Human Body Systems
I.
A.
B.
C.
D.
Organization of the Body (Review)
Cells
 Basic unit of structure and function
Tissues
 Group of cells that perform a single function
(e.g. epithelial, connective, nervous, muscle)
Organs
 Different types of tissues that work together to perform a closely related function (e.g. eye, liver, lungs)
Organ Systems
 Group of organs that perform closely related functions
(e.g. circulatory, respiratory, digestive)

II.
A.
Definition: the process by which organisms keep internal conditions relatively constant despite changes in their external environments
B.
Requires the integration of all organ systems at the same time
C.
Nervous system in conjunction with the endocrine system (hormones) is responsible for this integration

Examples of Feedback Inhibition
A. Negative feedback – your body’s response results in decreasing the effect of the stimulus
(e.g. body temperature)
Sensed by
Room Temperature
Drops
Room temp. rises Thermostat
Signals
Heater to turn on

B.

Nervous System

I.
A.
B.
C.
Recognizes and coordinates the body’s response to changes in its internal and external environments.
General Functions of the Nervous System
Sensory input – vision, hearing, balance, smell, taste, and touch
Motor output – muscle contraction and movement
Memory and integration of information

II. Organization of the NS
A. Central N.S.
1. Brain
2. Spinal Cord
B. Peripheral N.S.
1. Somatic N.S.
2. Autonomic N.S.
a. Sympathetic b. Parasympathetic

Nervous System
III.
A.
Central Nervous System (CNS)

1.
Control center of the body that relays messages, and processes and analyzes information
Brain a.
b.
Cerebrum – largest region; right and left hemispheres that are connected by corpus
callosum; voluntary activities and higher brain functions
Cerebellum – located at the lower back part of brain; coordination and balance

Nervous System c.
Brain stem – connects the brain and spinal chord; two regions: pons and medulla oblongata, control breathing, heart rate and swallowing d.
Thalamus and hypothalamus - between brain stem and cerebrum
Thalamus: relay station for sensory info
Hypothalamus: most important homeostatic site; hormones, body’s thermostat, fight or flight, thirst, hunger, reproduction

Cerebrum
Thalamus
Pineal gland
Hypothalamus
Pituitary gland
Pons
Medulla oblongata
Cerebellum
Spinal cord

Nervous System
2.

2.
1.

Nervous System
B.


Nervous System

1.
2.
Two divisions: a.
b.
Sensory - Made of sensory neurons that bring info to the
CNS
Motor - Made of sensory neurons that convey info from the CNS; two subdivisions
1)
2)
Somatic (voluntary): respond to external stimuli
Autonomic (involuntary): respond to internal stimuli w/the parasympathetic and sympathetic divisions
Sympathetic ↑energy consumption
Parasympathetic ↓energy consumption

Nervous System
Brain
Central NS Peripheral NS
Spinal chord
Sensory Division Motor Division
Sympathetic
(activities that increase energy consumption)
Autonomic NS
(Involuntary)
Somatic NS
(Voluntary)
Parasympathetic
(activities that gain and conserve energy)

Nervous System
IV.

Neurons (Nerve Cells)
A.
Specialized cells that carry electrical signals called impulses (Draw Fig. 35-5; pg. 897)
3 Types of Neurons:
1.
2.
3.
Sensory – carry impulses from the sense organs to the spinal cord and brain
Motor – carry impulses from brain and spinal cord to muscles and glands
Interneurons – Connect sensory and motor neurons and carry impulses between them

Nervous System
B.
Anatomy of a Neuron
1.
Cell Body
 Largest part of the neuron
 Contains the nucleus and most of the cytoplasm
 Metabolic activity takes place in the cell body
Cell
Body

Nervous System
2.
Dendrites
 Carry impulses from the environment or other neurons to the cell body

Nervous System
3.

Axon
Long fiber that carries impulses from the cell body
 Ends in axon terminals that contain vesicles for neurotransmitters

Nervous System
4.

Myelin Sheath
Insulates the axon
 Gaps in the myelin sheath allow an impulse to jump from node to node, thus increasing its speed

Which part of the neuron is yellow ? Which parts are blue ?

