HUMAN SEXUAL CHARACTERISTICS

There are two types of human sexual characteristics:

-Primary sexual characteristics enable human beings to reproduce. We have these when we are born.

-Secondary sexual characteristics differentiate men and women. They develop at puberty.

  - Men have lower voices, more developed muscles and a lot of facial and body hair.

  - Women have higher voices, breasts, wider hips and little body hair.

PUBERTY

Puberty occurs when the reproductive system matures, and secondary sexual characteristics appear.

Puberty starts when the pituitary gland sends hormones to the genital organs.

As a result of this, changes occur in boys and girls and their secondary sexual characteristics develop.

- Girls reach puberty between the ages of 11 and 14.

- Boys reach puberty between the ages of 13 and 15.

ACTIVITY "SEXUAL CHARACTERISTICS"

ANSWER THE FOLLOWING QUESTIONS:

1. When do secondary sexual characteristics develop?

2. Do men or women have more facial and body hair?

3. What gland sends hormones to the genital organs?

4. Which sexual characteristics do we have when we are born?

THE REPRODUCTIVE SYSTEM

Both the male and female reproductive systems consist of internal and external genital organs.

THE FEMALE REPRODUCTIVE SYSTEM

The female internal genital organs are:

- The ovaries:they produce the eggs necessary for reproduction.

- The Fallopian tubes: they connect the ovaries to the uterus.

-The uterus:is the organ where the baby develops during the pregnancy.

-The vagina: it is a channel which goes from the uterus to the outside of the body.

The female external genital organs have a collective name- the vulva.

The vulva includes creases of skin called labia, the clitoris, and the openings to the vagina and the urethra.

THE MALE REPRODUCTIVE SYSTEM

The male internal genital organs are:

- Two testicles or testes: They produce the sperm cells necessary for reproduction.

- The vas deferens: sperm travels through this tube to the uretha.

- The urethra: sperm travels through this passage to the outside of the body.

- The semical vesicles and the prostate gland: they produce a liquid to feed and transport sperm.

The male external genital organs are:

- The scrotum: it is a bag of skin which contains the testicles.

- The penis: the urethra passes through this organ.

ACTIVITY " THE REPRODUCTIVE SYSTEM"

READ THE DEFINITIONS AND WRITE THE CORRESPONDING WORDS

1. These organs produce sperm cells.

2. This is the bag of skin which contains the testicles.

3. This is the organ where the baby develops during pregnancy.

4. These connect the ovaries to the uterus.

5. These organs produce the female eggs necessary for reproduction.

A REFLEX MOVEMENT CONTROLLED BY THE SPINAL CORD

- First, the skin receives information.

- Next, the nerves transmit the information to the spinal cord.

- Then, the spinal cord receives the information and sends a command.

- After that, nerves transmit the command to the arm muscles.

- Finally, the muscles contract and the arm moves away.

INTERNAL COORDINATION

INTERNAL PROCESSES

The nervous system controls and coordinates al the body´s internal processes, such as the beating of the heart and the digestion of food.

To do this, it controls involuntary muscles and the endocrine system.

INVOLUNTARY MUSCLES

Involuntary muscles work automatically. We cannot control them with our decisions.

The body needs involuntary muscles in order to function correctly.

THE ENDOCRINE SYSTEM

The endocrine system is responsible for functions such as growth and reproduction.

It consist of endocrine glands, which secrete substances called hormones into the bloodstream.

ENDOCRINE GLANDS

The principal glands in the endocrine system are:

-Thyroid gland: it produces the hormone thyroxin, which enables the body to absorb nutrients.

-Pancreas:it produces insulin, which controls the amount of sugar in the bloodstream.

-Ovaries (female) and testes (male): they produce sex hormones, which are responsible for reproduction.

-Pituitary gland:it coordinates other endocrine glands and also produces growth hormone.

