Topic 11 - Response + Regulation Flashcards
What is the purpose of the nervous system?
To detect internal and external stimuli and to coordinate a response if necessary
Name receptors.
Skin
Eyes
Ears
Chemical receptors in taste buds/nose
What stimuli does the skin detect?
Pressure, temperature, pain
What stimulus does the eye detect?
Light
What stimulus does the ear detect?
Sound
What stimulus does the nose detect?
Smell/Chemicals
What stimulus does the mouth detect?
Flavour/Chemicals
Give the components of the nervous system.
Brain
Spinal cord
Neurones
What is an involuntary reflex?
The majority of reflexes - rapid, automatic (protective) responses
What is a voluntary reflex?
Controlled by brain, slower, informed decisions
What is the reflex arc?
Stimulus -> Receptor Cell -> Sensory Neurone -> Relay Neurone -> Motor Neurone -> Effector -> Response
What is the job of the sensory neurone?
Transfer sensory information from sense organ to CNS
Where is the nucleus in the sensory neurone?
Detached from the axon
What is the job of the relay neurone?
Transfer information from sensory to motor neurones
Where is the nucleus in the relay neurone?
In the middle of the axon
What is the job of the motor neurone?
Transfer information from the CNS to the effector
What are structural features of a neurone?
Myelin Sheath - surrounds axon, insulating fat layer
Dendrites - Nerve ending
Axon - Joins the sets of dendrites
Where is the nucleus in the motor neurone?
In the middle of the receiving dendrites, before the axon
Describe the synaptic process.
If a stimulus is large enough, the pre-synaptic knob on one neurone releases a chemical neurotransmitter which transfers across the synaptic cleft and causes the electronic signal to restart at the post-synaptic knob.
What can prevent signals from crossing the synaptic cleft?
Botox, cyanide
What is homeostasis?
Maintenance of constant environment in the body
Thermoregulatory processes in hot weather?
Vasodilation
Sweating
Hairs lie flat
Thermoregulatory processes in cold weather?
Vasoconstriction
Shivering
Piloerection
What is vasodilation?
Blood vessels dilate so more blood flows to the surface of the skin, losing heat to radiation
What is vasoconstriction?
Blood vessels constrict so less blood flows to the surface of the skin, so less heat is lost to radiation
What is sweating?
Sweat glands produce sweat which evaporates, using energy and thus cooling the skin
What is shivering?
Muscles contract quickly, using energy, creating extra heat and thus warming the body
What is piloerection?
Hair erector muscle contracts, hairs stand up creating an insulating layer of oxygen around the body
What is “hairs lie flat”?
Hair erector muscle relaxes, hairs lie flat reducing the insulating layer of oxygen around the body
What is the effect of low glucose on the pancreas?
Glucagon secreted into the blood
What is the effect of low glucose on the liver?
No conversion of glucose into insoluble glycogen
What is the effect of low glucose on blood glucose level?
Increased
What is the effect of high glucose on the pancreas?
Insulin secreted into the blood
What is the effect of high glucose on the liver?
Conversion of glucose into insoluble glycogen and storage thereof
What is the effect of high glucose on the blood glucose level?
Decreased
What is hypoglycaemia?
When blood sugar drops too low
What is hyperglycaemia?
When blood sugar rises too high
What is the cause of Type 1 Diabetes?
Damage to beta cells in the pancreas which produce insulin so poor/no level of insulin production
What are the symptoms of Type 1 Diabetes?
Increased thirst/hunger Fatigue Blurred vision Irritability + Mood changes Frequent urination
What are the treatments for Type 1 Diabetes?
Injecting insulin
Transplant of pancreatic tissue
What is the cause of Type 2 Diabetes?
Resistance to insulin
What are the symptoms of Type 2 Diabetes?
Increased thirst/hunger Fatigue Numbness + tingling Frequent infection Slow-healing sores
What are the treatments for Type 2 Diabetes?
Diets
Activity
What stimuli can plants respond to?
Gravity
Light
Water
What are a plant’s responses to stimuli called?
Tropisms - Geotropism
- Phototropism
- Hydrotropism
What are the three types of responses?
Positive, neutral, negative
What are tropisms caused by?
Auxin
What does auxin cause?
An elongation of cells by diffusing through the plant, accumulation on one side can lead to bending towards the stimulus
Investigation of tropisms
Plants grown upwards In a dark box with one open side Light source (i.e. window) Time period Name response Repeat with control (i.e. fully dark/open)
What is a tropism?
A plant’s growth response to stimuli
Investigation of Reflexes
Drop a ruler
Catch
Lower the number, the faster the reaction time
Repeat 3-5 times
What are hormones?
Chemical messengers, carried by the blood, which control many body functions
What is a negative feedback loop?
A change from optimal internal conditions
resulting in the body responding and
restoring balance.
How do repeats affect reaction time?
Reduce it
What happens to the eye in bright light?
In brighter light, the iris contracts to reduce pupil diameter, restricting light entering the eye, so the retina is protected from damage
What happens to the eye in low light?
The iris relaxes to increase pupil diameter, allowing more light to enter the eye so the retina can function properly
What is a sense organ?
An organ that contains receptor cells and responds to stimuli
