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Regulatory Systems: Nervous and Endocrine Systems. Function of Regulation Systems:. regulate the activities of the other systems to make sure homeostasis is maintained

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slide2

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
Nervous System

Uses Electrical signals (impulses) along nerves

Chemical signals (neurotransmitters) to pass the impulse to the next cell

endocrine system
Endocrine System

Uses:

Hormones made in glands

The bloodstream for transmission

slide6

Nervous system Functions:

Receive Stimulus

Integrate the Input

Send out motor commands

neurons functional units
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.
slide8

Neurons

The impulse is transmitted:

Dendrites

Cell body

Axon

Axon terminal

Cell body

Axon

Dendrites

Myelin sheath

slide9

Types of Neurons

Sensory neuronssense stimuli caused by changes in the internal or external environment

Interneurons integrate signals from different parts of the nervous system

Motor neuronstransmit signals to muscles and glands  

Muscles contract

Glands secrete substances

types of neurons
Types of Neurons

Sensory Neuron

Interneuron

Motor Neuron

the nerve impulse
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 impulse1
The Nerve Impulse

The transmission of a nerve impulse is rapid and self-propagating (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 impulse2
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

slide14

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 impulse3
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 impulse4
The Nerve Impulse

Saltatory conduction:

Transmission of the action potential in myelated axons (faster than in non myelated axons)

the nerve impulse5
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 potentialtravels 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 Pumprestores positions of ions (sodium out, potassium in)

Until the position of the ions is restored, the nerve can not carry another impulse

the nerve impulse6
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”
slide19

The synapse

Passing the impulse to the next cell

vesicles

Terminal end

Synapse

Synapse:gap in between an axon terminal and a dendrite

The neurotransmitters are released into the synapse

At the end of the terminal branches are vesicles with neurotransmitters

slide21

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
The Synapse
  • Two examples of NT:
    • Acetylcholine
    • Norepinephrine
  • Certain poisons/drugs interfere with synaptic activity
    • cause either paralysis or constant stimulation
slide23

The Nervous System

Two main components:

(1) Central Nervous System (CNS): Brain + Spinal Cord

  • Peripheral Nervous System (PNS): nerves outside the CNS
slide24

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
slide25

Major Areas of The Brain

speech, vision, hearing, thought

Sensory inputhunger, thirst, temperature

Balance, posture, coordination

Heart beat, breathing

slide26

Cerebrum

  • Two hemispheres
  • a core of grey matter covered by white matter
  • an outer grey layer (cerebral cortex).
  • Four lobes
    • Frontal
    • Parietal
    • Occipital
    • Temporal
slide27

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)

slide28

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)

slide29

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)

slide30

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.
slide31

Reflex Arc

  • Involuntary response, or reflexes, can be mediated by the brain or the spinal cord.
slide32

Anatomy of the Human Ear

pinna

Hammer

(Malleus)

Anvil (Incus)

Stirrup (Stapes)

slide33

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
slide34

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. 

slide35

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.
sound waves to nerve impulses
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 eye1
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 eye2
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 eye3
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 eye4
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
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 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