1. THE NERVOUS SYSTEM

2. NEURONS: The structural components of the nervous system…
Objectives:
Structure and mechanism of a neuron (nervous cell).
Types of neurons.

3. NEURONS: The structural components of the nervous system…
Structure and mechanism of a neuron (nervous cell).
Types of neurons.

4. Structure and mechanism of a neuron (nervous cell).
The human body is made up of trillions of cells. Cells of the nervous system, called nerve cells or neurons, are specialized to carry "messages" through an electrochemical process. The human brain has about 100 billion neurons that carry out the nerve impulses through a process called action potential.
A real view showing a neuron (nerve cell)
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5. Structure and mechanism of a neuron (nervous cell).
Neurons are similar to other cells in the body because:
1. Neurons are surrounded by a cell membrane.
2. Neurons have a nucleus that contains genes.
3. Neurons contain cytoplasm, mitochondria and other "organelles".
4. Neurons carry out basic cellular processes such as protein synthesis and energy production.
However, neurons differ from other cells in the body because:
1. Neurons have specialized extensions called dendrites and axons. Dendrites bring information to the cell body and axons take information away from the cell body.
2. Neurons communicate with each other through an electrochemical process.
3. Neurons contain some specialized structures (for example, synapses) and chemicals (for example, neurotransmitters).
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6. Structure and mechanism of a neuron (nervous cell).
Neurons are the oldest and longest cells in the body! You have many of the same neurons for your whole life. Although other cells die and are replaced, many neurons are never replaced when they die. In fact, you have fewer neurons when you are old compared to when you are young. On the other hand, data published in November 1998 show that in one area of the brain (the hippocampus), new neurons CAN grow in adult humans.
Neurons can be quite large - in some neurons, such as corticospinal neurons (from motor cortex to spinal cord) or primary afferent neurons (neurons that extend from the skin into the spinal cord and up to the brain stem), can be several feet long!
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7. Structure and mechanism of a neuron (nervous cell).
A single neuron consist of:
CELL BODY: is the metabolic center of the neuron, contains the Nucleus and Mitochondrion.
DENDRITES: convey incoming messages to the cell body.
AXON HILLOCK: a cone like region from where an axon arises.
AXONS: generates nerve impulses and topically conduct them away from the cell body." A nerve is a group of axons”.
Presynaptic terminals: The swollen, distal end of an axon; contains a neurotransmitter substance within synaptic vesicles. Also called synaptic ending or synaptic bouton.
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8. Structure and mechanism of a neuron (nervous cell).
There are several differences between axons and dendrites:
Axons
Take information away from the cell body
Smooth Surface
Generally only 1 axon per cell
No ribosomes
Can have myelin
Branch further from the cell body
Dendrites
Bring information to the cell body
Rough Surface (dendritic spines)
Usually many dendrites per cell
Have ribosomes
No myelin insulation
Branch near the cell body
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9. Structure and mechanism of a neuron (nervous cell).
What is inside of a neuron? A neuron has many of the same "organelles," such as mitochondria, cytoplasm and a nucleus, as other cells in the body.
Nucleus - contains genetic material (chromosomes) including information for cell development and synthesis of proteins necessary for cell maintenance and survival. Covered by a membrane.
Nucleolus - produces ribosomes necessary for translation of genetic information into proteins
Nissl Bodies - groups of ribosomes used for protein synthesis.
Endoplasmic reticulum (ER) - system of tubes for transport of materials within cytoplasm. Can have ribosomes (rough ER) or no ribosomes (smooth ER). With ribosomes, the ER is important for protein synthesis.
Golgi Apparatus - membrane-bound structure important in packaging peptides and proteins (including neurotransmitters) into vesicles.
Microfilaments/Neurotubules - system of transport for materials within a neuron and may be used for structural support.
Mitochondria - produce energy to fuel cellular activities.
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10. Types of neurons.
Neurons come in many different shapes and sizes. Some of the smallest neurons have cell bodies that are only 4 microns wide. Some of the biggest neurons have cell bodies that are 100 microns wide. (Remember that 1 micron is equal to one thousandth of a millimeter!!).
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11. Types of neurons.
One way to classify neurons is by the number of extensions that extend from the neuron's cell body (soma).
Bipolar neurons have two processes extending from the cell body (examples: retinal cells, olfactory epithelium cells).
Pseudounipolar cells (example: dorsal root ganglion cells). Actually, these cells have 2 axons rather than an axon and dendrite. One axon extends centrally toward the spinal cord, the other axon extends toward the skin or muscle.
Multipolar neurons have many processes that extend from the cell body. However, each neuron has only one axon (examples: spinal motor neurons, pyramidal neurons, Purkinje cells).
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12. Types of neurons.
Neurons can also be classified by the direction that they send information:
Sensory (or afferent) neurons: send information from sensory receptors (e.g., in skin, eyes, nose, tongue, ears) TOWARD the central nervous system.
Motor (or efferent) neurons: send information AWAY from the central nervous system to muscles or glands.
Interneurons: send information between sensory neurons and motor neurons. Most interneurons are located in the central nervous system.
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13. Neuroanatomy and an introduction to the Nervous system.

