2 - Circulatory System Flashcards
what is tissue fluid and what is it made up of?
fluid that bathes cells in tissues
made up of water, oxygen, glucose and mineral ions
contains the waste products released from cells, like carbon dioxide, water and urea
Formation of Tissue Fluid
ARTERIOLE END
-high hydrostatic pressure
-forces water and small molecules (ions, glucose, oxygen, fatty acids, amino acids) out of the blood
VENULE END
-low hydrostatic pressure due to loss of fluid
-Low water potential due to plasma proteins, red blood cells, and platelets that remain in blood
-Water re-enters through osmosis
-Waste products (CO2, urea) also dissolved in water so are reabsorbed
Fluid that is not absorbed enters lymphatic system and enters bloodstream near the heart
High blood pressure (hypertension) increases fluid loss, leading to oedema (swelling).
Atrial Systole
atria contract
ventricles relax.
decreases the volume inside the atria which increases the pressure
increased pressure forces the tricuspid and bicuspid valves open and pushes blood into ventricles
Ventricular systole
ventricles contract
atria relax
decreases the volume inside the ventricles which increases the pressure
forces atrioventricular valves closed and causes semi-lunar valves to open.
The closure of the AV valve prevents the back-flow of blood into the atria.
Blood is forced out of the ventricles and into the arteries (the aorta and the pulmonary artery).
Diastole
Both atria and ventricles are relaxed so the pressure is low in both chambers.
Since the pressure is higher in the arteries than in the heart chambers, the semi-lunar valves are forced closed which prevents blood flowing backwards into the ventricles.
Blood is returned to the heart and the atria fill with blood.
Atheroma
Build up of fatty deposits in endothelium of blood vessel leading to restricted blood flow
increases the risk of aneurysm (high blood pressure from weakened artery pushes on artery lining , causing artery to balloon out)
Myocardial infarction
heart attack
The atheroma ruptures and bursts through the endothelium of the artery, damaging the artery wall
This triggers blood clotting (thrombosis) which can cause complete blockage
prevents blood flow so lack of oxygen
cells within the tissue cannot carry out aerobic respiration and will start to die
how structure of vein allows it to pump blood even though blood is at low pressure
valves to prevent backflow
Large lumen so less resistance to flow
Thin walls that can be compressed
structure of aorta
thick muscular wall to withstand high pressure
thick elastic tissue that allows for stretch and recoil
wide lumen to carry large volume of blood
valve to prevent backflow
Lymphatic System
Lymph vessels surround blood vessels
Made up of lymph (excess tissue fluid)
Contains lymphocytes
Transports chylomicrons
Enters bloodstream again near heart
Lymph vessels have similar structure to vein (contains valves)
