Coordination & Response (Homeostasis, eye, reflex arc, tropisms) Flashcards
What does the CNS consist of?
The brain & spine
What is an effector?
A muscle producing a response
What carry signals from the receptor to the brain and spinal cord?
Sensory neurone
What carries messages within the CNS?
Relay neurone
What carries a signal from the CNS to the effector?
Motor neurones
What 3 things does a co-ordinated response require?
Stimuli, receptor, effector
What is homeostasis & give 2 examples in humans
The regulation of internal conditions
- Control of water content –> osmoregulation
- Temperature regulation –> thermoregulation
What is a synapse?
A gap where two neurones meet.
What happens at a synapse?
Signals cross the gap using chemicals - one neurone releases a chemical called a neurotransmitter and it diffuses across the gap making the next send another electrical signal.The neurotransmitter is then broken down by enzymes at the 2nd neurone.
Why are there reflex actions?
Sometimes a very quick response is needed
What are reflex actions?
Actions without unconscious thought
How do plants respond to stimuli?
Using tropisms such as geotropism, phototropism and hydrotropism
Geotropism response of roots?
Roots carry out positive geotropism, towards the earth & gravity (downwards) –> towards water
In root placed horizontally auxin will collect in bottom, making it grow less and bend towards gravity
Geotropism response of shoots?
Shoots carry out negative geotropism, away from gravity –> to get sunlight
In a shoot placed horizontally, bottom side contains more auxin making it grow less than top side and grow against gravity.
Explain positive phototropism in stems?
Stems want to grow towards the light to get the maximum sunlight. Auxins will collect in the shaded side, meaning this side grows longer, bending the shoot towards the light.
Is the hormone (endocrine) or nervous system faster?
Nervous system
Which response lasts longer: the hormone (endocrine) or nervous system?
Endocrine
Which of the hormone (endocrine) or nervous system has a localised response, and which is more widespread?
Nervous is localised, endocrine is widespread
What sort of messages are sent by the endocrine and nervous systems?
Nervous is an electrical impulse whereas endocrine is a chemical messenger/hormone
What is the message of the endocrine system transmitted by?
The blood stream
What is the message of the nervous system transmitted by?
Neurones
Describe the hormone: Anti-Dieuretic Hormone (ADH) {Secreted, where in body responds, effect}
It is secreted from the pituitary gland
The collecting duct of the nephron in the kidneys responds
It causes the duct to be impermeable or permeable according to whether water needs to be conserved or lost. More secreted –> more reabsorbed
Describe the hormone: Adrenaline {Secreted, where in body responds, effect}
Secreted from the adrenal gland
Heart, lungs and liver respond
It prepares body for physical activity by increasing heart and breathing rate (providing muscles with oxygen rich blood)
Describe the hormone:Insulin {Secreted, where in body responds, effect}
Secreted in the pancreas
Liver cells respond
It lowers blood glucose levels, stimulating the liver cells to convert glucose into glycogen (and absorb more)