Lecture 3 - Tissue Basics: Structure and Histology

Question 1

Cellular differentiation

Answer 1

Cells differentiate into cell types by expressing different combinations of proteins

Question 2

Cellular polarization

Answer 2

Asymmetry in molecular composition or structure between two sides

Ex. The ends of a neuron is different

Question 3

Organ

Answer 3

Two or more types of tissue working together to perform specific functions

Question 4

Tissue

Answer 4

A group of similar cells (and their products) working together to perform specific functions

Question 5

4 main types of tissue and where can they be found?

Answer 5

1. Epithelial tissue - covers exposed surfaces. Lines internal passageways/chambers and forms secretory glands
2. Connective tissue - fills internal space and provides structural support. Stores energy
3. Muscle tissue - contracts to produce movement. It includes skeletal muscle, cardiac muscle, and smooth muscle
4. Nervous tissue - conducts electrical impulses and carries information

Question 6

4 functions of epithelial tissue

Answer 6

1. Provide physical protection
2. Control permeability
3. Provide sensation
4. Produce specialize secretions

Question 7

Epithelium

Answer 7

A sheet of connected epithelial cells attached to a basement membrane

Question 8

3 basic features epithelial cells share

Answer 8

1. They form glands
2. They show polarization - they all have an apical surface and a basolateral surface
3. Cells within an epithelium are bound to each other in multiple different ways - intercell junctions

Question 9

Leaky tight junctions

Answer 9

Allow paracellular transport of water and solutes

Question 10

Tight tight junctions

Answer 10

Do not allow paracellular transport

Question 11

Simple epithelia and what are the different types?

Answer 11

A single layer of cells with every cell in direct contact with the basement membrane

Squamous - flat and sheet-like
Cuboidal - cube-like
Columnar - column-like - they are taller than they are wide

Question 12

Stratified epithelia

Answer 12

Contains two or more layers of cells. The shapes are the same as simple epithelia, just layered

Question 13

Pseudo-stratified

Answer 13

Closely packed cells that appear to be arranged in layers because they’re different sizes, but there’s actually just one layer of cells

Question 14

4 functions of connective tissue

Answer 14

1. Establish a structural framework for the body
2. Transport fluids and dissolved material
3. Protect organs, tissue (interconnect them too) and body from invading microorganisms
4. Store energy, especially in the form of triglycerides

Question 15

2 categories of connective tissue proper. Give examples in these categories

Answer 15

1. Loose: areolar tissue, adipose tissue, and reticular tissue
2. Dense: dense regular, dense irregular, elastic

Question 16

Fluid connective tissue examples

Answer 16

Blood and lymph

Question 17

2 categories of supporting connective tissues. Give examples in these categories

Answer 17

1. Cartilage: hyaline cartilage, elastic cartilage, fibrocartilage
2. Bone

Question 18

Cells types found in loose connective tissue and their functions

Answer 18

Fibroblasts - secrete proteins of the extracellular matrix

Fibrocytes - mature fibroblasts. They maintain the proteins of the extracellular matrix

Mesenchymal cells - stem cells that can divide to replace damaged cells (fibroblasts)

Question 19

Example of dense connective tissue proper

Answer 19

Tendons

Question 20

Wandering cells

Answer 20

Can move into or through tissue depending on physiological demands

Question 21

2 types of fibres found in connective tissue proper

Answer 21

1. Collagen fibres - high tensile strength. Not stretchy
2. Elastin fibres - elastic

Question 22

Tissue membrane

Answer 22

A layer of epithelial tissue + underlying layer(s) of connective tissue. They cover body surfaces (inside and out)

Question 23

Fasciae

Answer 23

Layers of connective tissue that surround organs, providing physical support. Not directly connected to an epithelium

Question 24

Process of epithelial and connective tissue healing after damage

Answer 24

The epithelium undergoes rapid proliferation, which forms blood clots

Most connective tissue undergoes increased rates of matrix secretion. A scar forms when a dense web of collagen fibres is secreted at the injury site