electrical impulse through the atria and redirects it to the bundle of ‘his’. This delays the signal, slowing its spread, allowing the atria to fully contract before the ventricles do so.
Function of bundle of ‘his’ (atrioventricular bundle)
a group of fibres in the septum which takes the impulse to the base of the ventricles
function of purkinje fibres
these fibres act like neurons and found in the walls of the ventricles. The impulse from the bundle of ‘his’ reaches purkinje fibres causing ventricles to contract
what is a baroreceptor
stretch receptor that detects pressure changes
what is the function of baroreceptors in the heart
sends signals to the CNS, which in turn can trigger vasodilation to decrease the systemic blood pressure; or change heart rate.