A.
1.
The Resting Neuron
At rest, the outside of the cell has a net positive charge and the inside has a net negative charge.
This charge difference is called the resting
potential.
(-70mVolts, about 5% of the voltage in AA battery)

2.
3.
The charge difference is created by active transport of ions across the cell membrane via the sodium-potassium pump.
Sodium ions (Na+) are pumped outside the cell and potassium (K+) ions are pumped into the cell.

1.
2.
An impulse begins when a neuron is stimulated by the axon of another neuron or by the environment.
Na+ pores open and the flood of Na+ ions makes the inside positive.
_
+
+
_

3.
4.
This reversal of charges, from negative to positive is called a nerve impulse, or an action potential.
As the impulse passes, K+ pores open and K+ flows out which restores the resting potential (charge difference)
+
_
+
_

5.
How do things get back to the original condition?
6.
The sodium potassium pump kicks in.
The minimum level of a stimulus that is required to activate a neuron is called the threshold.

1.
2.
3.
Impulse is received by the dendrites from the environment or another neuron, then gets rapidly channeled through the cell body to the axon
Axon branches out into axon terminals, which contain tiny vesicles filled with neurotransmitters, which are chemicals used by a neuron to transmit an impulse to another cell. (e.g. acetylcholine, serotonin, dopamine and adrenalin).
Vesicles release neurotransmitters into the open space between neurons called the synapse.

4.
The neurotransmitters diffuse across the
synapse and attach themselves to receptors on dendrite of neighboring cell
Axon
Vesicle
Axon terminal
Synaptic cleft
Direction of Impulse
Dendrite of adjacent neuron
Receptor
Neurotransmitter

Nervous System
VI.


Reflexes
1.
2.
3.
4.
Reflexes are automatic responses to stimuli
Controlled by 5-part reflex arc:
Sensory receptors on finger reacts to stimulus (heat)
Impulse is carried to the spinal cord by a sensory neuron
In the spinal cord, the impulse is transferred by an
interneuron to motor neuron
Motor neurons conducts the impulse to an effector
(arm muscles)
5.
Effector responds to the impulses by contracting (hand gets pulled away from the heat)

Nervous System
VIII.

A.
B.
C.
D.
The Senses
5 General Sensory Receptors: pain, thermo-, mechano-, chemo- and photoreceptors.
Where do you think these different types of receptors are found and what is their function?
Vision
Hearing and Balance
Smell and Taste
Touch

Nervous System
IX.
A.
Nervous System Disorders
Migraine Headaches – caused by change in serotonin levels? (affected by caffeine, estrogen, certain foods)
B.
Parkinson’s –caused by damage to dopamine transmitters; causes uncontrollable shaking, no cure
C.
D.
Tay-Sachs –lack enzyme to break down fatty deposits in the brain; neurological deterioration; death by age 4-5
Dementia - damaged brain cells caused by injury or disease
(Alzheimer’s); memory loss and personality change.

Nervous System
X.
A.
Drugs and the Nervous System
Stimulants
 Accelerate HR, BP, and breathing rate
 Increases the release of neurotransmitters; leads to release of energy and feeling of well-being

1.
2.
3.
When effect wears off, brain’s supply is depleted
Caffeine
Cocaine
Methamphetamines

Nervous System
B.
1.
Depressants
 Slow down HR, lower BP and breathing rate, relax muscles and relieves anxiety
Alcohol
2.
3.
Marijuana
Sleeping Pills

Section 35-5
Commonly Abused Drugs
Drug Type
Stimulants
Medical Use
Used to increase alertness, relieve fatigue
Examples
Amphetamines
Depressants Used to relieve anxiety, irritability, tension
Barbiturates
Tranquilizers
Opiates Used to relieve pain Morphine
Codeine
Effects on the body
Increase heart and respiratory rates; elevate blood pressure; dilate pupils; decrease appetite
Slow down the actions of the central nervous system; small amounts cause calmness and relaxation; larger amounts cause slurred speech and impaired judgement
Act as a depressant; cause drowsiness, restlessness, nausea