Neurophysiology

During sleep:
1. Pulse & RR decreases
2. BP falls
3. Tendon relex lost

Examples of Mechanoreceptors
Tactile receptors
1.Merkel cells- Specialised cells present in the epidermis, sense light touch and softness.
2. Meissner corpuscles- An encapsulated nerve ending, present at the upper part of the dermis. They can sense light touch and vibrations.
3. Ruffini endings- These are also encapsulated, present in the dermis. They sense heavy and continuous pressure.
4.Pacinian corpuscles- They are encapsulated by connective tissue, located deep in the dermis of the skin. They respond to deep pressure.

Propioreceptors
These receptors sense body movement and position and help in maintaining the posture. It is required for locomotion and motor skills.
1.Muscle spindles- sense muscular movement.
2.Golgi tendons- sense tension in the tendons during muscle contractions.
3.Joint receptors- sense movement in the ligaments.

Explanation : Root value for Jaw jerk is Pons – V cranial nerve, Biceps jerk is C5, C6,Triceps jerk is C6 to C8 , Supinator jerk or radial periosteal reflex is C7, C8 ,Wrist tendon or finger flexion reflex is C8, T1, Knee jerk or patellar tendon reflex is L2 to L4, Ankle jerk or Achilles tendon reflex is L5 to S2.
Ref : Sembulingam 6th edition (Table-142.3)

Explanation :

Ref : Sembulingam 6th edition (Table- 141.1)

Basal ganglia are part of extrapyramidal system. Hypothalamus is associated with temperature regulation. It controls food habit, emotion & sexual behavior.

Explanation : Trigeminal nerve acts as afferent nerve in case of corneal,conjunctival & nasal superficial mucous membrane reflexes. Glossopharyngeal nerve acts as afferent nerve in case of uvular & pharyngeal reflex.
Ref : Sembulingam 6th edition (Table- 142.1)

Based on differences in the resting tone in muscles and the limbs involved, CP is classified into different groups.
The most prevalent type is spastic CP that is characterized by spasticity, hyperreflexia, clonus, and a positive Babinski sign.
These are all signs of damage to the corticospinal tract .
Dyskinetic CP is characterized by abnormal involuntary movements (chorea and athetosis) and may reflect damage to extrapyramidal motor areas. It is not uncommon to have signs of both types of CP.
The rarest type is hypotonic CP that presents with truncal and extremity hypotonia, hyperreflexia, and persistent primitive reflexes.

Neurotransmitter of Fast pain- Glutamate & Substance P for slow pain.

Function of brainstem
1. Control of respiration
2. Control of the cardiovascular system
3. Partial control of gastrointestinal function
4. Control of many stereotyped movements of the body
5. Control of equilibrium
6. Control of eye movements

Explanation : All-or-none Law, Infatigability, Adaptation, Summation, Refractory period, Conductivity etc are the properties of a nerve fibre.
Ref : Sembulingam 6th edition (Page- 768, 769)

Explanation : Stretch reflex is a monosynaptic reflex,Golgi tendon reflex/Clasp-knife reflex is disynaptic reflex,flexor withdrawl reflex is a polysynaptic reflex.
Ref : BRS Physiology 7th edition (Table- 2.8)

Explanation :

Ref : Sembulingam 6th edition (Figure-139.2)

Explanation : Lateral nucleus of hypothalamus acts as feeding centre & Ventromedial nucleus of hypothalamus acts as satiety centre.
Ref : Sembulingam 6th edition (Table- 149.2)

Explanation : Diencephalon includes thalamus, hypothalamus, subthalamus, metathalamus.
Ref : Sembulingam 6th edition (Page- 758)

The interpeduncular fossa
infront by the optic chiasma,
behind by the antero-superior surface of the pons,
antero-laterally by the converging optic tracts,
postero-laterally by the diverging cerebral peduncles.

Myelinated Nerve Fibre:

1. The nerves that are insulated by a sheath or myelin called myelinated nere fibre.
2. These are made up of lipid & protein and so, appear white.
3. These have nodes of Ranvier which always constant in number.
4. Nerve fibres outside CNS and myelinated.

Non-Myelinated nerve fibre:
1. The nerves which lack such sheath are called non-myelinated nerve fibre.
2. They appear grey because of absence of myelin sheath.
3. They do not have node of Ranvier.
4. Post-ganglionic sympathetic nerves are non-myelinated.

Relative hypoxia ( Type 1 B Lactic Acidosis)
1.Seizure
2.Severe Exercise

ABC of Biochemistry 6th - P: 371

Loss of ankle jerk with extensor planter response
•       Subacute combined degeneration of spinal cord
•        Friedreich’s ataxia
•       Taboparesis
•       Multiple sclerosis
•       DM with cervical myelopathy.

