The Senses Flashcards
five senses
smell: through nasal passages
taste: tongue (bitter,sweet,salty,sour)
touch: skin
hearing: ear
sight: eye
central nervous system function
interprets, sorts and processes incoming impulses
skull
protects brain
cerebrospinal fluid
protects brain and spinal cord
meninges
protects brain and spinal cord
cerebrum
largest part of brain
located in forebrain
functions:
-sorts impulses specifically from sensory neurons
-memory, emotions, language, smell, hearing, vision, taste
hypothalamus
homeostasis
cerebellum
located in hind brain
-control and co ordination of voluntary movements: speech, movement, balance
medulla oblongata
located in part of brainstem
-controls involuntary actions: breathing, swallowing
thalamus
located in forebrain
-sorts impulses and sends to the correct part of the brain
the skin functions
protection
-epidermis protects against entry of pathogens
-melanin: protects against UV rays
-sebum: keeps skin moist, protects skin from cracking, acid nature kills bacteria
excretion
temperature regulation
vit D production
epidermis cells
produce keratin
build up of keratin causes hardening of cells
more keratin causes cells in cornified layer to dei
malpighian layer
produces melanin
dermis
contains connective tissue, protects internal organs
skin in hot conditions
skin receptors detect a change in temperature, send message to the brain:
- more sweat is produced by sweat glands
- vasodilation of skin arterioles
vasodilation of skin arterioles
blood vessels near surface of the skin dilate
more blood flows near skin surface
heat lost by evaporation of sweat
skin in cold conditions
skin receptors detect a change in temperature, send message to the brain:
- piloerection
- vasoconstriction of skin arterioles
- increased metabolism
increased metabolism
more thyroxine produced, more heat generated from respiration
the ear functions
hearing
balance
pinna
structure: cartilage
function: collect sound waves and channels them into the auditory canal
auditory canal
carries vibrations to eardrum
contains hair and wax glands to trap dirt and germs
eardrum
membrane that vibrates when sounds hit
differences in air pressure cause vibrations
eustachian tube
location: connects middle ear to the pharynx
function: keeps air pressure equal on each side of the eardrum
how: opens when we swallow, cough
ossicles
3 small bones: hammer, anvil, stirrup
pick up and amplify the sound
how sound is amplified
oval window is smaller than eardrum
cochlea
electrical impulse generated by cochlea travel to brain via auditory nerve
vibrations stimulated as pressure waves in lymph
these pressure waves stimulate receptors
vibrations lost back into the middle ear at the round window
semi-circular canals
three to allow balance in three planes
function: balance and posture
how: controlled by vestibular apparatus, detects position and movement of head, receptors send impulses through the vestibular nerve to the cerebellum
how sound is detected/ mechanism of the ear
- sound waves are collected by the pinna
- waves travel along the ear canal
- waves make the eardrum vibrate
- ossicles amplify vibrations
- cochlea turns these into electrical signals
- auditory nerve takes signals to the brain
ear disorder
glue ear
cause: collection of sticky fluid in middle ear as a result of a blocked eustachian tube
symptoms: pain, pus formation, hearing loss
treatment: nose drops with decongestants
grommet (drains fluid)
the eye function
sight
accomodation
ability of the lens to change its shape
eyelids
cover and protect the eye
eyelashes and tears provide external protection
sclera
holds shape of the eye
opaque white of the eye
conjuctiva
transparent part of the sclera that protects sclera from infection
pupil
allows light into eye
bright light: pupil constricts so less light can enter, avoids damage to retina
dim light: pupil dilates to increase amount of light entering eye
iris
controls the amount of light entering the eye through the pupil contracting
what gives eye colour
melanin
lens
focuses the light rays on the retina by changing curvature with the help of the ciliary body
adaption: transparent, curved
ciliary body
controls shape of the lens when looking at near or far objects
suspensory ligaments
attach ciliary body to lens
cornea
lets light in and bends light rays towards the retina
adaptation: transparent and curved
retina
contains light receptor cells and converts light into nerve impulses
light receptor cells
rods: at retina, detect black and white and vision in dim light
cones: at fovea, detect colour and vision in bright light
fovea
part of the retina that contains cones
where light rays join and an accurate image is focused
choroid
contains blood vessels supplying nourishment to the eye
contains melanin, which absorbs light into the eye and prevents internal reflection
aqueous humour
watery
keeps shape of the cornea and lens
located in front of the eye between the cornea and lens
vitreous humour
viscous
exerts pressure to support eye and gives shape
located in back of the eye behind the lens
blind spot
an area with no rods and cones on the retina
allows optic nerve fibres to pass through the retina and leave the eye
optic nerve
contains axons that carry optic nerve impulses to the cerebrum
cerebrum
interprets information received from retina and gives vision
how the eye takes in light and transmits the impulse to the brain
- the pupil allows light into the eye and is controlled by the iris, depending on how much light the eye is exposed to
- cornea bends light toward the retina
- lens focuses light on the retina
- light rays join at the fovea and an accurate image is focused
- retina converts light into electrical impulses
- optic nerve carries the nerve impulses to the cerebrum where they are interpreted
benefits of having two eyes
increased visual field
3D vision
