The Nervous & Endocrine System [Chapter 11 and 12]

– Endocrine System: – Nervous System:

General Purpose of Nervous System:

ORGANIZATION OF THE NERVOUS SYSTEM

Biology 30--- The Nervous System ---Chapter 11 and 12

Organization of the Nervous System

See p. 367 and attached Sheet

Central Nervous System-

Peripheral Nervous System-

• Somatic Nervous System:

• Autonomic Nervous System:

Nervous System Function

3 major functions:1. Sensory input –

2. Integration –

3. Motor output--

Neuron Types

3 Types of Neurons

• 1. Sensory neurons : Carry information from the environment to the _________ for processing (ex. Eyes responding to light).

• 2. Interneurons : Link or ________________ neurons together in the CNS. They carry impulses ____________ the CNS (found predominantly in the brain and spinal cord). They interpret the sensory information and connect neurons to outgoing motor neurons.

• 3. Motor neurons : Carry information from the CNS to the body effectors (_______________ and ____________ because they are what cause things to happen)

Anatomy of a Nerve Cell• 2 Types of cells found in the nervous system:

– Neurons and Glial Cells

• Neuron (nerve cell) - the fundamental structural unit of the nervous system that enables us to receive information, process it, and produce action.

– a “bundle” of neurons forms a nerve

• Glial cells - (“glue”) are ___________________________ cells that help the neurons out, tying them together

and providing support.( nourish and remove

wastes). – Largest concentration found in the

brain• Nerves are composed of

_______________________

Parts of the Neuron (Lable and Define the function of each part) add #8

Myelin Sheath

axon –

myelin sheath –

axon terminals -

node of Ranvier-

cell body-

nucleus-

dendrites –

Schwann's cells-

-

-in between parts of the myelin sheath are

-nerve impulses _____________from node to node, speeding up nerve impulseTransmission; therefore, nerve impulses move ____________________along a myelinated nerve.

Types of Nerves

1. Myelinated Nerves

•

•

•

• the neurilemma promotes ____________________________ of damaged axons or dendrites

2. Unmyelinated Nerves

•

• make up the __________ matter in the brain and spinal cord• •• Multiple Sclerosis • An auto-immune disease in which the immune system attacks and destroys the myelin sheath around

surrounding axons.• Results in a progressive loss of signal, muscle control, and brain function

Reflex Arcs

A reflex arc does not require coordination by the brain Contains 5 essential components:1. the ___________________________ receptor2. the sensory ______________________________3. the _____________________________________4. the motor __________________________________5. the ________________________________________

Draw a simple diagram of a reflex arc below

• When the patellar tendon is tapped, (1)sensory neurons detect the stretching and send a signal (2) to the CNS (in this case, the spinal cord).

• The information goes to a motor neuron (3) and to an interneuron (4).• The motor neuron stimulates the contraction of the quadriceps muscle which extends

the leg, while the interneuron sends an inhibitory signal to the flexor muscle.• Reflexes are a _________________ mechanism for the body• In general the following characteristics are used to describe reflex actions. They are:

– ________________ – mostly unaware of them until after the brain has registered what has occurred– purposeful and adaptive – most are essential to our survival– predictable – a specific given stimulus will continue to produce the same result– have a measurable reaction time – although extremely quick, do not occur instantaneously

• The more complex the reaction, the longer the reaction time• Physiological conditions can affect reaction time (fatigue, drugs)• Occur more rapidly in different people

****Check Your Understanding****

1. Differentiate between the PNS and the CNS.2. Describe the function of the following parts of a neuron: dendrites, myelin sheath, Schwann cells, cell body, and

axon.3. What is the relationship between the speed of a nerve impulse and the size of the axon along which it travels?4. What is the difference between gray and white matter?5. Name the essential components of a reflex arc and the function of each.6. What are the nodes of Ranvier?7. What the benefit of having an axon covered by neurillemma?

Quick Membrane Review--

Impulse Transmission• • • • • • • • • Voltage = membrane potential•

The electrochemical impulse results from small changes in sodium and potassium ions in the dendrites and then the axon of the neuron.

