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Regulation & Control

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Michelle Chew

on 22 April 2015

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Transcript of Regulation & Control

Am i a machine?
Or more complicated than that?
Regulation & Control
Excretion and its importance

Structure of kidney and nephron

Functions of kidney

Control of water and metabolic waste levels

How does my body works??
negative feedback

Importance of homeostasis
Principles of homeostasis
Importance of Homeostasis
Importance of Homeostasis
Homeostasis: maintenance of a constant internal body environment
Homeostasis helps maintain:
body temperature
blood sugar levels
blood thyroxine levels
blood pressure
other internal conditions at stable levels
Feedback mechanisms
Principle of homeostasis
these are cells / specific organ in the body that are capable of detecting a stimulus
Eg: Thermoreceptor in the skin
these are tissues/ organs in the body that causes the necessary action to bring affected condition back to normal level
Principles of homeostasis
There are 2 forms of feedback mechanisms:
Positive feedback
Negative feedback
Positive Feedback
Production of substance causes further activation of the process that produces more of the substances

During nervous transmission, influx of sodium ions into the membrane of neurone results in depolarisation.
Membrane became even more permeable to sodium.
Further depolarisation occurs until action potential is generated
Negative Feedback
Production of substance causes inhibits the process that produces the substances

Blood glucose level increase
Pancreas detects the change and produces insulin
glucose converts to glycogen
blood glucose level returns to normal
Excess insulin stops the pancreas from producing more insulin
Excretion and its importance
Excretion: the elimination of waste compound from the body which is produced during metabolism of cells (carbon dioxide & urea in human)
Excretion of carbon dioxide
Diffuses from the blood alveoli (lungs) air
Excretion of urea
Where is urea produced?
When our body has excess protein, amino acid must be removed (because nitrogenous compound is toxic to our body)

Liver salvages energy from amino acid by removing nitrogen atoms urea
Amino Acid
Keto Acid
(respire / converted
to glucose /fat)
Formation of urea
(less toxic)
Structure of Kidney
Describe the structure of a kidney nephron and its associated blood vessels
May/ June 2010 (41)
1) Renal / Bowman’s capsule
2) ref. Podocytes *
3) Proximal convoluted tubule / distal convoluted 4) tubule / capsule in cortex
5) Proximal convoluted tubule
6) Loop of henle
7) Distal convoluted tubule
8) Loop in medulla
9) Afferent arteriole
10) Efferent arteriole
11) Glomerulus
12) Capillary network around pct / loop/ dct
13) Collecting duct
Function of kidney
Involves filtering of small molecules & ions (including urea) out of the blood in the glomerulus into the renal capsule
Epithelium of renal capsule
Lumen of renal capsule
Light micrograph of a section through the cortex of a kidney
Oct / Nov 2008 (Q7)
Oct/ Nov 2008 (Q7)
4 key players in ultrafiltration:-

Basement membrane
Endothelium of blood capillary
Podocyte cells
Epithelial of renal capsule
Endothelium of blood capillary
Basement membrane
Podocyte cells
Epithelial of renal capsule
has gaps
any substances dissolved in the blood can pass through
acts as filter
stops large protein molecules from getting through
only protein with relative molecular mass of <68000 can pass through
White & red blood cell will be blocked as well
cells with many tiny finger-like projections
has gaps in between the projections
has gaps
any substances can pass through as well
Made of collagen + glycoprotein
Basement membrane
May/ June 2006 (Q3)
May/ June 2006 (Q3)
May/ June 2006 (Q3)
Relative concentrations of substances in the blood and in the glomerular filtrate
May/ June 2006 (Q3)
Now that you know all the important components in ultrafiltration……..

So, how does ultrafiltration
works exactly???
How ultrafiltration works
High pressure in the glomerulus leads to
high water potential .

Therefore, water moves from blood capillary (glomerulus) to renal capsule
Hydrostatic pressure
Diameter of afferent arteriole is wider than efferent arteriole
Causes ↑high pressure in the glomerulus
High pressure = high water potential↑Ψ
High [solute] in the glomerulus leads to
low water potential .

Therefore, less water moves from blood capillary (glomerulus) to renal capsule
Solute concentration

Solute [ ] in blood plasma (glomerulus) is ↑ than renal capsule
↑High [solute] = ↓low water potential Ψ
High pressure high water potential

High solute concentration low water potential
1) Endothelium of glomerulus
2) More gaps between endothelial cells
3) Podocytes
4) Large gaps between podocytes
5) Basement membrane, act as filter, selective barrier
6) Prevents large protein to pass through
7) No cells can pass through as well
8) Molecules filtered (urea, glucose, water, uric acid, creatinine,
Na+, K+, Cl-
9) High hydrostatic pressure in glomerulus
10) Afferent arteriole wider than efferent arteriole
11) Lower pressure in renal capsule
12) Fluid forced out into capsule = ULTRAFILTRATION
May/ June 2010 (41)
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