Homeostasis Flashcards
The ability of living organisms to maintain a stable and relatively constant internal environment despite external changes
Homeostasis
This involves the regulation of various physiological variables
Homeostasis
An organism that:
- is male at <28C
- is female at >31C
- is imbalanced at 28-31C
Red-eared slider turtle
An organism that:
- is female at either ≤22C or ≥28C
- is male between the said temperatures
- is predominated by males
Macrolemys
(Alligator snapping turtle)
An organism that:
- is female at >30C
- is male at <25C
- has an even sex ratio at 28.5C
Emys obicularis
(European pond turtle)
The 5 key components of homeostasis
- set point
- sensors or receptors
- control centers
- effectors
- feedback loops
Key Component of Homeostasis
Represents the ideal or optimal level of a variable
Set Point
Key Component of Homeostasis
Monitor the internal conditions and detect any deviations from the set point; located in various parts of the body
Sensors or Receptors
Key Component of Homeostasis
Involves the brain and other CNS structures which receive, process, and compare information to the set point and generate appropriate commands to regulate the variable
Control Centers
Key Component of Homeostasis
Carry out the control center’s commands
Effectors
Key Component of Homeostasis
Self-regulating mechanisms that maintain homeostasis
Feedback Loops
Feedback Loop
- Responds by amplifying the initial deviation from the set point
- Less common
- e.g. blood clotting
Positive Feedback Loop
Feedback Loop
- Responds by counteracting the deviation, bringing the variable back towards the set point
- Maintains stability
- e.g. body temperature regulation
Negative Feedback Loop
4 importance of homeostasis
- balance and stability
- optimal functioning
- protection against external factors
- prevention of diseases
The 4 negative feedback mechanisms
- Stimulation
- Reception
- Processing
- Counteract on Stimulus
The 5 mechanisms of temperature regulation
- sweat & vasodilation
- evaporative & convection cooling
- drop in temperature
- goosebumps & vasoconstriction
- less convection
The 3 mechanisms of blood pressure regulation (baroreflex)
- baroreceptors detect blood pressure in arteries
- if imbalanced, a chemical signal is sent to the brain via glossopharyngeal nerve
- brain sends chemical signal to heart to adjust pumping rate
The 4 mechanisms of osmoregulation in fish
- water enters gills by diffusion
- excess salt ions are released through excretion
- excess salt are removed via active transport by chloride secretory cells in the gills
- salt concentration is maintained
The 4 positive feedback mechanisms
- Stimulation
- Reception
- Processing
- Stimuli activated further
The 4 mechanisms of blood clotting
- blood clots when wounded
- platelets adhere to wounded area and attract more platelets
- accumulation of platelets
- clotting accelerated until bleeding stops
The 4 mechanisms of childbirth
- baby presses against ovary wall
- brain receives pushing feeling and pituitary is stimulated to generate oxytocin
- oxytocin causes uterine muscle contractions, causing fetus to come closer to the cervix
- continues until birth
4 common homeostatic disorders
- Diabetes
- Hypertension
- Hypothyroidism
- Hyperthyroidism
