B5 - Homeostasis And Response Flashcards
What is homeostasis?
Maintaining a stable internal environment for cells & enzymes to function properly
We have automatic control systems that regulate our internal conditions (e.g. water, temperature, & blood glucose levels)
Homeostasis ~ What are the 2 automatic control systems that regulate our internal conditions?
2 systems:
nervous system - rapid, short term, temporary response
endocrine system - slower, longer acting, sometimes permanent response
What is negative feedback?
If something in your body gets too high/too low, your body tries to reverse this by using negative feedback
How does negative feedback work?
- Receptor detects a stimulus - level is too high
- The coordination centre receives & processed the information, then organises a response
- Effector produces a response, which counteracts the change & restores the optimum level
Level decreases
- Receptor detects a stimulus - level is too low
- The coordination centre receives & processed the information, then organises a response
- Effector produces a response, which counteracts the change & restores the optimum level
Level increases
Sometimes the effectors can change the level too much in the opposite direction; the receptor detects this & negative feedback starts again.
What is the nervous system?
What are the parts of the nervous system?
Allows us to react to our surroundings & co-ordinate our behaviour
- Central nervous system (CNS)
= brain & spinal cord - Peripheral nervous system (PNS)
= nerves
What is a neurone?
What are the types of neurones?
Neurone = nerve cell
- they transmit information as electrical impulses
- Sensory neurone
= carries information from a receptor to CNS - Relay neurone (in CNS)
= joins sensory neurone to motor neurone - Motor neurone
= carries electrical impulses from CNS to erectors
What are receptors?
What are effectors?
What are the 2 types of effectors?
Receptors = specialised cells that detect a stimulus
(E.g. tastebuds, light sensitive cells in eyes, pressure receptors in skin, vibration sensitive cells in ears, etc)
Effectors = cause a change / response
1. Muscles (contract)
2. Glands (secrete hormones)
How does the nervous system work?
- Receptor
- Sensory neurone
- Relay neurone
- Motor neurone
- Effector
- Response
(2) Sensory neurones transmit signals to CNS
(3) Relay neurone processes the signal
(4) Motor neurone transmits the signal to the effector
(5) Effector carries out response
What is a synapse?
How do they work?
Synapse = a gap between 2 neurones
(They connect neurones)
- When an electrical impulse get to the end of a neurone it can’t go any further
- The nerve signal is transferred by chemicals which diffuse across the gap
- These chemicals then set off a new electrical signal in the next neurone
What are reflexes?
What do they do?
What is a reflex arc?
Reflexes
= rapid automatic responses to certain stimuli that don’t involve the conscious part of the brain
- help prevent injury
- help maintain homeostasis by regulating physiological processes
(E.g. control of heartbeat, control of breathing, & muscle contraction)
Reflex arc
= the passage of information in a reflex (from receptor to effector)
What is reaction time?
BLOOD GLUCOSE LEVELS
MENSTRUAL CYCLE
