Chapter 1 Flashcards
what is the human nervous system
an important control system in body coordination
Human nervous system consists of two types:
- central nervous system
- peripheral nervous system
Which parts are related to central nervous system
- brain
-spinal cord
Which parts are related to peripheral nervous system
- 12 pairs of cranial nerves ( connect brain to sensory & internal organs)
- 31 pairs of spinal nerves (connect spinal cord to skeletal muscles)
State main function of hns
controls n coordinates organs & parts of the body
State other functions of hns
- detects stimuli
- interprets impulses
- send information in form of impulses
- produce appropriate responses
- maintains a balanced internal enviroment
Cornea layer:
- transparent layer
- refracts n focuses light onto the retina
Iris:
- coloured part of the eye
- controls the size of the pupil
Pupil:
- opening in the centre of the iris
- controls the quantity of the light entering the eye
Aqueous Humour
- transparent fluid
- maintains the shape of the eyeball
- focuses light into the eye
Conjuctiva
- transparent membrane
- protects the front part of the sclera
Vitreous humour
- transparent jelly like substance
- maintains shape of the eyeball
- focuses light onto the retina
Blind Spot
- part of the retina thats not sensitive to light as there are no photoreceptors
- an exit point for all optic nerves fibres
Optic nerves
- nerve fibres
- carry nerve impulses frm retina to brain to be interpreted
Yellow Spot
- part of the retina
- most sensitive to light = many photoreceptors
Retina
- Layer containing photoreceptors
- detects light
- produces nerve impulses
Explain more on the photoreceptors found in the retina
Two types:
Rod Cells: senstive to diff light intensities
Cone cells: sensitive to the colors of light
(each is sensitive to diff types of light) red, green and blue light
Choroid
- black layer
- prevents reflection of light in the eye
- supplies oxygen and nutrients to the eye
Sclera
- strong layer
- maintains shape of the eye
- protects the eye
Eye Lens
- transparent and elastic convex lens
- focuses light onto the retina
Ciliary Muscle
- Muscle that changes the thickness of the eye lens
-> through contractions & relaxations
Suspensory ligaments
- strong fibres
- hold the eye lens in its position
3 parts in a ear
outer ear
middle ear
inner ear
outer ear consists of
earlobe
ear canal
middle ear consists of
eardrum
ossicles
oval window
eustachian tube
inner tube consists of
cochlea
semicircular canals
auditory nerve
function earlobe
collects n directs sound waves into the ear canal
function ear canal
directs sound waves to the eardrum
function of eardrum
thin membrane vibrates according to the frequency of the sounds waves received & transfers the vibration to ossicles
function of ossicles
made of 3 small bones to amplify sound vibrations and transfer them to the oval window
Function oval window
collect and transfer sound vibrations frm ossicles to the cochlea
function eustachian tube
balance the air pressure on both sides of the eardrum
function cochlea
detects and converts sound vibrations into nerve impulses
function semicircular canals
contains fluid , detect position of the head n help to balance the body
function auditory nerve
send nerve impulses frm cochlea to the brain to be interpreted
which 2 structure of the ear arent used in the hearing process
- eustachian tube
- semicircular canals
State the flow of path of light
cornea—> AH—-> Pupil —> eye lens —–> VH—> Retina—–> optic nerves—–> brain
When does an optical illusion occur
an object that is seen differs frm its actual state
Why do optical illusions happen
the brain is unable to accurately interpret the object seen by the eye due to distractions around the object
What is the meaning of tropism
directional response of plants to stimuli
The part of plant which grows towards a stimulus is known as
positive tropism
the part of plant which grows away from a stimulus is known as
negative tropism
why do plants need to responsive towards stimuli such as light , gravity n water
So that they can appropriately to ensure their sustainability n survival
name the 4 types of tropism
phototropism
hydrotropism
geotropism
thigmotropism
Explain phototropism
- response of plants towards light
- shoots of plants show positive phototropism
explain hydrotropism
- response of plants towards water
- roots plants show positive hydrotropism
- absorb dissolved mineral salts to stay alive
explain geotropism
- towards gravity
- roots of plants show positive geotropism
- pg allow roots grow deep into the ground to grip n stablilise the position of the plant in the ground
- shoots show negative tropism
- ng allow shoot n leaves to obtain sunlight
explain thigmotropism
- response towards touch
- tendrils or twining stems show positive
- pt enables plants to grow upwards obtain sunlight, grip objects to obtain support
- roots show negative thing bc avoid object that obstruct their search for water
Nastic movement
- response towards touch
- does not depend on direction of stimulus
- occurs more rapidly than tropism
- serves as a defence