• These changes “move down” the axon.The 3 Stages of Nerve Impulse Include:

1. _______________________Potential (aka Polarization)2. _______________________ Potential (aka Depolarization)3. _______________________ Period (Repolarization)

The Resting Membrane• outside the neuron’s membrane is a ___________ concentration of sodium

ions causing it to be ______________ charged compared to the inside• inside the neuron is a high concentration of potassium ions,

________________________ ions (- ions) and – charged proteins. • there is an electrical potential difference between the inside and outside of

about - 70mV• there are ion channels in the lipid bilayer membrane that allow certain ions to diffuse in and out (only certain ion

channels let sodium move and different ones let potassium move).• at resting membrane potential, more potassium ions have the potential to move out (because there are more

open potassium ion channels), than sodium ions have the potential to move in (almost no sodium ion channels open)

• also, another membrane protein called the sodium potassium __________ moves 3 sodium out while moving 2 potassium in (ATP must be used for this to happen = active transport)

The Action Potential— only occur at the Nodes of Ranvier in myelinated neuron s • a nerve impulse is an _______________________ _______________________. An action potential begins when

the dendrites are stimulated with certain chemicals or an electric jolt.• When the neuron receives a stimulus, the cell membrane becomes more permeable to Na+ than K+ (Na+ channels

open, and the K+ channels close).• The highly concentrated Na+ ions rush into the

cell by diffusion and charge attraction.• The rapid inflow of Na+ reverses the charges on

both sides of the membrane (approximately +40mV).

• This charge reversal is referred to as ______________________________

Refractory/Recovery• Once the voltage inside the cell becomes positive, the Na+ channels slam closed, stopping the inflow of Na+.• K+ channels then open and Potassium ions rush outside.• Once action potential has passed, sodium is actively pumped out of the cell while potassium is pulled back in

(Na+/K+ Pump)• The return to the resting states is called hyperpolarization• Cell is returning to its resting state• 3.Refractory/Recovery• Refractory period is the period of time the nerve will not respond to a stimulus (needs to return to resting

potential)– Period of time immediately after an impulse when the neuron will not respond to a stimulus – cannot c

Action Potential can be represented in Graphical Form

Saltatory Conduction

All or None Response

•

Strength & Type of StimulusHow do you distinguish between different stimuli? For instance, how is it that your body can tell the difference between the touch from a feather or a rock?1. 2.

Check Your Understanding

1. What is a polarized membrane?2. What causes the inside of a neuron to become negatively charged?3. Why does the polarity of a cell membrane reverse during an4. action potential?5. Why do nerve impulses move faster along myelinated nerve fibers?6. Some people report that they have a high pain tolerance. Explain this in7. terms of threshold levels.8. 6. What is the “all or none response”?

Review Concept

1.

5.

4.

3. 2.

Synapse• ____________________ between neurons or junction between neurons

& effectors• Synapses rarely involve just 2 neurons• _____________________________(chemicals) are released into the

synapse by axon terminal of the pre-synaptic neuron• neurotransmitters stimulate the dendrites on post-synaptic neurons or

receptors on effectors• each axon terminal is a swollen synaptic knob• makes sure that an impulse can only go in one direction• ______________of __________________ is slowed with an increased number of synapses (supporting the reason

why reflex arc is quick).

Presynaptic1.

2.

3.

4.

Post Synaptic Neuron

1.

2.

3.

4.

Draw synapse in here:

Neurotransmitters: Alter the membrane potentials of the postsynaptic neurons.

1. The Synapse An action potential reaches the axon terminal and triggers vesicles containing neurotransmitter to move to the presynaptic membrane. Neurotransmitter is released into the synaptic cleft.

2. The neurotransmitter binds to specific receptors on the post-synaptic dendrite membrane and causes sodium gates to open (begins an action potential).

3. When stimulus is finished, an enzyme (released from the pre-synaptic neuron) specific to the neurotransmitter binds to it and breaks it down. The broken neurotransmitter is reabsorbed into the pre-synaptic axon terminal to be recycled until the next stimulus.

Neurotransmitter Examples:• Acetylcholine

– Excites the ______________________ neurons by opening sodium ion channels; thereby, causing depolarization to occur.

– The presynaptic membrane will then release cholinesterase, which will destroy acetylcholine. This will cause the Na+ channels to close and the recovery phase can begin.

