Texts for additional reading

Text 1

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Anatomy and Physiology of the Nervous System

Nervous system is the vast network of cells specialized to carry information (in the form of nerve impulses) to and from all parts of the body in order to bring about bodily activity. The brain and spinal cord together form the central nervous system. The central nervous system controls the voluntary muscles of the head, trunk, and the limbs, and it is responsible for all movement in them and for all sensation in skin, muscles, bones and joints. The remaining nervous tissue is known as the peripheral nervous system and includes the autonomic nervous system which controls all involuntary muscles. It supplies all the internal organs, and is made up of nerve cells (neurons) supplying the glands and the muscular walls of the internal organs and the blood vessels. The autonomic nervous system is divided into the sympathetic and parasympathetic nervous systems.

Sympathetic nervous system has fibers that leave the central nervous system in the thoracic and lumbar regions. Sympathetic nerves are distributed to the blood vessels, heart, lungs, intestines and other abdominal organs, sweat glands and salivary glands.

Parasympathetic nervous system has fibers that leave the central nervous system from the brain and the lower portion of the spinal cord. The nerves are distributed to blood vessels, glands, and the majority of internal organs. The system works in balance with the sympathetic nervous system.

In human beings the nervous system has the ability to form cortical associations. All the human beings have this function which is formed upon signalization. It is a process in which the stimulus produces the same range of reactions as the stimulus with which it is associated. Such reflexes are called conditioned. And the stimuli producing reactions which don’t depend on surrounding conditions are called unconditioned.

 

1. Answer the following questions:

1. What is the main function of the nervous system?

2. What is the central nervous system formed by?

3. What does the central nervous system control?

4. What does the peripheral nervous system include?

5. How are nerve cells called?

6. Where are the nerves of sympathetic nervous system distributed?

7. What works in balance with sympathetic nervous system?

8. What is called conditional reflexes?

 

2. Complete the sentences:

1.… supplies all the internal organs, and is made up of nerve cells.

2. … form the central nervous system.

3. … includes the autonomic nervous system which controls all involuntary muscles.

4. … are distributed to blood vessels, glands, and the majority of internal organs.

5. The autonomic nervous system is divided into….

6. … are distributed to the blood vessels, heart, lungs, intestines and other abdominal organs, sweat glands and salivary glands.

 

 

Text 2

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The Brain

The brain (cerebrum) is the enlarged and highly developed mass of nervous tissue that forms the upper end of the central nervous system. The average adult human brain weighs about 1400 g and is continuous below with the spinal cord. The spinal cord is the portion of the central nervous system enclosed in the vertebral column, consisting of nerve cells and bundles of nerves connecting all parts of the body with the brain. It contains a core of grey matter and is enveloped in three layers of membrane (the meninges) and extends from the medulla oblongata in the skull to the level of the second lumbar vertebra.

The brain is a complicated organ which consists of grey matter or nerve cells on the surface, and white matter or nerve fibers in the center. It contains many important nerve centers which make it not only the largest but the most important part of the brain.

The functions of the brain. The role of nervous system in our body is often compared to that of a centralized computer which controls the functioning of an entire system. The nervous system plays an important role in the smooth functioning of the different parts of our body. It is basically a complex network of cells with specialized functions. These cells communicate with each other by means of electrochemical waves. The neurons are the important components of the nervous system.

Central nervous system is the seat of all sensation due to the bringing in of the stimuli from the tissues by afferent fibers to the sensory centers of the brain. These stimuli pass through three or more afferent neurons before they reach the sensory centers of the cerebrum. Central nervous system controls all movements of voluntary muscles – muscles of the head, limbs and trunk. Movement is due to nerve stimulus. Movement is classified as voluntary and reflex one. The brain is the special seat of all the special senses – sight, hearing, smell, touch, and taste. The brain is the seat of all the higher mental powers – reasoning, will power, consciousness, memory, emotions, etc. The brain also controls the vital functions of the respiration and circulation, the controlling centers being located in the medulla.

 

1. Answer the questions:

1. What is the brain?

2. What is the average weight of the human brain?

3. What is the spinal cord like?

4. Where does the spine extend?

5. What parts does the brain comprise?

6. What is the most important part of the brain?

7. What is the role of nervous system in the body?

8. What processes does CNS control?

9. What is movement due to?

 

2. Match terms with their definitions:

1. 2. 3. 4. 5. 6. 7.

consciousness   spinal cord   sensitivity   stimulus   brain   memory   medulla

a) It is the center of the nervous system in all vertebrate animals. It is located in the head, usually close to the primary sensory organs for such senses as vision, hearing, balance, taste, and smell; b) It is the ability to remember past experiences, and the power or process of recalling to mind previously learned facts, experiences, impressions, skills and habits; c) In physiology it is a detectable change in the internal or external environment; d) The ability of an organism or organ to respond to external stimuli; e) It is the quality or state of being aware of an external object or something within oneself; f) It is the part of the brainstem that is situated between the pons and the spinal cord; g) It is a long, thin, tubular bundle of nervous tissue and support cells that extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column.

