Coordination And Control Flashcards
What is the nervous system
Uses nerve impulses (electrical impulses) to react quickly to a stimulus
What is the hormonal system
Uses hormones to react slowly to a stimulus
What are the components of the nervous system
Brain
Spinal chord
Nerves (neurones)
What is the thing we respond to
Stimulus
What does each stimulus affect in the body
A receptor
What are receptors often grouped in
Complex sense organs
When a receptor is stimulated what happens
Cause an effector (muscle or gland) to produce a response
What are receptors and effectors linked by
Coordinator
What can the coordinator be
The brain or sometimes the spinal chord
What are the Brian and spinal chord known as together
The central nervous system (CNS)
What connects the receptors and effectors to the coordinator
Neurones which carry information in small electrical nerve impulses.
List the response of the nervous system in order
Stimulus
Receptor
Coordinator
Effector
Response
What are receptors
Specialised cells, found in your sense organs, that detect stimuli. Change from one energy into electrical impulses
What are effectors
Usually a muscle or gland that produces a response to the stimuli
What is a neurone
Specialised cell that carries electrical impulses around the body
What is a nerve impulse
Small electrical charge that carries information along a neurone
What is a synapse
A gap between the neurones
What does it mean if a body part is really sensitive
It has a lot of small neurones in a small area
What does it mean if a body part isn’t sensitive
It only has a few large neurones and they are more spreads out
What are voluntary actions
Actions that we deliberately choose to do and they inclue conscious thought
What is a reflex action
A action that does not involve conscious thought. They happen automatically and always occur in the same way
3 characteristics of reflex’s
Occur rapidly
Do not involve conscious control
Happen automatically and in the same way
Why is the nerve pathway so short
So it uses a minimum number of neurones to transfer the electrical impulses
Why is there very few gaps (synapses)
To make sure the reflex action is as fast as possible as in synapses electrical impulses slow down
3 types of receptor
Sensory
Associations
Motor
Why is it good that the axon is a long extension of the cytoplasm
It can vary in length- up to 1m this means a message can be sent long distances from the spinal chord to the foot
Why does the axon have branched ends
Allows it to transmit impulses over a greater area and to make connections with other neurones
Why do axons have a insulating myelin sheath
A fatty layer that surrounds the axon and helps transmit the impulses at a faster rate
What is a synapse
A junction between two neurones
Transmission across synapses is caused by
Diffusion of transmitter chemicals (neurotransmitters) across the junction
What is the neurotransmitter produced by
End of neurone
How does the neurotransmitter diffuse
Quickly between a High concentration to a low concentration across the synapse
While synapses may slow transmission, they allow a
Greater degree of control at these junction points
Where does the sensory neurone carry impulses
From receptor to the CNS
Where does the association neurone carry information
From the sensory neurone and motor neurone
Where does the motor neurone carry information
From the CNS to the effector
What is the conjunctiva function
Thin transparent protective outer layer and keep cornea moist
Cornea function
Transparent part of the eye to let light enter. Causes,some refraction
Iris function
Controls how much light enters the eye by changing its diameter
Pupil function
Space in iris that allows light to enter the eye
Lens function
Refracts light towards the retina
Ciliary muscle function
Circular ring of muscle that surrounds lens and changes the shape of the lens
Suspensory ligaments function
Attach the lens to the ciliary muscle and changes shape of lens
Retina function
Inner coat of eye where light sensitive receptor cells are found
Optic nerve function
Contains neurones that carry information from light sensitive receptor cells of the retina to the brain
Aqueous humour function
Watery fluid between the cornea and the lens. Keeps pressure correct, helps maintain shape of the eye and lens and allows light to pass through
Vitreous humour function
Jelly like fluid between lens and retina. Keeps eye spherical and allows light to pass through
What is accommodation
Refers to how the shape of the eye lens is changed to focus light rays on the retina
How do light rays arrive when focusing on a distant object
Parallel
What does the cornea do go light rays when focusing on a distant object
Refracts rays
What happens to the lens when focusing on a distant object
It is thin as little additional refraction is needed to focus light on the retina
What happens to light rays when focusing on a near object
Diverge
What does the cornea do to rays when focusing on a near object
Refracts rays
What is the lens like when focusing on a near object
Thicker as more refraction is needed to focus light on the retina
What happens if the ciliary muscle relaxes
It springs out to give a bigger diameter. When this happens suspensory ligaments pull lens and it becomes thinner
What happens when the ciliary muscle contracts
Forms a tighter circle with a smaller diameter. The suspensory ligaments then relax and with less pressure on the lens, it’s able to spring back to its original thick shape
2 muscles the iris contains
Radial and circular
What is the reflex called when ur pupil changes size
Pupillary reflex
What happens to the circular muscles in bright light
Contract
What happens to the radial muscles in bright light