Summation of Nerve Impulses

Why is it important to have inhibitory neurotransmitters in the body?In the CNS (brain):-inhibitory neurotransmitters allow ___________ important information to be ignored while the brain focuses on more important info. (sensory information is always the most important) (Think about your shirt or food moving through intestine!) Ex: GABAIn the PNS:-inhibitory neurotransmitters allow certain muscles to _______________ to ensure efficient movement.Ex: flexing arm muscles

Do

Section 11.1 Review p. 384 #1-8

Neurotransmitter Action Secretion Sites Major Effects

acetylcholine Excitatory to skeletal muscles: excitatory & inhibitory at other locations

Neuromuscular junctions: CNS, PNS

Skeletal muscle contraction

norepinephrine Excitatory or inhibitory CNS, PNS wakefulness

dopamine Generally excitatory CNS, PNS Voluntary movement & emotions

serotonin Generally inhibitory CNS sleep

GABA inhibitory CNS Motor behaviour

Human Brain Cerebrum: 2 hemispheres (left & right) Parietal Lobe: receives sensory info from skin (heat / pain) increase surface area gray matter (no regeneration) Frontal Lobe: conscious thoughts personality controls voluntary muscle movement Temporal lobe: auditory reception short term memory Occipital Lobe: vision Corpus Callosum: white matter controls left &right hemispheres Thalamus: cross talk, relay station Cerebellum: controls muscle contraction Hypothalamus: posture and balance controls pituitary and drive Pituitary: master Medulla Oblongata: (ANS) sub conscious activity Pons: relay station between controls heart rate, blood rate, swallowing M.O. and Cerebellum

The CNS• The ___________ in conjunction with

the ________________, regulates non-conscious processes and coordinates most voluntary movement. Furthermore, the brain is the site of consciousness, allowing humans to think and learn.

The Spinal Cord• The spinal cord carries sensory nerve

messages from receptors in the brain and relays motor nerve messages from the brain to muscles, organs, and glands.

• 2 types of nerve tissues are present in the spinal cord:Grey Matter:

• nonmyelinated interneuron's.• connect the spinal cord with the brain

White Matter: myelinated nerves from sensory and motor neurons.

• Protection of the Brain and Spinal Cord1. It is enclosed by the ____________ and vertebrae –hard and bony structures2. Three protective and nourishing membranes, the meninges, lie between the skull and the brain tissue itself

and around the spinal cord. Dura mater: Anchors brain to skull, has large arteries pass through this layer Arachnoid Layer: Cobweb appearance; contains CSF and holds it close to the brain Pia Mater(blood brain barrier): Fragile, inner most layer consists of blood vessels

3. The brain floats in a special cerebrospinal fluid (CSF)• Made in the brain, circulates and is reabsorbed by the blood• Provides protection from bumping into the skull• Bathes nerves with metabolites, ions, and nutrients (eases exchange of materials between body fluid and

the brain)4. A highly selective blood-brain barrier limits access of harmful materials to vulnerable brain tissue

Brain Parts

THE HINDBRAIN

A. Cerebellum

A. Medulla Oblongata

B. Ponso Acts as a bridge or relay center – has fibers which connect two hemispheres of cerebrum and

cerebellum to the rest of the brain

THE MIDBRAIN Located above the Pons Consists of four bundles of grey matter Relays visual and auditory info. between hindbrain and forebrain Forms connections between the pons, cerebellum, spinal cord and parts of the cerebrumC. Hypothalmus

D. Cerebrum

FRONTAL:

PARIETAL:

OCCIPITAL:

TEMPORAL:

** The brain produces natural pain killers.

ENDORPHINS: natural pain killers produced by the brain. They occupy sites in substantia gelatinosa (area of the brain) which are normally used by pain-signaling chemicals. The block these sites and thus reduce pain intensity

Opiates; Mimic endorphins and block neurotransmitters and those prevent the depolarization of pain sensing neurons.

Blood Supply To The Brain• The brain accounts for 2% of the total body weight, yet it requires 20% of the body’s blood.• Both oxygen and glucose are transported by the blood; without these essential elements, brain function quickly

deteriorates and dizziness, confusion, and loss of consciousness may occur.• With 4-8 minutes of oxygen deprivation, brain damage or death results.• Carotid artery (runs of the side of your neck) is the main source of blood to the brain.

