Neural Control and Coordination Class 11 Notes

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NEURAL CONTROL AND COORDINATION
SENSORY RECEPTION AND PROCESSING

  • Sensory organs detect all types of changes in the environment.
    Sensory receptors →Input→ CNS→output→ Parts/Organs
    (Detect stimuli)              (Process analyse)      (Response to stimuli)

SENSE ORGANS

Sense organ         Sense                                      Features associated

Nose                   Smell                          + Mucus coated olfactory epithelium        (single)                                                    having three types of cells.
                                                                + Neurons extend directly into been sized                                                                    olfactory bulb that are extensions of                                                                           limbic system
Tongue                Taste                         + Input from taste buds is conveyed to    (single)                                                    the brain and a complex flavour
                                                                 of food or drink is perceived.
Ear                    Hearing,balance          + Input from organ of Corti and                 (Paired)                                                   vestibular apparatus is conveyed
                                                                  to CNS
Eye                        Vision                        + Enclosed in sockets of skull (orbits)
(Paired)                                                   + Nearly spherical in structure.

Note:- The chemical sense of gustation (taste) and olfactory (smell) are functionally similar and interrelated as they detect dissolved chemicals.

EYE

  • The wall of the eyeball is composed of three layers.
    – External
    – Middle
    – Inner.
  • External Layer (Sclera):-
    – Anterior-Cornea
    – Posterior- Sclera

    +Composition – Dense connective tissue



    Middle layer (Choroid)
    Irish- Anterior, opaque, pigmented, visible coloured portion of the eye
             – Regulates the diameter of pupil through its muscle fibres

  • Ciliary body:– Thick anteriorly 
                            – Hold the lens in place through ligaments
  • Choroid:-  Thin over posterior 2/3rd part
                       – Contains many blood vessels and looks bluish.

Inner layer (Retina)
Retina:- 
-Outer- Photoreceptor cells
             Types : Rods and cones

Middle- Bipolar cells
Inner- Gangilon cells

Fovea:-
– Only cones are densely packed
– Thinned central portion of retina
– Point with greatest visual acuity or resolution.

Blind spot:-
– Lies medial to and slightly above posterior pole of eye ball
– No rods or cones here
– Retina blood vessels enter
– Optic nerve leaves the eye.

  • Macula lutea– Yellowish pigmented spot lying at the posterior pole of the eyelateral to the blind spot with a central pit called forvea

Photoreceptor cells     Vision         Photopigments (light sensitive proteins)
Rods                               Twilight/      Rhodopsin/purplish red protein/   
                                        Scotopic     visual purple
                                        vision 
Cones                        – Day light/         Types of cones
                          photopic vision  Red – Different photopigments in these cones
                      and colour vision  Green– Sensation of different colours by
                                                                    various combinations.
                                                       Blue- Equal stimulation of these gives                                                                                 sensation of white light

  • Photopigments contain an aidehyde of vitamin A/retinal and protein,opsin
NEURAL CONTROL AND COORDINATION-EYE
EYE

CHAMBERS IN EYE

                               Cornea ↔Between↔  Lens ↔ Between↔ Retina
                                                    ↓                              ↓
                                        Aqueous chamber     Vitreous chamber
Contains                                      ↓                              ↓ 
                                       Aqueous humor        Vitreous humor    
Appearance                                  ↓                            ↓ 
                                        Thin watery fluid      Transparent gel

MECHANISM OF VISION

                                          Focusses
                                          light rays                                         Opsin(change in)

                                               ↓                                                                 ↑
Vision→Enter→Cornea→Lens→Photo→contain→ Rhodopsin→↓ 
light                                                 Sensitive              dissociates      Retinal
rays                                                 cells                      into
Change in 
membrane permeability
→→→→→→→→→→→→  Generate potential difference in photoreceptor

        transmitted to                        Generate action potential sent forward to
cells→→→→→→→→ Bipolar cells→→→→→→→→→→→→→→→→→→→→→→

                         Impulse
Ganglion cells→→→→→Optic nerve →Visual cortex.

  • Brain analyse image formed on retina based on earlier memory and experience.

THE EAR

Anatomical→→→→ Outer→→→→→Middle Ear↔↔↔Internal Ear
  Division                       ↓                               ↓                                    ↓
                      Pinna+ Ear canal        Malleus Stapes                Labyrinths

  • Components:-
    +     Fine hair and wax glands are present in their skin.
    + Pinna gathers/collects the vibrations in the air
  • External auditory meatus/canal:- Extends inwards upto tympanum.
  • Eustachian tube:- 
    +     Connects middle ear cavity to the pharynx.
    + Equalises pressure on  either side of tympanum.

