Download Regulation Systems: Nervous and Endocrine Systems

Regulatory Systems:
Nervous and
Endocrine Systems
Function of
Regulation
Systems:
regulate the activities of the other systems
to make sure homeostasis is maintained
(homeostasis: keeping the internal environment of
the body constant; for example, body
temperature, blood pressure)
Nervous System
Uses Electrical signals (impulses) along nerves
Chemical signals (neurotransmitters) to
pass the impulse to the next cell
Endocrine
System
Uses:
Hormones made in
glands
The bloodstream for
transmission
The NERVOUS SYSTEM
Nervous system Functions:
Receive Stimulus
Integrate the
Input
Send out motor
commands
Neurons - Functional Units
Neurons (aka nerve cells):
•Generate and transmit
nerve impulses
•Have three main parts:
•Cell body – contains nucleus and other organelles
•Dendrite – receives impulse from another neuron
•Axon – sends impulses to other neurons, muscles or glands
•The axons of some neurons have a myelin sheath for
protection and faster transmission.
Neurons
The impulse is
transmitted:
Dendrites
Cell body
Axon
Cell body
Axon terminal
Axon
Dendrites
Myelin sheath
Types of Neurons
Sensory neurons
sense stimuli caused by changes in the internal or
external environment
Interneurons
integrate signals from different parts of the nervous
system
Motor neurons
transmit signals to muscles and glands
Muscles contract
Glands secrete substances
Types of Neurons
Sensory
Neuron
Interneuron
Motor
Neuron
The Nerve Impulse
• Transmission of
nerve impulses
depends upon a
difference in
charge across the
cell membrane.
• The interior of
neurons is more
negatively charged
compared to the
outside
Channel proteins
maintain the polarity
This is called its
Resting Potential
•Sodium ions are concentrated outside of the cell,
potassium ions are concentrated inside the cell
The Nerve Impulse
The transmission of a nerve impulse is rapid and selfpropagating (like dominoes)
The major players:
•
sodium ions (Na+) usually found outside the cell
•
potassium ions (K+) usually found inside the cell
•
sodium protein channels in the cell membrane
•
potassium protein channels in the cell membrane
The Nerve Impulse
The nerve impulse is transmitted along the neuron by
reversing the negative charge along the membrane
Inside becomes more positive than outside
This is called the action potential
Sodium channels open in part
of the membrane and Na+
ions enter the cell
Cell is more negative outside
As Sodium channels close
Potassium channels open
and K+ ions leave the cell
Cell is more positive outside
Sodium channels open in the
area next to the original
action potential, passing the
impulse along
Sodium-Potassium Pump
moves 3 sodium ions out of
the cell and 2 potassium ions
inside the cell, restoring the
original positions of ions
The Nerve Impulse
Sodium – Potassium Pump is Active transport:
Moving substances across membrane from lower to higher
concentration requires cell to expend energy.
The Nerve Impulse
Saltatory conduction:
Transmission of the action potential in myelated
axons (faster than in non myelated axons)
The Nerve Impulse
Summary:
• Resting (no impulse): Inside more negative than outside.
• Sodium ions (Na+) move inside through protein channels
 makes the inside of the cell less negative  action
potential generated
• The action potential travels along the axon (like dominoes
or in jumps (myelated axons))  nerve impulse
• Potassium ions (K+) move outside the cell through protein
channels negative charge restored inside the cell
• Sodium-Potassium Pump restores positions of ions
(sodium out, potassium in)
Until the position of the ions is restored, the nerve can not carry
another impulse
The Nerve Impulse
All or None Principle:
A nerve cell will either fire or not fire – once the
impulse begins, it will continue down the cell
Impulse is the same intensity each time
Different strengths of stimuli can be detected by:
• a different number of nerve cells that fire
– The more cells, the stronger the “message”
• the frequency of the repeated impulse
– The faster the impulse is repeated, the stronger the
“message”
The synapse
Passing the impulse to the
next cell
vesicles
Terminal end
Synapse
At the end of the
terminal branches
are vesicles with
neurotransmitters
The
neurotransmitters
are released into
the synapse
Synapse:
gap in between
an axon terminal
and a dendrite
The
synapse
The Synapse
1. Nerve impulse reaches axon end
2. Neurotransmitter (NT) released into synapse
(exocytosis)
3. Neurotransmitter diffuses across synapse
4. Neurotransmitter binds to receptors in the
cell membrane of the next neuron
5. Impulse generated at the next neuron.
The Synapse
• Two examples of NT:
– Acetylcholine
– Norepinephrine
• Certain poisons/drugs interfere with
synaptic activity
– cause either paralysis or constant stimulation
The Nervous System
Two main components:
(1) Central Nervous
System (CNS):
Brain + Spinal Cord
(2) Peripheral Nervous
System (PNS):
nerves outside the CNS
Central Nervous System (CNS)
• Functions:
• Integrates & interprets sensory impulses
• Generates motor impulses.
• Consists of the brain and spinal cord
• The spinal cord provides communication between
the brain and PNS.
• The Meninges:
three continuous sheets of connective tissue
covering the spinal cord and brain
Major Areas of The Brain
speech, vision,
hearing, thought
Sensory input
hunger, thirst,
temperature
Balance, posture,
coordination
Heart beat, breathing
Cerebrum
• Two hemispheres
• a core of grey
matter covered by
white matter
• an outer grey layer
(cerebral cortex).
