Neural Control And Coordination

Neurotransmitters

Explanation:

Neurotransmitters are the chemicals which are involved in the transmission of nerve impulses at the synaptic junction.

Hormones chemicals which act as intercellular messengers and are produced in trace amounts.

Cerebrospinal fluid is a clear, colourless fluid which is found in brain and spinal cord and provides shock resistance to the brain.

Lymph is a clear-to-white fluid made of white blood cells, especially lymphocytes, the cells that attack bacteria in the blood.

Explanation:

The electrical potential difference across the resting neural membrane is called the ‘resting potential’. The potential difference is –ve which is due to the distribution of the Na⁺ and K⁺.

The rest of the ions are not involved in neural system but in other biological functions.

Ion Pump

Explanation:

Resting membrane potential is maintained by ion pump which transports outward and inside the cell.

Neurotransmitter transmits signals across a chemical synapse from one neuron to another neuron.

Hormones are chemical substances secreted by endocrine glands directly into bloodstream. They act as messengers and control and coordinated activities of the body.

Sympathetic and parasympathetic neural system

Explanation:

Visceral organs are the internal organs present in chest or abdomen.

Sympathetic and parasympathetic neural system controls the functioning of the visceral organs of the body.

Somatic neural system is associated with peripheral nervous system and has no role in regulation of the visceral organs.

Central nervous system is associated with brain and spinal cord and has no control over visceral organs.

Brain

Explanation:

As we can see in the image, motor neuron and interneuron (relays signals between sensory neurons and motor neurons) are involved but brain is not. Therefore, brain is not involved in the knee-jerk reflex.

Limbic system

Explanation:

Limbic system and hypothalamus are associated with strong emotions.

The cerebellum coordinates voluntary movements such as posture, balance, coordination, and speech, resulting in smooth and balanced muscular activity.

Medulla directly controls heart-rate, breathing, blood-vessel dilation, digestion, sneezing, swallowing and vomiting.

Cerebral cortex, also known as cerebrum, is divided into four lobes and each lobe has different functions including- Determining intelligence, Determining personality, Motor function, Planning and organization, Touch sensation, Processing sensory information and Language processing.

Vit A

Explanation:

The rods of retina contain a biological pigment called Rhodopsin. It is composed of a protein and an aldehyde of vitamin A.
Vitamin B, Vitamin C and Vitamin D are not directly involved in the vision.

Lens, aqueous humor and vitreous humor

Explanation:

Only lens, aqueous humor and vitreous humor are enclosed by the three layers of the eye ball and the rest are not enclosed by all three layers.

Ceruminous gland

Explanation:

Ceruminous gland, also known as Sebaceous gland, is the wax secreting gland in the ear canal.

Sweat glands are responsible for the sweat production.

Prostate gland secretes fluid nourishes and protects sperms.

Cowper’s gland lubricates urethra for spermatozoa to pass through the viscous fluid released during pre-ejaculation.

Cochlea

Explanation:

Cochlea is a part of the internal ear which is responsible for hearing.

Semicircular canal is responsible for keeping the balance of the body.

The utricle and saccule are the two otolith organs in the vertebrate inner ear. They are part of the balancing system in the vestibule of the bony labyrinth.

Cochlea

Explanation:

Corti is present in cochlea. The organ of Corti is the sensitive element in the inner ear and can be thought of as the body's microphone. It is situated on the basilar membrane in one of the three compartments of the Cochlea. It contains four rows of hair cells which protrude from its surface.

The correct order of involvement of the given parts of neuron in electrical impulse is-

Dentrites → Cell body → Axon → Axon terminal → Synaptic knob

The inner ear is responsible for maintaining the balance of the body and posture. The semicircular canals and the vestibule are the two parts of the inner ear which are involved in balancing the body and maintaining its equilibrium.

The cone cells present inside the retina enable us to see coloured objects around us. They are photoreceptor cells of the eyes of the vertebrates which work best in relatively bright light.

