Lecture 17 - Muscle And Nervous Tissues

Question 1

What are membranes composed of?

Answer 1

An epithelium bound to an underlying connective tissue proper layer

Question 2

Four types of membranes

Answer 2

Mucous membrane
Serous membrane
Cutaneous membrane
Synovial membranes (lack epithelium)

Question 3

Mucous membrane

Answer 3

“Mucosa” indicates location, not cell composition.
also called mucosae, are wet membranes that line body cavities that open to the outside, such as the gastrointestinal tract
moist membranes that are bathed by secretions (or urine).
often secrete mucous.
contain either stratified squamous or simple columnar epithelia over a connective tissue called lamina propria.

Question 4

Serous membrane

Answer 4

also called SEROSA, are moist membranes within closed ventral body cavities.
consist of simple squamous epithelium resting on a thin layer of loose connective (areolar) tissue.
Parietal serosae line internal body cavity walls
Visceral serosae cover internal organs.
The cavity between layers is filled with slippery serous fluid.

Question 5

Cutaneous membrane (skin)

Answer 5

Consists of keratinized stratified squamous epithelium (epidermis) over areolar connective tissue and dense irregular connective tissue (dermis).
Unlike the other membranes, skin is a dry membrane.

Question 6

Synovial membranes

Answer 6

line synovial (joint) cavities and secrete synovial fluid to lubricate and support bones that move.
lack epithelium and are considered a specialized connective tissue.

Question 7

Skeletal muscle

Answer 7

attaches to the skeleton, and is composed of long, cylindrical, multinucleate cells. Skeletal muscle cells are also called muscle fibres

Question 8

Smooth muscle cells

Answer 8

unstriated, small, uninucleate and spindle-shaped.
found in the walls of the hollow organs.

Question 9

Cardiac muscle cells

Answer 9

are striated, uninucleate, and branched.
located only in the heart and have intercalated discs where cardiac cells are joined
Where one cell ends and next starts there is an intercalated disc, when one cell contracts it is passed on to the others, creating chain reaction and causing whole heart to contract

Question 10

Nervous tissue

Answer 10

main component of the nervous system (brain, spinal cord and nerves), which regulates and controls body functions.

Question 11

Neurons

Answer 11

are specialized cells that generate and conduct electrical impulses.

Question 12

Neuroglia

Answer 12

cells that do not conduct nerve impulses but are critical to support, insulate, and protect the neurons.

Question 13

Two ways tissue can be repaired

Answer 13

Regeneration, in which damaged cells are replaced with the same type of cell

Fibrosis, which replaces damaged cells with fibrous connective tissue

Question 14

Three steps of tissue repair

Answer 14

1. Inflammation prepares the area for repair by dilating blood vessels and increasing in blood vessel permeability.

Inflammatory chemicals are released by damaged tissues.

• When blood vessels become more permeable, it is easier for white blood cells, fluid and clotting proteins to seep into the injured area.
• Scabbing and clotting occurs.

2. Organization is a process that replaces the blood clot with granulation tissue (new capillary-rich tissue), restoring blood supply.

• Macrophages eat debris.
• Fibroblasts produce collagen fibres to in a process called fibrosis.
• Surface epithelial cells multiply and migrate over the granulation tissue.

3. Regeneration and fibrosis restore tissue.

The scab detaches as fibrous tissue matures.
Epithelium thickens and begins to resemble adjacent tissue.

• There may or may not be a visible scar under the regenerated epithelial tissue.

Question 15

What tissues regenerate extremely well?

Answer 15

epithelial tissues
bone
areolar connective tissue
dense irregular connective tissue
blood-forming tissue

Question 16

What tissues regenerate with moderate capacity?

Answer 16

smooth muscle
dense regular connective tissue

Question 17

What tissue do not regenerate?

Answer 17

cardiac muscle
nervous tissue of brain and spinal cord.

Question 18

Scar tissue

Answer 18

Scar tissue that forms in organs, particularly the heart, can severely impair organ function.
• Scar tissue may cause organ to lose volume capacity, block substances from moving through organ, interfere with ability of muscles to contract or impair nerve transmissions.
• Scar adhesions may also cause organs to adhere to neighboring structures, preventing normal functions.

Question 19

Tissues and aging

Answer 19

In adults, only epithelia and blood-forming tissues remain highly mitotic.

• Some tissues that regenerate throughout life do so by division of mature cells, while others have populations of stem cells that divide as necessary.

• Tissue repair decreases with age, causing epithelia to become thinner and bone, muscle and nervous tissue to atrophy. partially due to decreased circulatory efficiency and your diet, lifestyle and other factors relating to aging