tissue types Flashcards
what are the 4 tissue types in the body ?
. nervous - make up nervous system and sends electrical messages around the body
. muscular - involved in movement
. epithelial - covering or glandular
. connective- packing
what happens when light hits an object?
. can be absorbed , transmitted or reflected
What does the reflected light do in the eye?
- it hits the cornea
- Then enters eye and goes into lens
- Cornea and lens focus the light onto the light sensitive retina
- changes the light into electrical activity (as it is a layer of nerve cells)
- electric activity leaves eye via optic nerve
what does the eye do when it comes in contact with the eye?
. eye turns light into electrical signals which are transmitted along optic nerve and sent to the brain
how many bones is the orbit made of ?
7
what are the 6 muscles of the eye ?
. superior oblique . inferior oblique- rotate eye . medial rectus- eye go in . lateral rectus - eye go out . superior rectus - eye go up . inferior rectus - eye go down
explain the steps of when light rays impinge on the surface of the eye?
- light rays impinge on surface of eye and encounter the tear film
- the outer coat of eye is mostly opaque sclera which is modified into transparent cornea at front of eye
- (after light gone through cornea ) transversing anterior chamber , light reaches lens
- the lens(1/4) and cornea(3/4) act together to focus light on retina
- retina(back) converts light energy into electrical signals which are transmitted along optic nerve and sent to brain
what is the corneoscleral junction known as ?
limbus
what is between retina and sclera?
-choroid (capillaries within it) which contains the vascular blood supply to supply nutrients to the retina.
why are the cornea and lens avascular?
because they are transparent so we can see
where do cornea and lens receive their nutrients ?
from clear aqueous humour (transparent fluid) which fills the anterior chamber
what is aqueous humour made by ?
ciliary body
where is aqueous humour drained?
at filtration angle by canal of schlemm
if not drained eye pressure will increase causing glaucoma
what is posterior chamber filled with ?
jelly like vitreous humor
what are the 2 groups of muscles within the eye ?
. iris - can alter size of pupil to determine amount of light entering eye
. ciliary body - muscular structure (attached to iris) which can change shape of lens during accommodation
what does the adnexa of eye contain?
. extra ocular muscle
. eyelids
. conjunctiva
. lacrimal gland
what is conjunctiva ?
- thin mucous membrane which lines back surface of eye and front surface of exposed bit of sclera and stops near limbus.
- Between the sclera and air.
- Makes mucous component of the tearful
what are nerve cells known as ?
known as neurons which can be sensory or motor
What produces the bulk of the tearfilm?
Lacrimal gland- watery fluid
spread across eye from blinking and then drains into nasal-lacrimal sac.
what are skeletal muscle ?
. attached to skeleton . long fibres . unbranched . voluntary ( somatic ) e.g. 6 extraocular muscles eyelid muscle ( orbicularis oculi )
what are skeletal muscle ?
. attached to skeleton . long fibres . multinucleate . striated in appearance . unbranched . voluntary ( somatic ) e.g. 6 extraocular muscles and eyelid muscle ( orbicularis oculi ) . ability to generate a lot of force quickly
what are cardiac muscle ?
. only in heart . shorter . striated . branched . uninucleate . involuntary ( autonomic )
what are covering epithelia ?
line free surfaces of the body
what are smooth muscle ?
. hollow organ e.g respiratory tract, digestive tract . short spindles . weak/slow . non-striated in appearance . unbranched . uninucleate . involuntary ( autonomic ) e.g. muscles of ciliary body and contraction of this is responsible of accommodation . and iris . controls pupil size and accommodation
what is the shape of epithelial cells ?
polyhedral ( many sided ) in hexagonal shape with strong attachment to adjacent cells
what are the functions of covering epithelia ?
- protection ( skin )
- absorption ( digestive tract )
- filtering ( kidney )
- sensation ( taste , smell )
what are the two surfaces of epithelial cells ?
. free apical surface which can be smooth or covered in microvilli or cilia
e.g cilia move oviducts in ovary
. the opposite ( basal ) surface of an epithelial cell rests on basement membrane which is made of glycoprotein - this is where epithelial cells connect to rest of body tissues
how are covering epithelia classified ?
1. by shape of cell . squamous . cuboidal . columnar 2. number of layers . simple=one layer . stratified = more than one layer
what is the property of most covering epithelial tissue ?
. highly regenerative - quickly replaced
. avascular
. innervated by both sensory (touch) and motor( cause contract) nerve fibres
what are the 8 basic types of covering epithelia ?
. simple squamous . simple cuboidal . simple columnar . pseudo-stratified . stratified squamous . stratified cuboidal . stratified columnar . transitional
how can you usually determine shape of cell ?
you can usually determine shape of cell as it is mirrored in shape of nucleus
what is the outer layer of cornea known as ?
corneal epithelium
what are the 5 layers of human cornea?
- corneal epithelium- outer surface
- bowman’s layer
- stroma- bulk
- descemet’s membrane
- corneal endothelium- inner layer
where are stratified squamous epithelium mostly found?
. always found in areas subject to abrasion
e.g. oesophagus - for protection from food going stomach
. vagina
. specialised form of stratified epithelium os the keratinised epithelium of cell
what is a specialised from of stratified epithelium ?
transitional epithelium
it can change shape
e.g wall of bladder
where are stratified squamous epithelium mostly found?
. always found in areas subject to abrasion
e.g. oesophagus - for protection from food going stomach
. vagina
. skin- specialised form of stratified epithelium of the keratinised epithelium of skin- stratified squamous keratinised epithelium.
where are simple squamous epithelium ideal ?
they are ideal for areas where exchange of substances is required
where is simple squamous epithelium found in the eye ?
. the inner surface of cornea ( corneal endothelium )
it allows avascular cornea to exchange substances with aqueous humor