Animal Tissues: Quick Revision

A brief note on Animal Tissues. Try each question at the end before you open its answer.

Four kinds of tissue

• Epithelial: covers and lines. Squamous (flat), cuboidal (cube), columnar (tall), ciliated (with cilia).
• Connective: cells spread in a matrix. Blood (liquid), bone (hard), cartilage (flexible), ligament (bone to bone), tendon (muscle to bone), areolar (fills spaces), adipose (stores fat).
• Muscular: contracts.
• Nervous: carries messages.

Muscle at a glance

Blood and nerves

• Blood: plasma (about 55%), red cells (oxygen), white cells (germs), platelets (clotting).
• A neuron: dendrites receive, the axon carries the message away, up to about $100\ \text{m/s}$.

A worked example

A person has $5.2\ \text{L}$ of blood, $55\%$ of it plasma and $44\%$ red cells.

1. Plasma. $5.2\ \text{L} \times 0.55 = 2.86\ \text{L}$.
2. Red cells. $5.2\ \text{L} \times 0.44 = 2.29\ \text{L}$.
3. A nerve message of $1.3\ \text{m}$ at $65\ \text{m/s}$ takes $\dfrac{1.3}{65} = 0.02\ \text{s} = 20\ \text{ms}$.

Practice with new numbers

A program to try

The program works out the worked example.

Mistakes to avoid

• Ligament and tendon swapped. Ligament: bone to bone. Tendon: muscle to bone.
• Heart muscle called voluntary. It works by itself.
• All muscle striped. Smooth muscle is not.
• Blood not a tissue. It is connective tissue with a liquid matrix.

Check yourself

1. Which epithelium lines the windpipe, and what does it do?

2. What does a ligament join?

3. A person has $4\ \text{L}$ of blood with $56\%$ plasma. How much plasma?

4. Which part of a neuron carries the message away from the cell body?