Primary Tissue Types

Question 1

What is a tissue ?

Answer 1

Group of specialised cells with distinct function

Question 2

What are examples of simple multicellular organisms ?

Answer 2

Hydra and sponges

Question 3

What are the advantages of cells grouping into tissues ?

Answer 3

• Division of labor and coordinated function for tissues
• Possibility for larger organisms
• Support and motility
• Exploitation of resources (not available to single cells)

Question 4

What are the steps of differentiation ?

Answer 4

Each cell has genome of 1st cell of embryo –> selective expression and gene silencing (through DNA methylation) yields 100s of difference cell types

Question 5

What is the role of differentiation programmes ?

Answer 5

To determine levels and pattern of protein expression (determines cell function)

Question 6

What is asymmetric division ?

Answer 6

Process by which cell gives rises to 2 daughter cells with different contents. Some differentiate (New set of genes/proteins expressed to produce cells with distinct functions) whilst some remain stem cells.

Question 7

How is gene expression regulated ?

Answer 7

By transcription factors

Question 8

What are the types of stem cells?

Answer 8

Pluripotent- in early embryo

Tissue specific- in tissue

Question 9

What are organs ?

Answer 9

Many tissues grouped together

Question 10

What are the 4 basic body tissues ?

Answer 10

Epithelia, CT, muscle, neural tissue

Question 11

What are the functions of epithelia ?

Answer 11

Absorption
Secretion
Transport
Selective barrier + Protective barrier 
Strength and support

Question 12

Why may burning be dangerous ?

Answer 12

Loss of skin barrier function –> Loss of fluid and possible infection

Question 13

What are possible surface modifications for epithelia ?

Answer 13

Vili, microvili and cili

Question 14

What is the role of tight junctions ?

Answer 14

Sealing

Question 15

What is the role of desmosomes ?

Answer 15

Strengthening cell links

Question 16

What is the role of adherens junctions ?

Answer 16

Linking movement proteins for movement

Question 17

What is the role of gap junction ?

Answer 17

Connecting cytosol of adjacent cells

Question 18

What does the BM of epithelia contain ?

Answer 18

Proteins linking to surface of epithelial cells and

Filamentous proteins providing strength

Question 19

What is the CNS made up of ?

Answer 19

Brain and spinal chord

Question 20

What is the PNS made up of ?

Answer 20

“Nerves and ganglia outside brain and spinal chord”

Question 21

What is the neuron theory ?

Answer 21

Theory that neurons are seperate entities

Question 22

What are neurons ?

Answer 22

Excitable nerve cells which convey information as action potential

Question 23

What is the base and the apex of a neuron ?

Answer 23

Base is dendrites. Apex is axons.

Question 24

Which of dendrites and Axons direct the impulse towards the cell and which away from the cell ?

Answer 24

Dendrites- Towards cell

Axon- Away from cell

Question 25

What is an internode ?

Answer 25

Portion of Axon between 2 nodes of Ranvier. Covered with myelin sheath

Question 26

What is a major advantage of myelination ?

Answer 26

Allows for quicker rate of action potential since they are jumping between nodes of Ranvier through saltatory conduction

Question 27

Where does secretion occur ?

Answer 27

At the Axon end bulb, into the synapse.

Question 28

What is the difference between PNS myelination and CNS myelination ?

Answer 28

In the PNS, one shwann cell builds one internode. | In the CNS, one oligodendrocyte builds a number of interonodes

Question 29

What is the function of glial cells ?

Answer 29

Supporting the neurons

Question 30

What are the glial cells of the PNS ?

Answer 30

``` Shwann cells (responsible for myelination) Satellite cells (support cells in ganglia) ```

Question 31

What are the glial cells of the CNS ?

Answer 31

Oligodendrocytes (responsible for myelination) Astrocytes Microglia Ependyma (lining cells of CNS cavities)

Question 32

What is the shape and function of astrocytes?

Answer 32

Star shaped | Function includes metabolic and mechanical support, also found in CNS scar tissue

Question 33

What is the origin and function of microgial cells?

Answer 33

Their origin is hematopoietic stem cells. | They have a function in phagocytosis and antigen presentation

Question 34

What is the distinctive structural features of all muscle ?

Answer 34

Contain contractile filaments composed of actin and myosin.

Question 35

What are the three types of muscles ? Are they voluntary ? Are they striated ?

Answer 35

Skeletal (voluntary, striated) BUT reflexes are involuntary Cardiac (involuntary, striated) Smooth (involuntary, unstriated)

Question 36

What is the structure of each kind of muscle ?

Answer 36

Skeletal muscle - Draw it Cardiac muscle - Structural linkages of myocytes (myocytes found in all three) via intercalated discs Smooth muscle - Cells are spindle shaped. No striking array of myosin and actin

Question 37

What is the main feature of connective tissue ?

Answer 37

Mix of cells and ECM

Question 38

What are the different kinds of fibrocollaginous tissue ? Give examples for each. Which collagen is used in each ?

Answer 38

Loose (around epithelia/organs) Type 1 collagen Dense (tendons, ligaments) Type 1 collagen Reticular (liver, lymph nodes) Type III collagen

Question 39

What are the types of cells found in fibrocollaginous tissue ?

Answer 39

Fibroblasts Macrophages (phagocytose and present antibodies to stimulate immune cells) Mast cells Plasma cells (mature B cells) (synthesise antibodies) Stem cells Blood cells Adipocytes (specialised in storage of fat)

Question 40

What is the function of cartilage ?

Answer 40

Bring flexibility, smooth joint movement and strength

Question 41

Is cartilage vascular ?

Answer 41

NO

Question 42

Is bone vascular ?

Answer 42

YES

Question 43

Are proteoglycans present in bone ECM ?

Answer 43

Yes

Question 44

What types of adipose tissue exist ? What are the functions of each

Answer 44

``` White fat (white adipose tissue), energy storage, insulation and protection, producing adipokines Brown fat (brown adipose tissue), heat production ```

Question 45

Which cells are adipocytes derived from ?

Answer 45

Mesenchymal stem cells

Question 46

What are adipokines ?

Answer 46

Cytokines which send signals to regulate nutritional balance and other systems. E.g leptin

Question 47

How does brown fat make heat ?

Answer 47

By uncoupling oxidative phosphorylation in mitochondria. Hence, has multiple mitochondria (and multiple globules of fat)

Question 48

Where is brown fat located ?

Answer 48

In the upper trunk region.