Relax
What happens to the pupil in bright light
Smaller
What happens to the circular muscles in dim light
Relax
What happens to the radial muscles in dim light
Contract
What happens to the pupil in dim light
Bigger
What are the specialised cells in the retina that are sensitive to light r
Rod and cone cells
What do rod cells work in
Low light intensity and can’t distinguish between coloursm
What do cone cells work in
Provide colour vision and only work in bright light
Where are cône and rod cells placed in the retina
The cones are concentrated in the centre of the retina and the rods are more numerous at the outer edges
What are hormones
Chemical messengers produced by special glands which release them into the blood
Hormones only target certain organs what are these organ called
Target organs
Look at major glands
Pg 22
What is homeostasis
The ability of the body to maintain a constant internal environment
4 conditions in the body that must be controlled
Blood and glucose levels/concentration
Water content in the body
Ion content of the body
Temperature
Why is it important to maintain a constant internal environment
So enzymes have the correct conditions to work efficiently
Enzymes could denature in the wrong conditions which means cell activities will reduce
What is negative feedback
A mechanism to ensure the level of something doesn’t deviate too far from the normal value
Difference between nervous and hormonal systems: nature of message
Nervous : nerve impulse (electrical)
Hormonal: a hormone (chemical)
Difference between nervous and hormonal systems: mode of transmission
Nervous: travels along a neurone
Hormonal: travels in bloodstream
Difference between nervous and hormonal systems: speed of reaction
Nervous : usually rapid
Hormonal : usually slow
Difference between nervous and hormonal systems: duration of response
Nervous : usually short lived
Hormonal : often and long lasting
Difference between nervous and hormonal systems: area of response
Nervous : localised eg: contraction of a single muscle
Hormonal: wide spread
Difference between nervous and hormonal systems: message target
Nervous : messages carried to specific effectors
Hormonal: messages carried to target organs
What is insulin
A hormone that prevents concentration of glucose in blood from becoming too high
Why is it bad if there is too much glucose
It can damage the bodies cells due to water loss by osmosis
Why is it if glucose level fall below the normal Level
Respiration won’t be able to take place in cells so energy production would decrease
Where is insulin produced
Pancreas
What is the main target organs of insulin
Liver
What does insulin cause in the liver
Increased absorption of glucose from the blood so reduces blood glucose concentration
Conversation of excess glucose into glycogen which is stored in the liver and to a lesser extent in muscle cells
Increased respiration
What is glucagon
A hormone produced in pancreas when blood glucose levels are low. It acts by reversing the changes insulin brings about in the liver
When does type one diabetes normally develops
In childhood (before 20)
When does type 2 diabetes tend to develop
40+
What is type 1 diabetes treated by
Injection of insulin and a controlled diet where intake of carbs is closely monitored
What is type 1 caused by
Lack of insulin
How is type 2 caused
Insulin is produced but stops working effectively
What is type 2 associated with
Obesity, poor diet , lack of physical activity
Treatment to type 2
Reduce sugar intake
Exercise to achieve weight loss
Medication and insulin injections
Long term effects of people who have diabetes for long term (possibly undiagnosed or unknown)
Eye damage
Heart disease
Strokes
Kidney damage/failure
Why do people with diabetes eat something high in glucose before vigorous exercise
Will cause blood sugar to fall rapidly
Provide glucose to make sure blood glucose level doesn’t drop too quickly
Prevents a hypoglycaemic attack
What is osmoregulation
Ability to control amount of water in the body
How is water lost
Evaporation in the lungs, whilst sweating, production of urine by the kidneys and in faeces
What does osmoregulation ensure
The volume of water gained is equal to the amount lost
What is the function of the kidneys
Remove waste , carry out osmoregulation
Look at kidney diagram
Pg 34
What is the process of réabsorption of water back into the blood by the kidneys controlled by
A hormone, the anti-diuretic hormone (ADH)
Where is ADH produced
The part of the brain where water in the blood is monitored
Once ADH is produced what happens
It travels to its target organs the kidneys and in the kidney medulla ADH allows more water to pass from the urine into the blood
When concentration of water in the blood is too High what happens
ADH production is stopped/reduced
Less ADH allows less water to be re absorbed
How do plants respond to stimuli
In such a way that they receive optimum conditions to grow
What is phototropism
When a plant reacts to where the light source is and grows towards the light (eg: plant on a window sill will not grow straight upwards but will bend towards the light)
Why does phototropism occur
To ensure plant leaves receive more light and so more photosynthesis takes place allowing more growth
What is unilateral light
Light coming from one side only
How is the response of phototropism controlled
A hormone called auxin
Where does auxin accumulate
The side of the stem not exposed to light
What does the hormone cause
More rapid growth on the non illuminated side of the stem compared to the illuminated side
When is auxin produced
Tip of the shoot and diffuses down the shoot
What does the high concentration of auxin cause the cells to grow by
Elongation
