Fever and Thermoregulation Flashcards
What is the main role of cells?
Protein factories - proteins do all the work inside of the cell
What determines the shape of the protein?
Function
Define homeostasis
Maintenance of relatively stable internal environment notwithstanding changes in the external (ambient) environment
How do proteins denature?
- Disrupted hydrogen bonds between amino acids.
- normal protein –denaturing–> denatured protein –renaturation–>normal protein.
What disrupts hydrogen bonds?
- temp
- pH
- ions (salts)
- solvents (polar molecules)
Reflective (self-regulatory)
unconscious
regulatory systems
- endocrine = chemical signalling pathway of endocrine is hormones
- autocrine nervous system
describe the two types of feedback loops, give an example:
- negative feedback loop = self regulatory
(number of prey (+) – increase predators –> decrease number of prey) - positive feedback = amplification
What does the afferent pathways do?
carry info to toward integration centre.
What is another name for chemically signalling molecules?
Ligands
What are ligands?
- neurotransmitters
- hormones
- inflammatory mediators
How do ligands function?
- bind to receptors
- receptor binding initiates events inside the cell that produce a response
Are receptors specific?
- 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.
What are neurotransmitters?
- 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.
What is the endocrine system?
- Released into circulatory system
- Actions on any cell in the body with a receptor for the ligand.
What are some key neurotransmitters?
- Noradrenaline:
- released by neurons of the sympatheitic nervous system to evoke fear, fight or flight reponses
- activates a class of recptors called adrenergic receptors.
What are some key hormones?
- 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.
What are circadian rhythms?
- daily oscillations in homeostatic regulation
- can oscillate either side of the homeostatic set point
Explain the process of heat exchange (4 steps):
- Radiation = infrared radiation from fire or sun
- evaporation = heat transfer when water evaporates
- convention = heat exchange with surrounding medium
- conduction = heat exchange with another object
Give a detailed explanation of a physiological thermoregulatory response:
- Metabolism:
a. non-shivering thermogenesis
- sympathetic regulation
- endocrine
b. shivering thermogenesis
- somatic regulation
- endocrine - Skin/blood flow
a. sympathetic: vasoconstriction, active vasodilation - Sweating
a. sympathetic
Explain what causes a fever, and what follows:
- 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
Explain the process of immune activation:
- 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.
What is sepsis?
- uncontrolled inflammatory response - excess high temperature leaves us susceptible to organ damage
