Excretion

Question 1

why is excretion necessary?

Answer 1

Excretion - removal of waste products formed by the metabolism, ensure waste products ( co2; nitrogenous waste) do not build up to toxic levels

if harmful waste prods build up in cells = normal functioning of cells would be affected & metabolism would be affected

Question 2

What does the urinary system do?

Answer 2

maintain homeostasis by regulating the volume & concentration of body fluids. Does this by filtering & reabsorbing materials from the blood

Question 3

What is the urinary system made up of?

Answer 3

2 Kidneys ; a bladder a urethra

Question 4

Explain each organ of the urinary system

Answer 4

Kidneys - function as excretory organs which filter waste out the blood & as osmoregulatory organs which regulate water and salt balances. Each is attached to a renal artery & renal vein & ureter
- Renal Artery - branch from aorta; contain blood carrying waste prods. to kidney; supplies kidney with o2 and nutrients
- Renal Vein - contains blood with lowest concentration of metabolic/ nitrogenous wastes; carries CO2 away from kidney to inferior vena cava
- Ureter - carries urine from kidneys to the bladder

Bladder -stores urine; has sphincter muscles @ base to control the flow of urine
Urethra - carries urine from bladder to the outside
- males = passes through penis & carries both urine and semen
- females = carries urine which exits through seperate opening in front of the vaginal opening

Question 5

Explain the adrenal glands fully

Answer 5

AKA endocrine glands
above each kidney but not part of excretory system
glands secrete the hormone aldosterone -> regulates the salt concentr. in body ( homeostasis)

Question 6

Where are the kidney found?

Answer 6

In abdominal cavity on either side of vertebral column just below diaphriagm

Question 7

what do the kidneys do?

Answer 7

filter nitrogenous waste out of the blood - excretory function - regulate H2O and salt balance - osmoregulatory function

Question 8

Name the parts of the kidney

Answer 8

Renal capsule; cortex; medulla; renal pelvis ;ureter; renal vein; renal artery; position of nephron

Question 9

Explain the function of each part of the kidney

Answer 9

Renal capsule - protects kidney & prevents entry of micro orgs
Cortex - outer region
Medulla - middle region
Ureter - carries urine from pelvis to bladder for storage
Renal Vein - carry deoxygenated blood with low urea cont. out of kidney
Renal Artery - Carry oxygenated blood with high urea content to kidney
Position of nephron - microscopic functional units of kidney

Question 10

Microscopic structure of the kidneys

Answer 10

Made up of millions of tiny; tightly packed; tubular units called nephrons ( aka renal tubules)
Nephrons = found in cortex & medulla regions
Nephrons = structural units of the kidney - make up the bulk of kidney and are also t he functional units of the kidney - remove waste matter from the blood
Each nephron - surrounded by very dense network of capillaries
Nephrons incl. Brownians capsule; proximal convoluted tubule & distal convoluted tubule

Question 11

How does a nephron function?

Answer 11

Waste products are removed from blood & urine is expelled by excretion - bougth about by 2 processes as fluid passes along the nephron
- Filtration - metabolic wastes ( urea; uric acid; ammonium ion; amino acids; small amounts of various salts) are filtered out from the cluster of blood capillaries into the Bowmans capsule to become part of urine

    - Tubular Reabsorption - useful substances ( glucose; amino acids & H2O) filtered into Bowmans capsule are reabsorbed into bloodstream from proximal convoluted tubule

Question 12

What is osmoregulation?

Answer 12

Controlling of the water and the solute in the body

Question 13

Why is it important for the water in the body constant?

Answer 13

For the cells to function properly
Too little = cells to dry out
too much = cells burst

Question 14

Role of ADH in osmoregulation?

Answer 14

ADH ( antidiuretic hormone) controls amount of water reabsorbed from filtrate by the blood in capillaries within the medulla

Question 15

How is ADH produced?

Answer 15

The Hypthalamus ( part in the brain)
Stored and secreted into the blood streamby pituitary gland
Release depends on negative feedback

Question 16

What happens when H2O content in blood is too low?

Answer 16

• Excessive water loss ( eg. sweating on a hot day/ strenuous activity/ insufficient intake) hypothalamus detects the lower water levels in blood and is stimulated to send more nerve impulses to pituitary gland to release more ADH into bloodstream
• ADH causes walls of kidney tubules (nephrons) to become more permeable to H2O
• More H2O leaves the kidney tubules and enters the blood capillaries in the medulla
• More H2O is reabsorbed into the blood, causing an increase in H2O content of blood back to normal
  A small volume of concentr. urine is excreted

Question 17

What happens when the water content is too high?

Answer 17

• Large water intake/ inactivity/ cold day, hypothalamus detects higher H2O levels in the blood and is stimulated to send nerve impulses to the pituitary gland to release ADH into the bloodstream
• Less ADH causes walls of the kidney tubules to become less permeable to water
• Less H2O is reabsorbed into the blood ie. blood water levels drop back to normal, leaving more water int he tubules
• Larger volume of dilute urine is excreted

Question 18

What is the role of aldosterone in osmoregulation?

Answer 18

• Secreted by adrenal glands
• Controls sodium levels in the blood
  
  • takes place between the kidney / renal tubules and their surrounding capillaries
• Release depends on negative feedback

** Sodium levels must be controlled in order to maintain correct bloodpressure**

Question 19

What happens if sodium levels decrease?

Answer 19

• Low salt = drop in blood pressure/ blood volumes
• Adrenal glands secrete more aldosterone
• More sodium leaves the renal tubules and returns to the blood
• Sodium levels are brought back to normal

Question 20

What happens when sodium levels increase?

Answer 20

• Adrenal glands secrete less aldosterone
• Less sodium is reabsorbed into the blood from renal tubules
• Sodium levels return to normal

Question 21

What happens to the urine now?

Answer 21

-Urine = final product of excretion that flows from the collecting duct
- From kidney tubules = passes into renal pelvis for transport via ureters to the bladder
- Bladder sores urine until it can be expelled through urethra
- Expulsion of urine = urnation

Question 22

Diabetes and the Kidney’s?

Answer 22

• Diabetes l\mellitus = caused by combo of hereditary and enviro factors
• High blood glucose levels
• Causes = 1) lack of / not enough insulin produced
  2) Body cells = not responding to / becoming part of resistant to insulin
• Diagnosed by testing for glucose in the urine
  - glucose in blood and not absorbed by the cells then it leaves the body in the urine ( elimination of excess glucose)
• Diabetes and high blood pressure = chronic kidney failure

Kidney failure = kidney stops working properly
- toxic nitrogenous wastes will not be excreted and the pH concentr. of ion and water balance of the body will not be regulated
- short term sol = cleanse blood artificially ( dialysis)
- treatment takes 4-6 hrs and patients have to be treated 2-4 times a week