Mucsle Tissues

Question 1

Muscle tissues

Answer 1

Contract to shorten to make movement

Muscle tissues must be irritable (able to respond to stimuli) to contract

Question 2

Skeletal muscles

Answer 2

Skeletal muscle tissue is packaged by connective tissue into skeletal muscles (organs).
Skeletal muscles are attached to the skeleton.
These muscles are voluntary (can be controlled consciously).
They form the muscular system (which makes up the flesh of the body).
When skeletal muscles contract, they pull on bones or skin.
This leads to gross body movements or changes in facial expressions.

Question 3

Skeletal muscle cells are:

Answer 3

Long and cylindrical
Multinucleate (have multiple nuclei)
Have obvious striations (stripes)

Question 4

Cardiac muscle

Answer 4

is found only in the heart wall.
As it contracts, the heart pumps blood through blood vessels.
Striations are present in cardiac muscle, similar to skeletal muscle.
Cardiac muscle cells:
Have a single nucleus.
Are short and branching.
Fit tightly together at intercalated discs (like clasped fingers).
Intercalated discs contain gap junctions that allow ions to pass freely between cells.
This creates a functional syncytium, allowing rapid electrical conduction across the heart.
Cardiac muscle is under involuntary control, meaning we cannot consciously control the heart’s activity.
Imagine if we had to “tell” our heart to beat like we consciously tell our legs to walk!

Question 5

Smooth (visceral) muscle

Answer 5

has no visible striations.
The individual smooth muscle cells:
Have a single nucleus.
Are tapered at both ends.
Smooth muscle is found in the walls of hollow organs such as the stomach, uterus, and blood vessels.
When smooth muscle contracts:
The cavity of the organ becomes smaller (constricts).
The cavity enlarges (dilates) when the muscle relaxes.
This helps mix and propel substances through the organ along a specific pathway.
Smooth muscle contractions are longer and slower than in skeletal or cardiac muscle.
Peristalsis (a wavelike motion) helps keep food moving through the small intestine, which is typical of smooth muscle activity.

Question 6

Nervous tissue

Answer 6

consists mainly of neurons.
Neurons:
Receive and send electrochemical impulses throughout the body.
Have irritability and conductivity as their two major functional characteristics.
The structure of neurons is unique:
Their cytoplasm is extended into long processes (extensions).
Some neurons have processes as long as 3 feet or more (e.g., in the leg).
This long structure allows a single neuron to conduct impulses to distant body locations.