Diamond Learning Academy

Happy 56th Independence Day to my Mother land
ZAMBIA 🇿🇲🇿🇲🇿🇲🇿🇲🇿🇲🇿🇲🇿🇲

Happy national day of Prayer and Reconciliation.

BIOLOGY CORNER

Muscles:
A muscle is a tissue which contracts to produce movements in parts of the body or the entire body.

There are three types of muscles, namely,
- cardiac muscle,
- smooth muscle (visceral muscle)
- skeletal muscle (striated muscle).

1. Cardiac muscle
is found in the heart and has the following characteristics:
-It is myogenic (self-stimulating),meaning that the stimulus for contraction originates
from the muscle itself
- It does not get fatigued
- The muscle cells (muscle fibres) are branched and interconnected forming a net-like structure
- The muscle cells die easily when deprived of oxygen and food or exposed to toxins.

2. Smooth muscles (visceral muscles)
-are made of long, spindle-shaped cells and are found in the walls of several body tubes and organs.
NOTE:
Rings of smooth muscles are called sphincters.

3. Skeletal muscles
- are muscles which are attached to the skeleton and play a major role in
locomotion.
NOTE:
When viewed under the microscope they look striped (striated) and are therefore called striated muscles.
-They are multinucleated (each muscle cell has several nuclei).
- Skeletal muscles are voluntary while cardiac and smooth muscles are involuntary.
NOTE:
A voluntary muscle is a muscle whose contraction is consciously controlled by the brain.

-Skeletal muscles occur in pairs known as antagonistic muscles.
-Antagonistic muscles are
pairs of muscles which produce movement in opposite directions at the same joint.
The muscle that causes bending of the joint when it contracts is called a flexor muscle while the one that causes extending of the joint when it contracts is called the extensor muscle.
NOTE:
Skeletal muscles occur in antagonistic pairs because each muscle can only contract but requires the contraction of another muscle to relax or lengthen it.
-Examples of antagonistic muscles are the biceps and triceps which act on the elbow joint.
-The biceps are the flexor muscles while the triceps are the extensor muscles.

Tips on answering examination questions part two (2)
7. Describe and explain
‘Describe and explain’ means you give a reason for each point you give in your description.

8. Calculate/ find
To calculate means you workout the answer to a numerical problem. You show all your working so that even if you
make a mistake you will still get some marks. Make sure that you work in SI units and always give your final answer in SI units. Sometimes Find can be used instead of calculate. Find may mean measure.

9. Give three reasons / examples
This tells you how many reasons or examples, which are different from each other, to give. There are no extra marks
for giving more than what you are asked to give.

10. Compare
Compare means point out the differences and similarities. Explain which are which, do not just make two lists.

11. Outline
This requires a leaner to give a briefly over view of the topic. The number of marks will help you decide how much is
needed. Restrict your answer to main points only.

12. Predict
‘Predict’ or ‘ deduce’ means that you do not have to remember the answer. Instead you get the answer by applying the
logic to other information in the question.