HB TOPIC 2 HOMEOSTASIS

1. Homeostasis- define

   how is it achieved (what and loops)?

• maintaining a constant internal environment in the body eg. blood pressure, ph etc.

• nervous and endocrine system moniter changes to internal and external environment+ respond via feedback loops

1. Difference between negative and positive feedback loops

• Negative- body senses change and activates reactions to reduce/reverse in opposite direction

• Positive- body senses change and activates mechanisms to increase change in same direction

1. Steps to feedback system

1. Stimulus

2. Receptor

3. Modulator

4. Effector

5. Response

6. Feedback

1. Define Dynamic Equilibirum

Fluctuation of homeostasis around a set point

1. define tolerance limits

• upper and lower limits that body can function normally

2. Define thermoregulation and why do we need it?

• process which maintain the balance between heat production and loss

• needed as cell activity is heat sensitive

2. Central thermoreceptors

• found where

• role

• found in hypothalamus

• moniters INTERNAL body temp and controls activities to increase or decrease temo

2. Peripheral thermoreceptors

   • found where

   • role

• skin and mucus membranes

• moniters EXTERNAL environment via heat and cold receptors

2. Responses to high body temp

   • list them all

1. Vasodilation

2. Decreasing Metabolic rate

3. Sweat

4. Behavioural responces

2. Responses to high body temp- Vasodilation

   • Define

   • Effect- how is heat lost

• high BT= increased blood flow to skin via relaxation and dilation of peripheral blood vessels

• heat loss via radiation and evaporation= cooling of blood flowing through skin

2. Responses to high body temp- Decreasing metabolic rate

   • define

   • effect

• hypothalamus decreases release of TSH from anterior pituitary

• decreased TSH = decreased thyroxine from thyroid into blood = decreased metabolic rate = decreased body temp

2. Responses to high body temp- sweat

   • define

   • controlled by

   • response

• secreted via sweat glands to skin- controlled by sympathetic nervous system

• evaporation = decreased body temp

2. Responses to high body temp- behavioural responces

• decreased movement

• less clothing

• shade

• aircon

2. Response to low body temp- list

1. vasoconstriction

2. decrease metabolic rate

3. shivering

4. behavioral responses

2. Response to low body temp- vasoconstriction

   • define

   • effect (heat prod or decreasing heat loss)

• decreased body temp= restriction of blood vessels to decrease blood flow

• decreased blood flow to decrease heat loss

2. Response to low body temp- increasing metabolic rate

   • hormones released

   • explain each

   • effect of each (heat prod or decrease heat loss)

1. adrenaline and noradrenaline- hypothalamus stimulated adrenal medulla to secrete A+N to blood= increase metabolic rate= increase heat prod

2. Thyroxine- anterior pituitary released TSH to thyroid to release thyroxine = increased metabolic rate and increase heat prod.

2. Response to low body temp- shivering

   • define

   • effect (heat prod or decrease heat loss)

• rhythmic muscle tremors caused by hypothalamus to muscle tone

• muscle tone= movement = heat production

2. Response to low body temp- behavioral responses

1. huddling

2. curlling into ball

3. increased clothes

4. heat devices

3. Osmoregulation- define dehydration

low water concentration in blood plasma

3. water intake should =

water output

3. role of kidney in osmoregulation

• role

• how is it controlled?

• filters water out from blood and back into blood via collecting duct to urine to bladder.

• controlled by ADH

3. ADH- antiduretic hormone

• define

• role

• released from

• affects permeability of collecting duct in kidney

• controls reabsorption of water back into body

• released from posterior pituitary

3. how does increased adh affect reabsorption?

increased permeability of collecting duct = increased reabsorption= concentrated urine

3. how is osmoregulation detected?

• receptors

• define osmotic pressure and eg.

• osmoreceptors in hypothalamus detect osmotic pressure

• the tendency of water to move into a solution eg. high osmotic pressure= concentrated and low amount of water- water wants to move in

3. Aldosterone

• secreted by

• effect

• adrenal cortex into blood

• water follows via osmosis to decrease osmotic pressure

• = increased sodium reabsorption into blood and increase potassium excreted into urine

3. thirst reflex

• define

• give flow chart

• consious responce to drinking water when high osmotic pressure is detected

  1. Stimulus- low water concentration and high osmotic pressure

  2. Receptor - thermoreceptors in hypothalamus stimulated

  3. Modulator- hypothalamus

  4. Effector- cerebral cortex generates thirst feeling

  5. Responce- drink water and absorbed into blood via alamentary cana

  6. feedback- negative- water leaves blood and fluid returns to normal

3. Feeback loop of ADH release

1. Stimulus - low water concentration and high osmotic pressure

2. Receptor - osmoreceptors in hypothalamus stimulated

3. Modulator - hypothalamus

4. Effector - causes posterior pituitary to release ADH

5. Response - increased permiability in collecting duct = increased water reabsorbed into blood

6. Feedback - blood water levels return to normal and osmotic pressure decreases

4. Cellular respiration equation

oxygen + glucose = carbon dioxide + water + energy

4. Liver uses glucose in blood by

• list all 4

1. removed for energy

2. stored as glycogen

3. left in blood

4. stored as fat

4. Steps to decrease high blood glucose

1. chemoreceptors in beta cells of islet of langerhans detect high BSL

2. Insulin secreted

3. glucose absorbed by cells where either 1. GLYCOGENESIS or 2. LIPOGENESIS occurs IN PANCREAS