******Do Section 11. 2 review p.395 #1-7

Peripheral Nervous System (PNS ) 11.3 Composed of 2 Main Parts:

Somatic : ___________________________________________________________________

• Spinal nerves that emerge from each side of the spinal cord• Each nerve contains both sensory (give us info about external env.) and motor neurons• however, a reflex arc (involuntary) falls under somatic

Autonomic : ________________________________________________________________________________

• Controlled by the ________________________ and ______________________ _______________________

• Divided into __________________________ and ________________________ which carry info. to the effectors• Sympathetic and parasympathetic have opposing effects•

Sympathetic—__________________________________________________________– Neurotransmitter- norepinephrine

Parasympathetic—_____________________________________________________– Neurotransmitter- acetylcholine

THE

SENSES—EYES & EARSSensory neurons supply the CNS with information about the external environment and the quality of our internal environment.

• Example:– Light sensitive receptors in the eye are stimulated by light.– Specialized temperature receptors in the skin identify cold.

Organ Sympathetic Parasympathetic

heart Increases heart rate

Digestive tract Decreases peristalsis Increases peristalsis

liver Increases release of glucose Stores glucose

eyes Dilates pupils

Bladder Relaxes sphincter Contracts sphincter

skin Increases blood flow Decreases blood flow

Adrenal gland Causes release of epinephrine No effect

– Specialized chemoreceptor's in your carotid artery provide the CNS with information about blood carbon dioxide and oxygen levels.

– Osmoregulators in the hypothalamus monitor water concentration in the blood.– Stretch receptors in the arteries monitor blood pressure.

Define the following (pg 406-7)• Sensory Receptors:

• Sensation:

• Perception:

• Sensory adaptation: Types of sensory receptors:

• 1. Chemoreceptors: Sense specific chemicals. eg.(taste buds, lining of the nasal cavity = olfactory receptors, internal receptors like blood pH)

• 2. Photoreceptors: Sense __________________ light. eg. (eye)

• 3. Thermoreceptors: Sense ________________________ eg. (skin)

• 4. Proprioreceptors: Sense stretching in muscle fibers, ligaments, and tendons.

• 5. Mechanoreceptors: Sense changes in ___________________/touch/pain eg. (finger tips, hearing, balance, body position)

The Eye

The Eye is Comprised of 3 Layers:• Sclera

– The outermost layer _____ the eye.– Protectively layer– Maintains _____ eye’s shape

• Cornea – Acts as ____ window to the eye by bending light toward to pupil.– Does not receive blood supply– Does require ________________________ and nutrients.

•• Retina

– inner layer, covers 65% of inner surface, site of all _______________________ receptors• Other Important Eye Structures Include: • Choroid Layer

– Middle layer– Contains the blood vessels that nourish the retina.

• Iris – Thin circular muscle that acts as a diaphragm , controlling the size of the pupil.

• Pupil ________________________________________________________________.• Lens

– ________________________________________________________________– Found immediately behind the iris.

• Aqueous Humour – The transparent fluid in the chamber behind the cornea.

• Ciliary Muscles – Attached to both end of the lens; therefore, can alter its shape.

• Vitreous humour – Chamber that is behind the lens– Cloudy, jelly-like material– ________________________________________________________________

How Does the Eye Move?• Extrinsic muscles attach to the sclera and move the eye up, down, side to side• Intrinsic Muscles: Control lens and iris and are controlled by the ANS. You have two

sets , one for contracting and one for dilatingThe Retina

• Innermost layer of the eyeRetinal Cells

• Light-Sensitive Cells • Rods: Respond to ________-intensity light• Cones: ___________ intensity light and identify color.

• In the center of the retina there is a tiny depression called _____________________ centralis. This is the most sensitive area of the eye.

– It contains ______________ that are packed very closely together.

Optic Nerve – Carries the ______________ to the CNS.

• Rods are found surrounding the fovea.• ***There are 125 million rods and 6 million cones in your retina

Blind Spot • This is the area where the optic nerve comes in contact with the retina.• There are no rods or cones located here.

Color Blindness• Occurs when one or more types of cones are defective.• Most common type is red-green. Occurs when cones containing the red-sensitive pigments fail to work

properly.This is a genetic defect and is more common in males (we will discuss why in genetics)

The Sequence of Vision1. Rays of light enter the eye through the ____________________, where they are partly bent (refracted).2. The rays of light then pass through the transparent lens, which changes shape in order to fine-focus the image (accommodation).3. The light continues through the fluid matter, vitreous humor, with in the eyeball and shines an upside-down image onto the retina lining.4. The rods and cones of the retina, convert the light energy that falls on them into nerve impulses (action potentials).5. Nerve fibers that extend from the rods and cones and attach to neurons that are connected to the optic nerve.6. The optic nerve will direct the impulse to the necessary vision areas in the CNS.

