Homeostasis

Question 1

Describe feedback loop ( Low blood Glucose) ( Cortisol).

Answer 1

1. Stimulus-> detects the decrease in BGL ( below the set point)
2. Receptor-> Chemoreceptors within the hypothalamus
3. Modulator-> Hypothalamus stimulates the adrenal cortex to release cortisol, by stimulating a nerve impulse and storing the hormones adreno corticotropic hormone at the end of the SNC released from the anterior pituitary gland.
4. Effector-> Adrenal cortex releases cortisol-> Liver-> adipose tissue-> skeletal muscles.
5. Response-> Glycogenolysis ( the breakdown of glycogen to glucose) in liver and skeletal muscles
   Removal of amino acids from muscle cells
   Gluconeogenesis ( the conversion of amino acids to glycogen) in the liver. Therefore promotes mobilisation of fatty acids from adipose tissues. ( all responses increase blood glucose levels)
6. Feedback-> the BGL is increased, adrenal cortex does not release cortisol anymore, old stimulus is removed and negative feedback is present.

Question 2

Describe Feedback loop ( low blood glucose) ( Adrenaline and noradrenaline )

Answer 2

1. Stimulus-> detects the decrease in blood glucose levels ( below set-point)
2. Receptor-> Chemoreceptors located within the hypothalamus
3. Modulator-> The hypothalamus stimulates Sympathetic nervous conduction to adrenal medulla to stimulate the release of noradrenaline and adrenaline
4. Effector-> The adrenal medulla releases adrenaline and noradrenaline, liver and skeletal muscles.
5. Response-> Undergoes Glycogenolyosis( the breakdown of glycogen to glucose) into the liver and skeletal muscles
   The glycogen in the muscles convert into lactic acid
   The Lactic acid converted to glucose in the liver. (All responses increase blood glucose levels)
6. Feedback-> The blood glucose levels increase. The adrenal medulla stops releasing the adrenaline and noradrenaline, Old stimulation is eliminated and negative feedback is present.

Question 2

Describe the feedback loop for ( low blood glucose level) (Glucagon)

Answer 2

1. Stimulus-> detects Low blood glucose levels ( glucose levels below the set-point)
2. Receptor-> chemoreceptors located in the alpha cells of the Islets of Langherhans in the pancreas
3. Modulator-> Alpha cells in Islets of Langerhans are stimulated to release Glucagon.
4. Effector-> Liver, Skeletal muscles, body cells and adipose tissue.
5. Response-> Glycogenolysis( the breakdown of glycogen to glucose) in the liver/ skeletal muscles
   Glyconeogenesis ( the breakdown of lipids or proteins into glucose) in the liver
   Lipolysis ( the breakdown of lipids->energy) in the liver
   Mild stmulating effect of protein breakdown in body cells
   (ALL RESPONSES INCREASE BLOOD GLUCOSE LEVELS)
6. Feedback-> the Blood glucose levels increase, the Alpha cells of Langerhans stop releasing glucagon, the old stimulus is eliminated and the negative feedback is present.

Question 3

Describe the feedback loop ( high blood glucose level)( Hyperglycemic)

Answer 3

1. Stimulus-> detects the High blood glucose levels above the set-point
2. Receptor-> Chemoreceptors in the Beta cells of the Islets of Langerhans in the Pancreas.
3. Modulator-> Beta cells in The islets of langerhans are stimulated to release Insulin
4. Effectors-> Liver, Skeletal muscles, body cells, adipose tissues.
5. Response-> glycogenesis ( the formation of glycogen from the glucose) in the liver and skeletal muscles
   lipogenesis ( the conversion of glucose into lipids)
   Therefore -> accelerated transport of glucose from the blood in body cells ( in particular skeletal muscles)
   -> Protein synthesis ( conversion of glucose into protein) in body cells ( particularly the skeletal muscles)
   (ALL RESPONSES CAUSE A DECREASE IN BLOOD GLUCOSE LEVELS)
6. Feedback-> Therefore there is a decrease in blood glucose levels, Beta cells stop producing insulin, old stimulus is eliminated, and negative feedback is present.

Question 4

Increase in body temperature (vasodilation physiological response)

Answer 4

1. Stimulus-> detect an increase in body temperature (above the set-point)
2. Receptor-> Peripheral heat receptors in the skin and mucous membrane
   Central thermoreceptors located in the thermoregulatory centre in the hypothalamus
3. Modulator-> hypothalamus nervous conduction via the parasympathetic system
4. Effector-> Skin arterioles
5. Response-> Vasodilation occurs- the widening of the blood vessels causes increases in blood flow through vessels, therefore increase heat loss through convection, conduction and radiation.
6. Feedback-> Decrease in Body temperature, Old stimulus is eliminated , negative feedback is present.

