Nervous System Flashcards
How are organisms able to respond to changes in their environment?
they make a coordinated response (body is able to make things happened in different parts of the body at the right time). humans have the nervous and endocrine system and plants respond to the the direction of light (phototropism)
Describe the 3 things needed for a coordinated response?
stimulus - changes in the animal’s surroundings
receptor - organ that detects change
effector - muscles are the effectors and they contract as you catch the ball
How can responses be controlled by nervous communication? (give examples of the ear, eye, tongue, nose, skin (touch and temp)
receptors detect the stimulus and change its energy into nerve impulses
ear - sound, eye - light, tongue - chemical, nose - chemical, skin (touch) - pressure, skin (temp) - heat
Describe the central nervous system
consists of brain and spinal cord, coordinates all of the nervous responses such as moving or reflexes
Describe the peripheral nervous system
contains all of the other nerves which send impulses to all the effectors
What are neurones and the 3 types?
nerve cells (sensory, relay, motor). impulses from receptors pass along sensory neurones until they reach the brain and spinal cord, impulses pass to relay in the CNS, the impulse is then passed to effectors along motor
What is the nucleus, dendrite and cell body?
nucleus - contains all generic info
dendrite - tree like projections which connect to different neurones (one can connect to others)
cell body - man section of cell (contains nucleus)
What is the axon, myelin sheath?
axon - long section
myelin sheath - insulates the axon and speeds up transmission of the impulse
What is the reflex arc?
automated actions (not involve brain) involving 3 neurones receptors detect stimulus change in temp and send impulse along sensory neurone, sensory passes impulse to spinal cord to relay, then motor which then causes effector to contract and move away from stimulus
What is the synapse?
gap between 2 neurones - electrical impulse travles along axon, triggers nerve ending of neurone to release chemical messengers (neurotransmitters), diffuse across synapse and bind with receptor molecules on membrane of next neurone, receptor molecules on second neurone bind to specific chemicals form first stimulates 2nd to transmit electrical impulse
Describe the eye
sensory organ which detects light and sends an impulse to brain which converts information to an image
What is the cornea, pupil and iris?
cornea - curved transparent disc at front of eye, does most of focusing
pupil - circular opening whose size is controlled by iris (coloured part)
iris - ring of muscles with a hole in middle, controls how much light enters
What is the lens, ciliary muscles and sensory ligament?
lens - soft, flexible, transparent, shapes can be changed to fine tune focusing of light onto retina
ciliary muscles - ring of muscles at edge of eye which circles lens, when contracts the lens gets fatter, relaxes thinner
sensory ligament - strong fibres which attach the lens to ciliary muscle
what is the retina, optic nerve, fovea, conjunctiva?
retina - contains light sensitive cells called rods and cones
optic nerve - consists of many neurones, carry impulses from the retina to brain
fovea - region of retina w greatest no of cones
conjunctiva - mucous membrane that covers the eye to prevent infection
Describe the iris reflex
dim light - pupil big, bright - pupil small
