16: Coordination in Humans

Question 1

State the two main parts that the human nervous system consists of.

Answer 1

Central nervous system and periphery nervous system.

Question 2

State the organs and nerves the central nervous system consists of.

Answer 2

Brain and spinal cord.

Question 3

State the organs and nerves the periphery nervous system consists of.

Answer 3

Cranial nerves and spinal nerves.

Question 4

State the difference between cranial nerves and spinal nerves.

Answer 4

Cranial nerves link receptors and effectors in the head and the neck to the brain, while spinal nerves link receptors and effectors in the rest of the body to the spinal cord.

Question 5

Give two examples of cranial nerves.

Answer 5

Optic nerve and auditory nerve.

Question 6

Name three parts which a neurone consists of.

Answer 6

Cell body, dendrons, axons.

Question 7

State the difference between dendrons and axons.

Answer 7

Dendrons transmit nerve impulses towards the cell body, while axons transmit nerve impulses away from the cell body.

Question 8

State the names and properties of the branches of dendrons and axons respectively.

Answer 8

Dendrons branch into dendrites, which receive information from receptors or other neurones.
Axons branch into synaptic knobs with swollen tips, which have vesicles containing neurotransmitters.

Question 9

State the nature of myelin sheath.

Answer 9

It is a lipid covering around nerve fibres.

Question 10

State two functions of the myelin sheath.

Answer 10

It insulates nerve fibres, thus preventing the transmissions of nerve impulses to the surroundings.
It also speeds up the transmission of nerve impulses.

Question 11

State the types of neurones.

Answer 11

Sensory neurones, interneurones, and motor neurones.

Question 12

State the difference in the direction of nerve impulse of the sensory neurone, interneurone, and motor neurone.

Answer 12

Sensory neurones transmit nerve impulses from the receptors to the central nervous system.
Interneurones transmit nerve impulses from a sensory neurone to a motor neurone.
Motor neurones transmit nerve impulses from the central nervous system to the effectors.

Question 13

State the type(s) of neurone with a long axon.

Answer 13

Motor neurone

Question 14

State the type(s) of neurone with a long dendron.

Answer 14

Sensory neurone

Question 15

State the type(s) of neurone with a short axon and a short dendron.

Answer 15

Interneurone

Question 16

State the type(s) of neurone with dendrons connected to receptors.

Answer 16

Sensory neurone

Question 17

State the type(s) of neurone with axons connected to effectors.

Answer 17

Motor neurone

Question 18

State the type(s) of neurone with both dendrons and axons connected to other neurones.

Answer 18

Interneurone

Question 19

State the type(s) of neurone with cell body outside the central nervous system.

Answer 19

Sensory neurone

Question 20

State the definition of a synapse.

Answer 20

A synapse is a narrow gap between the axon ending of one neurone and the dendron of the next neurone.

Question 21

Describe the transmission of nerve impulses across a synapse.

Question 22

State two importances of synapses.

Answer 22

Synaptic vesicles containing neurotransmitter are present only in the endings of axons, so the synapsed allow nerve impulses to travel in one direction only.
Usually a neurone form synapses with more than one other neurone. This allows one neurone to communicate with many other neurones. The complex network of neurones enables the nervous system other than achieve coordination that involves many receptors and effectors.

Question 23

State three tissues which protect the spinal cord.

Answer 23

Vertebral column, three meninges, and cerebrospinal fluid

Question 24

Where is fluid located around the spinal cord?

Answer 24

It is in the spaces between the inner and middle meninges, and in the central canal of the spinal cord.

Question 25

State three functions of cerebrospinal fluid to the spinal cord.

Answer 25

1. It acts as a **shock absorber**. 2. It provides **mechanical support** to the spinal cord. 3. It **provides nutrients and oxygen** to the neurones in the spinal cord and **removes wastes** from them.

Question 26

State the locations of the three regions of a cross section of the spinal cord.

Answer 26

The outer region is made up of **white matter**, while the inner **H-shaped region** is made up of **grey matter**. At the centre of the grey matter is the **central canal**.

Question 27

State the difference between grey matter and white matter.

Answer 27

Grey matter consists mainly of **cell bodies** of neurones, while white matter consists of **nerve fibres only**.

Question 28

How many pairs of spinal nerves are there in our body?

Answer 28

31

Question 29

State the differences between the dorsal root and the ventral root.

Answer 29

The dorsal root contains **sensory neurones** which transmit nerve impulses from receptors to the spinal cord, while the ventral root contains **motor neurones** which transmit nerve impulses from the spinal cord to the effectors. The cell bodies of sensory neurones group together outside the spinal cord in the dorsal root to form a swelling called the **dorsal root ganglion**, while there is **no swelling** in the ventral root since the cell bodies of motor neurones are located in the **grey matter** of the spinal cord.

Question 30

State two functions of the spinal cord.

Answer 30

It **relays nerve impulses** between the brain and other parts of the body. It is the **reflex centre** for many reflex actions.

Question 31

Use 5 words to describe the nature of a reflex action.

Answer 31

Inborn, rapid, automatic, involuntary, stereotyped.

Question 32

Explain why a reflex action is involuntary.

Answer 32

It does not involve the cerebrum of the brain.

