Homeostasis Flashcards
(26 cards)
What is homeostasis?
The maintenance of a constant internal environment.
It gives us a survival advantage and is needed for proper functioning.
What are the main components of a homeostatic system?
- Input
2.receptor
3.coordinator
4.effector
5.output
Feedback loop
Input
This is a change to the system which requires a cell to react
Receptor
The change is detected in a living system.
Coordinator
Operational information is stored here and used to coordinate effectors
Effector
Brings about changes to the system in order to return it to the optimum point
Output
System returned to optimum point
Feedback loop
Positive or negative feedback
Positive feedback
When a deviation from the optimum point causes change that results in an even greater deviation from the normal.
Example of positive feedback
Influx of sodium ions in the neurone
This is because more is added in to the neurone
What is a con of POSITIVE FEEDBACK?
Usually harmful as it leads to instability
NOT INVOLVED IN HOMEOSTASIS
What is negative feedback?
Negative feedback occurs when the stimulus causes the corrective measures to be turned off so it returns the system to its original (optimum) level and prevents overshoot.
What is an ectotherm?
animals that obtain heat from sources outside the body, such as the environment.
What is an endotherm?
An animal that derives most of their hear from metabolic activities that take place inside their bodies.
Name 3 ways ectotherms regulate body temperature
Exposing themselves to the sun
Taking shelter
Gaining warmth from the ground
Describe how ectotherms exposing themselves to the sun regulated body temperature
Lizards orientate themselves so the maximum surface area of their body is exposed to the warming rays of the sun
Describe how taking shelter helps ectotherms regulate body temperature
Lizards will shelter in the shade to prevent over heating when the suns radiation is at its peaks.
They retreat to burrows in order to reduce heat loss when the external temperature is low.
Describe how gaining warmth from the ground helps ectotherms in regulating body temperature
Lizards will press their bodies against areas of hot ground to warm themselves up.
When they get to the right temperature they raise themselves up with their legs.
Name 5 ways endotherms conserve and gain heat in response to a cold environment
Vasoconstriction Shivering Raising of hair Increased metabolic rate Decrease in sweating
Describe how vasoconstriction hells endotherms conserve and gain heat in response to a cold environment
The diameter of the arterioles near the skin become smaller.
This reduces the volume of blood reaching the skin surface through capillaries.
Most of the blood entering the skin passes beneath an insulating fat layer and so very little heat is lost.
Describe how shivering helps endotherms conserve and gain heat in response to a cold environment
The muscles of the body undergo involuntary rhythmic contractions that produce metabolic heat.
Describe how the raising of hair helps endotherms conserve and gain heat in response to a cold environment
The hair erector muscles in the skin contracts, raising the hairs.
This enables a think layer of still air which acts as a good insulator.
Describe how increased metabolic rate helps endotherms conserve and gain heat in response to a cold environment
In colder conditions more of the hormones to increase metabolic rate are produced, as a result metabolic activity, including respiration is increased and so more heat generated.
Homeostasis and PH
If PH is too high or too low enzymes become denatured, this causes hydrogen bonds to break and the active site changes shape.
This means they cant do their job as biological catalyst and metabolic reactions are slowed down.
PH 7 is optimum for enzyme activity
