Homeostasis Prepared by :

Irfan Nafiz Bin Mazdi Faizal Bac (Hons) Information Technology

in Engineering MCSE : Enterprise Devices and Apps

(Microsoft)

1. Homeostasis is the maintenance of a relatively constant internal environment.Physical factor such as body temperature and blood

pressure while chemical factor are sugar level and osmotic pressure such as partial of carbon dioxide and oxygen

2. The excretory systemPlays an important role in homeostasisThe primary organs of the excretory system are the

kidneys.

Cortex

PyramidUreter

Pelvis

Renal Vein

Renal Artery

Medulla

Kidney

Nephron

Bowman’s Capsule

Renal Tubule : • Proximal convoluted

tubule• Loop of Henle• Distal convoluted

tubule

glomerulus

Bowman’s

campsuleRenal tubule

UltrafiltrationFormation of urine :o Ultrafiltrationo Reabsorptiono Secretion

Podocyctes/endhothelium of glomerulus form filtration membrane

High hydrostatic pressure : Afferent ateriole larger diameter than efferent

ateriole

The fluid enters into capsular space = glomerular filtrate

Glomerular filtrate: water, glucose , amino acids , urea mineral salts and

other small molecules

Red Blood cell and plasma protein

remain in the blood

because the too large too pass trough

filtration membrane,

Reabsorption

Proximal Convoluted Tubule :

1. Sodium ions2. Chloride ions

3. Glucose and Amino Acids4. Water (Osmosis)

Loop of Henle1. Water

2. Sodium ions3. Chloride ions

Distal Convoluted Tubule 1. Watery filtrate(low in

salt , high in wastes)2. Water

3. Sodium and chloride ions

Collecting Duct1. Little salt

2. 99% of water3. 1 % of urine

4. Filtrate call urine 5. Urea = remains and excreted in the urine

Secre

tion

Normal Value Normal Value

Excess – the value rises above the normal value

Corrective Mechanisms

Deficiency – the value drops below the normal value

Corrective Mechanisms

Negative Feedback Mechanisms

Negative feedback

Negative feedback

Detected by osmoreseptors in hypothalamus

Decrease in solute potential

Normal plasma osmotic level

Increased in solute potential

Detected by osmoreseptors in hypothalamus

Increased permeability of distal convoluted tubule and collecting duct to water

Greater proportion of water reabsorption in renal tubules

A small volume of concentration urine produced

A large volume of dilute urine produced

smaller proportion of water reabsorption in renal tubules

Decreased permeability of distal convoluted tubule and collecting duct to water

An increased in ADH released from posterior pituitary

A decreased in ADH released from posterior pituitary

Plasma solute potential decreases

Plasma solute potential increases

Increased water intake

Decreased water intake

TH

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Haemodialysis/Kidney

Transplant

Haemodialysis is the process of filtering blood by using an

artificial means that replaces the functions

of a failed kidney

After meal

Rise in blood glucose level

Secretion of more insulin(ẞ-cells) or less

glucagon by pancreas

Liver cells absorb glucose

from blood to form

glycogen

Increase in glucose

uptake by body cells for

respiration

Liver cell break down

glycogen into

glucose

Decrease in glucose

uptake by body cells for respiration

Drop in blood glucose level

Secretion of less insulin or more

glucagon(ɑ-cells) by pancreas

During fasting or after exercise

Blood glucose level returns to normal

++

THE REGULATION OF GLUCOSE LEVEL

Thermoregulation

Body tempratures

increase/decrease above 37◦ C

Thermoreseptors in the

hypothalamus detect the increase

/decrease in body temprature

Thermoreseptors in the skin detect

the increase/decereas

e in external temprature

Thermoregulatory centre in the hypothalamus

Effector