ANHB1102 Lecture Notes - Lecture 5: Amniotic Sac, Red Blood Cell, Genitourinary System
24 May 2018
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Urinary System:
- Maintain volume and composition of body fluids within normal limits (Osmoregulation)
- Rid the body of waste products of cellular metabolism (excretory system)
- Close association with the reproductive system - (urogenital system)
- (renal system)
Functions:
- Homeostasis
- Water balance
- Electrolyte balance
- Removal of toxins and
nitrogenous wastes
- Blood pH balance – excrete
H+ ions
-
reabsorb HCO3
-
maintain blood pH – 7.4
- Blood pressure regulation
(renin)
- Red blood cell production (erythropoietin)
Osmoregulation:
All animals balance the gain and loss of water and dissolved solutes
- NA+, Cl-, Ca2+, HCO3
Water gain: Water loss:
- Food - urinating
- Drink - defecating
- Metabolic water - evaporation - breathing
- sweating.
Terrestrial vertebrate adaptations to preventing dehydration:
- Outer skin of water-resistant cells
- Embryos develop in a fluid-filled amniotic sac surrounded by protective membranes
- Behavioural adaptations
- The kidney
Kidneys:
Role in conserving water and regulating osmotic pressure in blood.
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- When fluid intake is high, kidneys excrete dilute urine saving salts and excreting water
- When fluid intake is low, kidneys conserve water by forming concentrated urine.
- can concentrate urine to 4x blood osmotic concentration.
- enables excretion of wastes with minimal water loss
Excretion of nitrogenous wastes:
Ammonia: (NH3)
- too toxic to be stored in the body
- does’t diffuse readily ito air
- highly soluble in water
- diffuses rapidly across cell membranes
- if an animal is surrounded by water, NH3 readily diffuses
out of its cells.
- Must be transported and excreted in large volumes of
dilute solutions.
Urea:
- Highly water soluble
- 100,000x less toxic than NH3.
- Can be stored in concentrated solution
- Water required for disposal.
Uric Acid:
- More complex molecule
- Relatively non-toxic
- Largely insoluble in water
- Excreting uric acid minimizes water loss
- More energy required to excrete
- Energy cost balanced by savings in body water.
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Gross anatomy:
Ureters:
- Urine enters via renal pelvis
- Stretches ureters
- Contraction of ureter muscle wall
- Peristaltic wave
- Draws urine from renal pelvis down to bladder and enters bladder from below.
Urinary Bladder:
Bladder
- Muscular sac located on floor of pelvic cavity
- Capacity – 500ml (max 700-800mL)
Muscularis (muscle wall)
- 3 layers of smooth muscle
- Presence of rugae
Mucosa
- Lined with transitional epithelium
- Highly distensible
As the bladder fills:
- It expands superiorly
- Rugae flatten
- Epithelium thins from 5-6 layers to 2-3
find more resources at oneclass.com
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Document Summary
Maintain volume and composition of body fluids within normal limits (osmoregulation) Rid the body of waste products of cellular metabolism (excretory system) Close association with the reproductive system - (urogenital system) H+ ions reabsorb hco3 maintain blood ph 7. 4. All animals balance the gain and loss of water and dissolved solutes. Embryos develop in a fluid-filled amniotic sac surrounded by protective membranes. Role in conserving water and regulating osmotic pressure in blood. When fluid intake is high, kidneys excrete dilute urine saving salts and excreting water. When fluid intake is low, kidneys conserve water by forming concentrated urine. Can concentrate urine to 4x blood osmotic concentration. Enables excretion of wastes with minimal water loss. Ammonia: (nh3) too toxic to be stored in the body. Diffuses rapidly across cell membranes if an animal is surrounded by water, nh3 readily diffuses out of its cells. Must be transported and excreted in large volumes of dilute solutions.
