Chapter 5

Question 1

What are the three primary germ layers? Name one example of each.

Answer 1

• Ectoderm: epidermis
• Mesoderm: Cardiac Muscle
• Endoderm: Respiratory Tract lining

Question 2

Describe three functions of epithelial tissues.

Answer 2

• Protects deeper tissue from injury
• Produce chemical secretions
• Excrete Waste
• Absorb nutrients

Question 3

Identify the three types of cell junctions

Answer 3

Tight
Desmosomes
Gap Junctions

Question 4

What is a key characteristic of Tight junctions?

Answer 4

linkage between two adjacent cells by transmembrane cell-adhesion proteins

• Located near apical pole
• Seals off intracellular surface making it difficult for a substance to pass between cells

Question 5

What is a key characteristic of Desmosomes?

Answer 5

patches that hold cells together like a clothing snap

• Keeps cells from pulling apart,
• Resists mechanical stress
• Hemi-desmosomes are half, that anchor basal cells of an epithelium underlying basement membrane

Question 6

What is a key characteristic of Gap Junctions?

Answer 6

formed by ring-like connexons

• Ions, nutrients and small solutes pass between cells
• Located in cardiac and smooth muscle and embryotic tissues

Question 7

Identify the four main classes of connective tissues.

Answer 7

• Connective Tissue Proper
• Cartilage
• Bone
• Blood

Question 8

Two important functions of connective tissue

Answer 8

• Binding of organs

- Support for bones and cartilage

Question 9

What are the three main fiber types that provide support in connective tissues?

Answer 9

 Collagenous Fibers: most abundant, touch, flexible, ex: tendons, ligaments, deep skin
 Reticular Fibers: thin, highly branched, coated with glycoprotein, ex: spleen/ lymph nodes
 Elastic Fibers: thinnest, made from elastin, allows stretch and recoil

Question 10

What are the three main types of membranes?

Answer 10

• Cutaneous
• Mucous
• Serous

Question 11

What are characteristics of cutaneous membranes?

Answer 11

:skin, largest membrane in the body

• Stratified squamous epithelium
• Relatively dry layer
• Protection

Question 12

What are characteristics of Mucous membranes?

Answer 12

: lines passages that open to the external environment

• Digestive tract
• Goblet cells
• Sublayers: epithelium, lamina propria, muscular mucosa

Question 13

What are characteristics of serous membranes?

Answer 13

lines cavities that are closed to the exterior
- Simple squamous epithelium
- Produced serous fluid that arises from blood
- Covers organs and lines walls of body cavities
 Endothelium lines blood vessels and hear
 Mesothelium lines body cavities (pericardium, peritoneum, pleura)

Question 14

Identify and contrast the two major ways to repair tissue. Identify one tissue that has a great repair capacity and one that has no repair capacity.

Answer 14

 Regeneration: replacement of dead or damaged cells by a cell of the same type
- Restores normal function
- Ex: minor skin or liver injuries
 Fibrosis: replacement of damaged cells with scar tissue
- Scars hold organs together, but doesn’t restore function
- Ex: severe cuts, burns, scarring of lungs in tuberculosis

Question 15

Capillaries are vessels only a single cell layer thick. This allows for rapid exchange of oxygen, nutrients, carbon dioxide, and wastes. What specific epithelial tissue do you think makes up the capillaries?

Answer 15

Simple Epithelia

Question 16

A woman in labor is often told to push. In doing so, is she consciously contracting her uterus to expel the baby? Justify your answer based on the muscular composition of the uterus.

Answer 16

• No. The uterus is a smooth (and thus, involuntary) muscle. What she is really contracting are her abdominal muscles, which in turn help the uterus to move the baby down.

Question 17

When cartilage is compressed, water is squeezed out of it, and when pressure is taken off, water flows back into the matrix. This being the case, why do you think cartilage at weight-bearing joints such as the knees can degenerate from lack of exercise?

Answer 17

• Lack of exercise leads to poor oxygen and deficient nutrient delivery to the cartilage. This slowly and gradually leads to degeneration of cartilage particularly at weight bearing joints (as seen in knees) and cartilage undergoes necrosis.

Question 18

The epithelium of the respiratory tract is mostly of the pseudostratified columnar ciliated type, but in the alveoli – the tiny air sacs where oxygen and carbon dioxide are exchanged between the blood and inhaled air – the epithelium is simple squamous. Explain the functional significance of this. That is, why don’t the alveoli have the same kind of epithelium as the rest of the respiratory tract?

Answer 18

The alveoli have to have an epithelium that allows for easy gas exchange. Columnar epithelium would not exchange it easy or fast at all.