Human Body Systems

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Human Body Systems

• 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)

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

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Examples of Feedback Inhibition

• III. Maintaining Homeostasis
• Negative feedback your bodys response results
  in decreasing the effect of the stimulus (e.g.
  body temperature)

Section 35-1
Sensed by
Room Temperature Drops
Room temp. rises
Thermostat
Signals
Heater to turn on
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• Positive feedback your bodys response results
  in an increase in the effect of the stimulus,
  (e.g. the flight-fight response)

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Nervous System

• Recognizes and coordinates the bodys 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

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• Organization of the NS

• Central N.S.
• 1. Brain
• 2. Spinal Cord
• B. Peripheral N.S.
• 1. Somatic N.S.
• 2. Autonomic N.S.
• a. Sympathetic
• b. Parasympathetic

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Nervous System

• Division of Labor
• Central Nervous System (CNS)
• Control center of the body that relays messages,
  and processes and analyzes information
• Brain
• 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

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Nervous System

• Brain stem connects the brain and spinal chord
  two regions pons and medulla oblongata, control
  breathing, heart rate and swallowing
• Thalamus and hypothalamus - between brain stem
  and cerebrum
• Thalamus relay station for sensory info
• Hypothalamus most important homeostatic site
  hormones, bodys thermostat, fight or flight,
  thirst, hunger, reproduction

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Draw Fig. 35-9 The Brain
Cerebrum
Thalamus
Pineal gland
Hypothalamus
Cerebellum
Pituitary gland
Pons
Spinal cord
Medulla oblongata
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Nervous System

• Spinal Cord
• Two main fxns
• Processing of simple responses to certain stimuli
  (reflexes)
• Carries info to and from brain to body

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Nervous System

• Peripheral Nervous System (PNS)
• Receives information from the environment and
  relays to and from CNS and sensory, motor and
  gland cells

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Nervous System

• Two divisions
• Sensory - Made of sensory neurons that bring info
  to the CNS
• Motor - Made of sensory neurons that convey info
  from the CNS two subdivisions
• Somatic (voluntary) respond to external stimuli
• Autonomic (involuntary) respond to internal
  stimuli w/the parasympathetic and sympathetic
  divisions
• Sympathetic ?energy consumption
• Parasympathetic ?energy consumption

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• Nervous System Flow Chart

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Nervous System

• Neurons (Nerve Cells)
• Specialized cells that carry electrical signals
  called impulses (Draw Fig. 35-5 pg. 897)
• 3 Types of Neurons
• 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

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Nervous System

• Anatomy of a Neuron
• 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
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Nervous System

• Dendrites
• Carry impulses from the environment or other
  neurons to the cell body

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Nervous System

• Axon
• Long fiber that carries impulses from the cell
  body
• Ends in axon terminals that contain vesicles for
  neurotransmitters

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Nervous System

• Myelin Sheath
• Insulates the axon
• Gaps in the myelin sheath allow an impulse to
  jump from node to node, thus increasing its speed

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Which part of the neuron is yellow? Which parts
are blue?
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The Nerve Impulse

• 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)

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The Resting Neuron (cont)

• 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.

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The Moving Impulse

• 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.

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_
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The Moving Impulse (cont)

• 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)

_

_
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The Moving Impulse (cont)

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

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Nerve Impulse Summary
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Nerve Impulse Pathway Overview

• 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.

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Nerve Impulse Pathway (cont)

• The neurotransmitters diffuse across the synapse
  and attach themselves to receptors on dendrite of
  neighboring cell

Direction of Impulse
Dendrite of adjacent neuron
Axon
Receptor
Vesicle
Axon terminal
Synaptic cleft
Neurotransmitter
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Nervous System

• Reflexes
• 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)
• Effector responds to the impulses by contracting
  (hand gets pulled away from the heat)

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Nervous System

• 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

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Nervous System

• Nervous System Disorders
• Migraine Headaches caused by change in
  serotonin levels? (affected by caffeine,
  estrogen, certain foods)
• Parkinsons caused by damage to dopamine
  transmitters causes uncontrollable shaking, no
  cure
• 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 (Alzheimers) memory loss and
  personality change.

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Nervous System

• 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
• When effect wears off, brains supply is depleted
• Caffeine
• Cocaine
• Methamphetamines

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Nervous System

• Depressants
• Slow down HR, lower BP and breathing rate, relax
  muscles and relieves anxiety
• Alcohol
• Marijuana
• Sleeping Pills

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Commonly Abused Drugs
Commonly Abused Drugs
Section 35-5
Used to increase alertness, relieve
fatigue Used to relieve anxiety, irritability,
tension Used to relieve pain
Stimulants Depressants Opiates
Amphetamines Barbiturates Tranquilizers M
orphine Codeine
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
Drug Type
Medical Use
Examples
Effects on the body