What is Physiology ? & Homeostasis Flashcards
What is Physiology?
The Science of Life.
A branch of Biology aiming to understand the mechanisms of living things, from the basis of cell function at the ionic and molecular level to the integrated behaviour of the whole body and the influence of the external environment.
What are the type of Tissues?
- Muscle
- Nervous
- Epithelial
- Connective
What are the Organs?
- Lungs
- Brain
- Heart
- Kidneys
- Stomach
- Colon (intestines)
What are the Body Systems? (*10)
1.Nervous
2. Endocrine
3. Immune
4. Circulatory
5. Muscle/Skeletal
6. Integument (skin, hair, nails and exocrine glands)
7. Respiratory
8. Urinary
9. Digestive
10. Reproductive
What is Homeostasis?
Homeostasis is the state of steady internal, physical, and chemical conditions maintained by living systems. (E.g. Body temperature, fluid balance, pH kept within the homeostatic range).
The body reacts to changes to maintain conditions inside the body.
How does your body maintain homeostasis?
- Skin separates internal and external environments.
- Internal environment has fluid that bathes all cells of the organism.
- The circulatory system moves materials to and from all parts of the internal environment.
- Some organs carry out the exchange of materials between the internal and external environments.
- Cells of organs exchange materials with each other via the internal environment.
What factors are homeostatically regulated?
- Concentration of nutrients.
- Concentration of CO2 and O2.
- Concentration of waste products.
4.Concentration of water, salt and other electrolytes. - pH.
- Temperature.
- Volume and pressure.
What ions are mainly in the Extracellular and Intracellular fluid, and what is the direction of movement?
Extracellular: Na+ and Cl-.
Intracellular: K+ around Anions (-ve)
The direction of movement goes from Intracellular to Extracellular.
The Homeostatic Control System can be classified as:
- Intrinsic (local controls): The inherent compensatory responses of an organ to a change.
- Extrinsic controls: Responses of an organ that are triggered by factors external to the organ, usually by the nervous and endocrine systems.
How do the intrinsic and extrinsic control systems generally operate?
- Negative feedback mechanism. (Need less of something).
- Positive feedback mechanism. (Need more of something).
- Feedforward mechanism.
Positive and Negative feedback:
Positive: Initial stimulus —> Physiological response —> Reduce stimulus. (Reduction in stimulus shuts off loop).
Negative: Initial stimulus —> Physiological response —> Increase stimulus. (An outside factor is needed to cut off positive feedback cycle).
What is the Negative feedback mechanism?
Change in a homeostatically control factor triggers a response that seeks to restore the factor to normal by moving the factor in the opposite direction of its initial change or it is a pathway where the response opposes or removes the signal.
Limitations of negative feedback.
- It is initiated after variable has been disturbed.
- Incomplete correction: Amount of correction to be applied assessed by magnitude of error signal.
- Can be overcorrected.
How are the negative feedback limitations overcome?
- By multiple regulatory mechanisms.
Thermoregulation: Physiological response to the stimulation.
Skin barrier: hairs stand on end.
Etc.
What is Positive feedback?
The output is continually enhanced or amplified so that the controlled variable continues to be moved in the direction of the initial change or a pathway in which the response reinforces the stimulus.
Positive feedback example:
- Onset of labor.
- Oxytocin released from hypothalamus.
- Increased uterine contractions.
- Baby’s head pushed through cervix.
- Stretch of the cervix.
- More oxytocin released.
- Increased uterine contractions.
Positive feedback:
- Rising phase of the action potential.
- Depolarisation.
- Na+ channels open.
- Na+ entry.
- Further depolarisation. (+ feedback loop).
- STOP: Na+ channels shut.
Feedforward regulation:
It brings about a compensatory response in anticipation of a change in a regulated variable.
E.g. Increased production of saliva and gastric secretions at smell and sight of food.
Feedforward - anticipatory change>
Changes in renal function in preparation for changes brought on by food intake resulting in changes in concentration of ions in the plasma that will need to be controlled within physiological range.
