RAKHSHANDA HASHMI BS ED,EDUCATION DEPARTMENT NUML,ISB.

NERVOUS SYSTEM

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your nervous system

is divided into the central nervous system (CNS)

and the

peripheral nervous system (PNS)

which is the brain and

spinal cord

which connects everything to the brain and spinal cord

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your brain

as well as being responsible for

thinking, learning, memory and emotion

Different parts of your brain have different functions…

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interprets the information it gets though your senses in order to monitor and regulate your body

BRAIN

• The brain of all vertebrates develops from three swellings at the anterior end of the neural canal of the embryo.

• Human brain is divided into three parts;

• Fore-Brain• Mid-Brain• Hind-Brain

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Credit: Mark Lythgoe &

Chloe Hutton, Wellcom

e Images

different regions have different

functions Cerebral cortexFunctions include: planning; reasoning; language; recognising sounds and images; memory.Corpus

callosumconnects the brain’s right and left hemispheres

Cerebellumimportant for coordination, precision and timing of movement

Brain stemregulates heart rate, breathing, sleep cyclesand emotions

FORE-BRAIN

• Frontal Lobe- associated with reasoning, planning, parts of speech, movement, emotions, and problem solving.

• Parietal Lobe- associated with movement, orientation, recognition, perception of stimuli.

• Occipital Lobe- associated with visual processing.

• Temporal Lobe- associated with perception and recognition of auditory stimuli, memory, and speech.

FORE-BRAIN(DIENCEPHALON):

• Hypothalamus: Hypothalamus regulates the autonomic nervous system via

hormone production and release. Affects and regulates blood pressure, heart rate, Mood and motivation, hormonal body processes, hunger, thirst, sexual arousal, sexual maturation and the sleep/wake cycle.

• Amygdala: It involved in signaling the cortex of motivationally significant

stimuli such as those related to reward, punishment and fear in addition to social functions such as mating.

FORE-BRAIN(DIENCEPHALON):

HIPPOCAMPUS:

It belongs to the limbic system and plays important roles in long-term memory and spatial navigation. In Alzheimer's disease the hippocampus is one of the first regions of the brain to suffer damage; memory problems and disorientation appear among the first symptoms.

MID-BRAIN

• The midbrain is located between the two developmental regions of the brain known as the forebrain and hind brain. In mammals, particularly in man, mid brain is relatively very small. Within the midbrain is the reticular formation, which is part of a certain region of the brainstem that influences motor functions. It receives the sensory information from spinal cord and sends them to the fore-brain.

HIND-BRAIN

Cerebellum:

The cerebellum, or "little brain", is similar to the cerebrum in that it has two hemispheres and has a highly folded surface or cortex. This structure is associated with regulation and coordination of movement, posture, and balance.

HIND BRAIN

CEREBELLUM

MEDULLA OBLONGATA

RETICULAR FORMATION

PONS

HIND-BRAIN

• Pons : is a structure located on the brain stem. It is superior to (up from) medulla oblongata, inferior to (down from) the midbrain and ventral to (in front of) the cerebellum. The pons measures about 2.5 cm in length. It mainly controls with sleep, respiration, swallowing, bladder control, hearing, equilibrium, taste, eye movement, facial expressions, facial sensation, and posture.

• Reticular formation: is a group of nerve fibers located inside the brainstem. Reticular formation important in regulating Arousal, Attention, Cardiac Reflexes, Motor Functions, consciousness or wakefulness.

HIND-BRAIN

Medulla oblongata:

• Medulla oblongata also called the myelencephalon, the lowest part of the brainstem. The medulla oblongata looks like a swelling at the tip of the spinal cord.

• The medulla oblongata regulates the reflex responses that control breathing, heart beat, blood pressure, coughing, swallowing, hiccupping, sneezing, vomiting, digestion and other essential involuntary functions.

BRAIN-STEM

The lower extension of the brain where it connects to the spinal cord. It is formed by the combination of medulla oblongata, pons and mid–brain. Neurological functions located in the brainstem include those necessary for survival (breathing, digestion, heart rate, blood pressure) and for arousal (being awake and alert). The brainstem is the pathway for all fiber tracts passing up and down from peripheral nerves and spinal cord to the highest parts of the brain.

