1. Human Regulation
© Lisa Michalek

2. Regulation
Regulation is the life process by which cells and organisms respond to changes in and around them.
The actions of the nervous and endocrine systems control and regulate the body.
These two systems allow us to adjust to internal as well as external environmental changes.

3. Nerve Regulation There are three parts to nerve regulation:
The stimulus
The response
The impulse
A stimulus is a specific change in the environment that affects the nervous system.
A response is a reaction to this stimulus.

4. Nerve Regulation
Many organisms and glands of the body receive stimuli that are translated into impulses.
An impulse is an electrical or chemical message that is carried by nerve cells.
The impulses are then transferred to the central nervous system (brain and spinal cord).
The central nervous system then sorts out and interprets the incoming impulses.
The impulse is then sent to organs or glands.
These organs and glands provide responses to these impulses.

5. Human Nervous System
The human nervous system includes the brain, spinal cord, and nerves that lie outside of the brain and spinal cord.
Nerve cells receive impulses and send them to various body parts.

6. Nerve Cells Nerve cells are also called neurons.
A nerve cell is made up of a
Cell body – containing the nucleus and cytoplasm
Dendrites – branched parts that receive impulses from other neurons or sense organs
Axon – a single, long fiber that carries impulses away from the cell body

7. Nerve Cells
Between the dendrites of one neuron and the axon of another is a space called a synapse.
Impulses cross the synapse by means of chemical neurotransmitters.

8. Nerves A nerve is a bundle of neurons or parts of neurons.
Nerves can be classified as
Sensory – carry impulses to the brain and spinal cord
Motor – carry impulses from the brain and spinal cord to the various body parts such as muscles or glands
Mixed – contain both sensory and motor fibers
A nerve fiber is like a telephone line carrying messages to and from your home.

9. The Brain The brain is the major control center of the body.
The bones of the skull surround and protect the brain.
The cerebrum, cerebellum, and medulla are three parts of the brain.

10. The Brain - Cerebrum
The cerebrum is the center of thinking, memory, emotions, sensory impulse interpretation, and all voluntary activity.
It is the largest part of the brain.
When you take a test, you are using your cerebrum.

11. The Brain - Cerebellum
The cerebellum is responsible for coordination of muscles and is the center of balance.
When you bounce a basketball, you are using your cerebellum.
Alcohol reduces the ability of the cerebellum to coordinate muscle activity.
This results in slurred speech and unbalanced walking.

12. The Brain - Medulla
The medulla or brain stem is the center of respiration, heartbeat, and other involuntary activities.
Your medulla is controlling all the activities of your body that you cannot control such as breathing and peristalsis.

13. The Spinal Cord
The spinal cord is the tubular mass of nerve cells that extends from the brain stem downward through the center of the spinal column.
It is surrounded and protected by the vertebrae of the spinal column (backbone).
The spinal cord relays impulses to and from the brain and is the center of some reflex actions.

14. Receptors
Receptors are special structures that are sensitive to stimuli.
Receptors receive messages.

15. External Receptors External receptors, called sense organs include
Eyes
Ears
Nose
Tongue
Skin.

16. Internal Receptors
Internal receptors are located in the internal organs
They allow the brain to detect
Hunger
Thirst
Muscle position
Carbon dioxide levels in the blood.

17. Involuntary Behavior
The total response of an organism to stimuli is known as behavior.
The response may be inborn or learned, voluntary or involuntary.
Examples of Involuntary behaviors that occur automatically without conscious control include:
Contraction of heart and diaphragm muscles
Secretion of glands
Simple reflexes ( knee jerk and iris movement)

18. Involuntary Behavior
Examples of Involuntary actions that are acquired by the individual through repetition include:
Writing one’s name
Riding a bike
Playing a musical instrument

19. The Reflex The reflex is an example of involuntary behavior.
A reflex action does not require thought; it is an automatic action.
Blinking and the knee jerk are examples of a reflex.

20. Voluntary Behavior Voluntary behaviors require thinking.
The impulses start in the brain and are carried by nerve cells to muscles or glands.
The muscles or glands respond in a certain way.
Voluntary actions include
Measuring with a meter stick
Picking up a book
Building a model airplane.

21. Nervous System Disorders
Paralysis is caused by severe damage to the spinal cord.
It results in the loss of feeling and muscle function in the lower parts of the body.
Paralysis occurs because impulses to and from the lower body muscles cannot be transmitted to the brain.

22. Nervous System Disorders
Meningitis is an inflammation of the membranes that surround the brain and spinal cord.
The disease is caused by bacteria.
The symptoms include severe headache and stiffness of the neck.
Meningitis can be fatal.
Antibiotics are used to treat meningitis.

23. Nervous System Disorders
Polio is a viral disease of the central nervous system that can cause paralysis.
It can be prevented by immunization.

24. Drugs and the Nervous System
Drugs affect the nervous system in many different ways.
Some drugs create a feeling of euphoria (well-being).
Other drugs cause a decrease in inhibitions, or an inability to stop doing something that a person would not normally do.
Using some drugs results in tolerance when they are taken continually for a few weeks.
This means that increasingly larger amounts are needed to get the desired effect.

25. Drugs and the Nervous System
There are some drugs that cause stimulation (excitement) and feelings of high energy.
Physical dependence, or addiction, can result from using drugs.
When the drug is withheld, the addict suffers physical illness and withdrawal symptoms.

26. Chemical Regulation
The endocrine system is responsible for chemical regulation.
Stimuli may cause certain glands to secrete chemical messengers known as hormones.
These hormones cause other parts of the body to respond.

27. Human Endocrine System
The endocrine system includes the endocrine glands and their hormones.
The glands of the endocrine system release hormones directly into the bloodstream.
The bloodstream transports hormones throughout the body.
Each hormone acts on a certain kind of tissue.

28. Endocrine System Disorders
Diabetes
The pancreas does not release enough insulin to break down sugar.
This causes high blood sugar.
Diabetes is controlled by diet or insulin injection after eating.