Explanation : NGF plays an important role in treating many nervous disorders such as Alzheimer disease, neuron degeneration in aging and neuron regeneration in spinal cord injury. Commercial preparation of Brain-derived Neurotrophic Growth Factor is used to treat motor neuron diseases.
GDNF is found in neuroglial cells. It has a potent protective action on dopaminergic neurons. It is used for the treatment of Parkinson disease.
CNTF is secreted in peripheral nerves, ocular muscles and cardiac muscle. It protects neurons of ciliary ganglion and motor neurons.
Ref : Sembulingam 6th edition (Page- 763)

Effects of low ionized Ca2+
1.  Increased excitability of nerve & muscles.
2.  Increased membrane permeability
3.  Impaired blood clotting
4.  Tetany
5.  Rickets (in children)
6.  Osteomalacia (In adult)

Pain Initiators
• Glutamate - Central
• Substance P - Central
• Brandykinin - Peripheral
• Prostaglandins - Peripheral
• Aspartate
Pain Inhibitors
• Serotonin
• Endorphins
• Enkephalins
• Dynorphin
• GABA
• Glycine

Glycine has both excitatory and inhibitory effects in the CNS. When it binds to NMDA receptors, it makes them more sensitive to the actions of glutamate. Glycine may spill over from synaptic junctions into the interstitial fluid and in the spinal cord; for example, it may facilitate pain transmission by NMDA receptors in the dorsal horn. However, glycine mediates direct inhibition in the brainstem and spinal cord.

• ২০২৬ সালের বর্ষপণ্য : 
- পেপার ও প্যাকেজিংকে চলতি বছরের বর্ষপণ্য ঘোষণা করে ৩০তম ঢাকা আন্তর্জাতিক বাণিজ্য মেলার (ডিআইটিএফ) উদ্বোধন করা হয়েছে।
- 'পেপার ও প্যাকেজিং প্রডাক্টকে ২০২৬ সালের বর্ষপণ্য হিসেবে ঘোষণা করেন বাণিজ্য উপদেষ্টা শেখ বশিরউদ্দীন।
- বর্ষপণ্য ঘোষণার ফলে পেপার প্যাকেজিং শিল্পে নতুন বিনিয়োগ, আধুনিক প্রযুক্তির ব্যবহার, কর্মসংস্থান বৃদ্ধি এবং রফতানি আয় উল্লেখযোগ্যভাবে বাড়বে। 

উল্লেখ্য, 
- ২০২৫ সালের 'বর্ষপণ্য' ছিলো আসবাবপত্র বা ফার্নিচার। 

তথ্যসূত্র: বনিক বার্তা ও বাসস। (Link1) (Link2)

Explanation : Mesencephalon is also known as midbrain. Rhombencephalon or hindbrain is subdivided into two portions:
i. Metencephalon, formed by pons and cerebellum
ii. Myelencephalon or medulla oblongata.
Midbrain, pons and medulla oblongata are together called the brainstem.
Ref : Sembullingam 6th edition (Page- 758)

Explanation : Anterior hypothalamus & mamillary body regulate sleep & wakefulness.
Ref : Sembulingam 6th edition (Table- 149.2)

Brain Areas for Control of the Gamma Motor System
The gamma efferent system is excited specifically by signals from the bulboreticular facilitatory region of the brain stem
and, secondarily, by impulses transmitted into the bulboreticular area from the following: (1) the cerebellum; (2) the basal ganglia; and (3) the cerebral cortex.
Because the bulboreticular facilitatory area is particularly concerned with antigravity contractions, and because the antigravity muscles have an especially high density of muscle spindles, the gamma efferent mechanism is believed to be important for damping the movements of the different body parts during walking and running.

Lateral Rectus Muscle is supplied by Abducens Nerve
 
Functions of Facial Nerve
Main: Motor innervation to muscles of facial expression (SVE)
Others:  1.Taste innervation of anterior two-thirds of tongue and palate (SVA),
               2. parasympathetic innervation of lacrimal, nasal, palatine and salivary glands (except parotid) (GVE),
               3. sensation to parts of auricle and retroauricular region (GSA)

Snell 8th -351

Explanation : Functions of the cerebellum-
a. Vestibulocerebellum—control of balance and eye movement.
b. Pontocerebellum—planning and initiation of movement.
c. Spinocerebellum—synergy, which is control of rate, force, range, and direction of movement.

Ref : BRS Physiology 7th edition

Proprioceptive sensations include
•       Position sensations
•       Pressure sensation from the bottom of the foot
•       Sensation of equilibrium
•       Tendon & muscle sensation

Explanation : Normal duration of synaptic delay is 0.3 to 0.5 millisecond. Synaptic delay is one of the causes for reaction time of reflex activity.
Ref : Sembulingam 6th edition (Page- 785)

The other cortical cell types are local circuit interneurons and are classified based on their shape, pattern of projection, and neurotransmitter. Inhibitory interneurons (basket cells and chandelier cells) release GABA as their neurotransmitter. Basket cells have long axonal endings that surround the soma of pyramidal neurons; they account for most inhibitory synapses on the pyramidal soma and dendrites. Chandelier cells are a powerful source of inhibition of pyramidal neurons because their axonal endings terminate

exclusively on the initial segment of the pyramidal cell axon. Their terminal boutons form short vertical rows that resemble candlesticks, thus accounting for their name. Spiny stellate cells are excitatory neurons that release glutamate; these multipolar interneurons are located primarily in layer IV and are a major recipient of sensory information arising from the thalamus.

In addition to being organized into layers, the cerebral cortex is also organized into columns. Neurons within a column have similar response properties, suggesting they comprise a local processing network (eg, orientation and ocular dominance columns in the visual cortex).

Spinal Nerve:
1.They are 31 Pairs
2. Formed by Union of anterior and Posterior Nerve roots
3.The posterior ramus contains both motor and sensory axons
4. The anterior ramus contains only motor axons

Snell 8th -128