Topic 5: Homeostasis and Response Flashcards
(43 cards)
Homeostasis
The regulation of the conditions inside the body to maintain a stable internal environment in response to changes internally or externally
Why do internal conditions in your body need to be kept constant?
Cells need the right conditions in order to function properly
Give examples of automatic control systems (ACS) (2)
1) Nervous communication system
2) Hormonal communication system
Give examples of what ACS maintain (3)
1) Body temperature
2) Blood glucose
3) Water content
Parts of an ASC (3)
1) Receptors
2) Coordination centres
3) Effectors
Negative feedback
A mechanism used by ASCs to regulate internal environment conditions by reversing the levels of something if it is too high or too low
Process of negative feedback (3)
1) Receptor: stimulus = too high/low
2) Coordination centre: receives and processes, organises response
3) Effector: produces response, restores to optimum level - continues to decrease/increase
Parts of the nervous system (5)
1) Receptors: cells that detect stimuli
2) Sensory neurones: carry information via electrical impulses from receptors to CNS
3) CNS or central nervous system: the brain or spinal chord connected to the body by sensory and motor neurones
4) Motor neurones: carry information via electrical impulses from CNS to effectors
5) Effectors: muscles or glands that respond to nervous impulses
How do effectors respond to nervous impulses? (2)
1) Muscles contract
2) Glands secrete hormones
Synapses
The connection between neurones which chemical messengers diffuse across stimulating an electric impulse in the next neurone
Reflexes
Rapid, automatic responses to certain stimuli that don’t involve the conscious part of the CNS - the brain
Process of the reflex arc (6)
1) Receptors detect stimulus
2) Electric impulses sent along sensory neurone until synapse
3) Chemicals diffuse across synapse causing electric impulses along relay neurone
4) Chemicals diffuse across synapse causing electric impulses along motor neurone
5) Electric impulses sent along motor neurone until effector
6) Effector responds by contracting or secreting
REACTION TIME PRACTICAL
-
Endocrine system
An automatic control system that coordinates responses to changes in the environment using hormones
Nervous system
An automatic control system that coordinates responses to changes in the environment using nerves and electric impulses
Pituitary gland (4)
1) Found in the brain
2) Linked to the hypothalamus which receives signals from receptors
3) Releases hormones in response to stimuli
4) Hormones trigger other glands to release hormones
Thyroid gland (3)
1) Found in the neck
2) Releases thyroxin
3) Regulates metabolism, heart rate and temperature
Pancreas (2)
1) Releases insulin and glucagon
2) Regulates blood glucose levels
Ovaries/Testes (3)
1) Releases oestrogen/testosterone
2) Controls puberty
3) Regulates menstrual cycle/sperm production
Adrenal glands (3)
1) Found above kidney
2) Releases adrenaline
3) Triggers the “fight or flight” response
Differences between nervous and hormonal systems (3)
1) Fast action VS Slow action
2) Short time VS Long time
3) Precise area VS General area
Purpose of thyroxine (2)
1) Increases basal metabolic rate
2) Responsible for regulating growth and brain development in young
Regulation of thyroxine (2)
Negative feedback
1) Low: thyroid-stimulating hormone (TSH) production increases –> more thyroxine is secreted by stimulated thyroid gland
2) High: TSH production decreases –> no thyroxine is secreted by inhibited thyroid gland
Purpose of insulin and glucagon
Controls the level of blood glucose concentration
