2) Responding To Change Flashcards
What is osmoregulation?
Regulating water content
What is homeostasis?
Maintaining a stable internal environment
What are some ways of gaining and losing water internally?
Gaining-
Drinking
Eating
Respiration
Losing-
Sweating
Breathing out water
Peeing
What is thermoregulation?
Regulating body temperature
Name the three types of homeostasis in a human.
Osmoregulation,
thermoregulation,
blood glucose regulation
What is negative feedback?
1) A change in environment triggers a response that counteracts the changes
2) this means that the internal environment tends to stay at a constant, where the cells work best
3) this has limits so if the environment changes too much then it may not be able to counteract the changes and regulate the internal environment
What is the hypothalamus?
A part of the brain that detects a change in the internal environment so causes a response in the dermis
When you’re too hot, how to you thermoregulate?
- erector muscles relax so hairs lie flat
- lots of sweat is produced. When the sweat evaporates it transfers heat from your skin to the environment
- blood vessels close to the skin dilate (widen-vasodilation). This allows more blood to flow near the surface of the skin so it transfers more heat to surroundings
When you’re too cold, how do you thermoregulate?
- erector muscles contract so hairs stand up which traps an insulating layer of air to keep you warm
- little sweat produced
- blood vessels near the surface of the skin constrict (vasoconstriction) so less blood flows near the surface meaning less heat is transferred to surroundings
What are hormones?
Chemical messengers which travel in the blood to activate target cells
Which is a faster information transmitter - hormones or nerves?
Nerves
What is a target organ?
An organ that contains target cells which have he right receptors to respond to a hormone
How fast do hormones travel?
At the speed of blood
How lasting are the effects of hormones?
Long lasting
What are neurones?
Nerve cells which transmit information as electrical impulses around the body
What are dendrons?
Branched endings of neurones which enable them to connect with other neurones
Where is the electrical impulse passed along?
The axon
What does a myelin sheath do?
Acts as an electrical insulator which stops the impulse getting lost and speeds uo the impulse
Why are neurones long?
It speeds up the impulse one long neurone is much quicker than lots of short ones joined together
What is a synapse?
A tiny gap between two neurones
How does an impulse travel alone a synapse?
1) The nerve impulse is transmitted by chemicals called neurotransmitters which diffuse across the gap
2) the neurotransmitters then set of a new electrical impulse in the next neurone
What are the differences between hormones and nerves?
- nerves are fast messages, hormones are slower messages
- nerves act for a short time, hormones act for a long time
- nerves act on a very precise area, hormones act in a more general way
- nerves are an electrical message, hormones are a chemical message
What is a stimulus?
A change in your environment that causes a reaction
What are reflexes?
Automatic responses to certain stimuli
Describe a reflex arc.
1) neurones in a reflex arc go through the spinal cord or an unconscious part of the brain to make the process quick and thoughtless
2) when a stimulus is detected by receptors impulse are sent along a sensory neurone to the central nervous system
3) in the cns the sensory neurone diffuses the impulse over a synapse to a relay neurone
4) relay neurones relay the impulses to a motor neurone (again diffuses across the synapse)
5) the impulses then travel along the motor neurone to the effector (muscle or gland)
6) the effector responds to the stimulus
7) quicker than normal responses because you don’t have time to think about the response
