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

Send out motor commands 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.

The impulse is transmitted: Neurons The impulse is transmitted: Dendrites Cell body Axon Axon terminal Cell body 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 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 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 Synapse 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

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 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)

(ganglion = collection of cell bodies) 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" Conjunctiva 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 Pupil 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 Lens 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 Retina 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 Optic nerve 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