Functions of the Blood Flashcards
(23 cards)
Four main components of blood
Plasma
Platelets
RBCs
WBCs
Plasma
Liquid part
Carries nutrients - blood cells, platelets, CO2, glucose, amino acids, urea, hormones, heat energy
Platelets
When a cell is damaged they clump together to clot blood and prevent blood loss and pathogens entering
Held together by a mesh of protein called fibrin in a clot
Red blood cells
Transport oxygen from lungs to all cells in the body
Adaptations:
- biconcave shape to increase SA
- have haemoglobin to react with oxygen
- no nucleus - more space for more haemoglobin for more oxygen
Pathogens
Microorganisms that cause diseases (eg certain bacteria and viruses)
Once pathogens enter the body they reproduce rapidly until destroyed - WBCs and immune system stop this
Two types of WBC
Lymphocytes
Phagocytes
Phagocytes
Engulf and digest pathogens
Non-specific so attack anything that’s not meant to be there
Lymphocytes
Produce antibodies complementary to antigens on the pathogen
Lock into invading pathogens and mark them out for destruction via other WBCs
Specific to that antigen - won’t lock on any others
Memory cells
Produced in response to a foreign antigen
Remain in the body and remember a specific antigen
Can reproduce very quickly if that antigen enters again
Vaccination
Involves injecting dead or inactive pathogens into body
These carry antigens so trigger an immune response
Lymphocytes produce antibodies to attack them
Memory cells will also be produced and remain in the blood, therefore if live pathogens of the same type appear they will be killed much faster
Arteries
Carry blood away from heart
High pressure
Strong and elastic walls
Elastic fibres allow arteries to expand
Thick walls with layers of muscle
Capillaries
Involves Involved in gas exchange
Tiny
Permeable walls
Walls are one cell thick
Small lumen
Veins
Take blood back to the heart
Lower pressure
Thinner walls
Large lumen
Valves - prevent backflow
Three main roles of the kidney
Remove urea from the blood (urea is produced in live from excess amino acids)
Adjustment of ion (salt) levels in blood
Adjustment of water content in blood
Nephron
- Glomerulus - where ultrafiltration occurs
- Bowman’s capsule
- Proximal convoluted tubule (PCT) - selective reabsorption
- Descending loop of Henle - osmosis
- Ascending loop of Henle - active transport
- Distal convoluted tubule (DCT) - remaining reabsorption
- Collecting duct - selective reabsorption of water
Glomerulus
Ultrafiltration
Blood enters from a high pressure arteriole
The blood vessel which removes blood from glomerulus has a smaller diameter so blood is contained
The pressure forces fluid into the Bowman’s capsule - glomeruluar filtrate
The glomerulus acts as a filter - allowing water, ions and small molecules (glucose) through but not large molecules (proteins) and blood cells
Bowman’s capsule
Fluid that passes into bowman’s is called filtrate
It does not contain any blood cells or proteins as they are too big to pass out if the capillaries and into the tubule
PCT
Selective reabsorption
More reabsorption occurs here
All glucose is reabsorbed back into blood - needed for respiration to release energy
All amino acids reabsorbed - useful for protein synthesis
Most Na+ and Cl- ions reabsorbed
Some urea reabsorbed
Descending loop of Henle
Water reabsorbed via osmosis
Ascending loop of Henle
Na+ and Cl- ions are actively transported out of the ascending limb to create a lower water potential in the tissue fluid so more water moves out in the descending limb
DCT
Any remaining reabsorption occurs
More Na+ and Cl- ions reabsorbed
Osmoregulation - more water
More water
Change detected by osmoreceptors in hypothalamus
Less ADH released
Collecting duct less permeable
Less water reabsorbed
Higher volume of water and lower concentration of urine
Water level decreases
Osmoregulation - less water
Less water
Change detected by osmoreceptors in hypothalamus
More ADH released
Collecting duct more permeable
More water reabsorbed
Lower volume of water and higher concentration of urine
Water level increases