Question 5

Increase in body temperature (sweating physiological response)

Answer 5

1. Stimulus-> detect an increase in body temperature (above set point)
2. Receptor-> Peripheral heat receptors located in the skin and the mucous membrane
   Central thermoreceptros located in the thermoregulatory centre in the hypothalamus
3. Modulator-> hypothalamus- nervous conduction via the sympathetic system
4. Effector-> sweat glands
5. Response-> Sweat glands release sweat
   Increase of heat loss via the evaporation of sweat from the surface of the skin
6. Feedback-> Sweatglands stop producing sweat, body temperature decrease, old stimulus eliminated, negative feedback present.

Question 5

Increase in body temperature ( behavioural)

Answer 5

1. Stimulus-> detect increase in body temperature ( above set point)
2. Receptor-> Peripheral heat receptors in skin and mucous membrane
   Central thermoreceptors in thermoregulatory centre in hypothalamus
3. Modulator-> Hypothalamus undergoes nervous conduction to activate cooling processes.
4. Effector-> Cerebrum receives messages and stimulates a behavioural response via skeletal muscles
5. Response-> All these responses are done with conscious thoughts
   Take of clothes-> increase heat loss via convection, conduction and radiation
   Turn on aircon-> increase heat loss via convection
   increase body surface area-> increase heat loss via convection, conduction, radiation
   Stand in shade reduce heat gained by radiation
   Reduce physical activity-> decrease heat production
   (ALL RESPONSES DECREASE BODY TEMPERATURE
6. Feedback-> Decrease in body temperature, old stimulus eliminated, negative feed back is present

Question 5

Decrease in body temperature ( shivering physiological)

Answer 5

1. Stimulus-> detects the decrease in body temperature( below set-point)
2. Receptor-> The peripheral cold receptors in the skin and mucous membrane
   Central Thermoreceptors in thermoregulatory cetnre in hypothalamus.
   3.Modulator-> Hypothalamus initiates the nervous conduction via the effererent pathway.
3. Effector-> Skeletal muscles
4. Response-> Shivers occur ( rhythmetic oscillations of the muscles causing tremors) generating heat
5. Feedback-> Increase in body temperature, old stimulus eliminated, negative feed back occurs

Question 6

Increase in body temperature ( Hormonal response thyroxine)

Answer 6

1. Stimulus-> detect increase in body temperature (above the set-point)
   2.Receptor-> the peripheral heat receptors on the skin and the mucous membrane.
   Central thermoreceptors located in thermoregulatory centre in hypothalamus
2. Modulator-> hypothalamus release TSH inhibiting factors
   Anterior pituitary gland stops release thyroxine stimulating hormone
3. Effector-> Thyroid gland-> stops stimulating thyroxine
4. Response-> Reduced levels in thyroxine, reduce metabolic rate in body cells, therefore decreased heat production
5. Feedback-> Hypothalamus stops releasing TSH inhibiting factors, temperature decreases, old stimulus eliminated, negative feedback is present

Question 7

Decrease in body temperature ( vasoconstriction physiological)

Answer 7

1. Stimulus-> detect Decrease in body temperature (below setpoint)
2. Receptors-> Peripheral cold receptors in skin and mucous membrane
   Central thermoreceptors in thermoregulatory centre in hypothalamus
3. Modulator-> hypothalamus intiates nervous conduction via the sympathetic pathway
4. Effector-> skin arterioles
5. Responses-> Vasocontriction-> the blood vessels contrict, less blood flow, therefore there is decreased heat loss via convection, conduction and radation.
6. Feedback-> Increase body temperature, old stimulus eliminated, negative feedback present.

Question 8

What is the point of adding a layer of blanket when your cold

Answer 8

decreaes heat loss via radiation and convection

Question 9

What is dynamic equilibrium?

Answer 9

stable balance of physiological processes within the body, where various systems and organs maintain homeostasis (internal balance) through constant adjustments and interactions.

Question 10

Describe tolerance limit

Answer 10

range of environmental or physiological conditions that an organism can endure without harm. Beyond these limits, the organism’s health and survival may be compromised.

Question 11

Decrease in Body temperature ( hormonal response-> thyroxine)

Answer 11

1. Stimulus-> decrease in Body temperature ( below the set point)
2. Receptor-> Peripheral cold receptors in the skiin and mucous membrane
   Central thermoreceptors in thermoregulator centre in hypothalamus
3. Modulator-> hypothalamus release of TSH promoting facators
   Anterior pituitary stimulated to release TSH
4. Effector-> Thyroxine gland-> release more TSH
5. Response-> more thyroxine hormones-> higher metabolic rate for body cells therefore increase heat production
6. Feedback-> Old stimulus eliminated, INcrease in body temperature, Stops Hypothalamus from release of more TSH, negative feedback occurs.