• Four lobes
–
–
–
–
Frontal
Parietal
Occipital
Temporal
Lobotomy:
destruction of the prefrontal
cortex:
Treatment for a wide range of
mental illnesses including
schizophrenia, clinical
depression, and various
anxiety disorders.
Phineas Gage (1848)
Peripheral Nervous System
(PNS)
Functions:
Carry sensory impulses from receptors to CNS
Carry motor impulses from CNS to muscles and
glands.
Composed of
nerves
(bundle of axons)
Peripheral Nervous
System (PNS):
The bundled axons make
up the nerves of the PNS
Cell bodies of neurons are
found in the CNS or in
ganglia present in the PNS
(ganglion = collection of cell
bodies)
Peripheral Nervous System
Divided into Two main Sections:
• The Somatic system
– the nerves that convey sensory information to the
CNS
– the motor nerves that transmit impulses to muscles
– voluntary control as well as involuntary reflexes
• The Autonomic system
– involuntary control of glands, cardiac muscle, and
smooth muscle.
Reflex Arc
• Involuntary response, or reflexes, can be
mediated by the brain or the spinal cord.
Anatomy of the Human Ear
pinna
Hammer
(Malleus)
Anvil
(Incus)
Stirrup
(Stapes)
Anatomy of the Human Ear
Outer Ear:
Pinna – visible part of ear:
•composed of cartilage
•presence on both sides of the head allows
us to localize the source of sound from the
front vs. the back.
External Auditory Canal:
the tube through which sound travels to the
eardrum.
Tympanic membrane (eardrum):
•between the outer and middle ear
•transmits sound waves to middle ear
Anatomy of the Human Ear
Middle Ear
Eustachian tube (auditory tube)
•connects the middle ear to the back of the nose
•equalizes the pressure between the middle ear
and outside air.
Ossicles:
Hammer - (malleus)
passes vibrations from the eardrum to the anvil.
Anvil - (incus)
passes vibrations from the hammer to the stirrup
Stirrup - (stapes)
U-shaped bone that passes vibrations from the
stirrup to the cochlea.
smallest bone in the human body.
Anatomy of the Human Ear
Inner ear
Cochlea
•spiral-shaped, fluid-filled structure
•lined with cilia (tiny hairs)
•move when vibrated and
•cause a nerve impulse to be
generated.
Semicircular Canals –
•three loops of fluid-filled tubes
•attached to the cochlea
•help maintain sense of balance.
Auditory Nerves –
•carry electro-chemical signals from
the inner ear (the cochlea) to the brain.
The spiral organ of
the cochlea
To cochlear
nerve
Sound Waves to Nerve Impulses
Air pressure waves in the ear canal (sound energy) causes...
Ear drum motion (vibrational energy), which causes...
Motion of the ossicles (vibrational energy), which causes...
Inner ear fluid pressure waves (vibrational energy), which
causes…
Nerve impulses within the cochlea, which are then carried via
a series of nerve connections to the portion of the brain
that perceives "sound," the auditory cortex
(electrochemical energy.)
Anatomy of the Eye
Anatomy of the Eye
• Sclera "the white of the eye"
– is the tough, opaque tissue that
serves as the eye's protective
outer coat
– Completely surrounds eye
• Conjunctiva
– thin, transparent tissue that
covers the outer surface of the
eye.
– begins at the outer edge of the
cornea, covers the visible part of
the eye, and lines the inside of
the eyelids
– nourished by tiny blood vessels
that are nearly invisible to the
naked eye.
Anatomy of the Eye
• Cornea
– transparent, dome-shaped
window covering the front
of the eye
– a powerful refracting
surface
– provides 2/3 of the eye's
focusing power
• Pupil
– black, circular opening in
the center of the iris.
– opens and closes
– regulates the amount of
light entering the eyeball
Anatomy of the Eye
• Iris
– Colored part of the eye
– controls light levels inside
the eye similar to the
aperture on a camera.
– embedded with tiny
muscles that dilate (widen)
and constrict (narrow) the
pupil size.
• Lens
– focus light onto the back of
the eye
Anatomy of the Eye
Vitreous
– thick, transparent
substance that fills the
center of the eye
– composed mainly of water
– comprises about 2/3 of the
eye's volume
– gives it form and shape
Retina
•Very thin layer of tissue lining the inner part of the eye
•captures the light rays that enter the eye
•light impulses are then sent to the brain for processing, via the
optic nerve.
Anatomy of the Eye
• Choroid
– Lies between retina
and sclera
– composed of layers of
blood vessels that
nourish the back of the
eye.
• Optic nerve
– transmits electrical
impulses from the
retina to the brain.
Vision
• Humans have binocular
vision
– Eyes see slightly different
angles
– Allows for depth perception
• Two types of
photoreceptors in retina
– Rods: very sensitive, night
vision
– Cones: detect bright light,
colors, detail
Light Waves to Nerve Impulses
• Light energy passes
through the pupil
• Lens focuses light on
photoreceptors in the retina
• Photosensitive pigments
are split and release energy
• Electrochemical signal
generated
• Intermediate cells in the
retina integrate signals
• Signal is passed on to the
optic nerve
• Nerve impulses sent to the
brain for processing into an
image