Lecture 4

Question 1

What is the definition of a tissue ?

Answer 1

aggregate of cells in an organism with similar structure that work together to achieve a particular function and derive from a common embryonic origin

Question 2

5 steps of sample preparation

Answer 2

fixation, dehydration, embedding, sectioning, staining

Question 3

what are the three types of staining ?

Answer 3

1) histochemical : uptake of different chemical stains (ex H&E, Massons tri-chrome)

2) immunohistochemical : primary antibpdy binds to the antigen we want, secondary AB recognizes the first and is coupled to an enzyme -> reaction forms a colored precipitate

3) immunofluorescent : same principle wuth the two AB but the second is coupled to a fluorophore

Question 4

what are the 2 elements consisting a tissue ? 4 tissue types ?

Answer 4

specialized cells and ECM.

Connective, nervous, muscular, epithelial

Question 5

connective tissue : characteristics and main functions, 3 types

Answer 5

variable, a lot of ECM.

connects different tissues, structural support, cell transportation (blood)

3 types : proper, supporting, fluid

Question 6

epithelial tissue : characteristics, main functions, 2 levels of characterization

Answer 6

tightly joined cells (little ECM), avascular, polarised (apical and basal).
Protection, sensory, separation, absorption, gas exchange, secretion.

Can be simple or stratified (pseudostratified), and 3 shapes : squamous, cuboidal, columnar

Question 7

3 specifications of the epithelium ?

Answer 7

Ciliated (sensory, mucus)
Glandular (secretion)
Keratinised (skin)

Question 8

nervous tissue : characteritics, function, location

Answer 8

2 cell types (neurons, neuroglia for electrical insulation), form CNS and PNS.

Coordination of actions by signal transmission and communication.

In brain, spinal cord, nerves.

Question 9

muscle tissue : characteristics, main functions, 3 types

Answer 9

Respond to stimuli by contraction, elastic (returns to shape).

Voluntary and involuntary movements.

Skeletal, smooth, cardiac

Question 10

characteristics of the three muscle types

Answer 10

1) skeletal : striated, long, multinucleated, voluntary movements, functional unit is the sarcomere

2) smooth : unstriated, mononucleated, spindle shaped, unit is contractile filament, involuntary movements, in visceral organs, blood vessels, …

3) cardiac : striated, mononucleated, synchronous contraction, pumps blood

Question 11

Describe the steps of early embryonic development

Answer 11

1) zygote by fusion of gametes in oviduct -> zygote is omnipotent
2) 2, 4, 8 cell stage through mitotic division (zona pellucida protects)
3) Morula (16 -32) : embryo reaches uterus and differentiation begins
4) blastocyst formation : outer layer = trophoblast, inner mass = embryoblast, fluid filled cavity (blastocoel), disintegration of zona pellucida

Question 12

Describe the germ layer development

Answer 12

Embyroblasts differentiate into a bilaminar disc formed by epiblast and hypoblast.
Primitive streak (day 15) -> migration to form 3 germ layers.
1) hypoblast is replaced by endoderm
2) cells between endoderm and epiblast form mesoderm
3) remnants of epiblast form ectoderm

Question 13

From what germ layer comes every tissue type ?

Answer 13

nervous : ectoderm
connective + muscular : mesoderm
epithelial : endoderm

Question 14

What follows the formation of the three germ layers ?

Answer 14

organogenesis

Question 15

what does tissue regeneration describe ?

Answer 15

renewal of tissues for maintenance (homeostasis) and repair (after injury)

Question 16

2 ways to restore tissues with regenerative medicine

Answer 16

1) stimulate intrinsic growth / repair processes

2) replacement of injured tissue by newly generated tissue

Question 17

What balance is important to control ?

Answer 17

Between cell degeneration and regeneration (avoid problems such as cancer)