Homeostasis Flashcards
What is Homeostasis ?
Maintaining a stable internal environment
List 3 internal conditions that your body needs to keep constant to survive
- Temperature
- Glucose level
- Water levels
What is meant by negative feedback ?
Your automatic control systems keeps your internal environment stable using a mechanism called negative feedback .
When the level of something (eg water or glucose ) gets too high or too low your body uses negative feedback to bring it back to normal.
What steps does your control systems take to restore blood glucose temp and water levels to normal.
- Receptor detects a stimulus - level is too high
- The coordination centre recieves and processes the information the organises a response
- Effector produces a response which restores the optimum level.The level decreases
What is the central nervous system made up of ?
Brain
Spinal Cord
note - the central nervous systems is connected to sensory and motor neurons
What do sensory neurons do ?
Carry information as electrical impulses from receptors to the CNS
What do motor neurons do ?
Carry electrical impulses from the CNS to the effector
What are effectors ?
All of your muscles and glands that respond to nervous impulses
What are receptors ? examples
Cells that detect stimuli eg: taste receptors on the tongue touch receptors on the skin
The central nervous system coordinates the response.
A bird is eating some seeds and a cat is approaching.
Describe the pathway for a bird that sees a cat approaching ?
The bird can see - receptors in the bird’s eye detect the cat (stimulus)
The sensory neurons carry information from the receptors to the CNS. The CNS decides what to do with it
The CNS send information to the muscles in the birds wings the effectors along the motor neurons. The muscles contract and the bird flies away.
Summarise the coordinates response for the CNS
stimulus –> receptors –> Sensory neurons –> CNS –> Motor Neurons –> Effectors –> Response
What is a synapse ?
Connection between 2 neurons
How is the impulse sent across a synapse ?
The nerve signal is transferred by chemicals which diffuse across the gap. These chemicals then set off a new electrical signal in the next neuron.
What is a reflex ?
How does it protect you from harm ?
A reflex is a rapid automatic response.
It does not involve the conscience part of your brain. eg : if you touch something hot.you move your hand immediately. eg: if someone shines a bright line in your eye your pupils automatically get smaller to stop your eyes being damaged.
A chef touches a hot tray A reflex action causes him to immediately move his hand away
A) State the effector in his reflex action
B) Describe the pathway of the reflex from the stimulus to the effector.
A) The muscles in your hand
B) The stimulus is detected by the receptors.Which sends an impulses along a sensory neurone to the CNS.The impulse is transferred to the relay neurone.It is then transferred to a motor neurone and travels along it to the effector.
Summarise the pathway of the reflex arc.
Stimulus –> Sensory neurone –> relay neurones –> motor neurone –> effector –> response –>
What is a reaction time ?
How quickly you respond to a stimulus
What factors can effect your reaction time ?
Age Gender Drugs
Describe an experiment to measure the effect of caffeine on reaction time
1) The person being tested should sit with their arm resting on the edge of a table.This stops their arm from moving up or down during the test.
2) Hold a ruler vertically between their thumb and fore finger.Make sure the zero end of the ruler is level with the thumb and finger.
3) Then let go without warning .The person being tested should try to catch the ruler as quickly as they can.
4) Reaction time is measured by the number where the ruler is caught. The number should be read from the top of the thumb.The furhter down the ruler is caught the slower the reaction time.
5) repeat the test to calculate the mean time.
6) The person being tested should then have a caffeine drink after 10 minutes repeat steps 1-5.
Describe how you can obtain valid results for monitoring someones reaction time.
You should use the same person to catch the ruler each time and they should use the same hand.
The ruler should be dropped from the same height.
Make sure the person has not had any caffeine before the start of the experiment
Suggest a safety precaution for someone carrying out the reaction time test
They should not drink anymore caffeine for the rest of the day. There are some unpleasant side effects
Suggest another way you can accurately measure someones reaction time and the advantages it had over catching a ruler.
A simple computer test could be used. More precise. Can record reaction time to milli seconds. Also eliminates the possibility of the catcher predicting when to respond to the persons body languages.