Question 12

Decrease in Body temperature ( hormonal response -> Noradrenaline and adrenaline)

Answer 12

1. Stimulus-> detect decrease in body temperature
2. receptor-> Peripheral cold receptors in skin and mucous membrane
   Central thermoreceptors in thermoregulator in hypothalamus
3. MOdulator-> hypothalamus stimulates adrenal medulla by nervous conduction via sympathetic pathway
4. Effector-> Adrenal medulla stimulates the releasse of adrenaline and noradrenaline into the blood
5. Response-> high levels of adrenaline and noradrenaline in the blood, body cell respond= increasing metabolic rate, increase heat production
6. Feedback-> Increase in body temperature, old stimulus elimnated, Adrenal medulla stops releasing adrenaline and noradrenaline and negative feedback occurs.

Question 12

High water concentration ( hormonal)

Answer 12

1. Stimulus-> The osmotic pressure decreases and the water concentration increases
2. Receptor-> osmoreceptor located in the hypothalamus.
3. MOdulator-> The hypothalamus reduces nervous stimulation via to posterior pituitary gland which reduces the release of ADH.
4. Effector-> the nephron in kidney more specifically:
   Distal convulated tubule and collecting duct
5. Response-> Therefore decrease the permeability of Distal convulated tubule and Collecting duct, Less water reabsorbed, more urine produced, Urine is less concentrated

All processes increase osmotic pressure

6. Feedback-> Osmotic pressure increase and water concentration decreases, old stimulus is eliminated, the posterior pituitary gland stops reducing adh released, Negative feedback occurs.

Question 13

Decrease in body temperature ( behavioural)

Answer 13

1. Stimulus-> detect decrease in body temperature ( below set-point)
2. Receptor-> Peripheral cold receptors in skin and mucous membrane
   Central thermoreceptor in Thermoregulatory centre in hypothalamus
3. Modulator-> hypothalamus initiates nervous conduction to activate warming processes
   4.effector-> Cerebrum stimulates a message to the skeletal muslces
4. Repsonse-> put on more clothes ( reduce heat loss via heat convection and radiation)
   More physical activities ( increase heat production)
   Decrease body surface area ( decease heat loss via radiation and convection
   Turn on heater-> increase heat gained via convection and radiation
5. Feedback-> Body temperature is increased, old stimulus is eliminated, Negative feedback occurs

Question 14

Thirst reflex ( involuntary)

Answer 14

1. Stimulus-> low water concentration therefore increase in osmotic pressure
2. Receptor-> osmoreceptors in the thirst centre located in hypothalamus and in the mouth.
3. Modulators-> Thirst centre in the hypothalamus stimulated.
4. Effector-> Cerebrum/ cerebral cortex activates drinking behaviour= conscious decision to drink
   Skeletal muscles-> carry out this decision of drinking
5. Response-> Person drinks, water is absorbed into the blood stream via the alimentary canal / water concentation increase therefore osmotic pressure decreases
6. Feedback-> water conc increase, osmotic pressure decrease, old stimulus eliminated and negative feedback occurs.

Question 14

Low water concentration (hormonal)

Answer 14

1. Stimulus-> a decrease in water concentration, an increase in osmotic pressure.
2. Receptor-> osmoreceptor in the hypothalamus
3. Modulator->The hypothalamus via nerve conduction stimulates the posterior pituitary gland to increase release of ADH
4. Effector-> The distal convulated tubule and the collecting duct located in the nephron in the kidney.
5. Response-> The permeability of distal convulated tubule and collecting duct increase, higher concentration of urine, more wter reabsorbed, therefore more urine passed.
6. feedback-> hypothalamus stops stimulating posterior pituitary gland, old stimulus eliminated, osmotic pressure decreases and water conc increases, negative feedback occurs.

Question 15

How does gene therapy treat Diabetes mellitus?

Question 16

INcreased Co2 levels

Answer 16

1. stimulus-> high carbon dioxide levels = low ph, low H+ ions, low o2)
2. Receptor-> central chemoreceptors in medulla oblongata (Co2)
   Peripheral Chemoreceptors in aortic and carotid bodies (pH)
3. Modulator-> Respiratory centre in medulla oblongata and pons.
4. Effector-> Respiratory muscles –> intercoastal muscles ( internal and external via intercostal muscles)
   Diaphragm via phrenic nerve.
5. response-> increase in rate and depth of breathing ( all processes decrease co2 levels)
   Muscle contract more forcefully and frequently
6. feedback-> the co2 levels decrease, original stimulus is eliminated and the negative feedback occurs.