BRAIN-STEM

SPINAL CORD• It is thick, whitish nerve cord that lies below

the medulla and extends down through the neural canal of vertebrae up to the hips.

• The spinal cord extends down from the brain stem at the base of the skull, enclosed in the vertebral column. Brain and spinal cord in continuity comprise the central nervous system.

• The outer layer of the spinal cord consists of white matter, i.e., myelin-sheathed nerve fibers. These are bundled into specialized tracts that conduct impulses triggered by pressure, pain, heat, and other sensory stimuli or conduct motor impulses activating muscles and glands.

SPINAL CORD ANATOMY

• The inner layer, or gray matter, has a butterfly-shaped cross-section and is mainly composed of nerve cell bodies. Within the gray matter, running the length of the cord and extending into the brain, lies the central canal through which the cerebrospinal fluid circulates.

• The spinal cord mediates the reflex responses to some sensory impulses directly, i.e., without recourse to the brain, as when a person's leg is tapped producing the knee jerk reflex.

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the cells of the nervous system are called neurones

cell body

axon

myelin sheath

dendrites nerve endings

nucleus

structure of a neurone

sense organ

muscle

there are different types of neurone

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sensory neuronemotor neurone relay neurone

direction of electrical

signal

sends signals to your muscles to tell them to move

sends signals from your sense organs

connects neurones to other neurones

dendritescell body

axon

myelin sheath

nerve endings

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neurones communicate with each other using a

mixture of electrical & chemical signals

cell body

axon

myelin sheath

dendrites nerve endings

nucleus an electrical signal is transmitted along the axon

But what happens when the signal reaches the end of the axon?

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cell body

axon

myelin sheath

dendrites nerve endings

nucleus the signal is transmitted to

another neurone across a

junction called a synapse by chemicals called

neurotransmitters.

synapse

signals cross between neurones at the synapse

neurotransmitter

vesicle

synaptic cleft

receptor

the signal is transmitted to

another neurone across a

junction called a synapse by chemicals called

neurotransmitters.

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cell body

axon

myelin sheath

dendrites nerve endings

nucleus

synapse

signals cross between neurones at the synapse

neurotransmitter

vesicle

synaptic cleft

receptor

electrical impulse triggers vesicles to move to the synapse membrane

1

vesicles fuse with the membrane and release neurotransmitter into the synaptic cleft

2

neurotransmitter diffuses across the cleft and binds to receptors on the other side

3

Once enough receptors have neurotransmitters bound to them, the signal is transmitted…

4

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The point where your muscles and nervous system meet is called the

neuromuscular junction (NMJ)

muscle

Signals sent from your central nervous system to the NMJ tell muscles to move

The synapses at the NMJ use a neurotransmitter called

acetylcholine

Autonomic Nervous System

• Autonomic Nervous System is the division of the peripheral nervous system that controls the glands and the muscles of the internal organs.

• The Autonomic Nervous System operates on its own and is involuntary.

• The two divisions of Autonomic Nervous System are • Sympathetic Nervous System• Parasympathetic Nervous System

Your brain changes and adapts

What happens as our brains mature?

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your brain changes and adapts all the time and all through your life

your brain learns and forms memories by strengthening synapses that are used a lot and weakening those that are used less often

As your brain matures, it prunes synapses to make it more efficient

During adolescence your brain has a major tidy-up and gets rid of lots of connections it isn’t using

This is a critical and delicate process. It is thought that conditions such as schizophrenia could be the result of it going wrong

Some evidence suggests that using drugs can disrupt this process

Between birth and age 3 your brain makes lots of new synapses

A toddler has 2-3 times more synapses than an adult

What happens as you grow?

• Your Nervous System is your body’s control center.

• Your nerves are made of special cells.

• Your nervous system keeps your balance.

• Thousands of nerve cells die each day

• There are around 47 miles of nerves in your body.

• One nerve cell may be connected to 1000 more.

• Your nerve impulses can travel up to 390 feet per second.

Cont...