Section 9.3 AssignmentThe Central Nervous System

Biology 12S.Dosman

Meninges

• Protective membranes that surround the brain and spinal cord.

Cerebrospinal fluid• Cushioning fluid that

circulates between the innermost and middle membranes of the brain and spinal cord; it provides a connection between neural and endocrine systems.

• It is contained within the ventricular system of the brain and it continuous with the spinal cord.

Olfactory lobes

• Areas of the brain that process information about smell.

• Also known as the olfactory bulbs.

Cerebrum

• Largest and most highly developed part of the human brain, which stores sensory information and initiates voluntary motor activities.

Cerebral cortex

• Outer lining of the cerebral hemispheres.

• The cortex contains groves known as sulci and bumps called gyri.

• The folds and wrinkles increase the surface area of the cerebrum.

Corpus callosum

• Nerve tract that joins the two cerebral hemispheres.

Thalamus

• Area of brain that coordinates and interprets sensory information and directs it to the cerebrum.

Cerebellum

• Part of the hindbrain that controls limb movements, balance, and muscle tone

Pons

• Region of the brain that acts as a relay station by sending nerve messages between the cerebellum and the medulla.

Medulla Oblongata

• Region of the hindbrain that joins the spinal cord to the cerebellum; one of the most important sites of autonomic nerve control.

• http://www.youtube.com/watch?v=UfC4u5GCy3I

1. What are the three membranes that make up the meninges of the brain and what is their function?

• The meninges of the brain are composed of three membranes known as the dura mater, arachnoid mater and the pia mater.

• Together they form the blood-brain barrier which determines what chemicals will reach the brain

2. What is the function of the cerebrospinal fluid and how can it be used to diagnose infection?

• The function of the cerebrospinal fluid is to absorb shock and act as a transport medium that carries nutrients to the brain cells and also relaying wastes from the cells to the blood.

• Doctors can withdraw this fluid in a process known as a lumbar puncture or spinal tap and it can be tested for the presence of bacteria or viruses.

3. Summarize the function, location, and composition of the spinal cord. You may use point form.

• The spinal cord is part of the central nervous system and its function is to carry sensory nerve messages from receptors to the brain and to relay motor nerve messages from the brain to muscles, organs and glands.

• It extends from the base of the brain and through an opening in the skull known as the foramen magnum. It continues down through the openings in the vertebrae and is effectively protected within the backbone.

3. Summarize the function, location, and composition of the spinal cord. You may use point form.

• The spinal cord is composed of both white (myelinated) and grey (nonmyelinated) matter.

• The central grey matter (interneurons) is surrounded by the white matter (sensory and motor neurons).

4. Identify the three distinct regions of the brain. (Hint: they all have the word brain in them!)

• The brain has three distinct regions known as the forebrain, the midbrain and the hind brain.

• Forebrain consists of the cerebrum, thalamus and hypothalamus.

• Midbrain is the top portion of the brainstem and it connects forebrain to hindbrain.

• Hindbrain consists of the cerebellum, pons and medulla oblongata.

5. What happens within the cerebrum of the human brain?

• The cerebrum is the largest portion of the forebrain and it contains a right and left hemisphere.

• It is the major coordinating centre from which sensory information and coordinating motor actions originate.

• It also controls speech, reasoning, memory and personality.

6. What is the difference between the left and right side of the brain and how are they connected?

• The cerebrum has a right and left hemisphere. • The right hemisphere is associated with visual

patterns or spatial awareness.• The left hemisphere is linked to verbal skills. • The hemispheres are connected by the corpus

callosum which allows for communication between the left and right side.

7. What are the four lobes of the brain?

• Each hemisphere of the cerebrum is further divided into four lobes: the frontal lobe, temporal lobe, occipital lobe and the parietal lobe.

• Table 1 on page 429 identifies the four lobes and the functions associated with each lobe and we will explore them in further detail at a later point.

8. Why are there more nerve tracts going to certain areas of the body?

• Certain areas of the body such as the thumb and fingers are capable of and responsible for delicate or fine motor skills.

• Due to this fact they have more nerve tracts leading to them than areas such as the wrist which has limited movements.

9. What occurs in the midbrain?

• The midbrain connects the forebrain and the hindbrain.

• It is composed of four spheres of grey matter and it acts as a relay center for some eye and ear reflexes.

• Portions of the midbrain are also involved in the control of body movement.

• Degeneration of neurons in the midbrain is linked to Parkinson’s disease.

10. What are the parts of the hindbrain?

• The hindbrain is composed of the cerebellum, pons and the medulla oblongata.

• The cerebellum controls limb movements, balance and muscle tone.

• The pons is a relay station that passes information between the two regions of the cerebellum and between the cerebellum and the medulla oblongata.

11. What is the function of the medulla oblongata?

• The medulla oblongata is the connection between the peripheral and the central nervous system.

• It controls involuntary muscle actions such as breathing movements, the diameter of blood vessels and heart rate.

• It also acts as the coordinating center for the autonomic nervous system.

12. How do we know what parts of the brain are responsible for different actions?

• Scientists gathered evidence about the regions of the brain and their associated actions from stroke patients.

• When a stroke occurs brain cells are denied oxygen and nutrients and the cells are damaged. Damage to cells on the right side of the motor cortex affect actions or cause paralysis on the left side of the body.

13. Read the case study on Phineas Gage on page 432. Why do you think he experienced such changes in behaviour following his accident?

• http://www.youtube.com/watch?v=FrULrWRlGBA

• Destroyed connections in his brain controlling social behaviour.

• The iron bar destroyed areas of his frontal lobe, a portion of the brain associated with intellectual activities and personality.