Ear Structure

3 Sections– Outer Ear– Middle Ear– Inner Ear

The Outer Ear• Pinna:

• The external ear ____________________, which collects ___________ sound.• Auditory Canal:

• Carries sound ________________________ to the eardrum.• Lined with specialized sweat glands that produce ________________________________ (traps

foreign particles)The Middle Ear

• Tympanic Membrane:– Thin layer of tissue that receives _________________________ vibrations (eardrum).

• Ossicles:– Tiny _________________________ that amplify and carry sound vibrations.

• Malleus (hammer)• Incus (anvil)

• Stapes (stirrup)• Eustachian Tube:

– Air-filled tube of middle ear that _________________________ pressure between the external and internal ear.

– Extends from ear, mouth and nose.The Inner Ear

• Vestibule:– Chamber found at the base of the

semicircular _________________________ that provides information about static equilibrium.

– Houses 2 small sacs, the _________________________ and _________________________, which establish head position.

– Oval Window: oval shaped hole in the vestibule, covered by a thin layer of tissue.

• Semicircular Canals:– Fluid-filled structures that are arranged at

different angles.– Movement of the fluid in the canals helps you identify _________________________ movement.

• Cochlea: – Coiled structure that contains rows of specialized _________________________ cells. The hair cells

respond to sound waves and _________________________ them into nerve impulses.– Organ of Corti----organ of ___________________________

Hearing1. The ___________________________ collect sound waves and send them down auditory canal2. Sound vibrations cause the ___________________________ membrane (eardrum) to vibrate (*sound waves

are converted into mechanical energy)3. The movement of tympanic membrane causes the ___________________________ (3 tiny bones) to move

concentrating the vibrations on the ___________________________ window in the inner wall of middle ear (vestibule)

4. The vestibule is attached to a snail-shaped structure called the cochlea (fluid filled). The fluid in cochlea moves and causes movement of tiny cilia (hairs) in the Organ of Corti

5. The cilia are mechanoreceptors and cause depolarization of ___________________________ nerves• Nerve impulses are sent to the ___________________________ lobe of brain

Organ of Corti• Comprised of a single inner row and

three outer rows of specialized ____________________ cells.

• Anchored to the ___________________ membrane.

identifying Pitch and Loudness• Identifiable because of the cochlea• Close to the oval window, the basilar membrane is narrow and stiff.

– Activated by high-frequency sound waves– Energy high enough to move the membrane, which in turn causes the hair cells to move.– Hair cell movement triggers an action potential, which is carried to the brain and understood as a high

pitch sound.• Further in the cochlea, the membrane widens and becomes more flexible.

Sound waves in the cochlea animationBalance (Equilibrium)

Static Equilibrium• Movement along ______________ plane, such as vertical or horizontal (head position)1. When head position changes, fluid in saccule and utricle causes calcium carbonate crystals (otoliths) to move2. This movement causes tiny cilia to bend

3. Trigger nerve impulses sent to cerebellum for interpretation via the vestibular nerve

Dynamic Equilibrium• Movement along ___________________________

planes.1. When the body moves, fluid in the semicircular

canals move. (There are 3 canals positioned in 3 different planes)

2. The fluid moves tiny cilia which initiates depolarization of adjacent neurons

3. A nerve impulse travels down nerves to the cerebellum via the vestibular nerve

Vertigo: A false sensation of movement and a spinning sensation are often associated with nausea and sometime serve vomiting.

• Result of disturbances in the inner ear or areas of the brain concerned with balance.Skin Receptors

• Skin receptors include: ___________________________, heat, pressure, and pain. • The brain is what registers and interprets the sensation.

Taste Receptors• Taste receptors found on the

___________________________ (taste buds)• Chemicals dissolve in saliva and stimulate receptors in

taste buds• 5 main types of taste:

– sweet, sour, salt, bitter and savory• Each taste is associated with the molecular structure

and charges on the food molecules• For Example:

– Sodium chloride ions – salty (potatoes chips)

– Monosodium glutamate- savory (Asian food)

Taste and Smell• Both taste and smell (olfaction) work closely

together.• For Example:

– When you nose is clogged do you have difficulty tasting food?

– This is b/c your olfactory cells are less effective

– Reduced taste a result of needing both receptors.

• Nose: detects ___________________________ borne chemicals

• Tongue: detects ___________________________ chemicals