Question 33

Explain how a reflex action is stereotyped.

Answer 33

The same stimulus always results in the same response.

Question 34

State the difference between spinal reflex and cranial reflex.

Answer 34

Spinal reflexes are reflex actions that involve the spinal cord, while cranial reflexes are reflex actions that involve the brain.

Question 35

Give 2 examples of spinal reflexes.

Answer 35

Knee jerk reflex, withdrawal reflex

Question 36

Give 6 examples of cranial reflexes.

Answer 36

Saliva secretion, swallowing, blinking, sneezing, coughing, dilation and constriction of the pupil.

Question 37

Describe the pathway of the shortest reflex arc.

Answer 37

Receptor -> sensory neurone -> motor neurone -> effector

Question 38

Describe the nervous pathway of the withdrawal reflex.

Question 39

State all neurones which are involved in withdrawal reflex.

Answer 39

There are 3 neurones: sensory neurone, interneurone, and motor neurone.

Question 40

State the importance of withdrawal reflex.

Answer 40

Nerve impulses travel along the reflex arc very quickly. This **rapid withdrawal** of the hands from the sharp object helps **protect the body from further damage**.

Question 41

Describe the nervous pathway of the knee jerk reflex.

Question 42

State all neurones which are involved in knee jerk reflex.

Answer 42

There are 2 neurones: sensory neurone and motor neurone.

Question 43

State the importance of knee jerk reflex.

Answer 43

It helps to maintain **body posture and balance**.

Question 44

State three structures which protect the brain.

Answer 44

Cranium, three meninges, cerebrospinal fluid.

Question 45

State three functions of cerebrospinal fluid to the brain.

Answer 45

1. It acts as a **shock absorber**. 2. It provides **mechanical support** to the brain. 3. It **provides nutrients and oxygen** to the neurones in the brain and **removes wastes** from them.

Question 46

State the three main parts of the brain.

Answer 46

Cerebrum, cerebellum, medulla oblongata

Question 47

State the two parts the cerebrum is divided into.

Answer 47

Left cerebral hemisphere and right cerebral hemisphere.

Question 48

State the way the two cerebral hemispheres connected and the importance.

Answer 48

They are connected with each other by nerve fibres for communication.

Question 49

State the properties of the cerebral cortex.

Answer 49

It is the **outer part** of the cerebrum, and it is made up of **grey matter**. It consists mainly of **cell bodies of neurones**. It is **highly folded** to increase its capacity enabling it to **hold more neurones** in a limited space.

Question 50

State the properties of the inner part of the cerebrum.

Answer 50

It is made up of **white matter** and it consists of **nerve fibres** only.

Question 51

State the three areas the cerebral cortex is divided into.

Answer 51

Sensory areas, motor areas, and association areas.

Question 52

State the function of the sensory areas.

Answer 52

They receive **nerve impulses** from **receptors** and interpret them to give **sensations**.

Question 53

State the function of the motor areas.

Answer 53

They **send nerve impulses** to **effectors** to produce **voluntary responses**.

Question 54

State the function of the association areas.

Answer 54

They **integrate** information from different sensory areas and relate the information to past experience. The brain makes decisions and **sends nerve impulses** to the **motor areas** to give a response.

Question 55

State the type of matter making up the cerebellum.

Answer 55

The outer part of the cerebellum is made up of **grey matter** and its inner part is made up of **white matter**.

Question 56

State the functions of the cerebellum.

Answer 56

The cerebellum receives sensory information about body movement from the ears, eyes, muscles and joints. It then **coordinates muscular actions** for smooth body movements such as walking, dancing and writing. It is also important in **maintaining body posture and balance**.

Question 57

State the type of matter making up the medulla oblongata.

Answer 57

The outer part of the medulla oblongata is made up of **white matter** and its inner part is made up of **grey matter**.

Question 58

State the functions of the medulla oblongata.

Answer 58

It controls many **involuntary actions** such as breathing and heart beat. It is the **reflex centre** for many cranial reflexes.

Question 59

State the difference between voluntary action and involuntary action.

Answer 59

Voluntary actions are actions that are **under conscious control**, while involuntary actions **occur automatically** and are **not under conscious control**.

Question 60

State the difference between involuntary action and reflex action.

Answer 60

A reflex action must require a **stimulus**, but involuntary actions **may not require a stimulus**.

Question 61

Describe the nervous pathways of a voluntary action.

Question 62

State the difference between endocrine glands and exocrine glands.

Answer 62

Endocrine glands have **no ducts** while exocrine glands do. Endocrine glands secrete hormones **directly into the blood**.

Question 63

Give 6 examples of major endocrine glands.

Answer 63

Pituitary gland, thyroid gland, adrenal glands, pancreas, ovaries, testes

Question 64

State the nature of hormones.

Answer 64

They are mostly **protein or lipid** in nature.

Question 65

State the functions of hormones.

Answer 65

They serve as **chemical messengers**, which are important for the **regulation of body processes** and **internal environment**.

Question 66

State the properties of the actions of hormones.

Answer 66

They are produce in **very small amounts** by the endocrine glands. They trail throughout the body, but **only act on target organs** whose cells have **receptors** specific to those hormones. The action of hormones is **wide-spread** and they usually have a **long-lasting effect**.