Topic 2 - Responding To Change Flashcards
Osmoregulation is
Regulating water content.
Thermoregulation is
Regulating body temperature
What is another example of homeostasis?
Blood glucose regulation
Body temperature is controlled by
The hypothalamus
The enzymes in the human body work best at
37 C
The hypothalamus contains
Receptors that are sensitive to blood temperature in the brain
The hypothalamus is found
In the brain
The hypothalamus relieves
Impulses from receptors in the skin providing information about the skin temperatures
What happens when your body temperature is too high
- Erector muscles relax so the hairs lie flat
- Sweat is produced as when it evaporates it transfers heat from your skin to the environment
- Blood vessels close to the surface of the skin dilate.!This allows more blood to flow near the surface and transfer more heat to the surroundings
What is vasodilation?
When blood vessels near the skins surface dilate to allow more blood to flow near the surface and transfer more heat into the surroundings.
What happens when your body temperature is too cold
- The erector muscles contract to make hairs stand on end so they can trap an insulating layer of hair
- Very little sweat is produced
- Blood vessels near the surface of the skin constrict so less blood flows near the surface and less heat is transferred to the surroundings
What is vasoconstriction?
When blood vessels near the surface constrict so that less blood can flow near the surface and less heat is transferred to the surroundings
Hormone are
Chemical messengers that travel in the blood to activate target cells
Hormones are produced in
Endocrine glands
Hormones are released
Directly into the blood
Hormones travel
All over the body but they only affect particular cells
Cells that have been affected by hormones are
Target cells that have the right receptors to respond to that hormone
How fast do hormones travel
At the speed of blood
Hormones have _________ effects
Long lasting
Neurones :
Transmit information around the body as electrical impulses
Describe the structure of a neurone
- branched endings called dendrins so they can connect with lots of other neurones
- Axon - where the electrical impulse is passed along
- Myelin sheath along the axon that acts as an electrical insulator to stop impulse getting lost and speeds it up
- Long to speed up impulse as connecting with another neurone slows impulse down so one long neurone is quicker that lots of short ones joined together
The connection between two neurones is called
A synapse
Describe a synapse
- the nerve impulse is transmitted by chemicals called neurotransmitters which diffuse across the gap
- the neurotransmitters then set off a new electrical impulse in the next neurone
Describe the differences between hormones and nerves
Nerves - fast message, act for very short time, act on precise area, electrical message
Hormones A slower message, act for a long time, act in a more general way, chemical message
A stimulus is
A change in your environment that you may need to react to
Sense organs contain different
Receptors