tissue types Flashcards
1
Q
what are the 4 tissue types in the body ?
A
. nervous - make up nervous system and sends electrical messages around the body
. muscular - involved in movement
. epithelial - covering or glandular
. connective- packing
2
Q
what happens when light hits an object?
A
. can be absorbed , transmitted or reflected
3
Q
What does the reflected light do in the eye?
A
- 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
4
Q
what does the eye do when it comes in contact with the eye?
A
. eye turns light into electrical signals which are transmitted along optic nerve and sent to the brain
5
Q
how many bones is the orbit made of ?
A
7
6
Q
what are the 6 muscles of the eye ?
A
. 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
7
Q
explain the steps of when light rays impinge on the surface of the eye?
A
- 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
8
Q
what is the corneoscleral junction known as ?
A
limbus
9
Q
what is between retina and sclera?
A
-choroid (capillaries within it) which contains the vascular blood supply to supply nutrients to the retina.
10
Q
why are the cornea and lens avascular?
A
because they are transparent so we can see
11
Q
where do cornea and lens receive their nutrients ?
A
from clear aqueous humour (transparent fluid) which fills the anterior chamber
12
Q
what is aqueous humour made by ?
A
ciliary body
13
Q
where is aqueous humour drained?
A
at filtration angle by canal of schlemm
if not drained eye pressure will increase causing glaucoma
14
Q
what is posterior chamber filled with ?
A
jelly like vitreous humor
15
Q
what are the 2 groups of muscles within the eye ?
A
. 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
16
Q
what does the adnexa of eye contain?
A
. extra ocular muscle
. eyelids
. conjunctiva
. lacrimal gland
17
Q
what is conjunctiva ?
A
- 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
17
Q
what are nerve cells known as ?
A
known as neurons which can be sensory or motor
18
Q
What produces the bulk of the tearfilm?
A
Lacrimal gland- watery fluid
spread across eye from blinking and then drains into nasal-lacrimal sac.
19
Q
what are skeletal muscle ?
A
. attached to skeleton . long fibres . unbranched . voluntary ( somatic ) e.g. 6 extraocular muscles eyelid muscle ( orbicularis oculi )
21
Q
what are skeletal muscle ?
A
. 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
22
Q
what are cardiac muscle ?
A
. only in heart . shorter . striated . branched . uninucleate . involuntary ( autonomic )
22
Q
what are covering epithelia ?
A
line free surfaces of the body
23
Q
what are smooth muscle ?
A
. 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
24
what is the shape of epithelial cells ?
polyhedral ( many sided ) in hexagonal shape with strong attachment to adjacent cells
25
what are the functions of covering epithelia ?
- protection ( skin )
- absorption ( digestive tract )
- filtering ( kidney )
- sensation ( taste , smell )
26
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
27
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
```
28
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
29
what are the 8 basic types of covering epithelia ?
```
. simple squamous
. simple cuboidal
. simple columnar
. pseudo-stratified
. stratified squamous
. stratified cuboidal
. stratified columnar
. transitional
```
30
how can you usually determine shape of cell ?
you can usually determine shape of cell as it is mirrored in shape of nucleus
31
what is the outer layer of cornea known as ?
corneal epithelium
32
what are the 5 layers of human cornea?
1. corneal epithelium- outer surface
2. bowman's layer
3. stroma- bulk
4. descemet's membrane
5. corneal endothelium- inner layer
33
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
34
what is a specialised from of stratified epithelium ?
transitional epithelium
it can change shape
e.g wall of bladder
35
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.
36
where are simple squamous epithelium ideal ?
they are ideal for areas where exchange of substances is required
37
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
38
what is a specialised form of simple epithelium ?
pseudo-stratified
| . all cells sit on a basement membrane but appears stratified as all cells are different shape
39
what are examples of simple squamous epithelium ?
. lining of blood vessel
. alveoli of lungs
.cornea
41
why do many epithelia lining the inside of eye are pigmented with melanin?
this serves to absorb stray light and improve image quality ( black box effect )
42
What are muscle tissues made of?
cells known as fibres.
43
examples of simple cuboidal epithelium?
kidney
44
Examples of simple columnar epithelium?
Oviduct
jejunum
Gall bladder.
45
What are the 2 main types of glands? (glandular epithelia)
Endocrine- secretion into blood stream
| Exocrine- secretion into ducts
46
What are the modes of glandular secretion?
- Merocrine- secreted via exocytosis (involves vesicles)
- Apocrine- tip of cell is shed- apex of cell breaks off and releases substances
- Holocrine- whole cell ruptures releasing contents into ducts
47
What are the types of glandular secretion?
- mucous- sticky
- Serous- watery
- Sebaceous- oily
48
What do the mucous cells stain microscopically?
light
49
What do the serous cells stain?
darkly
50
What gland produces more types of secretion?
lacrimal gland- mucous light granules and serous dark granules
51
What does the tear film consist of ?
Nearest to cornea
- Mucous layer
- aqueous layer
- lipid layer
52
What is structure of exocrine glands?
- Unicellular
| - multicellular
53
What is unicellular?
- Made of one cell
54
What is multicellular?
- made of many cells
55
What are the unicellular glands?
