circulatory system Flashcards
blood vessel names:
- heart
- lungs
- liver
- kidneys
- coronary
- pulmonary
- hepatic
- renal
veins
- contains valves to prevent blood flowing backwards (not all veins have valves e.g. those in hands)
- wide lumen
- thinner walls with less muscle and elastic tissue than arteries
- carries blood at lower pressure.
- carries deoxygenated blood (except pulmonary vein)
- carries blood to heart
arteries
- no valves
- narrow lumen
- thicker walls with more muscle and elastic tissue than veins to prevent bursting
- carries higher pressure blood
- carries oxygenated blood (except pulmonary artery)
- carries blood away from heart
capillaries
- small vessels with walls made of a single layer of cells
- allow substances to pass easily from the blood into body cells
electrocardiogram (ECG)
- the contraction of the heart muscle cells is coordinated using electrical impulses which pass between the different regions of the heart
- these impulses can be detected with an ECG which using electrodes placed on the skin to show the heart rate and rhythm
- the small bump shown on an ECG shows the electrical activity causing the atria to contract
- the large spike shows the electrical activity causing the ventricles to contract
what factors can affect heart rate?
- exercise
- hormones e.g. adrenaline
what effect does increased heart rate have on aerobic respiration?
blood can circulate faster and deliver more oxygen to muscle cells for aerobic respiration
blood composition
- plasma 55%
- RBCs 44%
- WBCs and platelets 1%
plasma
- watery liquid that the cells are transported in
- contains dissolved glucose, urea and amino acids, carbon dioxide and some proteins like hormones and antibodies
RBC function and shape
- function: to transport oxygen around the body
- biconcave disc shape
- oxygen binds to the protein haemoglobin in the cytoplasm of the red blood cells
mature red blood cell adaptations
- has a large surface area for diffusion of oxygen
- contains lots of haemoglobin protein in its cytoplasm
- has no nucleus or other structures to make more room for haemoglobin (so cannot replicate/ synthesise proteins)
lymphocytes
- produce antibodies that target specific antigens on bacteria and viruses, destroying them
- some lymphocytes form memory cells which are involved in a secondary immune response (exposure to the same pathogen again)
phagocytes
-engulf pathogens and digest them using enzymes to prevent damage to body cells
platelets
- small fragments of cells
- contain no nucleus
- function: to help blood clot at a wound site, stopping blood loss and preventing microbes from entering the body
- clotting occurs when a series of enzymes convert the soluble protein fibrinogen into the insoluble fibrin, creating a mesh of fibres that traps platelets and RBCs to form the clot
ABO system - blood groups
- the gene for the ABO system codes for the protein immunoglobulin (I) which is found on the cell surface membrane of RBCs
- the gene has three alleles but only two are present in any one person
blood groups and genotype
- A: homozygous or heterozygous, IA allele is dominant to the IO allele.
- B: homozygous or heterozygous, IB allele is dominant to the IO allele.
- AB: IAIB, IA allele and IB allele are co-dominant so both are expressed
- O: homozygous recessive, IOIO
blood group phenotype:
- A
- B
- AB
- O
antibodies present in blood plasma:
- b
- a
- none
- a and b
blood transfusion donors and recipients
- A: donate=A and AB, receive=A and O
- B: donate=B and AB, receive=B and O
- AB: donate=AB, receive=universal recipient
- O: donate=universal donor, receive=O
Why do we need gas exchange and transport systems?
- since we are large multicellular organisms we have a small SA:V ratio
- therefore, animals cannot rely on diffusion to provide oxygen to cells (this would take too long)
- thus, animals have a transport system which takes the oxygen close to a large number of cells throughout the body, ensuring that their cells are supplied with oxygen more rapidly
hepatic portal vein
transports blood from small intestine to liver
is blood an organ?
no it’s a tissue
are skeletal muscles organs?
no they are tissues
systole and diastole
- Systole is when the heart muscle contracts -> heart pushes the blood out of the heart and into the large blood vessels of the circulatory system -> blood pressure increases (systolic pressure)
- Diastole is when the heart muscle relaxes -> the chambers of the heart fill with blood -> blood pressure decreases (diastolic pressure)
blood pressure
- blood pressure results consist of 2 numbers: 1st-systolic, 2nd-diastolic
- units: mm of mercury (mm Hg)
- normal: under 120/80
heart valves
- Tricuspid valve = between RA and RV, open during diastole
- Bicuspid/mitral valve = between LA and LV, open during diastole
- Pulmonary valve = between RV and pulmonary artery, open during systole
- Aortic valve = between LV and aorta, open during systole
