Blood and Organs Flashcards
What are the four main components of the blood?
Plasma
Red blood cells
White blood cells
Platelets
What does plasma carry?
- Blood cells (white, red and platelets)
- Digested food products (e.g. glucose or amino acids)
- Carbon dioxide to the lungs
- Urea from the liver to the kidneys
- Hormones
- Heat energy
What are platelets?
Small fragments of cells that help blood clot
How do platelets allow the blood to clot?
- When a blood vessel is damaged, platelets clump together and ‘plug’ the damaged area
- They are held together by a mesh of protein called fibrin
How are red blood cells adapted for their job?
- Small with a biconcave shape to give a LSA
- Contain haemoglobin which carries the oxygen
- Don’t have a nucleus, freeing up space for more haemoglobin
What are the two main white blood cells?
Phagocytes
Lymphocytes
How do phagocytes deal with pathogens?
- Detect the foreign pathogens
- They engulf and digest them
How do lymphocytes deal with pathogens?
- Every pathogen have unique molecules (antigens) on their surface
- When a foreign antigen is encountered, lymphocytes produce antibodies
- These antibodies are specific to each antigen, and they lock onto the antigen and ‘mark them out’ for destruction from other WBC
- Antibodies are produced quickly and flow around the body to mark similar pathogens
What are memory cells?
Produced in response to a foreign antigen and remain in the body after the first encounter.
If the same antigen re-enters the body, the reproduce quickly to mark out that pathogen
Reason why the body is immune to disease you’ve already had
Why are vaccinations needed?
When infected with a pathogen, it can take a while to produce the antibodies. In this time, the person can get very ill and even die
How do vaccinations work?
- Inject a dead or inactive pathogen into the body. This will carry antigens from that pathogen
- These antigens will then trigger an immune response and antibodies are produced
- Memory cells are also produced and will remain in the blood. If live pathogens of the same type reappear, antibodies can be produced very quickly
What are the three types of blood vessels?
Arteries
Capillaries
Veins
What function do arteries provide?
Carry blood away from the heart
What function do capillaries provide?
Involved in the exchange of materials at the tissue
What function do veins provide?
Carry blood to the heart
How are arteries adapted for their job?
- Carry blood at high pressure, so the artery walls are strong and elastic
- The walls are thick compared to the size of the lumen
- The walls contain several layers of muscle
How are capillaries adapted for their job?
- Thin, one cell thick walls, increasing rate of diffusion by decreasing distance
- Carry the blood really close to every cell in the body to exchange substances with them
- Permeable walls so substances can easily diffuse in and out
How are veins adapted for their job?
- Blood is at a lower pressure so the walls are less thick
- Bigger lumen to help the blood flow despite low pressure
- Valves prevent blood flow in the wrong direction
Where does ultrafiltration take place and what happens?
Glomerulus (bundle of capillaries at the start of the nephron -> Green part)
A high pressure build up squeezes water, urea, ions and glucose out of the blood into the Bowman’s capsule
Big molecules like proteins and blood cells are not squeezed out
What process reabsorbs glucose back into the body and where does it take place?
Selective reabsorption
Proximal convoluted tubule (purple part)
All the glucose is reabsorbed from the proximal convoluted tubule so that it can be used for respiration (involves active transport)