Goblet cells - produce mucous
- Goblet cells sit along columnar epithelial cells.
- Secretions stored in the lumen of goblet cells
56
Where are the goblet cells?
In the gut (wine shape)
57
What is the role of the goblet cells secretion in the gut?
Protect and lubricate
58
Where else do you find goblet cells?
Conjunctiva (eye)- they from the mucous layer of the tear film- sticks the tear film to the eye
59
What are the other examples of goblet cells in structures?
- Trachea- traps impurities from getting to lungs
| - Ducts of salivary glands- produce saliva
60
What are multicellular glands?
-Consist of groups of secretory cells which are connected to the body surfaces via ducts (lined with epithelial cells)
61
What ducts can the multiceullular glands have?
Simple - single duct with bundle of secretory cells
| Compound - several ducts with further several secretory cells
62
What is a good example of a simple multicellular gland?
-Meibomian gland of the eyelid- produces oily part of tearfilm
63
What is a non-ocular example of a simple multicellular gland?
-Found at various points of the digestive tract- Colon
64
What is a good example of a compound multicellular gland?
Lacrimal gland- known as ascinar (Shape of secretory cell) compound gland- several ducts.
65
What secretions do the lacrimal gland conduct?
- Mainly serous
| - But also mucous
66
What are the 3 layers of the tear-film and what are they made up of?
- Mucous layer- made up of conjunctival goblet cells
- Aqueous layer- made up of lacrimal gland
- Sebaceous layer- made up of meibomian gland of upper and lower eyelid
67
What are the 4 types of connective tissue?
- Cartilage
- bone
- Blood
- Connective tissue proper
68
What is connective tissue?
- Largely acellular
69
What is connective tissue proper made up of?
- ground substance
- fibres
- cells
70
What is the ground substance ?
- background substance - made up of glycoproteins and proteoglycans in which other elements of the connective tissue are suspended
- Its consistency (fluid or gel) depends on the connective tissue type.
71
What is a good example of ground substance?
- vitreous humour which fills posterior segment of eye-which is composed largely of a gel-like substance
72
What are the 3 fibres suspended in ground substance of connective tissue proper?
- Collagen
- Elastic
- Reticular
73
What is collagen?
thickest of the c.t fibres
- high tensile strength
- Unstretchable
- accounts for 30% of body dry weight protein
74
What is elastic?
- composed of elastin
- fibres which are thinner than collagen
- stretch readily and return to original form
75
What is reticular?
- Thicken than elastic but thinner than collagen
| - known as fine collagen fibres
76
What is the bulk of c.t made of?
fibres
77
What are the connective tissue proper cells?
- Fibroblasts
2. derived from wbc's:
- Plasma cells
- Macrophages
- Mast cells
78
What are fibroblasts?
-abundant cell type
-secretes ground substance and fibres
- can be re activated
often 2D - flat and wide
79
What is the stroma of the cornea made up of?
- Tightly packed collagen fibres
| - within the collagen fibres are darker streaks which are fibroblasts sandwiched between the collagen
80
What are the fibroblasts known as in the cornea collagen fibres?
keratocytes
81
What are plasma cells?
produce antibodies
82
What are macrophages?
- Phagocytosis
| - engulf material and destroy it
83
What are mast cells?
-Produce histamine and heparine which are important in inflammatory response
84
What are the different types of connective tissue?
- Loose- fibres are loosely arranged
a) aereolar- space in-between
b) adipose - made of fatty cells
- Dense- fibres are densely arranged
a) regular
b) irregular
85
What are loose areolar connective tissue?
- Soft, pliable, gaps between fibres
- Fills spaces around organs
- Most widely distributed type of c.t
- It traps fluid (causes bruising)
86
What is a good example of loose areolar connective tissue?
-stroma of iris- which allows it to change shape ( as the pupil expands contracts) easily
87
What is loose adipose c.t?
- Larlgely made up of fat cells (adipocytes)
- Appear as white spaces(adipocytes)- as all organelles been pushed to the side and virtually the whole cell is occupied by a fat droplet.
88
How is the loose adipose c.t in adults and newborns?
In adults known as uniocular fat (yellow fat)- each cell contains 1 lipid droplet
in new borns (neonates)- much fat. is multiocular (brown) - more than one droplet
89
What does the fat serve as?
- energy store
- insulation- thermal insulation in skin and some as protection
- protection- shock absorber
90
What is an obvious location for fat cells?
under the skin
91
Where else is fat in eye?
-Surrounds the lacrimal gland
92
What is dense regular connective tissue?
fibres tightly packed together in a regular arrangement
- compact c.t with regularly arranged collagen fibres.
- Very high tensile strength in that one direction
93
What is a good example of dense regular connective tissue ?
tendon- all fibres are the same size and run in the same direction
-Corneal stroma- collagen fibres are same size and are arranged in regular lamellae- - run in regular direction not necessarily all in the same direction!
94
What is dense irregular connective tissue?
- less regularly collagen fibres giving strength in all different directions.
95
examples of dense irregular connective tissue?
-Skin
96
What is another example of irregular dense c.t?
- the collagen in the "Sclera".- this makes the structure opaque.