14. Neuroanatomy and an introduction to the Nervous system.
Neuroanatomy is the structure of the nervous system. To learn how the nervous system functions, you must learn how the nervous system is put together.
the nervous system maintains body homeostasis with electrical signals; provides for sensation, higher mental functions, and emotional response; and activates muscles and glands.
the nerves system is the master controlling and communicating system of the body. Every thought, action and emotion reflects its activity. Its signaling device, or means of communicating with body cells, is electrical impulses, which are rapid and specific and cause almost immediate responses.
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15. Neuroanatomy and an introduction to the Nervous system.
To carry out its normal role, the nervous system has three over lapping functions:
1) Much like a sentry, it uses its millions of sensory receptors to monitor changes occurring both inside and outside the body. These changes are called stimuli, and the gathered information is called sensory input.
2) It processes and interprets the sensory input and makes decisions about what should be done at each moment – a process called integration.
3) It then effects a response by activating muscles or glands (effctors) via motor output.
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16. Structural classification of the nervous system
Objectives:
Central Nervous system (CNS)
Peripheral Nervous system (PNS)

17. Structural classification of the nervous system
The nervous system can be divided into several connected systems that function together. Let's take the simple division:
The Nervous System is divided into:
First: The Central Nervous System
Second: The Peripheral Nervous System
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18. The Central Nervous System
Structural classification of the nervous system
The Central Nervous System
The central nervous system is divided into two parts: the brain and the spinal cord. The average adult human brain weighs 1.3 to 1.4 kg (approximately 3 pounds). The brain contains about 100 billion nerve cells (neurons) and trillions of "support cells" called glia. The spinal cord is about 43 cm long in adult women and 45 cm long in adult men and weighs about grams. The vertebral column, the collection of bones (back bone) that houses the spinal cord, is about 70 cm long. Therefore, the spinal cord is much shorter than the vertebral column.
The Central Nervous System (Brain and Spinal Cord)
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19. The Peripheral Nervous System
Structural classification of the nervous system
The Peripheral Nervous System
The peripheral nervous system is divided into two major parts: the somatic nervous system and the autonomic nervous system.
1. Somatic Nervous System The somatic nervous system consists of peripheral nerve fibers that send sensory information to the central nervous system AND motor nerve fibers that project to skeletal muscle. The picture on the left shows the somatic motor system. The cell body is located in either the brain or spinal cord and projects directly to a skeletal muscle.
2. Autonomic Nervous System The autonomic nervous system is divided into three parts: the sympathetic nervous system, the parasympathetic nervous system and the enteric nervous system. The autonomic nervous system controls smooth muscle of the viscera (internal organs) and glands The preganglionic neuron is located in either the brain or the spinal cord. This preganglionic neuron projects to an autonomic ganglion. The postganglionic neuron then projects to the target organ..
Notice that the somatic nervous system has only one neuron between the central nervous system and the target organ while the autonomic nervous system uses two neurons.
The enteric nervous system is a third division of the autonomic nervous system that you do not hear much about. The enteric nervous system is a meshwork of nerve fibers that innervate the viscera (gastrointestinal tract, pancreas, gall bladder).
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20. Structural classification of the nervous system
In the Peripheral Nervous System, neurons can be functionally divided in 3 ways:
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21. Structural classification of the nervous system
Some differences between the Peripheral Nervous System (PNS) and the Central Nervous System (CNS):
In the CNS, collections of neurons are called nuclei. In the PNS, collections of neurons are called ganglia.
In the CNS, collections of axons are called tracts. In the PNS, collections of axons are called nerves
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22. Structural classification of the nervous system
The following table shows how the nervous system can be divided. The bottom row of the table contains the names of specific areas within the brain. Divisions of the Nervous System
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23. The Brain…
Although some people may think that the brain is like a bowl of jell-O, the brain is NOT a bowl of jell-O. Unlike a bowl of jell-O, the brain is not a uniform material. Rather, the brain is made up of many different areas, each having a particular structure and function.
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24. The skull: home of the brain
Your brain is protected by several bones. There are eight bones that surround your brain: one frontal bone; two parietal bones, two temporal bones, one occipital bone, one sphenoid bone and one ethmoid bone. These eight bones make up the cranium.
