Incisors- cut food Canines- tear food Pre-molars



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Class Notes for Health Unit 2 Teeth, Nervous, Skeletal and Muscular Systems
Four Types of Teeth

  1. Incisors- cut food

  2. Canines- tear food

  3. Pre-molars- crush food

  4. Molars- grind food

Basic Structure of a Tooth



  1. Crown- part of tooth above the gum line

  2. Root- part of tooth below the gum line

  3. Enamel- hard outer layer of each tooth. It is the hardest substance in the human body

  4. Dentin- yellowish bonelike substance that surrounds the pulp cavity

  5. Cementum- outer covering of the dentin

  6. Pulp- soft tissue filling the center of each tooth

  7. Gingiva- gum tissue

  8. Root Canal- area containing the nerve of the tooth


Primary Teeth- first set of twenty teeth (10 upper, 10 lower)

Permanent Teeth- second set of thirty two teeth (16 upper, 16 lower)
Plaque- a colorless film of bacteria covering each tooth. If not removed, the plaque creates an acid that destroys the tooth enamel
Tartar- hardened plaque that will irritate the gums and cause them to bleed. This is gingivitis. If not treated it may lead to severe gum disease
Halitosis- bad breath
Dental Care- well balanced diet, regular dental visits for cleaning, daily brushing and flossing
The Nervous System
The nervous system is responsible for sending outgoing (efferent) electrical messages and receiving incoming (afferent) electrical messages (impulses)
The Neuron

The basic cell of the nervous system has four parts



  1. Dendrites- carry the message to the cell body

  2. Cell Body (Soma)- contains the DNA and controls the growth and reproduction of the cell

  3. Axon- carries the message away from the cell body

  4. Terminal Endings or Axon Terminal- passes the message to the dendrites of the next neuron either electrically or chemically

Between any two neurons is a space or gap called the synapse


CNS (Central Nervous System) - comprised of brain and spinal cord
PNS (Peripheral Nervous System)- comprised of the nerves that emerge from the brain stem and spinal cord and lead to the extremities
The Autonomic Nervous System is a sub system of the peripheral nervous system. It is responsible for:

  1. Coordinating nutrition

  2. Removing waste products

  3. Responding to Stress

The Autonomic Nervous System is composed of two additional sub systems, the sympathetic and parasympathetic nervous systems.
The sympathetic nervous system prepares the body for stressful situations, controls blood pressure, heart rate and respiration. This is also referred to as the “fight or flight response”.
The parasympathetic controls more vegetative activities such as consumption, digestion of food and reproduction. We refer to this as the “feed or breed response”.
Chemicals called neurotransmitters are located in the terminal endings of the neuron. These chemicals transfer the message from one neuron to another.
There are three types of neurons:

  1. Sensory- carry the need of the body to the CNS

  2. Inter-neurons- interpret the need of the body and send a command message

  3. Motor- execute the command

The Brain
Cerebrum- larger, upper part of the brain responsible for conscious thought, learning and memory
Cerebellum- smaller, lower part of the brain responsible for skeletal muscular movement
The brain sits in the cranium and is covered by a protective membrane called the meninges

The meninges has three layers



  1. Dura Mater (Latin for hard mother). It is the outer layer

  2. Arachnoid layer- the middle layer receives it’s name from it’s resemblance to a spider’s web

  3. Pia Mater (Latin for soft mother). It is the inner layer

Both brain and spinal cord are surrounded by the meninges as well as cerebrospinal fluid
The cerebrum has two sides called the left and right hemispheres. The hemispheres seem to be separated by a space called the longitudinal fissure.

The hemispheres are actually connected by tissue called the corpus callosum


The right hemisphere controls the left side of the body and visa versa

People are said to be “right brained” or “left brained”. This is not right or left handedness.

The right side of the brain is responsible for are creativity and abstract thinking skills

The left side of the brain is our analytical, ordered side.


The cerebral cortex (surface of the brain) is composed of “folds of tissue” called convolutions
The cerebrum is divided into regions or lobes. They have different responsibilities

  1. Frontal lobe- voluntary movement

  2. Temporal lobe- hearing, smelling (olfactory), memory and thought judgment

  3. Parietal lobe-sensory information, heat, cold, pain, touch and body positions

  4. Occipital lobe- vision

The Cerebellum lies inferior and dorsal to the cerebrum and dorsal to the pons and medulla oblongata. It is the control center for voluntary muscular movement


The Brain Stem- is located inferior to the cerebrum and ventral to the cerebellum. It is composed of the following structures

  1. Pons- breathing and eye movements

  2. Medulla Oblongata- breathing, heart rate and swallowing

  3. Midbrain- vision

  4. Spinal Cord- approximately 44 cm. long (18 inches). It is the center for reflex action

The spinal cord sits inside the vertebral column and is also protected by the meninges and cerebrospinal fluid

