epithelium

Question 1

what are the 4 basic tissue types

Answer 1

• Epithelium
• Connective tissue
• Muscle
• Nervous tissue

Question 2

what do these make up

Answer 2

almost all tissues and organs are made up of a combination of these

Question 3

what is epithelium composed of

Answer 3

closely aggregated, polyhedral epithelial cells with a minimum
of intercellular substance.

Question 4

what does surface epithelia cover

Answer 4

surfaces, cavities and tubes

Question 5

how does epithelilal cells protect its structures

Answer 5

Adhesion between cells is strong; thus cellular sheets are formed which cover exposed external surfaces and line internal cavities and form solid organs

Question 6

what are the functions of the epithelia

Answer 6

▪Mechanical barrier (e.g. skin)
▪ Chemical barrier (e.g. lining of stomach)
▪ Absorption (e.g. lining of intestine)
▪ Secretion (e.g. salivary gland)
▪ Containment (e.g. lining of urinary bladder)
▪ Locomotion (by cilia) (e.g. oviduct

Question 7

what are the characteristic of epithelal cells

Answer 7

• typically polarised (head and tail JOINED to basal membrane)
• basal surfacea ttatched to basal lamina
• non vascular
• tend to adhere toghether in sheets where cells are closely spposed to one another requiring a cytoskeleton and
  prominent intercellular junctions.

Question 8

what 3 main classes of filaments form the cytoskeleton of cells

Answer 8

microfilaments - 5nm dia
intermediate filaments - 10nm dia
microtubules - 25nm dia

Question 9

how do they form the cytoskeleton

Answer 9

these filamentous protiens attatch to cell membrane and each other, by anchoring and jpining protien to form dynamic 3d internal scaffolding

Question 10

what are the 3 types of junctions in between the epithelial cells

Answer 10

occluding - form between diffusion barrier
anchoring - provides mechanical strength
communicating - allows movement of molecules between cells

Question 11

what is the junctional complex

Answer 11

close association of several types of junctions found in certian epithelial and other tissue
e.g - ZO, ZA, MA

Question 12

what are epithelia classified on

Answer 12

Cell Shape:
▪ Squamous (flattened, like a fish scale)
▪ Cuboidal (cube shaped)
▪ Columnar (like a column, relatively tall and thin)

The Number of Layers:
▪ ‘Simple’ = one layer
▪ ‘Stratified’ = two or more layers
▪ ‘Pseudostratified’ = tissue has multiple layers, but all cells are in contact with the basal lamina

presence of specialised cells of cell/tissue surface or within epithelium

Question 12

what is cilia

Answer 12

motile cell process
propel mucosa or fluid over cell surface

Question 12

what is keratin

Answer 12

tough structural protiens found associated with some stratisfied squamous epithelia

Question 13

what solid organs are formed of epithelium cells

Answer 13

glandular organs mostly

Question 14

where is exocrine gland product secreted

Answer 14

toward the apical end of the
cell into the lumen of internal space, into a duct, or onto
the body surface.
Termed ‘ducted’ glands
e.g Lacrimal glands
Pancreas
Salivary glands
Sweat glands
Mammary glands
Liver
Brunner’s glands
Sebaceous glands

Question 15

where is endocrine gland product secreted

Answer 15

toward the basal end of the
cell (end sitting on basal lamina), then distributed by
vascular system throughout body.
Termed ‘ductless’ glands.
e.g Pituitary gland
Thymus gland
Thyroid gland
Adrenal glands
Pancreas
Ovaries/Testes