Another 14 bones in the face make up the entire skull. There are also 3 small bones in each ear. Also protecting your brain are 3 layers of tissue called the meninges. A few of the bones have been colored in the diagram to the right.
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25. The skull: home of the brain
There is a large opening, called the foramen magnum, located in the back of the occipital bone. This is where the medulla ends and projects out of the skull. Smaller holes in the skull, called foramina, allow nerves and blood vessels to enter and leave the cranium. The picture in the bottom shows the base of the skull. The places in the skull where the bones come together are called sutures. These sutures are flexible in young children, but become fixed as you age.
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26. Divisions of the Brain
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27. Division of the brain
Lobes of the brain
The average human brain weighs about 1,400 grams (3 lb). When the brain is removed from the skull, it looks a bit like a large pinkish-gray walnut. The brain can be divided down the middle lengthwise into two halves called the cerebral hemispheres. Each hemisphere of the cerebral cortex is divided into four lobes by various sulci and gyri...the sulci (or fissures) are the grooves and the gyri are the "bumps" that can be seen on the surface of the brain. The folding of the cerebral cortex produced by these bumps and grooves increases the amount of cerebral cortex that can fit in the skull. (In fact, the total surface area of the cerebral cortex is about 324 square inches - about the size of a full page of newspaper!). Although most people have the same patterns of gyri and sulci on the cerebral cortex, no two brains are exactly alike.
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28. Lobes of the brain Next Division of the brain FRONTAL LOBE
Located in front of the central sulcus.
Concerned with reasoning, planning, parts of speech and movement (motor cortex), emotions, and problem-solving.
PARIETAL LOBE
Located behind the central sulcus.
Concerned with perception of stimuli related to touch, pressure, temperature and pain.
TEMPORAL LOBE
Located below the lateral fissure.
Concerned with perception and recognition of auditory stimuli (hearing) and memory (hippocampus).
OCCIPITAL LOBE
Located at the back of the brain, behind the parietal lobe and temporal lobe.
Concerned with many aspects of vision.
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29. Division of the brain
A top view of the brain
From a top view, notice how the brain is divided into two halves, called hemispheres. Each hemisphere communicates with the other through the corpus callosum, a bundle of nerve fibers. (Another smaller fiber bundle that connects the two hemispheres is called the anterior commissure).
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30. Brain structures
Click on one of the question marks beside each structure to view its characteristics…
hypothalamus
hypothalamus
Brain stem
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31. Cerebral Cortex Functions: Thought Voluntary movement Language
Brain structures
Cerebral Cortex
Functions:
Thought
Voluntary movement
Language
Reasoning
Perception
The word "cortex" comes from the Latin word for "bark" (of a tree). This is because the cortex is a sheet of tissue that makes up the outer layer of the brain. The thickness of the cerebral cortex varies from 2 to 6 mm. The right and left sides of the cerebral cortex are connected by a thick band of nerve fibers called the "corpus callosum." In higher mammals such as humans, the cerebral cortex looks like it has many bumps and grooves. A bump or bulge on the cortex is called a gyrus (the plural of the word gyrus is "gyri") and a groove is called a sulcus (the plural of the word sulcus is "sulci"). Lower mammals, such as rats and mice, have very few gyri and sulci.
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32. Cerebellum Functions: Movement Balance Posture
Brain structures
Cerebellum
Functions:
Movement
Balance
Posture
The word "cerebellum" comes from the Latin word for "little brain." The cerebellum is located behind the brain stem. In some ways, the cerebellum is similar to the cerebral cortex: the cerebellum is divided into hemispheres and has a cortex that surrounds these hemispheres.
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33. Brain stem Functions: Breathing Heart Rate Blood Pressure
Brain structures
Brain stem
Functions:
Breathing
Heart Rate
Blood Pressure
The brain stem is a general term for the area of the brain between the thalamus and spinal cord. Structures within the brain stem include the medulla, pons, tectum, reticular formation and tegmentum. Some of these areas are responsible for the most basic functions of life such as breathing, heart rate and blood pressure.
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34. Hypothalamus Functions: Body Temperature Emotions Hunger Thirst
Brain structures
Hypothalamus
The hypothalamus is composed of several different areas and is located at the base of the brain. Although it is the size of only a pea (about 1/300 of the total brain weight), the hypothalamus is responsible for some very important functions. One important function of the hypothalamus is the control of body temperature. The hypothalamus acts as a "thermostat" by sensing changes in body temperature and then sending signals to adjust the temperature. For example, if you are too hot, the hypothalamus detects this and then sends a signal to expand the capillaries in your skin. This causes blood to be cooled faster. The hypothalamus also controls the pituitary.
Functions:
Body Temperature
Emotions
Hunger
Thirst
Circadian Rhythms

