Homeostasis Flashcards
What is homeostasis?
Process of maintaining a constant internal environment within tolerance limits, despite changes in the internal and external environment
In a homeostatic feedback loop, what is a stimulus?
Deviation from optimal or normal value
In a homeostatic feedback loop, what is a receptor?
Cells or tissues that detect the stimulus and sends message to modulator
In a homeostatic feedback loop, what is the modulator?
Recieves message from receptor and coordinates a response, sending message to effector
In a homeostatic feedback loop, what is the effector?
Muscle or gland that recieves a message from the modulator and carries out a response
In a homeostatic feedback loop, what is a response?
The action of the effector that counteracts the stimulus
In a homeostatic feedback loop, what is negative feedback?
Factor returns to optimal or normal value
What are 4 types of receptors and their purpose?
- Chemoreceptor: detects oxygen and ion levels
- Osmoreceptor: detects changes in blood, osmotic pressure and solute concentrations
- Photoreceptor: Detects light
- Thermoreceptor: External or internal temperature variations
What are 9 homeostatic variables?
- Body temp
- pH levels
- CO2 levels
- O2 levels
- Ion levels
- Nutrients
- Water
- Blood pressure
- Red blood cell number
Draw a tolerance range diagram.
What are 4 factors that need to be maintained in homeostasis?
- Body temp (through thermoregulation)
- Fluid levels (through osmoregulation)
- Concentration of glucose
- Concentration of nutrients, wastes and gases
Why are negative feedback loops important?
Brings change that reduces the effect of the original stimulus
What are 2 glands that play a part in the endochrine system?
Posterior pituritary gland
- Antiduretic hormone
- From kidney
- Stimulates reabsorbtion of water
Thyroid gland
- Thyroxine
- From all tissues
- Increases metabolic rate
Draw a negative feedback loop for thermoregulation, when body has an increased temp
- Stimulus: Increased body temp
- Receptor: Thermoreceptors in skin and hypothalamus
- Modulator: Hypothalamus, sends message to sweat glands
- Effector: Body cells, sweat glands, skin, blood vessels
- Response: Increased sweating, change in behaviour
- Negative feedback: Body temp lowers
Give an example of thermolegulation mechanisms in a plant for a cold climate.
Eucalyptus tree
- thick, leathery, waxy leaves reduce heat loss providing insulation
Give an example of thermolegulation mechanisms in a plant for a hot climate.
Hakea
- Narrow vertical leaves reduce amount of direct sunlight
- Increases resistance to cold temps at night as well as frost
What is thermoregulation ?
The process animals maintain an
internal temperature within a tolerance range.
What is an endotherm?
Organisms that maintain a constant body temperature independent of the environment
What is an ectotherm?
Organisms that cannot maintain a constant body temp, it fluctuates with the external environment
What are 2 costs for endothermic organisms?
- Use more energy to maintain higher metabolic rate
- Need more food and hunting time to supply energy
What are 3 benifits for endothermic organisms?
- Body temp is independent of external temp, can live in extreme environments
- Can be active more often (night or day)
- Being active at specific may reduce predation
What are 2 costs for ectothermic organisms?
- Body temp reliant on external temp, limited to living in less extreme environmtents
- Can’t tolerate very high or very low temps
What are 3 benifits for ectothermic organisms?
- Heat source mainly environmental, lower energy requirements
- Don’t need as much food
- Wide tolerence range for internal temp
Give 3 reasons why temperature homeostasis is important
- Metabolic processes require an optimal temp
- Internal temps of higher then 37 degrees, enzymes can denature and stop functioning
- Internal temps lower than 37, chemical reactions in body start to slow