epithelium and connective tissues Flashcards
4 types of primary tissues
muscular tissue (muscle)
epithelial tissue (epithelium)
connective tissue
nervous tissue
Skin epithelium (?)
Lines the body tubes:
Digestive tract …
Respiratory tract…
Blood vessels…
Lines the body (Abdominal) cavity…
- Covers the surface of the body: Skin Epithelium (Ectoderm)
- Lines the body tubes:
Digestive tract: Simple Columnar Epithelium (Endoderm)
Respiratory tract: Respiratory Epithelium (Endoderm)
Blood vessels: Endothelium (Mesoderm) - Lines the inside of body (Abdominal) cavity: Mesothelium (Mesoderm)
Functions of epithelium
- Protection: (e.g. Skin: Stratified Squamous Keratinized Epithelium)
- Secretion: by Simple columnar epithelium of Duodenum: Cholecystokinin (CCK) Vitamin D hormone synthesized in the skin with help of UV-B in sunlight
- Absorption of nutrients: e.g. simple columnar epithelium of small bowel
- Sensory reception: example:
(i) Olfactory receptors for smell sensation.
(ii) Vision: Rods & Cones, Retinal ganglion cells [photoreceptors]
k how simple, squamous, stratified, cuboidal, columnar, pseudo stratified look like
k how pseudo stratified columnar cell look like (e.g. trachea) - see notes if dk
Cilia components
1.–> 5.
See pic in notes
1. Ciliary membrane
2. Axoneme (microtubules) –> 9 doublets (each doublet got subunit A and subunit B) + 2 subunits
3. Basal body
4. Basal foot
5. Rootlets
Connective tissue
- [what origin?] that forms a matrix beneath the epithelial layer
- sparsely populated by cells and contains an extensive Extra Cellular Matrix consisting of protein fibers, Glycoproteins, and proteoglycans
- function?
- where is it roughly?
- mesodermal origin
- (function) provide structural and mechanical support for other tissues and to mediate the exchange of nutrients and waste between the circulation and other tissues
- in dermis
Classification of connective tissue
a. (1. 2. 3.)
b. (1. 2. 3.)
c. - hyaline, …, …
d.
e.
Loose connective tissue – 1.Areolar connective tissue
2. Adipose tissue
3. Reticular connective tissue
B. Dense connective tissue:-
1.Dense regular connective tissue – Tendon
2. Dense irregular connective tissue- Dermis of skin, Heart valves
3. Elastic connective tissue
C. Cartilage - Hyaline ,Elastic and Fibrocartilages
D. Bone tissue
E. Blood tissue
Components of connective tissue
*see summary graph in notes
- Fibroblasts (synthesizes the collagen & ground substance of the extracellular matrix) –> can see how it looks like in notes
- Mast cells
- Plasma cells (clock-face nucleus)
- Macrophages (phagocytes)
- Fat cells (adipocytes) - adult humans - white fat (unilocular), newborn got some brown fat in neck and lower abdomen
Intercellular Ground substance
- fibres
1.
2.
3.
- Collagen
- Reticular
- Elastic
Collagen types I, II, III, IV
I:
II:
IV:
I: bone
II: cartilage
IV: basement membrane of epithelium
two types → based on the Ratio of collagen fibers to ground substance:
(i) ? - most abundant form of collagenous connective tissue; occurs in small, elongated bundles separated by regions that contain the ground substance
(ii)? - enriched in collagen fibers with little ground substance
regular:
irregular:
two types → based on the Ratio of collagen fibers to ground substance:
(i) Loose Areolar connective tissue- most abundant form of collagenous connective tissue
occurs in small, elongated bundles separated by regions that contain the ground substance
(ii) Dense connective tissue is enriched in collagen fibers with little ground substance.
regular: closely packed bundles of fibers are located in one direction [e.g. of regular dense connective tissue → tendons]
Irregular: oriented in multiple directions, it is referred to as irregular [e.g. irregular dense connective tissue → dermis]
*collagen: pink pink colour fibrils on microscope
Tropocollagen molecule: triple helix –> 2 …chain and 1…chain
2 alpha 1 chain and 1 alpha II chain
Reticular fibres
[see notes for pic] Resemble collagen fibrils
Show striations structurally
Produced by fibroblasts and reticular cells
Coated by greater amounts of carbohydrates as compared with collagen
easily impregnated by silver stain
Composed of type 3 collagen → thin reticular network [NOT thick and course like collagenous fibres]
Elastic fibres
Provide elasticity to tissues → stretchable cuz they are disorganised → stretch → organised structure
Branched structures
Produced by fibroblasts and smooth muscle cells
Structural components: elastin & microfibrils (containing fibrillin)
often organised into lamellar sheets (e.g. in the walls of arteries)