 

Text 3

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The Urinary System

The urinary system is a group of organs in the body concerned with filtering out excess of fluid and wastes from the bloodstream. Wastes in the blood come from the normal breakdown of active tissues and from food. The body uses food for energy and self-repairs. After the body has taken what it needs from food, wastes are sent to the blood.

The urinary system keeps the chemicals and water in your body balanced. A type of waste called urea is removed from the blood by the urinary system. Urea is produced when foods containing protein, such as meat, are broken down in the body. Urea is carried in the bloodstream to the kidneys.

The urinary system consists of two kidneys, which secrete the urine, the ureters, or ducts, which convey urine to the urinary bladder, where it is stored for some time; and the urethra, through which it is discharged from the body.

The kidneys are paired bean-shaped organs with two surfaces, two borders, and an upper and lower extremity. There are three major regions of the kidney: the renal cortex, the renal medulla and the renal pelvis. The kidneys are situated in the posterior part of the abdomen, behind the peritoneum. They are covered by the renal capsule. The left kidney is longer and narrower, than the right one.

There are more than 1000000 nephrons in each kidney. The nephron carries out nearly all of the kidney's functions. Its chief function is to regulate the concentration of water and soluble substances like sodium salts by filtering the blood, reabsorbing what is needed and excreting the rest as urine. The nephron eliminates waste substances from the body, regulates blood volume and blood pressure, controls levels of electrolytes and metabolites, and regulates blood pH. The inflammation of nephrons in the kidneys is called nephritis.

The ureters are two tubes which measure from 25 to 30 cm in length. They convey the urine from the kidneys to the urinary bladder. Muscles in the ureter walls continually tighten and relax forcing urine away from the kidneys. If urine backs up or stands still, a kidney infection can develop.

The urinary bladder is a triangle-shaped, hollow musculomembranous organ. It is located in the lower part of the abdomen and is held in place by ligaments that are attached to other organs and the pelvic bones. The urinary bladder is a temporary storage for the urine. The bladder's walls relax and expand to store urine, and contract to empty it. Nerves in the bladder alert a person when it is time to urinate.

The urethra is a tube that connects the urinary bladder with the outside of the body. Male and female urethra differs in shape and length. Male urethra length varies from 17.5 to 20 cm; and it is divided into three portions, the prostatic, membranous, and cavernous. The female urethra is a narrow membranous canal, about 4 cm. long. The brain signals the bladder muscles to tighten, which squeezes urine out of the bladder. At the same time, the brain signals the sphincter muscles to relax to let urine exit the bladder through the urethra. When all the signals occur in the correct order, normal urination occurs. Normal urine is sterile fluid. It contains fluids, salts and waste products, but it is free of bacteria, viruses and fungi.

 

1. Answer the questions:

1. What does the urinary system consist of?

2. What is urine?

3. Where are the kidneys situated?

4. What is the function of nephrons?

5. What is the function of the ureters?

6. Where is the urine stored before it is discharged from the body?

7. What is urethra?

8. What is the function of the urethra?

9. What conveys urine from the kidneys?

10. What is the function of the urinary bladder?

 

2. Fill in the gaps with words from the box:

nephrons

urine

bladder

kidneys

wastes

urea

ureters

nerves

 

1. … in the blood come from the normal breakdown of active tissues.

2. Normal … contains fluids, salts and waste products.

3. … usually holds 300-350 ml of urine.

4. … carry urine from the kidneys to the bladder.

5. All the blood in our bodies passes through … several times a day.
6. Urine is formed by … together with water and other waste substances.

7. A person gets an alarm from the … in the bladder when it is time to urinate.

8. In humans, a normal kidney contains 800,000 to 1.5 million ….

 

3. Agree or disagree with the following statements:

1. Urine is stored in the urethra before discharging from the body.

2. A nephron regulates the concentration of water and soluble substances.

3. The urinary bladder is a hollow bean-shaped organ, which discharges urine from the body.

4. The ureters convey the urine from the kidneys to the urinary bladder.

5. Kidney is a muscular sac which stores the urine before eliminating it from the body.

6. The urine is discharged from the body through the ureters.

7. Urethra is a tube that connects the kidney and the urinary bladder.

8. The main function of the ureters is to regulate the concentration of water and soluble substances.

 

Text 4

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