ACTIVITY "INTERNAL COORDINATION"

MATCH THE TWO HALVES OF EACH SENTENCE

1.The endocrine system                                 a.produces insulin.

2.The thyroid gland                                       b.produces the growth hormone.

3.Thyroxin enables the body                          c.is responsible for growth and reproduction.

4.The pancreas                                             d. to absorb nutrients.

5.Insulin controls                                           e.produces thyroxin.

6.The pituitary gland                                      f.the amount of sugar in the bloodstreeam.

THE MUSCULAR SYSTEM

The muscular system consists of all the muscles in the body.

The muscular system:

- Enables the body to move.
- Gives the body its shape.
- Protects organs, such as the liver.

Muscles can change in length:

- When they contract, they become shorter and thicker.

- When they relax, they return to their original length and thickness.

Tissues called tendons connect muscles to bones.

MOVEMENT

Body movement occurs at movable joints.Two muscles are used in each movement.

These muscles are called antagonistics because they perform opposite actions. When one muscle contracts, the other relaxes.

For example, arms bend at the elbow with a flexing movement. They straighten with an extending movement.

ACTIVITY " THE MUSCULAR SYSTEM"

TRUE OR FALSE? DECIDE IF THE FOLLOWING STATEMENTS ARE TRUE OR FALSE. IF THEY ARE FALSE, CORRECT THEM.

1. When muscles contract, they become longer.
2. When muscles relax, they return to their original length and thickness.
3. Tendons connect the bones of a joint.
4. Antagonistic muscles perform the same actions.
5. Arms bend at the elbow with a flexing movement.

REFLEX AND INVOLUNTARY MOVEMENTS

There are two types of movements:

- Reflex movements: these are involuntary movements in response to external stimuli.

- Voluntary movements: these movements are the result of decisions.

NEURONS

NEURONS are the principal cells of the nervous system. They receive and transmit information. They are grouped together to form nerves.

PARTS OF THE NERVOUS SYSTEM

The central nervous system consists of the brain and the spinal cord. This system receives information, interprets it, and decides on a response.

The brain has three parts:

- The cerebrum controls voluntary movements.

- The cerebellum coordinates movements and maintains balanced.

- The brain stem regulates internal organs.

The spinal cord controls reflex movements.

The peripherial nervous system consists of nerves. It transmits information from the sense organs to the central nervous system and from the central nervous system to other organs.

THE NERVOUS SYSTEM

FUNCTIONS

The nervous system sends and receives information.

It coordinates the functions of internal organs.

It also coordinates systems like the digestive system.

ACTIVITY " THE NERVOUS SYSTEM"

READ THE FOLLOWING DEFINITIONS AND WRITE THE CORRESPONDING WORDS:

1. This part of the brain controls voluntary movements.
2. This part of the brain coordinates movements and maintains balance.
3. This part of the brain regulates internal organs.
4. These are the principal cells of the nervous system.
5. These are involuntary movements in response to external stimuli.

THE MUSCULOSKELETAL SYSTEM

The musculoskeletal system consist of the skeleton and the muscular system. Both systems work together to make the body move.

THE SKELETON

The skeleton consist of all the bones in the body.

It supports the body, and enables us to move. It protects delicate organs, such as the heart, lungs and brain.

JOINTS

Joints are the places where two bones meet.
There are:

- Fixed joints, such as the skull.

-Movable joints, such as the knee or elbow.

-Gliding joints, such as between vertebrae.

The ends of the bones are covered with flexible tissue called cartilage. The bones of a joint are connected by strong elastic tissues called ligaments.

ACTIVITY "THE SKELETON"

WRITE THE WORDS OF EACH SENTENCE IN THE CORRECT ORDER TO MAKE SENSE

1. body / supports / the / the / skeleton.

2. meet / places / bones / two / joints / where / are / the.

3. ends / the / of / cartilage / covers / bones / the.

4. flexible / cartilage / tissue / is.

5. elastic / strong / ligaments / are / tissue.