5.1-NOmeostasis Flashcards
What’s an example of an an animal responding to gradual change ?
Arctic fox- thick white coat in winter, thinner grey brown coat in summer- greater insulation and camouflage, enabling survival.
What will a good communication system do ?
- cover the whole body
- enable cells to communicate with eachother
- enable specific communication
- enable rapid communication
- enable both short term and long term responses.
What are the 2 major systems of communication?
Neuronal system
Hormonal system
What is the neuronal system?
An interconnected network of neuronal that signal to eachother across synapse junctions. The neurons can conduct a signal v quickly + enable rapid responses to stimuli that may be changing v quickly.
What is the hormonal system?
System that uses the blood to transport its signals. Cells in an endocrine organ release the signal-a hormone-into the blood. The hormone is transported throughout the body but is only recognised by specific target cells. The hormonal system enables longer term responses to be coordinated.
What is an effector ?
A cell, tissue, or organ that brings about a response.
What is homeostasis?
Maintaining a constant internal environment despite changes in external and internal factors.
Whah is negative feedback?
The mechanism that reverses a change, bringing the system back to the optimum.
What is positive feedback?
The mechanism that increases a change, taking the system back away from the optimum.
What is sensory receptor?
Cells/ sensory nerve endings that respond to a stimulus in the internal or external environment of an organism and can create action potentials.
What conditions do living things need to maintain?
Temperature
pH
Aqueous environment that keeps substrates and products in solution
Freedom from toxins and excess inhibitors
What are some aspects maintained by homeostasis ?
Body temperature Blood glucose concentration Blood salt concentration Water potential of blood Blood pressure CO2 concentration
What is an example of positive feedback?
At the end of pregnancy to bring about dilation of the cervix: as cervix stretches posterior pituitary gland secretes oxytocin, which increases uterine contractions, which stretches the cervix more, which causes more secretion of oxytocin.
What is an ectotherm?
An organism that relies on external sources of hear to maintain body temperature.
What is an endotherm?
An organism that uses heat from metabolic reactions to maintain body temperature.
Do ectotherms or endotherms control their body temperature within very strict limits and why?
ENDOtherms control their body temperature within very strict limits.
Ectotherms aren’t able to because they rely on external sources of heat so their body temp fluctuates with external temp.
If ectotherms are cold what do they do?
Move to a sunny area
Lie on a warm surface
Expose a larger surface to the sun
If ectotherms are warm what do they do?
Move out of the sun
Move underground
Reduce body surface exposed to the sun
Is a lot of ectotherms’ food used for respiration?
Nah, because they rely on external sources to keep warm
What are the advantages of being an ectotherm?
Less food used in respiration
More energy gained from food can be converted to growth
Need to find less food
Can survive for longer periods without food
What are the disadvantages of ectothermy?
Less active in cooler temperatures- at risk from predators when cold, unable to escape, can’t take advantage of food available when cold.
What does the skin do if the body is too hot ?
Sweat glands secrete fluid onto skin surface
Hairs and feathers lie flat to reduce insulation+allow greater heat loss
Vasodilation of arterioles and precapillary sphincters directs blood to skin surface so more heat can be radiated out.
What does the gaseous exchange system do if the body’s too hot?
Panting, increasing evaporation of water from surface of lungs and airways- latent heat of vaporisation
What does the skin do when endotherms are too cold?
Less sweat secreted
Hairs and feathers stand erect to trap sit
Vasoconstriction of arterioles and precapillary sphincters leading to skin surface - blood diverted away from skin.
What does the gas exchange system do in endotherms when cold?
Less panting
What does the liver do when endotherms are too hot?
Less respiration-less heat released
What does the liver do when endotherms are too cold?
Increased respiration in hepatocytes- more energy from food converted to heat
What do the skeletal muscles do when endotherms are too hot?
Fewer contractions- less heat releases
What do skeletal muscles do when endotherms are too cold?
Spontaneous muscle contractions- shivering- to release heat
What do blood vessels so when endotherms are too hot?
Dilation to direct blood to extremities so more heat can be lost
What do blood vessels do when endotherms are too cold ?
Construction to limit blood flow to extremities
What are the advantages of endothermy?
Endotherms can:
Maintain a constant body temp despite outside conditions
Remain active even when external temps are low so can take advantage of prey+ escape predators
Inhabit colder parts of planet
What are the disadvantages of endothermy?
Use a significant part of energy to maintain body temp in cold
Need more food
Use for growth a lower proportion of energy gained from food
May overheat in hot weather
what are some examples of ectotherms?
snake
locust
lizard
horned lizard
what does the locust do to its breathing when it’s hot and why?
increases rate and depth of breathing-more water evaporates from tracheal system, cooling body.
what monitors core body temperature?
temperature receptors in thermoregulatory centre of hypothalamus
what monitors temperature at the extremities?
peripheral temprature receptors in skin
why would something be described as endothermic?
it produces its own heat from RESPIRATION so doesn’t rely on the surroundings for heat. gotta say respiration.