4. protein synthesis and increased cell respiration

5. decreased BSL

4. Define Glycogenesis

• glucose to glycogen in liver and muscles

4. Define Lipogenesis

• glucose to fat

4. 3 ways to increase low blood sugar levels

1. Conversion via Glycogenolysis and Gluconeogenesis

2. adrenal cortex

3. adrenal medulla

4. Steps to increase low BSL via glycogenolysis and gluceogenesis

1. chemoreceptors in ALPHA CELLS IN ISLET OF LANGERHANS detect low BSL

2. GLUCAGON is secreated

3. IN PANCREAS either 1. glycogenolysis or 2. gluceogenesis or 3. lactic acid to glucose

4. Blood glucose levels increase

4. Adrenal cortex to increase low BSL

• releases what hormone and from where

• 3 effects of hormone

• glucocorticosteroids stimulated by adreonocorticotropic hormone from anterior pituitary

  1. regulated carb and fat metabolism

  2. energise cells

  3. stimulate glycogenolysis and gluceogenesis

4. Adrenal medulla to increase low BSL

   • effect

• counteracts effect of insulin by causing glycogen → lactic acid → glucose

5. Breathing

• how does it occur

• controlled by

• contractions and relaxation of diaphragm and intercostal muscles

• respiratory centre in medulla oblongata

5. How are changes to gas concentrations detected?

• How fast is each responce?

• Oxygen, CO2 and Hyrogen Ion concentration- chemoreceptors on aortic and carotid bodies→ immediate responce

• CO2- +medulla too→ several minutes

5. Oxygen concentration change

• how large is the impact on breathing

• what happens if change is detected

• small impact on breathing rates unless O2 is very low

• Nerve impulses→ intercostal and phrenic nerves → intercostal muscles and diaphragm= increased BR

5. CO2 concentration change

• size of impact on breathing rate

• formula of carbon dioxide and water

• small increase of CO2= large impact

5. Changes to H+ iron concentration

• high hyrdogen ion concentration = decrease blood plasma ph= acidic

• detected and then increase breathing rate

5. Voluntary breathing

• controlled by… and why?

• role

• how is breathing stimulated again

• cerebral cortext- bypasses respitory in medulla oblongata

• protect the body from dangerous gas or water into lungs by holding breath

• build up of CO2

5. hyperventilation

• caused by…

• what happens to O2 and CO2

• why is it dangerous before holding breath?

• stress or anxiety

• deep breathing = more O2 and less CO2 than required

• lack of CO2 reduces urge to breath and too low oxygen = black out

5. Explain this graph

1. Oxygen increases by little but CO2 decreases dramatically

2. Dive = decreased O2 and increased CO2

3. O2 levels reach O2 blackout zone before response to breath is met

6. Disruptions to homeostasis

   • list all 4

1. type 1 diabetes

2. type 2 diabeted

3. hyperthyroidism

4. hypothyroidism

6. Type 1 diabetes

• define

• causes/ risks

• when autoimmune system destroys beta cells in ISLET OF LANGERHANS= no production of insulin= always high BGL

• autoimmune, genetic and environmental factors

6. Symptoms of type 1 and 2 diabetes

• thirst

• high urine production

• blurry vision

• weight loss

• acidic blood

6. treatment of type 1 diabetes

• insulin injection

• gene therapy- transfer/ growth of new beta cells or gene cells to replace cytotoxic T cells = fixed insulin production

6. Type 2 diabetes

   • define

• insulin produced but cells do not use properly

• overtime, pancreas decreases/ loses ability to produce insulin

6. Type 2 diabetes causes

1. older age, obesity, genetics etc

2. DIET= high sugar diet= increased insulin exposure over time and cells become resistant.

6. type 2 diabetes treatment

• careful diet

• regular excersise

• moniter glucose levels

• medication

6. Hyperthyroidism

   • define

   • caused when

• thyroid gland produces too much thyroxine and T3 (iodine)

• caused when bodies own antibodies imitate TSH = too much thyroxine production

• influenced by graves disease or genetics

6. Hyperthyroidism symptoms

• rapid heart beat

• weight loss (high metabolism)

• increased appetite

• sweating

• anxiety

• protruding eyeballs

6. Treatment of hyperthyroidism

• drugs- blocks use of iodine

• surgery to remove part/all of thyroid

• drink radioactive iodine- kills thyroid cells

6. Hypothyroidism

   • define

• thyroid gland produces too little thyroxine

6. causes for hypothyroidism

1. diseased thyroid

2. pituitary doesnt prod enough TSH

3. lack of iodine in diet

4. autoimmune disease

6. symptoms of hypothyroidism

• slow heart rate

• weight gain

• fatigue

• intolerance to cold

• swelling of face

• goiters

• Cretinism- retardnation, decreased growth, motor and sensory function in babies

6. treatments for hypothyroidism

• increased iodine diet

• thyroid hormone tablets