Nerve Tissue and Wound Repair

nervous tissue

consists of nerve cells (neurons)

neurons...

receive and conduct impulses from one part of the body to another

characteristics of nervous tissue

irritability: ability of a neuron to detect a stimulus and respond
conductivity: ability of a neuron to transmit signals from one neuron to another and from a neuron to a muscle or gland

True/False: Neurons touch one another.

False: there is a gap between one neuron and another, information has to jump from one neuron to another

What physical attribute of neurons allows them to conduct impulses?

Their long shape (the longest one that has been found is three feet long)

wound healing

tissue repair

protection and prevention of wound healing

physical barriers at the tissue level include the skin, mucous membranes, cilia, acid from stomach glands

response of wound healing

inflammatory: swelling to prevent further injury (skin gets warm and red) --> GENERAL response
immune: white blood cells attack invaders --> SPECIFIC response

repair of wound healing

regeneration: replacement through mitosis of destroyed tissue with the same type of cells
fibrosis: formation of dense fibrous connective tissue leads to the formation of a scar

specific steps of repair

1. clotting proteins and other substances from the blood stream come in and create a clot (which acts like a plug) to: hold wound edges together and stop blood loss
2. injured area is "walled off", preventing bacteria or other substances from spreading to surrounding tissue
3. clot dries and hardens with exposure to air, forming a scab

granulation tissue formation

pink and delicate tissue underneath the scab
composed of new capillaries that grow into the damaged are from undamaged blood vessels
they are very fragile and easily bleed, which is why scabs that are picked off bleed

scar tissue

glandular tissue also contains phagocytes that dispose of the blood clot
fibroblasts produce the building blocks of collagen fibers, which is a type of scar tissue that will permanently close the wound

final and permanent repair

epithelium regenerates (cells are made across the area below the scab)
the scab detaches, and the regenerated surface covers the wound that used to be there
the scar is invisible or visible, depending on severity of the wound

types of scars

acne scars
stiching scars
cut/scrape scars

True/False: Neurons do not regenerate.

True

Dendrite

Branches of the nerve cell body
- the cytoplasm and cell membrane reach/cover all of these branched out areas

Axon

One long dendrite that stretches much farther

Schwann cells

What makes up the axon

Myelin Sheath

A covering of the axon

Axon Terminal End

Where the signal ends and then jumps to the next cell

Nodes of Ranvier

"beads" in between schwann cells

The signal moves from... to...

The end of the nerve cell with the nucleus
To the Axon Terminal end