7.7 - Introduction to Tissues

Question 1

What are the levels of organisation of the human body?

Answer 1

simple elements/atoms –> complex molecules –> cell organelles –> cells –> tissues –> organs –> systems –> organism

Question 2

Light microscopy

Answer 2

• easy and simple to use
• samples of tissues are processed - fixing and dehydration in alcohol solutions
• very thin slices cut, stained and mounted on glass slides
• details restricted by resolving power of LM, usually 0.2um and x1500 magnification

Question 3

Transmission electron microscopy

Answer 3

• requires expensive equipment and laboratory time
• very detailed structures of tissues can be seen e.g. cell membrane, filaments, ribosomes
• resolving power 0.2-0.35nm

Question 4

What are the three germ layers of the embryo?

Answer 4

• ectoderm
• mesoderm
• endoderm

Question 5

What is primary tissue and what are the types of it?

Answer 5

Primary tissue - one cell type predominates
- connective tissue
- epithelium
- muscle
- nerve tissue

Question 6

Connective tissue

Answer 6

• derived from mesodermal layer of embryo - occurs everywhere in the body forming a ‘packing material’
• provides mechanical and metabolic support
• components: cells and extracellular matrix
• most abundant and widely distributed tissue

Question 7

What are the types/subdivisions of connective tissue?

Answer 7

• loose areolar CT, dense CT, reticular CT
• adipose (fat) CT
• cartilage and bone
• blood and lymph

Question 8

Epithelial tissue

Answer 8

• derived from all three embryonic germ layers
  Two groups:
• covering/lining or surface epithelia - oral cavity, skin, vagina, respiratory tract, alimentary tract
• glandular epithelia - sebaceous, salivary and mammary glands, exocrine and endocrine glands

Question 9

What are the types of surface epithelia?

Answer 9

• simple squamous (small blood vessel)
• stratified squamous (skin, mouth, vagina)
• simple cuboidal (salivary gland ducts, kidney tubules)
• simple columnar (stomach, intestine, gall bladder)
• simple columnar ciliated (fallopian tube)
• pseudostratified columnar ciliated (respiratory tract)
• transitional (urinary tract, bladder)

Question 10

Muscle tissue

Answer 10

• derived from mesodermal layer of the embryo
• function: produce movement
  Types of muscle fibres:
• skeletal - voluntary movement
• cardiac - contraction of heart
• smooth - visceral structures

Question 11

Nerve tissue

Answer 11

• derived from ectoderm layer of the embryo
• function: generate and conduct electrical impulse
  Components:
• neurons/nerve cells - excitable cells
• nerve fibres - axons and dendrites
• neuroglia - supportive cells