transport in humans Flashcards
what is a double circulatory system?
blood flows through the heart twice in one circuit
advantages of a double circulatory system
ensures blood is pumped at a low pressure to the lungs so it can be properly oxygenated and oxyenated blood can be pumped out at a high pressure to all body cells
name of blood vessels connecting the LIVER
- hepatic artery and vein
- hepatic portal vein (gut to liver)
name of blood vessels connecting the KIDNEY?
renal artery and vein
blood vessels in cardiac cycle?
- pulmonary vein
- pulmonary artery
- vena cava
- aorta
components of blood?
1.plasma (55%)
2.erythrocytes(red blood cells)
3.leukocytes (white blood cells)
4.platelets
main functions of blood?
(a) to transport:
* oxygen
* food substances
* hormones
* waste materials
* heat
from one part of the body to another
(b) to protect the body by preventing entry of foreign bodies and fighting infections
details about PLASMA
- 55% of blood volume
- 90% water, 10% dissolved substances
- substances dissolved in plasma: mineral ions, digested food substances, plasma proteins, metabolic waste products, hormones
details about ERYTHROCYTES
1.produced in bone marrow and broken down in the spleen
2.lifespan of about 4 months
structural adaptations of erythrocytes
(1) haemoglobin
- binds reversibly to oxygen to form oxyhaemoglobin
- each molecule of haemoglobin can bind up to 4 molecules of oxygen
(2) absence of nucleus
- more space for haemoglobin –> more oxygen transported
(3) circular and biconcave shape
- increases surface area to volume ratio, allowing for quicker diffusion of oxygen
(4) elastic/flexible cell surface membrane
- allows cell to change shape while squeezing throuh capillaries
details about leukocyte
- less numerous than erythrocyte
- lifespan of about a few days
details of platelets (thrombocytes)
- fragments of larger bone marrow cells called megakaryocytes
- clots blood by forming sticky plugs at wound sites
importance of blood clotting
- prevents entry of foreign bodies through the wound
- prevents excessive loss of blood
mechanism of blood clotting
1.damaged tissues produce thrombokinase (enzyme).
2.thrombokinase catalyses process of prothrombin (inactive) turning into thrombin (active enzyme)
3.fibrinogen turns into fibrin threads with the help of thrombin
4.fibrin threads form a mesh to trap blood cells
details of ABO blood groups
blood type A
* anti-B antibodies
* A antigens
blood type B
* anti-A antibodies
* B antigens
blood type AB (universal recipient)
* no antibodies
* A and B antigens
blood type O (universal donor)
* anti-A and anti-B antibodies
* no antigens