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By:Jitendra Bhangale

M.Pharm. DIPL

By the end of the lesson you should be able to Describe the transmission of impulses from senses

to central nervous system and back to muscles. Describe the reflex action and the pathway of the

reflex arc. Describe the function of reflex response. Describe the role of the central nervous system.

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nervous system

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sensory neurone

relay neurone

motor neurone

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Carries impulses from receptors e.g pain receptors in skin to the CNS( brain or spinal cord)

Carries impulses from sensory nerves to motor nerves.

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Carries impulses from CNS to effector e.g. muscle tobring about movement or gland to bring aboutsecretion of hormone e.g ADH

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Central Nervous System (CNS): brain and spinal cord

Peripheral Nervous System (PNS): craniospinalnerves

Autonomic Nervous System (ANS): nerves that control vital organs: heart, lungs, brain, etc.

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The Central Nervous System includes

White matter: bundles of axions and dendrites

Gray matter: masses of nerve cell bodies

The brain: inside the cranium

The spinal cord: inside the vertebral column

(the “backbone”)

envelop the entire CNS

(central nervous system)

dura mater The outer, hardest, toughest

arachnoid The middle, web like

pia mater The inner, thinner

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Cerebrum

Cerebellum

Diencephalon:- hypothalamus and thalamus

Brainstem:- medulla oblongata, pons andmidbrain

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is divided into two cerebral hemisphereshas an outer surface,

or CORTEX,

made of “gray matter”

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1. Left hemisphere:- controls the right side of the body2. Right hemisphere: - controls the left side of the body

is divided into parts called lobes:1. the frontal lobe

2. the parietal lobe

3. the temporal lobe

4. the occipital lobe

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is the center for voluntary movement

is called the “motor area” (movement)

includes the prefrontal area,for intelligence, creativity, memory, and ideas.

Collects, recognizes, and organizes sensations:feelings of

pain

Temperature

Touch

Position

movement

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processes auditory (hearing) information

stores auditory (hearing) and visual (seeing) memories

is at the back of the cerebral hemisphereinvolves

Vision

visual memory

eye movements

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coordinates muscle activityhas three parts:the vermis

the right cerebellarhemisphere

the left cerebellarhemisphere

has three parts:the thalamus: receives sensory information and sends it to the cerebral cortex.

the epithalamus: contains the pineal body and olfactory centers.

the hypothalamus: connects the endocrine and nervous systems.

is located between the midbrain and the cerebrum

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connects the endocrine and nervous systems.controlsthe autonomic nervous systembody temperaturecarbohydrate and fat metabolismappetiteemotions

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Pons: connects the medulla oblongata, the cerebellum, and cerebrum

Midbrain: contains auditory (hearing), visual (sight), and muscle control centers.

Medulla oblongata: lowest and most posterior(at the back of the brain)

The hindbrain includes the pons and the medulla.

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Connects the medulla oblongata, cerebellum, and cerebrumAssociates with sensory nerves: taste, hearing, and balance.

Controls muscles of the face.

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controlsalertness

heart action

respiration (breathing)

blood pressure

connects the CEREBRUM with the SPINAL CORD

the RIGHT side of the brain controls the LEFT side of the body.the LEFT side of the brain controls the RIGHT side of the body.

controlsVision

Hearing

Muscles

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A reflex is an action that:occurs below the brain, within in the spinal cordis an automatic reactionis not conscious (voluntary)can be inborn (a baby has it at birth, such as sucking, swallowing, urinating)can be learned (such as talking,walking, driving)

* An automatic reaction that happens without thinking about it.

* A reflex happens quickly in less than a second.

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INBORN

knee jerk reflexpupillary reflexswallowingcoughingblinking

LEARNEDreadingtypingswimmingdancingskatingplaying football

knee jerk: lower leg jerks when knee is tapped Babinski: toes curl up when sole of foot is stroked pupillary: pupils of eyes contract in bright light

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Continuation of the base of the brainsurrounded by vertebrae

Covered by three protective membranes(meninges)

The spaces between the meninges are filledwith cerebrospinal fluid (CSF), whichcushion and protect the CNS

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1. Center for many reflex actions

2. Provides means of communication between the brain and the spinal nerves

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- Consists of cell bodies and short unmyelinated fibers

- H-shaped in a cross section

- Includes interneurons and portions of sensory neurons and motor neurons

- Consists of bundles of myelinated long fibers of interneurons (tracts)

- Connects the spinal to the brain

- Dorsally, contains ascending tracts taking information to the brain

- Ventrally, contains descending tracts carrying information from the brain

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- In humans, there are 12 pairs of cranial nerves attached to the brain

- Include the vagus nerve which has branches to the pharynx and larynx and most of the internal organs

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- In humans, there are 31 pairs if spinal nerves emerged from the spinal cord

- All spinal nerves are mixed nerves conducting impulses to and from the spinal cord

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Includes all nerves that serve the internal organs automatically and usually without need for conscious intervention

Divided into sympathetic and parasympathetic systems

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Nor epinephrine (NE) is neurotransmitter

Preganglionic fibers arises from the middle portion of the cord

Accelerates heartbeat, dilates the bronchi, increases the breathing rate

- Acetylcholine (ACh) is neurotransmitter-

- Preganglionic fiber is longer than postganglionic fiber

- Preganglionic fiber arises from the brain and lower portion of the cord

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THANK YOU