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Transcript of Nervous System
-includes brain & spinal cord
-composed of interneurons that interact w/ other nerves in the body
-recieves, interprets, & sends signals to the PNS
CNS: Central Nervous System
PNS: Perpheral Nervous System
-processes & interprets signals & generates responses
-contains 3 main functions: cerebrum, cerebellum, & brainstem
-controls the most basic activities needed for life.
-connects brain to spinal cord
-3 major parts: midbrain, pons, & medulla oblongata
-controls reflexes (involuntary movements)
-delivers messages to proper muscles
-If damaged, may lead t paralysis
-Reflex arcs: nerve pathways that need to cross only to synapses before producing a response
*protects body from injury
CNS Parts, Function, & Details
PNS Parts, Function, & Details
-a connected network of cells, tissues, and organs
By: Thy Banh
-is a collection of nerves that connects the CNS to all of organs
-Controls thoughts, movements, and simpler life processes such as swallowing
-uses sensory neurons to detect stimuli from in & out of the body
-uses motor neurons to carry signals from CNS to other parts of the body & stimulate muscles or other target organs
-most reliable sense
-contains 70% of all sensory receptors
-The nervous system allows you to respond to your environment and maintain homeostasis.
There are 2 types of signals
The rate of communication of the nervous system is very fast and they communicate to different parts of the body system through a neuron.
The five senses are vision, touch, taste, smell, and hearing
The signal is obtained through our five senses.
Thank you for listening!
Somatic Nervous System
-regulates all movement that you can control
-connects the CNS to target organs
-its a division of PNS
Automatic Nervous System
-controls automatic functions you do not have to think about
-important for maintaining homeostasis
-takes message from hypothalamus to organs
Sympathetic Nervous System (action and stress)
-prepares body for action and stress
-improve physical abilities & allows to think quickly
Parasympathetic Nervous System (calm and relaxation)
-calms body & helps to conserve energy
-it lowers blood pressure and heart rate
-Humans skin contains receptors that senses touch, temperature, and pain.
Mechanoreceptors detect touch through pressure, movement, and tension on skin.
-Two Types of Mechanoreceptors:
* detect gentle touch, located in the upper layer of the skin.
* other recognize the heavy pressure found deeper within the skin.
-Thermoreceptors: detect temperature such as hot and cold whereas Pain receptors detect chemicals that are released by damaged cells.
-Two Types of Pain Receptors:
*detect sharp pains (example: when you bump into the corner of a table)
*detect blunt or throbbing pain( example: a bruise)
Cell Body: contains the nucleus and organelles
Dendrites: Receive messages from neighboring cells
-includes the brain & spinal cord
-composed of interneurons that interact W/ other nerves
-receives, interprets, & sends signals to PNS
Axon: Carries the electrical message away from the cell and to other cells
A NEURON IS A SPECIALIZED CELL THAT STORES INFORMATION AND CARRIES MESSAGES WITHIN THE NERVOUS SYSTEM AND BETWEEN OTHER BODY SYSTEM
THERE ARE THREE TYPES OF NEURONS:
1. Sensory neurons: detect events and transmit the signal to the brain and spinal cord
2. Interneurons: Receive the signal from the sensory neurons, process the info. and then pass the info to the
3. The motor neurons the pass the signal to other parts of the body and the signal is responded
-Most of photoreceptors like rod and cone cells are in the back of layer of tissue called retina.
*used in black and white vision
*are sensitive to low amount of light
Transmission Within a Neuron
-Action Potential: stretching causes change in charge distribution that triggers a moving electrical impulse
*requires ion channels in membrane that have gates that open & close
-when a neuron is stimulated, open gated channels for Na+ open fast, & Na+ ions rush into cell
-this stimulates adjacent Na+ channels down the axon to spring open.
-Na+ ions rush into cell, & those ion channels snap shut.
*Area of positively charges membrane moves down the axon
*At same time, K+ ion channels are opening & closing more slowly.
-K+ ions diffuse out of axon & cause part of the membrane to return to resting potential
-Cause K+ channels are slow to respond to change in axon's charge, they appear to open & close behind the moving impulse.
*need bright light to function
After the signal is obtained, transferred and responded an action can occur. This process happen every moment of everyday in events such as blinking.
Transmission Between Neurons
-Synapse: before action potential moves into the next neuron, it crosses a tiny gap between neurons.-Axon terminal: part of the axon through which the impulse leaves the neuron
*contains chemical-filled vesicles
*when impulse reaches terminal, vesicles bind to the terminal's membrane & release their chemicals into the synapse.
-Neurotransmitters: chemical signals of the nervous system
*bind to receptor protiens on the adjacent neuron & cause Na+ channels in that neuron to open, generating an action potential
*they must be removes from the synapse so ion channels on the 2nd neuron will close again.
*neurotransmitters will be broken down by enymes in the synapse or transported back into the terminal that released them.
-The amount of light is important to vision.The eye must have a way to limit the light from bright sources and allow more light to enter from dim light source
-Changing the size of the pupil can adjust the amount of light that enters.
_the iris controls the pupil.
-Nerve impulses must travel to the brain to interpret images. It must go through a procedure:
1. Lights enters the eye through a protective transparent layer (cornea) and moves through the pupil
2. After the pupil, the light will pass through the lens
3. The lens will focus the light onto the retina
4. When the light gets to the retina, the rod and cone cell will generate nerve impulses
5. The impulses will travel along a group of axons that form the optic nerve
6. Finally, the optic nerve will carries the impulses to the brain and create images
*The ear collects, amplifies and converts vibrations from the air into nerve impulses which are interpreted in the brain as sound.
To turn vibrations into sounds:
1.Sounds waves enter through outer ear
2.The pinna collects sounds and funnels it into the auditory canal.
3.The sounds hit the eardrum (tympanic membrane) and vibrates (like the head of a drum)
5.After the vibrations are amplified, they're transferred to the cochlea
6.The fluid in the cochlea move in response to the vibrations & produce an impulse as it causes the hair cells to bend
7.The impulse will be carry by the auditory nerve to the brain, where it is perceived as a sound
-There are organs that regulate balance in the ear.
*The semicircular canals is one of the organs.
*When your head moves, the semicircular canals' fluid moves. *The movement will bend the hair cells and as the cells bend, the impulse will be transmitted to the brain
*Vibrations are amplified by 3 small bones in the middle ear:
-The malleus -The incus -The stapes
-the sense of taste is less sensitive when your nose is stuffed up
-Just like the nose, the tongue has chemoreceptors that detect molecules dissolved in liquid.
*The chemoreceptor generate impulses that are sent to the brain.
-Taste buds are chemoreceptors that detect tastes.
*buds can be found in bumps on the tongue(the papillae)
-The t ongue can detect five basic tastes -sweet, sour, salty, bitter, and savory.
*The brain interprets the five basic tastes as complex flavors
-Chemicals must be dissolved before they can be detect
-has chemoreceptors that can sense molecules that dissolve in liquid or become vapor or gas in the air.
-In smell, chemical molecules enter the nose, they dissolve in the mucus, and are detected by oldfactory cells
-The oldfactory cells generates impulses and delivers it to the brain