human transport Flashcards
what is the blood composed of
45% red blood cells
white blood cells <1%
platelets <1%
55% plasma
what is the role of plasma in transport?
transports:
- CO2
- digested food & mineral ions
- urea
- hormones
- heat energy
how does plasma transport CO2?
dissolved in plasma as hydrogen-carbonate ions and transported from respiring cells to the lungs
how does plasma transport digested food and mineral ions?
dissolved particles absorbed from the small intestine and delivered to requiring cells around the body
how does plasma transport urea?
dissolved in the plasma and transported to the kidneys
how are red blood cells adapted?
- full of haemoglobin, a protein that binds to oxygen to form oxyhaemoglobin
- no nucleus - allows more space for haemoglobin to be packed in
- biconcave disc - large surface area to volume ratio to maximise diffusion of oxygen
what is the role of phagocytes?
carry out phagocytosis by engulfing and digesting pathogens
how do phagocytes carry out phagocytosis?
- have a sensitive cell surface membrane that can detect chemicals produced by pathogenic cells
- Once they encounter the pathogenic cell, they will engulf it and release digestive enzymes to digest it
- This is a non-specific immune response
what is the role of lymphocytes?
To produce antibodies
What are antibodies?
Y-shaped proteins with a shape that is specific to the antigens on the surface of the pathogen
How do antibodies destroy pathogens?
- Antibodies attach to the antigens and cause agglutination (clumping together)
- So, the pathogenic cells cannot move very easily
- At the same time, chemicals are released that signal to phagocytes that there are cells present that need to be destroyed
what is an antigen?
a molecule found on the surface of a cell
what is the point of vaccinations?
to induce immunity to infectious diseases
How do vaccines work?
- Lymphocytes recognise the antigens in the bloodstream
- The activated lymphocytes produce antibodies specific to the antigen encountered
- Memory cells and antibodies subsequently remain circulating in the blood stream
- Future infection by the same pathogen will trigger a response that is much faster and much larger compared to the initial response
- Due to the rapid nature of the response, the pathogen is unable to cause disease and the individual is said to be immune
why are vaccines important?
reduce the likelihood that an infected individual will spread the pathogen to others
what is the role of platelets?
fragments of cells that are involved in blood clotting
how do platelets cause blood clotting?
- When the skin is broken platelets arrive to stop the bleeding
- A series of reactions occur within the blood plasma
- Platelets release chemicals that cause SOLUBLE FIBRINOGEN PROTEINS to convert into INSOLUBLE FIBRIN and form an insoluble mesh across the wound, trapping red blood cells and therefore forming a clot
- The clot eventually dries and develops into a scab to protect the wound from bacteria entering
WHAT’S THE IMPORTANCE of blood clotting
prevents continued / significant blood loss
prevents entry of microorganisms that could cause infection
where does oxygenated blood come from
from the lungs enters the left side of the heart and is pumped to the rest of the body (the systemic circuit)
where does deoxygenated blood come from
from the body enters the right side of the heart and is pumped to the lungs (the pulmonary circuit)
why does the left ventricle have a thicker muscle wall than the right
it has to pump blood at high pressure around the entire body,
do veins pump blood towards or away from the heart?
Blood is pumped towards the heart in veins
do arteries pump blood towards or away from the heart?
away from the heart
what is. the role of valves?
to prevent backflow of blood
