102.8 The nervous system

Lower leg and foot nerves

1. Sciatic 2. Tibial 3. Common peroneal 4. Deep peroneal 5. Superficial peroneal 6. Dorsal 7. Saphenous 8. Sural

Ophthalmic branch (top 1/3 of face)

1. Supraorbital 2. Supratrochlear 2a. Infrateochlear 3. Nasal

The nervous system is divided into three subsystems

1. The central or cerebrospinal nervous system 2. The peripheral nervous system 3. The autonomic nervous system

Arm and hand nerves

1. Ulnar 2. Radial 3. Median 4. Digital

Cervical nerves originate in the spinal cord with branches into the scalp and neck

14. Greater occipital 15. Lesser occipital 16. Greater auricular 17. Cervical 18. Accessory

Skin

20 feet of the body, largest organ. Releases water, carbon dioxide and other waste through sweat glands.

Maxillary ( Middle 1/3 of the face)

4. Zygomatic 5. Infraorbital

Mandibular (lower 1/3 of face)

6. Auriculotemporal 7. Mental

Lungs

Are spongy organs composed of cells into which air enters when you inhale. These cells process oxygen for absorption into the blood and release carbon dioxide as you exhale.

Digestive (gastrointestinal) system

Breaks food down into simpler chemical compounds that can be easily absorbed by cells, or if not absorbed, eliminated from the body in waste products.

Dendrites

Bring information to the cell body

Motor (efferent) Nerves

Carry messages from the brain to the muscles and glands

Sensory (afferent) Nerves

Carry messages to the brain and spinal cord.

Endocrine system

Composed of a group of specialized ductless glands that regulate and control the growth, reproduction and health of the body. It directly affects hair growth, skin conditions and energy levels.

The spinal cord

Composed of long nerve fibers, originates in the base of the brain and extends to the base of the spine. The spinal cord holds 31 pairs of spinal nerves that branch out to muscles, internal organs and skin

The peripheral nervous system

Composed of sensory and motor nerves that extend from the brain and spinal cord to other parts of the body. This network of nerve cells carries messages to and from the central nervous system.

The central (cerebrospinal) nervous system

Composed of the brain, spinal cord, and spinal and cranial nerves . The central nervous system is responsible for all voluntary action.

The brain

Controls the nervous system. Referred to as the command center. The average adult human brain weighs between 45-49 ounces.

Liver

Converts and neutralizes ammonia from the circulatory system to urea.

Nephrons

Filters waste products and water, allowing unstable nutrients to be reabsorbed into the blood. Excreted waste products travel through the ureter and bladder and are eliminated from the body in urine.

Kidneys

Receives urea from the liver and then pass the urea through small tub like structures known as nephrons.

The autonomic nervous system

Responsible for all involuntary body functions, operates: the digestive, excretory, respiratory, circulatory, endocrine and reproductive systems.

Reproductive system

Responsible for the process by which a living organism procreates. Estrogen and testosterone are two hormones produced by it.

Trifacial nerve

The Chief sensory nerve, responsible for transmitting facial sensations to the brain and for controlling the motor nerve function of chewing (Mastication)

Axons

take information away from the cell body in the form of nerve impulses

Excretory system

Eliminates solid, liquid and gaseous waste products from the body includes: skin, liver, and the kidneys.

Facial nerve

Emerges from the brain at the lower part of the ear and is the primary motor nerve of the face. Controls muscles of facial expression and sensation from the skin and tongue. Of its many branches there are 6 important ones: 8.Posterior auricular 9. Temporal 10. Zygomatic 11. Buccal 12. Marginal mandibular 13. Cervical cutaneous

Nerve cells (Neuron)

Has a nucleus, cytoplasm and membrane. Differ in appearance from other cells due to long and short threadlike fibers called axons and dendrites that extend from the cell.

Respiratory system

Made up of organs and tissues that help you breathe. Primary functions: .The intake of oxygen to be absorbed into the blood . The exhalation of Oxygen's toxic byproduct, carbon dioxide. Primary organs: the lungs, and diaphragm.

Diaphragm

Muscular organ that separates the chest cavity from the abdomen. The diaphragm expands and contracts automatically, forcing air into and out of the lungs.

Receptors (sensory nerve endings)

Send sensory messages like touch, temperature, sight, sound, taste, smell, pain and pressure to the brain for processing.