Electrical impulses (messages) are sent along the pathways of neurons in the human body at the speed of 300 ft. /sec. (200-300 mph)


Disorders of the Nervous System
Spinal Meningitis- inflammation of the meninges caused by a virus, bacteria or other organism causing fever, headaches, back pains, vomiting and possible spotting of the skin
Epilepsy- a condition caused by irregular brain impulses. The impulses causes seizures of two types

  1. Petit Mal (French for small illness)- patient appears to be day dreaming

  2. Grand Mal (French for large illness)- loss of consciousness, involuntary muscular contractions (convulsions)

The drug of choice is Dilantin although other anti-epileptic drugs exist


The Skeletal System
The skeleton gives the body shape and protection. Of the 206 bones in the human body, 80 are in the trunk or torso (body without the head and limbs) and 126 are in the extremities
All bone begins as cartilage (dense connective tissue similar to bone but more flexible)
Bones continue to form and harden during a process called ossification. This process continues until the age of 25 when minerals change most of the calcium in the body to bone
Osteoporosis- when bones become thinner and more porous usually as a result of age
Red Marrow- soft inner tissue of bone concerned with the production of red blood cells and hemoglobin (iron protein which carries oxygen and gives blood its red color)
Yellow Marrow- soft inner tissue of bone consisting of primarily fat cells
Joints or Articulations- where two or more bones meet in the body and are connected by ligaments

  1. Hinge- has a 180° forward and backward range of motion. Examples are the knee and elbow

  2. Ball and Socket- has a 360° range of motion. The round end of one bone fits into the cavity of another bone. Examples are the shoulder and hip

  3. Pivot- permits rotation of a bone around a fixed point. Example is the neck

  4. Gliding- opposing bones move freely providing a slight movement or gliding movement. Example is the wrist


Bones to Know

  1. Cranium- skull

  2. Clavicle- collar bone

  3. Sternum- breast bone

  4. Scapula- shoulder blade

  5. Vertebral Column- backbone

  6. Ribs

  7. Humerus- arm

  8. Radius and Ulna- fore arm

  9. Pelvic Girdle- pelvic area

10. Sacrum- base of vertebral column

11. Coccyx- tailbone

12. Carpals- wrist

13. Metacarpals- hand

14. Phalanges- fingers and toes

15. Femur- thigh (largest bone in the human body)

16. Patella- kneecap

17. Tibia and Fibula- leg (tibia is larger)

18. Tarsals- ankle

19. Metatarsals- foot



The Muscular System
Muscle tissue is made of fibers. The fibers are composed of smaller myofibrils. This produces the strength of the muscle.
When a muscle is stimulated it shortens in length or contracts. Muscle tissue has several properties

  1. Irritability- changes is response to the environment

  2. Conductivity- electric ability of the muscle

  3. Elasticity- ability to return to its original size after contraction


Types of Muscle Tissue

  1. Smooth- cells are arranged in sheets or layers. Found in internal organs

  2. Striated- fibers are grouped into bundles. Found in skeletal muscles

  3. Cardiac- fibers branch out forming a network. Found in the heart tissue (myocardium)



Tendons- connective tissue connecting muscle to bone
All muscles have two connection points

  1. Point of origin- fixed attachment point

  2. Point of insertion- movable part the muscle is attached to

Isometric contraction- tension increases but not the length

Isotonic contraction- muscle changes its length during the action
Fatigue- if the muscle is continuously stimulated, the strength of the contraction will become progressively less until the muscle refuses to contract (buildup of CO2 and lactic acid)
Major Muscles to Know


  1. Stenocleidomastoid- Location: neck. Action: turns head sideways and flexes head forward

  2. Trapezius- Location: upper back and neck. Action: raises shoulders and draws head back

  3. Deltoid- Location: shoulder. Action: raises arms

  4. Pectoralis Major- Location: chest. Action: brings arms across chest

  5. Latissimus Dorsi- Location: lower back. Action: Rotates arms inward

  6. Biceps Brachii- Location: superior, anterior portion of arm. Action: flexes arm

  7. Triceps- Location: superior, posterior portion of arm. Action: extension of arm

  8. Rectus Abdominus- Location: abdomen. Action: flexes the trunk

  9. Quadriceps- Location: front thigh (group of four muscles). Action: extension of leg

10. Hamstrings- Location: rear thigh (also a muscle group). Action: flexion of leg

11. Gastrocnemius- Location: calf. Action: extends foot



12. Tibialis Anterior- Location: front of leg. Action: flexion of foot

Disorders of the Skeletal and Muscular Systems
Fracture- a break in the bone

  1. Hairline- bone is cracked only

  2. Simple or Closed- bone is broken, no external wound

  3. Compound or Open- bone is broken and there is an external wound

  4. Complicated- bone is broken and injures an internal organ


Cramp- painful contraction of a muscle. A muscle spasm. Usually caused by dehydration
Scoliosis- curvature of the spine


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