Fever and Thermoregulation

Question 1

What is the main role of cells?

Answer 1

Protein factories - proteins do all the work inside of the cell

Question 2

What determines the shape of the protein?

Answer 2

Function

Question 3

Define homeostasis

Answer 3

Maintenance of relatively stable internal environment notwithstanding changes in the external (ambient) environment

Question 4

How do proteins denature?

Answer 4

• Disrupted hydrogen bonds between amino acids.
• normal protein –denaturing–> denatured protein –renaturation–>normal protein.

Question 5

What disrupts hydrogen bonds?

Answer 5

• temp
• pH
• ions (salts)
• solvents (polar molecules)

Question 6

Reflective (self-regulatory)

Answer 6

unconscious

Question 7

regulatory systems

Answer 7

• endocrine = chemical signalling pathway of endocrine is hormones
• autocrine nervous system

Question 8

describe the two types of feedback loops, give an example:

Answer 8

1. negative feedback loop = self regulatory
   (number of prey (+) – increase predators –> decrease number of prey)
2. positive feedback = amplification

Question 9

What does the afferent pathways do?

Answer 9

carry info to toward integration centre.

Question 10

What is another name for chemically signalling molecules?

Answer 10

Ligands

Question 11

What are ligands?

Answer 11

• neurotransmitters
• hormones
• inflammatory mediators

Question 12

How do ligands function?

Answer 12

• bind to receptors
• receptor binding initiates events inside the cell that produce a response

Question 13

Are receptors specific?

Answer 13

• yes, while many diff chemicals act as chemical signalling molecules, receptors are specific for particular signalling molecules (similar to lock being specific for a key).
• determined by the way the cell expresses the receptor that denotes if the ligand will be responded to.

Question 14

What are neurotransmitters?

Answer 14

• released in small packets at the synapse (synapse - functional connection between two neurons or neuron muscle cell, or neuron and gland).
• action discrete = restricted to receptors at the synapse.

Question 15

What is the endocrine system?

Answer 15

• Released into circulatory system
• Actions on any cell in the body with a receptor for the ligand.

Question 16

What are some key neurotransmitters?

Answer 16

• Noradrenaline:
  - released by neurons of the sympatheitic nervous system to evoke fear, fight or flight reponses
  - activates a class of recptors called adrenergic receptors.

Question 17

What are some key hormones?

Answer 17

• Adrenaline:
  - secreted by the adrenal glads (under sympatheic nervous system)
  - activates a class of recpetors called adrenergic receptors
• Thyroid hormone:
  - secreted by thyroid gland, under hypothalamic regulation, increases energy expenditure.

Question 18

What are circadian rhythms?

Answer 18

• daily oscillations in homeostatic regulation
• can oscillate either side of the homeostatic set point

Question 19

Explain the process of heat exchange (4 steps):

Answer 19

1. Radiation = infrared radiation from fire or sun
2. evaporation = heat transfer when water evaporates
3. convention = heat exchange with surrounding medium
4. conduction = heat exchange with another object

Question 20

Give a detailed explanation of a physiological thermoregulatory response:

Answer 20

1. Metabolism:
   a. non-shivering thermogenesis
   - sympathetic regulation
   - endocrine
   b. shivering thermogenesis
   - somatic regulation
   - endocrine
2. Skin/blood flow
   a. sympathetic: vasoconstriction, active vasodilation
3. Sweating
   a. sympathetic

Question 21

Explain what causes a fever, and what follows:

Answer 21

• altered temp regulated ‘set point’ higher than normal
• infectious agent activates immune response
• releases inflammatory mediator
• stimulates production of prosta glandin
• alters neuronal activity in hypothalamus leading to altered set point
• denature essential enzymes in: some bacteria = reduces bacterial protein function. viruses = reduces viral infection by slowing down our own bodies mechanisms
• fever helps activate or enhance immune response

Question 22

Explain the process of immune activation:

Answer 22

• certain proteins within the immune system operate better at higher then normal body temperatures.
• adaptive advantage to survival:
  
  • immune response is low activity during normal temp.
  • immune response is selectively activated during infection.

Question 23

What is sepsis?

Answer 23

• uncontrolled inflammatory response - excess high temperature leaves us susceptible to organ damage