YR 1 - HUMAN PHYSIOLOGY CHPTR 4

Question 1

What does the epithelial tissue cover?

Answer 1

Epithelial tissues cover and protect surfaces both inside and outside the body.

Question 2

What are the major functions of epithelial tissues?

Answer 2

1. Protecting underlying structures- they protect from abrasions
2. Acting as a barrier- Epithelium prevents many substances from moving through it
3. Permitting the passage of substances- epithelium acts as a barrier but it also exchange between the air and blood by diffusion through the epithelium in the lungs. It also acts as a filter.
4. Secreting substances- many glands such as sweat glands and mucous glands secrete their products onto surfaces or into ducts which carry them to other areas of the body.
5. Absorbing substances- The plasma membrane of certain epithelial cells contain carrier proteins which regulates the absorption of materials.

Question 3

What are the classifications of epithelial tissues?

There are 4 major types

Answer 3

The 4 major types of epithelial tissues are:

-Simple epithelium
Consists of single layer of cell with each cell extending from the basement membrane to the free surface

-Stratified epithelium
Consists of more than one layer of cells but only the basal layer attached the deepest layer to the basement membrane

-Pseudostratified columnar epithelium
Consists of one layer of cell with all the cells attached to the basement membrane. There appears to be 2 or more layers of cells because some of the cells are tall and extend to the free surface. Others are shorter and don’t extend to the free surface

-Transitional epithelium
Special type os stratified epithelium and the shape of its cells changes from cuboidal and columnar to squamous like when stretched

Question 4

What are the 3 types of epithelium based on idealised shapes of the epithelial cells?

Answer 4

-Squamous
Cells are flat or scalelike

-Cuboidal
Cells are cube-shaped-about as wide as they are tall (Cubelike)

-Columnar
Cells tend to be taller than they are wide (Tall and thin, similar to a column)

Question 5

SIMPLE SQUAMOUS EPITHELIUM

Answer 5

Structure: Single layer of flat, often hexagonal cells; the nuclei appear as bumps when viewed as a cross section because the cells are so flat

Function: Diffusion, filtration, some secretion, and some protection against friction

Location:

• Lining of blood vessels
• The heart
• Lymphatic vessels
• Small ducts
• Alveoli of the lungs

Question 6

SIMPLE CUBOIDAL EPITHELIUM

Answer 6

Structure: Single layer of cube shaped cells; some cells have microvilli (kidney tubules) or cilia (terminal bronchioles of the lungs)

Function: Secretion and absorption by cells of the kidney tubules; secretion by cells of glands and choroid plexuses; movement of particles embedded in mucus out of the terminal bronchioles by ciliates cells

Location:

• Kidney tubules
• Glands
• Choroid plexuses of the brain
• Lining of terminal bronchioles of the lungs

Question 7

SIMPLE COLUMNAR EPITHELIUM

Answer 7

Structure:Single layer of tall, narrow cells; some cells have cilia (bronchioles of lungs, auditory tubes, uterine tubes,and uterus) or microvilli (intestines)

Function: Movement of particles out of the bronchioles of the lungs by ciliates cells; partially responsible for the movement of locates through the uterine tubes by ciliated cells; secretion by cells of the glands the stomach and the intestines; absorption by cells of the small and large intestines

Location:

• Glands
• Ducts
• Bronchioles of the lungs
• Auditory tubes
• Uterus
• Uterine tubes
• Stomach

Question 8

STRATIFIED SQUAMOUS EPITHELIUM

Answer 8

Structure: Multiple layers of cells that are cube shaped in the basal layer and progressively flattened toward the surface; the epithelium can be moist (non keratinised) or keratinised