External auditory canal → Ear Drum → Malleus → Incus → Stapes → Cochlea → Cochlear nerve

So, the order of reception and transmission of sound wave from the ear drum is –

Ear Drum → Malleus → Incus → Stapes → Cochlea → Cochlear nerve

• In response to a signal, the soma end of the axon becomes depolarized.

• The depolarization spreads down the axon. Meanwhile, the first part of the membrane repolarizes. Because positive channels are inactivated and additional positive channels have opened, the membrane cannot depolarize again.

• The action potential continues to travel down to the axon.

• The human brain is protected by the skull.

• Inside the skull, there are cranial meninges that cover the brain.

• The cranial meninges is made up of three layers, namely – Duramater (outer layer), Arachnoid (middle layer) and Pia mater (inner layer which is in contact with the brain).

• Duramater is thick, tough, fibrous membrane

• Arachnoid is a membrane with spider-like structure.

• Piamater is a very thin, delicate and vascular membrane.

• The space between duramater and arachnoid is called subdural space.

• The space between arachnoid and piamater is called subarachnoid space. It is filled cerebrospinal fluid which acts as cushion for CNS from shock.

Limbic system (the inner part of the cerebral hemisphere and a group of associated deep structures) and hypothalamus (a small region located at the base of the brain near the pituitary gland) are responsible for such reactions.

Grey matter – The cerebral cortex is referred to as Grey matter due to its greyish appearance. It is the layer of cells covering the cerebral hemisphere and is thrown into prominent folds. There are neuron cell bodies concentrated, hence giving the grey colour.

White matter – Fibres of the tract are covered with myelin sheath. It constitutes the inner part of the cerebral hemisphere. They give an opaque white appearance to the layer.

The hunger centre is located in hypothalamus in human brain. It contains many centres which control the urge for eating and drinking.

The vestibular system of the inner ear is associated with vertigo.

The symptoms of dizziness and vomiting are experienced by the person when he goes on higher altitudes because sudden elevation in height causes disturbance in maintaining pressure by Eustachian tube.

The vestibular system of the inner ear is associated with vertigo.

The symptoms of dizziness and vomiting are experienced by the person when he goes on higher altitudes because sudden elevation in height causes disturbance in maintaining pressure by Eustachian tube.

a – iii, because the resting potential is the electrical potential difference across the neural membrane.

b – iv, because nerve impulse is an electric wave like response of a neuron to a stimulation.

c – ii, because synaptic cleft is the gap between the pre-synaptic and the post-synaptic neurons

d – i, because neurotransmitters are the chemicals involved in the transmissions of the impulses at synapses.

The Human Neural System is divided into two parts Central Neural System (CNS) and Peripheral Neural System (PNS).

The CNS is further divided into Brain (which has three parts – fore brain, mid brain and hind brain) and Spinal Cord and PNS is divided into Somatic Neural System and Autonomic Neural System (divided into sympathetic neural system).

In computers, the input devices are mouse and keyboard while in neural system, the sensory neurons act as input devices which take inputs from the environment.

The message from input devices is sent to the brain in neural system and to the CPU in computers.

The CPU processes the information and gives command to the output devices i.e. monitor and printer. The brain processes the information from the input devices.

The brain commands the concerned organs accordingly. This is done with the help of motor neurons which act as the output devices in neural system.

If someone receives a blow on the back of the neck, it may lead to the dislocation of cervical vertebrae (located right below the skull). The injury of spinal cord may pass to the neural canal which can result in paralysis or severe damage to the emotional behaviour.

The Eustachian tube is the tube that connects middle ear cavity with the pharynx.

It helps in equalising the pressure on either sides of the ear drum. There is a valve present at the pharyngeal opening. This usually remains closed. It opens up during yawning, swallowing, or due to abrupt change in altitude to let the air enter or leave the tympanic cavity to equalise the pressure.

The anterior portion of sclera (the external layer of eye ball) is called cornea.
The eye ball contains a transparent crystalline lens which is held in place by ligaments attached to the ciliary body

The inner layer of the human eye is the retina.

The space between the cornea and the lens is called the aqueous chamber and contains a thin watery fluid called aqueous humor.

