Coordination And Control Flashcards
What is positive tropism in plants
When a plant grows towards a stimulus
What two organ systems do humans use for coordination and what part do they play
- nervous system - endocrine system
They create the link between the stimulus and the response in an action
What type of stimulus do the tongue and nose react to
Chemical
What two stimuli does the skin react to
Pressure and heat
What makes up the central nervous system
Consists of the brain and the spinal cord and is linked to the sense organs by nerves
What makes up the peripheral nervous system
All the nerves which send impulses to the effectors (excluding the brain and the spinal cord)
What are the three types of neurones
Sensory
Relay
Motor
Explain in terms of neurones the journey of an impulse from a receptor to an effector during a reflex arc
Once a dangerous stimulus of detected, impulses pass from receptors to sensory neurones until they reach the spinal cord. They pass to the relay neurones there, then the motor neurones which cause the effectors to action
What is a dendrite
Tree like projections that connect a neurone to others
What is the myelin sheath
Insulates the axon on a neurone to speed up the transmission of the impulses
What is a reflex
An automated action that doesn’t involve the brain but instead use the sensory, relay and motor neurones.
What is a reflex arc
The movement of the impulse from receptor to effector
What is a synapse
The gap between neurones
What is the cornea
A curved transparent disc at the front of the eye which does most of the focusing.
What is the pupil
And opening in the eye whose size is controlled by the iris
What is the iris
A ring of muscles with a hole in the middle that controls how much light enters the eye
What is the lens
Soft, flexible, transparent disk whose shape can be changed to fine tuner the focusing of light onto the retina
What are ciliary muscles
A ring of muscles at the edge of the eye that circle the lens, when it contracts the lens gets fatter
in order to create a coordinated response we require:
a receptor, a stimulus, and an effector
what are suspensory ligaments
strong fibre which attach the lens to the ciliary muscle
what is the retina
contains light sensitive cells called rods and cones
what is the optic nerve
consists of many neurones which carry impulses form the retina to the brain
what is the fovea
the region of the retina with the greatest number of cones
what is the conjunctiva
a mucous membrane that covers the eye to prevent infection
describe how the eye focuses on close up objects
- ciliary muscles contract
- suspensory ligaments therefore slacken
- lens becomes more rounded
- so light is refracted more
how does the eye respond to sudden bright light
- circular muscles contract
- radial muscles relax
- so pupil shrinks
describe how an electrical impulse travels across the synapse
- the nerve ending of a neuron releases chemical messengers called neurotransmitters
- these chemicals diffuse across the synapse and bind with receptor molecules on the membrane of the next neuron
- the receptor molecules bind only to the specific chemicals released from the first neurone
- this stimulates the second neuron to transmit the electrical impulse
where is insulin produced and what does it do
- pancreas
- causes liver and muscles to take up glucose and convert it to glycogen for storage
where is ADH produced and what does it do
- Pituitary gland
- reduces amount of water lost in urine by affecting the permeability of the walls of the convoluted tube
where is oestrogen produced and what does it do
- ovaries
- stimulates the uterus lining to develop and the development of secondary sexual characteristics
where is progesterone produced and what does it do
- ovaries
- maintains uterus lining
where is testosterone produced and what is it used for
- testes
- stimulates the development of secondary sexual characteristics
where is adrenaline produced and what is it used for
- adrenal gland
- increases heart and breathing rate, pupil dilation, vasodilation/vasoconstriction for fight or flight
where is FSH produced and what is it used for
- pituitary gland
- stimulates an egg to mature in the ovary
where is LH produced and what is it used for
- pituitary gland
- stimulates the release of the egg in the ovary
how does insulin reduce blood sugar
- enters the blood stream
- insulin allows glucose to be absorbed by body cells
- so blood sugar reduced
how is thermoregulation done in the body
- hairs stand on end (trap a layer of air in)
- no sweat (less heat loss through evaporation)
- vasoconstriction (blood flows further away from skin)
what is homeostasis
the maintenance of a constant internal envrionment
what are some examples of homeostasis
- body water content
- body temperature regulation
what is geotropism
- when plants grow towards or away from gravity
what is phototropism
when plants grow towards or away from light
what hormone in plants controls phototropism
auxin
how does auxin affect plant growth
- the tip of the shoot produces auxin which diffuses down the shoot causing elongation of the cells
- when light intensity is higher on one side of the stem, auxins build up on the shaded side
- this causes one side to elongated more than the other causing a bend towards the light stimulus
