values despite fluctuations from the external environment

Osmotic concentration is the concentration of solutes dissolved in a watery solution. Osmotic concentration is usually measured in milliosmoles per liter (mOsm/L)

-> It is crucial because it maintains the proper balance of water and salts within an organism's body, ensuring that cells function optimally by preventing them from shrinking or swelling due to drastic changes in solute concentration.

What is the effect of this hormone?

ADH controls the release of water from the collecting duct by increasing the duct's permeability to water, allowing more water to be reabsorbed from the urine back into the bloodstream. This process helps the body conserve water and reduces the amount of urine produced. 

- Receptor that detects the change

- Input, information is sent to the control center

- Control center, receives input then provides

- Output, the result of the body reaction

- Effectors, restores the condition

- Response, restoring homeostasis

Diabetes type I is an autoimmune condition in which the immune system mistakenly attacks and destroys the beta cells of the pancreas that produce insulin, causing the pancreas to stop producing insulin. The caused of type I diabetes is still unclear, but most of it is caused by genetic factor and environment, like virus or bacterial.

Symptoms of Diabetes Type I

• Frequent urination (polyuria)

• Excessive thirst (polydipsia)

• Extreme hunger (polyphagia)

• Unexplained weight loss

• Fatigue and weakness

• Blurred vision

• Sometimes diabetic ketoacidosis (DKA) as the first sign

Treatment

Monitoring blood glucose levels and injecting human insulin throughout the day (Particularly after meals consumed).

Definition of Diabetes Type II

Diabetes type II is a insulin resistance condition, the pancreas still produce insulin but body’s cell do not respond to it properly.

Symptoms of Diabetes Type II

• Frequent urination

• Increased thirst

• Increased hunger

• Fatigue

• Blurred vision

• Slow-healing sores or frequent infections

• Numbness or tingling in hands/feet (neuropathy)

• Often develops gradually, may go unnoticed for years

Treatment

Maintain a low carbohydrate diet and regular exercise to reduce need for insulin

- small window-like pores

- found in the endothelial lining of the glomerular capillaries in the kidney

- 70–100 nanometers in diameter

- the first layer of the filtration barrier in the Bowman’s capsule.

- allow the passage of water and small solutes such as ions, glucose, amino acids, and urea

- preventing larger structures like red blood cells, white blood cells, and platelets from leaving the bloodstream

2) Basement membrane:

- second layer of the glomerular filtration barrier

- thick, gel-like structure made of extracellular matrix proteins such as collagen, laminin, and negatively charged glycoproteins.

- a size-selective and charge-selective filter.

-stops large molecules, especially plasma proteins like albumin, are prevented from crossing

- Ensuring useful cells and proteins remain in the blood, while smaller substances like water, ions, glucose, amino acids, and nitrogenous wastes pass through into the Bowman’s capsule.

3) Podocyte:

- epithelial cells that cover the outside of the glomerular capillaries in the Bowman’s capsule

- branch further into tiny foot processes (or pedicels), leaving narrow gaps called filtration slits

• Peripheral thermoreceptors detect increased skin temperature.

• Signals sent to hypothalamus trigger cooling mechanisms:

• Sweat glands produce sweat → evaporative cooling.

• Vasodilation of skin blood vessels → more heat lost through skin.

• Metabolic rate may decrease to reduce heat production.

When Body Temperature Falls (Too Cold):

• Peripheral thermoreceptors detect low temperature.

• Hypothalamus activates heat-producing responses:

• Muscle shivering: rapid muscle contractions generate heat.

• Vasoconstriction: skin blood vessels constrict to reduce heat loss.

• Thyroxin secretion increases, raising metabolic rate for more heat.

• Brown adipose tissue (brown fat) generates heat by burning fats (non-shivering thermogenesis).

Sodium and chloride ions are pumped out of the filtrate in the ascending limb of the loop of Henle into the surrounding medulla region, lowering its water potential

Describe osmoregulation in the descending limb:

• The neighbouring descending limb is permeable to water, so water moves out of the descending limb by osmosis due to the low water potential of the medulla created by the ascending limb

  • The descending limb has few transport proteins in the membranes of its cells, so has low permeability to ions

  • The water potential of the filtrate decreases as the descending limb moves down into the medulla due to the loss of water and retention of ions

    
    

Describe osmoregulation in the ascending limb:

• The ascending limb of the loop of Henle is impermeable to water, so water is unable to leave the loop here by osmosis

• The water potential of the ascending limb increases as it rises back into the cortex due to the removal of solutes and retention of water

• The low water potential in the medulla created by the ascending limb also enables the reabsorption of water from the collecting duct by osmosis

• Vasoconstriction of skin blood vessels – decreases blood flow to the skin, reducing heat loss.

• Shivering of skeletal muscles – rapid muscle contractions generate heat.

• Piloerection (hair stands on end) – traps an insulating layer of air near the skin (in humans, minimal effect but part of the response).

• Increased metabolic rate – more cellular respiration produces additional heat.

• Behavioral responses – seeking warmth, adding clothing, or curling up.

• Vasodilation of skin blood vessels – increases blood flow to the skin, enhancing heat loss.

• Sweat gland activation – sweating and evaporation cool the body surface.

• Reduced metabolic rate – less heat is produced internally.

• Behavioral responses – seeking shade, removing clothing, or drinking fluids.

These mechanisms restore homeostasis by bringing body temperature back to the normal set point.

ADH, which increases the collecting ducts' permeability to water, allows water to be reabsorbed into the bloodstream via aquaporins.

When the body is hydrated, ADH levels decrease, reducing water reabsorption and producing dilute urine; conversely, dehydration increases ADH, leading to greater water reabsorption and concentrated urine. 

Which hormone controls the release of water from the collecting duct?

• Antidiuretic hormone (ADH), or vasopressin.

  The effects are :

• increases the permeability of the collecting duct walls to water.

• stimulates the insertion of aquaporin water channels to collecting duct cell membranes.

• This allows more water to be reabsorbed back into the blood by osmosis.

• As a result, urine becomes more concentrated, and water is conserved in the body.

What happens when a person is dehydrated?

• The pituitary gland releases more ADH.

• More water is reabsorbed into the bloodstream, reducing water loss in urine.

• Urine volume decreases and becomes darker/more concentrated.

• Thirst is also stimulated, encouraging the person to drink water.

• Osmoreceptors in the hypothalamus detect this and reduce ADH secretion from the pituitary gland.

• With less ADH, the collecting ducts become less permeable to water.

• Less water is reabsorbed into the blood, and a larger volume of dilute urine is excreted.

• blood water potential is balanced.

• This maintains normal blood osmotic pressure.

1. During exercise the muscles will require more oxygen and glucose to fuel muscle contraction, so will need an increased blood supply

2. After a meal the digestive system will require more oxygen and glucose to fuel digestion and absorption, so will need an increased blood supply

How Insulin Works

1. Glucose Absorption:

   1. Insulin binds to receptors on muscle and liver cells, prompting them to absorb glucose.

   2. Glucose transporters (e.g., GLUT4) move glucose into cells.

2. Glycogen Formation:

   1. In the liver and muscles, insulin activates enzymes to store glucose as glycogen.

3. Inhibits Glucose Production:

   1. Suppresses the liver’s production of glucose from non-carbohydrate sources.

How Glucagon Works

1. Glycogen Breakdown:

   1. Glucagon signals the liver to break down glycogen into glucose.

2. Glucose Production:

   1. Promotes gluconeogenesis, synthesizing glucose from amino acids and other sources.