Chapter 44 - Animal Excretory System

Question 1

What is the constant osmolarity of body fluids (that should be maintained)?

Answer 1

300 mOsm of blood and interstitial fluid

Question 2

Osmolarity

Answer 2

the measure of osmotic pressure of a solution
= number of moles of solute per liter of solution
-from the perspective of the cell
-the measure of the amount of solute in the solution
-the capacity of the system itself (the cell) to gain/lose water

Question 3

Tonicity

Answer 3

• perspective of surrounding solution
• the capacity of the surrounding solution to cause a cell to gain/lose water

Question 4

Hypertonic

Answer 4

Higher concentration in surrounding solution than system
-cell loses water

Question 5

Hypotonic

Answer 5

Lower concentration in surrounding solution than in the system
-water moves into the cell

Question 6

Stenohaline

Answer 6

• organisms that cannot tolerate substantial changes in external osmolarity
  e. g. humans

Question 7

Euryhaline

Answer 7

• organisms that can survive large fluctuations in external osmolarity
  e. g. salmon

Question 8

Kidney

Answer 8

excretory organ mainly epithelial tissues that carry out active transport

the functional unit of kidney : Nephron

Question 9

4 stages of excretory system

Answer 9

1. Filteration : glomerulus -> Bowman’s capsule
   - blood, protein, lipid can not go throw.
2. Reabsorbtion : reabsorb glucose, amino acid, mineral ions.
   - proximal convoluted tube : reabsorb most nutrients.
   - descending loop of Hennle : many aquaporin, only water absorption
   - ascending loop of Hennle : only salt permeable, no water absorption
   - distal convoluted tube : most mineral ions absorption.
   - collecting duct : only water reaborption (ADH works on here)
3. Secretion : making urine
4. Excretion : urine leaves the system and the body

Question 10

ADH (anti diuretic hormone)

Answer 10

ADH

• increases the number of aquaporin on collecting duct (peptide hormone)
• synthesized from hypothalmus
• stored and release from posterior pituitary

Question 11

countercurrent multiflier system (in human)

Answer 11

• make a salt concentration gradient btw renal cortex and renal medulla
• maximize the concentration gradient
• passive water absoption

Question 12

regulation of blood volume and pressure

Answer 12

• RAAS = Renin Angiotensin Aldosterone System

when there is a heavy bleeding,

JGA (juxtaglomerular apparatus) detects blood volume and BP

→ release renin → angiotensinogen becomes angiotensin 1.

→ ACE (angiotensin converting enzyme) activates angiotensin 1 →angiotensin 2. → stimulate adrenal cortex to release aldosterone

angiotensin 2 also acts → arteriole contraction ; increase BP

• regulate osmolarity using (1) hypothalsmus & (2) medulla oblangata

chemoreceptor detects pH ( CO₂ ) concentration → causing thirst & ADH

Question 13

Aquaporin

Answer 13

specialized water channel.

found in descending loop of Hennle & collecting duct

ADH makes more aquaporin at collecting duct