1. List the 4 major ways of water loss from the human body.
(1) Urination
(2) Sweating
(3) Exhalation
(4) Defaecation
2. List the 3 major ways how the human body take in water.
(1) Drinking
(2) Eating
(3) Respiration
3. How will an imbalance between water intake and water loss affect the function
of the human body?
If there is an imbalance of between water intake and water loss, the water
content of blood and hence the water potential of the tissue fluid that surround
body cells will change. Water will therefore enter or leave the cells by osmosis. If
too much water is gained or lost, the concentration of various substances inside the
cytoplasm will be affected, consequently affecting the rate of various chemical
reactions (metabolic rate), and the cell cannot function normally.
4. What is the meaning of osmoregulation?
The process of which a stable water potential is maintained in the body fluid.
5. Which system and organ is responsible for osmoregulation?
System: urinary system
Organ: kidney
6. List the related structures of the urinary system, what is the function of each structure?
Kidney: produce urine
Ureter : carry urine to the urinary bladder
Bladder: store urine temporarily
Urethra: carry urine from the urinary bladder to the outside
7. What are the roles of the kidneys?
(1) osmoregulation
(2) excretion
8. How is urine released from the urinary bladder to the outside of the body?
When the volume of urine in the bladder increases, the wall of the bladder is
stretched. This gives us the feeling of an urge to urinate.
The muscles of the wall of the bladder to contract
and the sphincter muscles to relax, leading to urine passing out of the body
through the urethra.
9. What structures can be observed from the external look of the longitudinal section of the kidney?
Cortex, medulla, pelvis, renal vein, renal artery, ureter
10. What is a nephron?
The functional unit of the kidney.
11. What is a nephron composed of?
(1) Glomerulus ( afferent arteriole, efferent arteriold )
(2) Bowman’s capsule
(3) long tubule (including proximal convoluted tubule, loop of Henle (U-shape),
distal convoluted tubule)
12. Which duct will the many distal convoluted tubules connect to?
Collecting duct
13. What are the networks of blood capillaries in a nephron? Where is each of them?
glomerulus
network of capillaries surrounding the kidney tubule
14. What are the two processes that are involved in the formation of urine?
Ultrafiltration (Most substance in blood enters the Bowman’s capsule at the
Glomerulus)
Reabsorption (Some substances inside the kidney tubule return to the
blood capillaries)
15. What are the substances that will not be passed into the Bowman’s capsule? Why?
Red blood cells, white blood cells, blood platelets, plasma protein
Reason: too large
16. What are the three categories that the reabsorbed molecules are put into?
What are the major examples of reabsorbed molecules in each categories?
(1) All reabsorbed (glucose and amino acids)
(2) Partially reabsorbed (water and minerals)
(3) Basically not reabsorbed (urea)
17. What are the 5 features of the proximal convoluted tubules that are adapted to reabsorption?
(1) long and highly coiled
(2) Its wall consist of a single layer of epithelial cells
(3) epithelial cells have many microvilli on the surface
(4) contain many mitochondria
(5) surrounded by a dense capillary network
18. Which location are glucose and amino acids mainly reabsorbed? What are the mechanisms involved?
Proximal convoluted tubule
Diffusion and active transport
19. Which locations are minerals mainly reabsorbed? What are the mechanisms involved?
Proximal convoluted tubule, Loop of Henle,
Distal convoluted tubule, collecting duct.
Diffusion and active transport
20. Which locations is water mainly reabsorbed? What are the mechanisms involved?
Proximal convoluted tubule
Osmosis
21. Which locations is urea mainly reabsorbed? What is the mechanism involved?
Proximal convoluted tubule, Loop of Henle,
Distal convoluted tubule, collecting duct.
Diffusion.
(Note: this is a totally passive process)
22. Why is the urine appear yellow in colour?
It contains metabolic waste formed from the breakdown of bile pigments.
23. How is osmoregulation regulated by hormones? (use too much water as an example)
When a large amount of water is drunk,
The water potential of the blood becomes higher than normal.
When the blood flow pass the hypothalamus, the osmoreceptors in the
hypothalamus detect the increase,
and release less ADH.
Less ADH cause the wall of the collecting duct to become less permeable to water.
Thus a smaller proportion of water is reabsorbed from the glomerular filtrate.
As a result, a larger volume of diluted urine is produced.
24.Which structure is responsible for producing ADH? What is the function of ADH?
Pituitary gland
Increase the permeability of the collecting duct to water.
25. What is the function of a dialysis machine? Can it serve the purpose of
osmoregulation?
Remove metabolic waste
Note: CANNOT carry out osmoregulation!