The space between the lens and the retina is called the vitreous chamber and is filled with a transparent gel called vitreous humor.

Blind spot is the small region in the eye where photoreceptor cells are absent. Therefore, there is no photo detection in this area.

• A neuron can be divided mainly into three parts –

i) Axon

ii) Cell body

iii) Dendrites

• Any nerve impulse (bioelectric/electrochemical disturbance that passes along neuron during conduction of an excitation) is passed from one neuron to another neuron via axon.

• Transport and release of a neurotransmitter occurs within a synapse.

• At a chemical synapse, the membranes of the pre- and post-synaptic neurons are separated by a fluid-filled space called synaptic cleft.

• Chemicals called neurotransmitters are involved in the transmission of impulses at these synapses.

• The axon terminals contain vesicles filled with these neurotransmitters.

• When an impulse (action potential) arrives at the axon terminal, it stimulates the movement of the synaptic vesicles towards the membrane, where they fuse with the plasma membrane and release their neurotransmitters in the synaptic cleft.

• The released neurotransmitters bind to their specific receptors, present on the post-synaptic membrane.

• This binding opens ion channels allowing the entry of ions which can generate a new action potential in the post-synaptic neuron.

• Human Forebrain consists of 3 parts – Cerebrum (makes the major part of the human brain), Thalamus and Hypothalamus.

• Cerebrum - It is further divided into 4 lobes :

a. Frontal lobe -> associated with parts of speech, reasoning, planning, problem-solving and movement.

b. Parietal lobe -> Helps in movement, perception of stimuli and orientation.

c. Occipital lobe -> Visual processing

d. Temporal lobe -> perception and recognition of memory, auditory smell, speech.

The cerebrum also includes:

a. Sensory areas -> receive messages

b. Association areas -> Associate information with the previous and other sensory information.

c. Motor areas -> Responsible for the action of voluntary muscles.

The cerebrum is also responsible for thinking, intelligence, consciousness and memory.

• Thalamus- It is a small structure located right above the brain stem.

a. It responsible for relaying sensory information from the sense organs, relaying motor information for movement and coordination.

b. Thalamus is found in the limbic system within the cerebrum. The limbic system is mainly responsible for the formation of new memories and storing past experiences.

• Hypothalamus - The hypothalamus is a small and important part of the brain, located exactly below the thalamus.

a. It Controls the mood and emotions.

b. It coordinates the messages from the autonomous nervous system.

c. It synthesises of body’s essential hormones.

d. It receives the impulses, sense of taste and smell

e. It is involved in controlling body temperature, peristalsis, the rate of heartbeat, and blood pressure.

f. It is involved in forming an axis with the pituitary which is the main link between the nervous and the endocrine systems.

• Middle ear –

a. It contains three ossicles called malleus (hammer), incus (anvil) and stapes (stirrup) which are attached to one another in a chain-like fashion.

b. The malleus is attached to the tympanic membrane and the stapes is attached to the oval window of the cochlea.

c. A Eustachian tube connects the middle ear cavity with the pharynx and helps in equalising the pressures on either sides of the ear drum.

• Inner Ear –

a. It is also called Labyrinth.

b. It is fluid-filled.

c. It has two parts – the bony and the membranous labyrinth.

d. The bony labyrinth is a series of channels.

e. Inside these channels lies the membranous labyrinth. It is surrounded by a fluid called perilymph.

f. The membranous labyrinth is filled with a fluid called endolymph.

g. The coiled portion of the labyrinth is called cochlea.

h. The space within cochlea called scala media is filled with endolymph.

i. At the base of the cochlea, the scala vestibuli ends at the oval window, while the scala tympani terminate at the round window which opens to the middle ear.

j. The inner ear also contains a complex system called vestibular apparatus composed of three semi-circular canals and the otolith and is located above the cochlea.

k. Each semi-circular canal lies in a different plane at right angles to each other. The base of canals is swollen and is called ampulla

l. Ampulla contains a projecting ridge called crista ampullaris which has hair cells. The saccule and utricle contain a projecting ridge called macula.