Tissues

Question 1

Define the term ‘epithelium’ and describe the basic functions of epithelial surfaces, those covering the body and lining internal structures.

Answer 1

Epithelial tissue covers surfaces and separates compartments. It has no contact inhibition and forms cell-cell and cell-ECM junctions to fill any gaps between cells and cover surfaces effectively.

Epithelia have very good regenerative and adaptive powers.

Function depends on the cell itself, not the ECM.

• Movement- cilia -(group of 9 microtubules)- not really part of the cell
• Absorption- Microvilli- projections from the cell

Question 2

Describe cell-cell junctions and cell-ECM junctions.

Answer 2

Cell-Cell junction

• Desmosomes (adhering junctions) provide firm anchorage
• Tight/Occluding Junctions seal intracellular spaces
• Gap Junctions allow for cell-cell communication (literally have gaps between the cells)

Cell-ECM Junctions
- Hemidesmosomes

Question 3

Describe the types of simple surface epithelia and explain how the structural properties of each correlate to its function

Answer 3

Simple

• Squamous e.g Alveoli and Capillaries. Thin to allow for easy diffusion
• Cuboidal e.g. lining of nephrons. Perform secretion and absorption/pumping.
• Columnar e.g Lining digestive tract. When ciliated, move mucus

Question 4

Describe the types of stratified surface epithelia and explain how the structural properties of each correlate to its function

Answer 4

Stratified

• Squamous e.g Epidermis. Thick, and layers can be sloughed off to allow new growth.
• Cuboidal e.g. ducts of sweat glands, Protection.
• Columnar e.g Pharynx, Protection, and secretion.

Question 5

Describe the types of pseudostratified surface epithelia and explain how the structural properties of each correlate to its function

Answer 5

Such epithelia are called pseudostratified columnar epithelia. … Pseudostratified columnar epithelia are most commonly found along the respiratory airways. These cells contain cilia on their apical surface. Cilia are motile, beating in a synchronous rhythm to move fluid in a constant direction.

Question 6

Describe the epithelial components of the liver

Answer 6

Liver

• Hepatocytes
• Arranged in rows (or cords) between blood vessels
• Multiples functions including secretion
• Support epithelial cells line blood vessels and bile ducts.

Question 7

Describe the epithelial components of the kidney

Answer 7

Kidneys

• Epithelial cells
• Arranged into nephrons
• Multiple functions including filtration of blood, partial absorption of the filtrate
• Support cells line blood vessels and the renal pelvis which receives toxic urine

Question 8

Consider the consequences of abnormal function of covering and lining epithelia

Answer 8

• Over/Under proliferation- skin conditions
• Over/Under secretion
• Loss of ciliary beat- e.g cough due to stuff getting caught

Question 9

Define the term ‘gland’ and describe the basic functions of glandular epithelium

Answer 9

Glands are collections of multi or single cellular secretory epithelial cells.

• Endocrine secretes into blood e.g Adrenal Cortex
• Exocrine secretes to surface e.g sweat glands

Question 10

What are Simple and compound types of glands

Answer 10

Tubular looks like a rod
Acinar looks like a bud
Compound- Tubuloacinar is a tunnel system of the combination of the two.

Question 11

Consider the consequences of abnormal glandular function.

Answer 11

Overproduction- Pituitary giantism

Under production- Pituitary dwarfism

Question 12

What are the types of connective tissues?

Answer 12

Fibres
Ground substance
Tissue Fluid
Loose connective tissue

Question 13

Describe fibres in terms of connective tissues?

Answer 13

Fibers
- Collagen makes up 30% of body weight. Flexible, but inelastic with great tensile strength. Produced by fibroblast.
Elastic fibers protein elastin. Stretch 1.5x length and return to the original shape. Microfibrils an amorphous component. Found in sheets. Yellow color

Question 14

Describe Ground substance in terms of connective tissues?

Answer 14

• Proteoglycans (Protein core and GAGS)
• Hyaluronic acid
• Glycoprotein

Question 15

Describe tissue fluid in terms of connective tissues?

Answer 15

Blood and lymph are fluid connective tissues. Cells circulate in a liquid extracellular matrix. The formed elements circulating in blood are all derived from hematopoietic stem cells located in bone marrow. Erythrocytes, red blood cells, transport oxygen and some carbon dioxide

Question 16

Describe loose connective tissue in terms of connective tissues?

Answer 16

• Fixed cells- Fibroblasts, Macrophages, Adipocytes, Mast cells
• Transient cells- White Blood Cells

Question 17

Consider the consequences of abnormal function of connective tissues?

Answer 17

Blood/Bone Marrow - Leukaemia

Loose/Dense- Loss/abnormal fibres

Cartilage- Tear

Bone- Osteoporosis