2. Homeostasis Pt3 Flashcards
How would you make you experiment about does practice improve reaction speed a fair test? (7)
- use the same arm
- the same person dropping and catching
- same seating position
- same ruler
- ruler held at the same position relative to hand
- fingers same distance apart
- no prior practise
What do the brain and spinal chord do?
Receive impulses and then coordinate an effective response
What’s the function of the nervous system in humans?
It enables the body to respond to the stimulus and trigger their reaction
What’s the spinal cord in the nervous system?
A coordinator
A bright light is a …………
Stimulus
Blinking is a ……….
Response
Name 2 types of effectors and what do they do?
Glands-secret hormones
Muscles-contracts and relaxes
What does the lens (in the eye) do?
Focus light on the retina
What does the iris do?
It controls the amount of light entering the eye
If a person cut off there are how would it affect them physically and why?
Loss of movement as impulses would be unable to reach the muscle
Reflexes can be coordinated by the brain or spinal cord. The reflexes from sense organs in the head or co-ordinated by the brain. What 2 sense organs are involved with reflexes co-ordinated by the spinal cord?
Joints
Skin
Which type of eyesight gets worse with age?and why?
Long-sightedness
Ciliary muscles become weaker
What are plant growth hormones used for?
Agriculture & horticulture
Explain why plants produce hormones?
- to coordinate and control growth and responses to light (phototropism) and gravity (gravitropism or geotropism)
- unequal distributions of auxin cause unequal growth rates in plant roots and shoots
What does gibberellins do in plants?
It’s Important in the initiating seed germination
What does ethene do in plants?
It controls cell division and ripening fruits
What 2 types of responses can the homeostasis produce?
Nervous responses
Chemical responses
What happens to your eye when there’s a very bright light?
- bright light can damage your retina so you have a reflex to protect it
- when light receptors detect very bright light a reflex is triggered to make the pupil smaller
- the circular muscles in the iris contract & the radial muscles relax.
- reducing the light entering the eye
What happens to your eye when there’s a very dim light?
- the radial muscles contract & the circular muscles relax, which makes the pupil wider
- letting in more light
What’s an eye?
It’s a sense organ contains receptors sensitive to light intensity & colour
What do ciliary muscle & suspensory ligaments do?
They control the shape of the lens
What does the nervous system do?
Allows human to react to their surroundings & coordinate there behaviour
What does the endocrine system do and how?
- it’s made up of glands which secret chemicals (hormones) into the blood stream
- the bloodstream carries the hormone to a target organ where it produces an effect
- the effects it’s slower than the nervous system but act for longer
Why are reflex arcs important?
It helps prevent injuries
Define a reflex?
A rapid, automatic responses to certain stimuli that don’t involve the conscious part of the brain - reducing the chance of you getting injured
What’s are the steps in a reflex arc?
Sensory neurone > synapse > relay neurone > motor neurone
What makes up the central nervous system?
The spinal chord & the brain
What do all control systems include?
- receptor cells, which detect stimuli (changes in the environment)
- coordination centres (eg. Brain, spinal chord and pancreas) that receive & process information from receptors
- effectors, muscles or glands which bring about responses which restore optimum levels
What are the 2 types of effectors?
- muscles
- glands
What does the pituitary gland do in the endocrine system?
- it’s in the brain aka ‘master gland’
- it secrets several hormones into the blood in response to the body conditions
- these hormones act on other glands to stimulate other hormones to be released to bring about effects
What makes up your endocrine system?
Pituitary gland Pancreas -thyroid -adrenaline gland -ovary -testes
