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Coordination and Homeostasis - Coggle Diagram
Coordination and Homeostasis
The nervous sytem
CNS
Spinal chord
Brain
Role
Coordinate the information traveling through the nervous systems
PNS
Receptors
Nerves
Reflex Arc
Stimulus
Receptor
Sensory neuron
Relay neuron
Brain
Motor neuron
Effector
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Voluntary
where you make a conscious decision to carry out a particular action
Takes longer
Involuntary
You are not aware you have completed it until after you have carried it out.
Are rapid
Neurons
Relay
Relay neurones are found inside the CNS and connect sensory and motor neurones
Relay neurones are short and have a small cell body at one end with many dendrites branching off it.
Motor
Motor neurones carry impulses from the CNS to effectors (muscles or glands)
Motor neurones are long and have a large cell body at one end with long dendrites branching off it.
Sensory
Sensory neurones carry impulses from sense organs to the CNS (brain or spinal cord)
Sensory neurones are long and have a cell body branching off the middle of the axon.
Synapes
Where two neurons meet or join
Sense organs
They detect a change in the environment and stimulate electrical impulses in response.
Types
Ears
Noes
Tongue
Eyes
Structure
Retina
Contains light receptor cells
Rods
Detect light intensity
Cones
Detect colour
Optic nerve
Sensory neuron that sends impluses to the brain
Lens
Transparent disc that can change shape in order to focus light on the retina.
Pupil
Hole that allows the light to enter
Iris
Controls how much light enters the pupil
Cornea
Refracts light as it enters
Accomodation
Object is close up
suspensory ligaments to loosen
lens becomes fatter
The ciliary muscles contract
Object is far away
suspensory ligaments to tighten
lens becomes thinner
The ciliary muscles relax
Pupil reflex
Bright light
Circular muscles relax
Pupil constricts
Radial muscles contract
Dim light
Circular muscles contract
Pupil dialates
Radial muscles relax
Skin
Hormones in the body
Defination
A hormone is a chemical substance produced by a gland and carried by the blood.
Hormones only affect cells with target receptors that the hormone can bind to.
The liver regulates levels of hormones in the blood; transforming or breaking down any that are in excess.
Types
Insulin
Insulin is produced when blood glucose rises and stimulates liver and muscle cells to convert excess glucose into glycogen to be stored.
Adreneline
Adrenaline is known as the 'fight or flight' hormone as it is produced in situations where the body may be in danger.
Effects
Increasing blood glucose concentration
Increasing pulse rate and breathing rate.
Diverting blood flow towards muscles
Dilating pupils
Glucagon
Glucagon is produced when blood glucose falls and stimulates liver and muscle cells to convert stored glycogen into glucose to be released into the blood.
Negative feedback
Blood glucose levels are controlled by a negative feedback mechanism involving the production of two hormones - insulin and glucagon
Negative feedback occurs when conditions change from the ideal or set point and returns conditions to this set point.
Tropism
Gravitropism
Growth towards or away from gravity
Phototropism
Growth towards or away from light
Shoots and roots
Shoots
Shoots must grow upwards, away from gravity and towards light, so that leaves are able to absorb sunlight
shoots have a positive phototropic response and a negative gravitropic response.
Roots
Roots need to grow downwards into the soil, away from light and towards gravity.
This means that roots have a negative phototropic response and a positive gravitropic response.
Auxin
Plants respond to stimuli by producing a growth hormone called auxin
Shoots
When light shines on the shoot predominantly from one side though, the auxin produced in the tip concentrates on the shaded side, making the cells on that side elongate and grow faster than the cells on the sunny side.
causes the shoot to bend
Roots
In roots, higher concentrations of auxin results in a lower rate of cell elongation.
The auxin that accumulates at the lower side of the root inhibits cell elongation.
As a result, the lower side grows at a slower rate than the upper side of the root. This causes the root to bend downwards.