The Function of the Nervous System

A. Receives informationB. Transmits the informationC. Sorts and interprets the incoming informationD. Determines a responseE. Transmits the responseF. Activates the response.

Neuron StructureA.Parts of a Neuron:

1. Dendrites – short branches of a neuron that receives stimuli and conduct impulses to the cell body.2. Cell Body – the center of metabolic activity in a neuron, it is where the nucleus and much of the cytoplasm are located.3. Axon – the long fiber that carries impulses away from the cell body.

Dendrites

Cell Body

Axon

Synapse

Neuron Structure, cont.4. Synapse- is a small space

between the axon of one neuron and the dendrites of an adjacent neuron.

In order for an impulse to be carried on, the synapse must be crossed.

Chemicals called neurotransmitters are released by the ends of the axons and are received by the dendrites to carry on the impulse.

If the synapse is blocked in any way, the nerve impulse cannot be conducted.

Dendrites

Cell Body

Axon

Synapse

Types of Neurons

1. Sensory Neurons – carry impulses from outside and inside the body to the brain and spinal cord.

2. Motor Neurons – carry response impulses from the brain and spinal cord to muscles or glands.

3. Interneurons - connect sensory neurons and motor neurons and carry impulses between them. They are concentrated in the brain and spinal cord.

Human Nervous System

Central Nervous System

Peripheral Nervous System

A B

C D

Cerebrum Cerebellum

Brainstem

Conscious Control Unconscious

Control

BrainSpinal Cord

Brainstem

Medulla oblongata

Hypothalamus

Thalamus

Somatic Nervous System

Autonomic Nervous System

Reflex Arc

2 divisions: Sensory (From sense organs to Brain) & Motor Divisions (From CNS to muscles or glands)

CENTRAL NERVOUS SYSTEM

Consists of the brain and spinal cord.

It is the control center.

It relays messages, processes information, compares and analyzes the information, and coordinates the body’s activities.

The Brain

a. Cerebrum – Divided into two halves called hemispheres. Controls conscious activities, intelligence, memory, language, skeletal muscle movements, and senses.

b. Cerebellum – Controls balance, posture, and coordination of muscle movements.

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2

4

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5

3

Cerebrum

Cerebellum

The Brain, cont.c. Medulla Oblongata –

Controls involuntary functions such as breathing, blood pressure, heart rate, swallowing, and coughing.

d.Thalamus – Passes information to proper region of cerebrum for further processing.

e. Hypothalamus – Controls center for hunger, thirst, fatigue, anger, and body temperature.

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2

4

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5

3

Thalamus

Medulla Oblongata

Pons

Hypothalamus

The Brain, cont.

f. Pituitary Gland—the master control gland; the gland that triggers all other glands.

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3

Pituitary Gland

Spinal Cord

Relays information to and from the brain.

PERIPHERAL NERVOUS SYSTEM

* consists of all nerves running to and coming from the brain and spinal cord. * makes contact with the body’s environment. * consists of all the nerves and associated cells that are not part of the brain and spinal cord.

There are two parts of the peripheral nervous system: the autonomic nervous system and the somatic nervous system.

Human Nervous System

Central Nervous System

Peripheral Nervous System

A B

C D

Cerebrum Cerebellum

Brainstem

Conscious Control Unconscious

Control

BrainSpinal Cord

Brainstem

Medulla oblongata

Hypothalamus

Thalamus

Somatic Nervous System

Autonomic Nervous System

Reflex Arc

2 divisions: Sensory (From sense organs to Brain) & Motor Divisions (From CNS to muscles or glands)

Somatic Nervous System

regulates activities under conscious control such as movement of skeletal muscles.Reflexes— Receptors in the skin stimulate the sensory

neurons to carry impulses to the spinal cord. Before the information is relayed to the brain, a group of neurons in the spinal cord called interneurons automatically activates motor neurons, causing the muscle to contract.

Examples: Step on a tack Touch a hot object React to a loud noise

A “reflex arc” is the route followed by nerve impulses to produce an involuntary response to a stimuli (a reflex).

Autonomic Nervous System

Regulates activities that are automatic.

Carries impulses from the central nervous system (CNS) to the internal organs and is involuntary.

Sensory Division

transmits impulses from sense organs – such as the ears and taste buds – the CNS.

Motor Division

transmits impulses from the CNS to the muscles or glands.

They are all controlled by hormones!

What do all these pictures have in common?

The Endocrine System

Function:Controls all of the metabolic activities of body structures; includes all of the glands in the body that secrete chemical messengers called hormones which travel in the blood stream to target tissues where they alter the metabolism of the target tissue.

The Endocrine System

Comparison to Nervous System:The endocrine system is slower and uses chemical messengers called hormones sent throughout the blood stream.

The nervous system is faster than the endocrine system and operates by use of electrical impulses and neurotransmitters.

The Endocrine System

Comparison to Nervous System:The hypothalamus and the pituitary glands are the major areas where the nervous system and endocrine system interact. The hypothalamus controls the secretions of the pituitary gland. The pituitary gland secretes hormones that affect other glands in the body. The level of hormones secreted by those glands signal the hypothalamus. By monitoring these signals, the hypothalamus maintains the correct level of hormones.

NAME LOCATION HORMONES FUNCTIONS

Pituitary Under the hypothalamus at the base of the brain

1. TSH – thyroid stimulating hormone2. GH – growth hormone3. FSH/LH- Reproduction Hormones4. ADH – antidiuretic hormone

1. Regulates thyroid

2. Stimulates growth of bones3. Regulate reproduction cycle

4. Helps kidneys reabsorb water

Thyroid Base of neck 1. Thyroxine 1. Regulates metabolic rate

Adrenal Top of the kidneys 1. Adrenalin 1. Regulates normal body functions, example:Increase sodium and potassium levels in bloodIncrease rate of metabolism of carbohydrates, fats and proteinsIncrease blood pressureIncrease blood sugar levels“fight or flight” response

Pancreas Behind the stomach 1. Insulin 2. Glucagon

1. 2. Regulates the release and storage of blood sugars

Ovaries Lower abdomen (see Fig. 42-3) 1. Estrogen2. Progesterone

1. Estrogen – female secondary sexual characteristics2. Progesterone – prepares the uterus for an embryo

Testes Lower abdomen 1. Testosterone and other androgens

1. Sperm production and male secondary sexual characteristics