Thursday, February 25, 2016
Wednesday, February 24, 2016
Study material for class XI Biology and other Subjects
https://drive.google.com/file/d/0B8JX9SS-0ql0Mkp4d1BNRElqRzQ/view
Tuesday, February 23, 2016
INVESTIGATORY PROJECTS FOR CLASS XI AND XII BIOLOGY
INVESTIGATORY PROJECTS IN BIOLOGY
FOR CLASSES XI AND XII
Tuesday, February 16, 2016
Monday, February 15, 2016
Thursday, February 11, 2016
LINKS FOR ENTRANCE EXAMINATIONS
ALL INDIA PRE-VETERINARY TEST (AIPVT)
LINK- WEBSITE.
Admission Notice: MBBS Course (2016-17) MGIMS WARDHA
LINK: INFORMATION
All India Institute Of Medical Sciences
Wednesday, February 10, 2016
Neural Control and Coordination
Neural Control
and Coordination
Action potential: A sudden change in the electrical charges in the plasma membrane of
a nerve fibre.
Aqueous humour : The thin watery fluid that occupy space between lens and cornea in
eye.
Blind spot: A spot on retina which is free from rods and cones and lack the
ability for vision.
Cerebrospinal fluid: An alkaline fluid present in between inner two layers of meninges.
Cerebellum: A part of hind brain that
controls the balance and posture of the body.
Cochlea: A spirally coiled part of
internal ear which is responsible for hearing.
Corpus callosum: A curved thick bundle of nerve fibres that joins two cerebral hemisphere.
Depolarisation: A condition when polarity of
the plasma membrane of nerve fibre is reversed.
Endolymph: The fluid filled within
membranous labyrinth.
Eustachian tube: A tube which connects ear cavity with the pharynx.
Fovea: An area of highest vision on
the retina which contain only cones.
Meninges: Three sheets of covering of
connective tissue wrapping the brain.
Grey Matter: This shows many convolutions which increase the amount of vital nerve
tissue.
Medulla oblongata: Posterior most part of the brain which is continuous with spinal cord
and
control respiration, heart
rate, swallowing, vomiting.
Pons: Thick bundles of fibres on
the ventral side of brain below cerebellum.
Foramen magnum: A big aperture in the skull posteriorly through which spinal cord emerges
out.
Spinal cord: A tubular structure
connected with medulla oblongata of brain and situated in the
neural canal of the
vertebral column, covered by meninges.
Synaptic cleft: A narrow fluid filled space
which separates two membranes of the two neurons at
the synapse.
Synaptic vesicles: These are membrane bound
vesicles in the axoplasm of the axon terminal and
these store
neurotransmitter.
Neurotransmitter: These are chemicals stored
in synaptic vesicles, diffuse to reach the membrane
of next neuron for its
stimulation.
Synapse: A physiological junction
between axon of one neuron and dendrite of next neuron.
CNS − Central neural system
PNS − Peripheral neural system
ANS − Autonomic neural system
Functions of parts of brain:
Cerebrum: Centre of intelligence,
memory and imagination, reasoning, judgement, expression
of will power.
Thalamus: Acts as relay centre to
receive and transmit general sensation of pain, touch and
temperature.
Hypothalamus: Centre for regulation
of body temperature, urge for eating and drinking.
Mid brain: Responsible to
coordinate visual reflexes and auditory reflexes.
Cerebellum: Maintains posture and
equilibrium of the body as well as coordinates and regulates
voluntary movement.
Pons varoli: Relays impulses between
medulla oblongata and cerebral hemisphere and between the
hemisphere of cerebrum and cerebellum.
Medulla oblongata: Centre that
control heart beat, breathing, swallowing, salivation, sneezing,
vomiting and coughing.
Reflex Action: as a spontaneous, automatic and mechanical response to a stimulus
acting on a specific
receptor without the will of an animal.
Eg.- movement of diaphragm
during respiration, blinking of eyes, coughing, yawning,
sneezing etc.
Reflex arc –
The path travelled by an impulse in a reflex action is called a reflex arc.
It comprises - i) A specific
receptor, ii) an afferent nerve iii) a portion of central
nervous system, iv) an efferent nerve, v) an effector.
STEP 1
Nerve cell is at resting potential with
diffusion of Na+ & K+ down concentration gradient as cell pumps up the
gradient
STEP 2
neurons recieve stimulation causing local
potentials which may lead to reach threshold
STEP 3
sodium channels in trigger zone of axon
opens
STEP 4
sodium ions diffuse inward, depolarizing
the membrane
STEP 5
potassium channels in the membrane open
STEP 6
potassium ions diffuse outward,
repolarizing the membrane
STEP 7
action potential causes electric current
that stimulates adjacent portions of the membrane
STEP 8
action potentials occurs sequentially along
the length of axon as nerve impulse
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