Neural Control and Coordination, Study notes of Biology

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Neural control

and Coordination

Neural

system

Action

potential Brain sensory Receptors Eyes

Ears

• (^3) Ols

Neural System

• Neural and Endocrine (^) system coordinate and

integrate

all activities (^) of organs .

• neural (^) System provides point to (^) point connections for quick coordination^.
• Neural^ system composed (^) of highly specialised cells called Neurons which^ can detect (^) , receive^ I transmit different kinds^ of stimuli^. Hydra : (^) Network of Neurons

Human Neural System

• Divided^ into^ two^ parts :

1.^ Central^ Nervous^ system Cavs)

(^2).

Peripheral

Nervous System (PNS)

CNS includes Brain and spinal cord and is site

of information^ processing.

PMS (^) consists all nerves of body^ associated with CMS^. Nerve (^) fibres are (^) of 2 types : (a) (^) afferent nerve^ fibres :^ transmit^ impulses from (^) organs to Cros

(b) efferent nerve^ fibres :^ transmit^ regulatory impulses from

CNS to peripheral

organs.

• Myelinated Nerve^ fibres enveloped with^ Schwann cells (^) , which^

form myelin^

sheath around anon (^).

• (^) Gaps between^ two^ adjacent (^) myelin sheath are called :^ nodes of Ranveer^ . Cranial (^) and (^) Spinal Nerves :^ Myelinated Autonomic (^) and somatic (^) neural

fibres

: (^) Non - myelinated. Action Potential

• On^ Resting phase :^ when^ neuron^ is^ not^ conducting

an impulse , axonal^ membrane^ is^ polarised

At (^) Rest : Anoplasm inside^ anon^ : high ki ' conan : low^ Noi ' conc (^).

Outside fluid :^ low K+ ; high Nat

Resulting in^ inner^ surface

: - ve E outer membrane : (^) we

• Electric^ potential difference across

resting plasma

membrane : Resting potential.

• when^ nerve^ fibre is stimulated^ :^ Noi ' permeability increased at (^) point of stimulus (^) (rapid Nat (^) Influx) and hence (^) polarity reversed^. (^) ( now membrane^ said to be DE POLARISED)
• (^) Depolarisation is very rapid^ so that conduction (^) of nerve (^) impulse along entire (^) length occurs in^ fraction of seconds^.
• (^) Depolarisation (^) followed (^) by increase^ in^ K+^ permeability leading to

change

in (^) polarisation ( tue^ :^ outside (^) ,

• ve : (^) inside (^) RE POLARISATION )
• Regain of (^) potential takes^ place due^ to^ action

of Natl

ht (^). It continues till^

resting potential

becomes -70mV Types of^ Synapse Electrical (^) chemical

Pre and post synaptic Pre and

post synaptic

membrane in (^) close membrane separated by^ a

proximity

without any (^) fluid filled synaptic cleft^ . cleft.

• Well (^) protected (^) by skull
• Covered^ by Cranial (^) meninges -
• Outer Duramater
• Middle^ Arachnoid ° Inner Piamater
• further divided^ as -
  • forebrain ° Midbrain ° Hindbrain FOREBRAIN
• Consists^ of cerebrum Thalamus

Hypothalamus

• Deep cleft (^) dividing cerebrum^ longitudinally into^ two halves (^) called as cerebral (^) hemispheres. Hemispheres connected^ by tract^ of nerve^ fibres called CORPUS CALLOSUM (^).
• Cerebral^ cortex^ referred as (^) Grey matter^ due^ to^ cell bodies concentrated^ here.
• Cerebral^ cortex^ contains^ motor^ areas^ , (^) sensory areas

and large ASSOCIATION^ REGIONS .

Responsible for complex^ functions

like intersensory associations (^) , memory and (^) communication.

• fibres^ of tracts^ covered^ with^ myelin sheath^ forms inner (^) part of cerebral (^) hemisphere

giving an^ opaque

white (^) appearance ; hence called white matter (^).