35. Functions: Sensory processing Movement Thalamus
Brain structures
Thalamus
Functions:
Sensory processing
Movement
The thalamus receives sensory information and relays this information to the cerebral cortex. The cerebral cortex also sends information to the thalamus which then transmits this information to other areas of the brain and spinal cord.

36. Midbrain Functions: Vision Audition Eye Movement Body Movement
Brain structures
Midbrain
Functions:
Vision
Audition
Eye Movement
Body Movement
The midbrain includes structures such as the superior and inferior colliculi and red nucleus. There are several other areas also in the midbrain.
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37. Pons Functions: Cardiovascular and respiratory control center.
Brain structures
Pons
Functions:
Cardiovascular and respiratory control center.
The pons are continuous with the medulla

38. Medulla Functions: Heart rate Breathing. Blood pressure.
Brain structures
Medulla
Functions:
Heart rate
Breathing.
Blood pressure.
Swallowing and vomiting
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39. She brain – He brain
Bigger - Stronger - Faster...are there really any differences between female brains and male brains? Differences between the brains of men and women have generated considerable scientific and public interest. If there are differences in the way that men and women behave, then it is reasonable to suppose that their brains have something to do these behavioral differences. Just what are these differences and where in the brain might these differences be located?
For hundreds of years, scientists have searched for differences between the brains of men and women. Early research showing that male brains were larger than female brains was used to "prove" that male brains were superior to female brains. Of course, this "proof" is NOT so simple and straight forward as you will see. Nevertheless, even today, there is plenty of controversy about the differences in the brains of men and women. Not only from an anatomical point of view, but also from a functional point of view - in other words, just what do the differences in the brains mean?
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40. Women and Men - Boys and Girls
She brain – He brain
Hormones that are present during a baby's development will affect the brain and determine whether the brain will be female or male. Studies that have looked at differences in the brains of males and females have focused on:
Total Brain Size
The Corpus Callosum
The Hypothalamus
Women and Men - Boys and Girls
The behavioral and neurological differences between men and women require further study. Perhaps new studies will find neuroanatomical differences that explain some of the complex differences between male and female behavior. However, from a review of the current scientific evidence, it appears that differences in many cognitive behaviors (for example, memory) are related more to individual differences between people than to whether people are female or male.
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41. How the nervous system interacts with other body systems.
Objectives:
skeletal system
cardiovascular system
muscular system
endocrine system
lymphatic system
respiratory system
digestive system
reproductive system
urinary system

42. How the nervous system interacts with other body systems.
All of the systems within the body interact with one another to keep an organism healthy. Although each system has specific functions, they are all interconnected and dependent on one another. The nervous system controls various organs of the body directly. The brain also receives information from many organs of the body and adjusts signals to these organs to maintain proper functioning.
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