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.