• Thalamus^ : major coordinating centre (^) for sensory and motor signaling.
• Hypothalamus :^ dies^ at^ base^ of thalamus^. i contains centres which control

body

temperature ,^ urge for (^) eating E^ drinking. : (^) Has groups of neurosecretary cells^ which secrete hormones called^ hypothalamic hormones (^).

• Inner^ parts (^) of cerebral^ hemispheres have^ group of

associated deep structures like

amygdala ,

hippocampus forms a^ complex^

structure called (^) the limbic (^) system. Along with hypothalamus ,^ it is involved (^) in regulation of sexual (^) behaviour (^) , (^) expression of emotions^ (^ pleasure^ , rage ,^ fear ,^ encitement) and motivation (^). Midbrain

• Located^ between^ hypothalamus of (^) forebrain E^ hindbrain^.
• Canal^ called^ cerebral^ aqueduct (^) passes. . Dorsal^ frontier consists^ of 4 round^ swellings ( lobes) called (^) corpora quadri gemina .
• (^) Midbrain t^ Hindbrain = Brain Stem

Sensory Organs

• Sensory organs

detect all types of

changes in the environment (^) and send (^) appropriate signals to^ CNS. Nose

. Contains^ mucus coated (^) receptors specialised (^) for receiving

sense of smell^ called^ olfactory receptors.

• Neurons^ of (^) olfactory epithelium (made^ of 3 kinds^ of cells) entered from outside^ environment (^) directly into a (^) pair of

olfactory

bulb (^) ( which (^) are extensions of limbic system) Tongue

• Detect dissolved^ chemicals
• Detects^ taste^ through taste (^) buds

having gustatory

receptors. chemical (^) sensation

of gustation (tongue)^

and

Olfactory

(nose) are^

functionally

similar and inter-^ related (^). Eyes

• (^) Human Eye ball^ nearly spherical

• External (^) layer :^ sclera (^) ( Dense connective tissue) TV Anterior (^) portion (^) of this :^ CORNEA
• Middle^ layer :^ choroid^ (contains^ blood^ vessels^ and bluish)

Thin over posterior

zg Thick over anterior

Lg

to form ciliary^ Body continues (^) to form surrounds PUPIL^ IRIS (^) ( visible coloured portion)

• Inner^ layer :^ RETINA
  • Three^ layers of neural^ cells^ from inside^ to^ outside^ : Ganglion cells 1 Bipolar Cells t

Photoreceptor Cells

FAR.

• Perform (^2) functions : Hearing :^ Maintaining balance
  • Anatomically Divided into 3 major sections - Outer (^) ear middle^ ear Inner ear (^). ° Outer (^) ear :^ consists (^) of Pinna & External (^) Auditory meatus Pinna (^) collects vibrations in air which

produce

sound (^). Ex.

Auditory

meatus leads (^) inwards (^) upto

tympanic

membrane (^). ° Middle^ Ear^ :^ Has^3 ossicles malleus Incurs (^) stapes Mls malleus attached to^ tympanic membrane while (^) stapes to oval window.

• Increase efficiency (^) of transmission^ of sound^ waves^.

Eustachian tube connects middle (^) ear cavity with pharynx.

• Fluid^ filled inner^ Ear :^ Labyrinth consists (^2) parts : Bony Labyrinth Membranous^ Labyrinth^. Bony Labyrinth^ : (^) series of channels membranous :^ filled^ with (^) fluid endolymph. Coiled portion of (^) labyrinth : (^) cochlear membranes

constituting

cochlea (^) , Reisner's and Basilar divide surrounding perilymph filled bony labyrinth^ into (^) upper scala vestibule and lower scala tympani .

. Organ of Corti^ :^ located^ on basilar membrane which^ contains

hair cells

acting

as (^) Auditory receptors. Above rows (^) of hair cells :^ Tectorial^ Membrane^ present. Inner (^) Ear :^ Also has^ a (^) complex Vestibular (^) apparatus located (^) above cochlea. Vestibular (^) apparatus : composed (^) of 3 semi - circular organs and (^) Otolith (^) ( macula : Sensory part of^ saccule and utricle^ ) Each semi -^ circular^ canal lies in (^) different plane 1-^ to^ each other.