Note:- 
– Tympanic membrane  (a)Connective tissue covered with skin on the outside
   is composed of            (b) Mucus membrane on the inside.
– Ear ossicies→Arranged in a chain (M→|→S)
      – Structure details:- (a) Malleus is attached to tympanum
                                         (b) Stapes is attached to the oval window
      – Function:-  Increase efficiency of transmission of sound waves to the                                   inner ear

NEURAL CONTROL AND COORDINATION-THE EAR
THE EAR

LABYRINTH

It is a fluid filled inner ear,consists of two parts: Bony and Membranous labyrinths.
                                  Encloses
Bony Labyrinth→→→→→→→→→→ Membranous Labyrinth
(filled with perilymph)                (filled with endolymph)

Parts of Membranous      Sub-parts         Receptors          Basic functions
labyrinth
-Vestibular apparatus    (a) Semicircular      Crista       – Maintenance of 
(complex system)              canals (3)           ampullaris     balance of the body
                                          (b) Otolith organ                           and posture 
                                         |_________________|   Macula    – Influenced by gravity
                                       Utricle          Saccule                      and movements.

-Cochlea 
(coiled apparatus)                                         Sensory hair            Hearing
                                                                          cells in organ
                                                                          of Corti

Notes:-

  • Semicircular canals lie at right angle to each other and the base of each canal is swollen called ampulla.
  • These membranous canals are suspended/surrounded by perilymph of the bony canals
  • Vestibular apparatus is present above the coiled cochlea.
  • Receptors present in vestibular apparatus have hair cells.

COCHLEA

Demarcating           Chambers                Fluid present        Terminating
membrane                                                 within                     region

Reisnner’s   – Scala vestibuli→ Perilymph→ Oval window
Basilar         – Scala media→ Endolymph
                     – Scala tympani → Perilymph→Round window

NEURAL CONTROL AND COORDINATION-SECTIONAL VIEW OF COCHLEA
SECTIONAL VIEW OF COCHLEA

ORGAN OF CORTI

  • Located on Basilar membrane
  • Contains sensory hairs present in rows on internal side of organ of corti, that act as auditory nerve
  • Sensory hair cells-
    -Apical part- possess stereocilia
    – Above them there is thin elastic membrane called Tectorial membrane.
    – Basal part- Is in close contact with afferent nerve fibres forming the      auditory nerve.
NAURAL CONTROL AND COORDINATION-SECTIONAL OF ORGAN CORTI
SECTIONAL OF ORGAN OF CORTI

MECHANISM OF HEARING

  • Ear converts sound waves into neural impulses.
  • The cerebelium integrates information received from the semicircular canals of the ear and the auditory system.

                 Sound waves
            Received ↓by                                                Vibration transmitted
                   External ear →→→→→→→Ear drum→→→→→→→→→→→
                                       extends inward                        through

    → Ear ossicles→→→→→→→→→→→→Oval window→→→→→→→
                                Transmits vibration to                        Generate waves in

    →Perilymph→Endolymph→→→→→→Ripples in basilar membrane→
                                                   induce                                   Germinates
    →→→ Hair cells of cochlea against tectorial membrane→→→→→→
    Bend                                                                                      impulses in

    →Afferent neurons→→→→→→→→→→Auditory nerve→→→→→→
                                     transmitted further to               Transmit impulse to

    →Auditory cortex (Impulse is analysed and sound is recognised).


                                                   
  • The eye works by capturing light rays, focusing them onto the retina at the back of the eye, where photoreceptor cells (rods and cones) convert light into electrical signals. These signals are then transmitted via the optic nerve to the brain, where they are interpreted as visual images.
  • The main parts of the eye include the cornea, iris, pupil, lens, retina, optic nerve, and various muscles responsible for eye movement. Each part plays a specific role in the process of vision.
  • The blind spot is a small area on the retina where the optic nerve exits the eye. This area lacks photoreceptor cells, so light that falls on the blind spot cannot be detected. However, our brains fill in the missing information, and we are usually unaware of our blind spots.
  • The ear works by capturing sound waves and converting them into electrical signals that can be interpreted by the brain. The ear consists of three main parts: the outer ear, middle ear, and inner ear, each of which plays a role in the process of hearing.

he inner ear contains the cochlea, a spiral-shaped structure filled with fluid and lined with hair cells. These hair cells detect sound vibrations and convert them into electrical signals, which are then transmitted to the brain via the auditory nerve.

  • The cochlea is responsible for converting sound vibrations into electrical signals that can be interpreted by the brain. It contains thousands of tiny hair cells that are sensitive to different frequencies of sound, allowing us to perceive a range of pitches.

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