Neurophysiology (CNS) Flashcards
Briefly talk about the nervous system?
The nervous system is a highly complex part of an animal that coordinates its actions and sensory information by transmitting signals to and from different parts of its body.
There are 3 types of neurons, name them?
- Afferent
- Efferent
- Interneuron (association neurons)
There are 2 type of motor (efferent) neurons, name them and where they supply;
- Somatic motor neurons: they provide both reflex and somatic control of skeletal muscle.
- Autonomic motor neurons: innervate involuntary effectors like Smooth muscles, glands, cardiac muscles. They can be divided into sympathetic and parasympathetic
What nervous system functions to control the GIT?
Enteric nervous system
Define Basal ganglia?
Basal ganglia refers to large clumps of grey matter found in the cerebrum and cerebellum.
Folds in the brain are called _______ and, the crevices between them are called _______?
Gyri
The crevices between them are known as Sulci
Each part of the brain stem connects to he cerebellum via;
The Superior, Middle, & Inferior Cerebellar Peduncles
What is the corpus calosum?
Corpus callosum is a large commissure of fibre tract that joins the 2 cerebral hemispheres.
Mention some functions of the hypothalamus?
- Regulation of bodyβs visceral functions
- Regulation of anterior pituitary gland, water balance, eating and drinking behaviours.
- Reinforcement of certain behaviors and regulation of the circadian rhythm
Briefly talk about the Thalamus?
The Thalamus is a large cluster of nuclei that serves as a synaptic relay station and is an important integrating center for most of the cortex.
For easy remembrance, the Thalamus is like an office secretary that collects all information going to the oga office(higher cerebral centres) then integrates them to where they ought to go and how
The Diencephalon is composed of?
The Thalamus + Hypothalamus
The forebrain is composed of ?
The Thalamus + Hypothalamus + Cerebrum
Talk about spinal nerves?
Each spinal nerve has 2 roots;
The dorsal root which consist about entirely of sensory nerve fibres being information into the CNS, and
A Ventral route which consist almost entirely of motor fibres carrying information out of the nervous system to the muscle and gland.
In the CNS, oligodendrocytes function to?
Make Myelin
The 3 meninges that cover the brain are;
Pia matter (the innermost meninges, closest to the brain)
Arachnoid matter (has spider web-like nature and is the middle layer)
Dura matter (the hardest and outermost meninge)
Define meningitis?
Meningitis is an inflammation of the meninges, usually the pia or arachnoid matter. It is caused by bacteria, virus and other micro organisms that reach the meninges via blood flow
Explain the ventricular system of the brain?
The pia-arachnoid space is continuous with a series of cavities inside the brain called Ventricles. There is one lateral ventricle inside the center of each cerebral hemisphere and these communicates with the 3rd ventricle through the foramen of Munroe
The 3rd ventricle communicates with the 4th ventricle through?
AQUEDUCT OF SYLVIUS
The 4th ventricle opens into the sub arachnoid space through 3 small openings, name them?
Two lateral foramina of Luschka, and 1 midline foramen of magnedie.
The choroid secretes ________ which fills the Ventricles and sub-arachnoid space
Cerebrospinal Fluid
Mention the classifications of receptors you know, and what they do.
- Mechano-Receptors: respond for mechanical energy like; touch, pressure, vibrations. Found in almost all parts of the body.
- Chemo-Receptors: e.g Taste receptors, olfactory receptors, carotid & aortic bodies, Osmoreceptors.
- Thermos receptors: respond to cold/warmth energy. Found in the skin & Hypothalamus
- Nociceptors: respond to painful (noxious) stimuli. Found everywhere except in the CNS.
- Electromagnetic receptors: respond to light rays (electromagnetic waves). Found in the eye.
Talk about type A fibres.
Type A has the largest fibres. They are myelinated fibres with conduction rates of 50-100m/s.
It is further sub divided into Ξ±,Ξ², Ι£, Ξ.
What are the functions of each sub division of Type A fibres
Type A Ξ± is concerned with proprioeption, to carry impulses from muscle spindles and Golgi tendon organ
Ξ² fibres are concerned with touch, pressure and other somatomotor impulses carrying from muscle spindle.
Ι£ fibres are concerned with motor functions to muscle intrafusal fibres.
Ξ fibres are similar to Ξ² in function.
What are propriospinal or intersegmental tracts?
Propriospinal fibres are the fibres that run from one segment of the cord to another. They inter connect adjacent or distant segment of the spinal core.
Write short note on motor cortex
Motor cortex is sub divided into 3 sub areas, namely
1. The primary motor cortex
2. Premotor area
3. Supplementary motor area.
What are the components of the Brainstem?
Midbrain
Pons
Medulla
Basilar artery
Vertebral arteries
Briefly explain the medulla oblongata (myelencephalon)?
It is the lower half of brain stem continues with the spinal cord. Itβs upper part is continuous with the Pons.
The medulla contains the cardiac, respiratory, vomiting, and vasomotor centers (regulating heart rate, breathing and blood pressure).
Talk about the mesencephalon (Midbrain)
The Midbrain is associated with vision, hearing, motor control, sleep and wake cycles, alertness and temperature regulation.
The medulla is often divided into 2 parts;
Name them
- A superior part where the dorsal surface of the medulla is formed by the 4th ventricle
- A closed or inferior part where the metacoel lies within the medulla.
Explain the Brainstem?
It is the most inferior portion of the brain, joining the brain and spinal cord. The Brainstem gives rise to cranial nerves 3 through 12 and provides the main motor and sensory innervation to the face and neck via the cranial nerves.
It has many basic functions e.g; regulation of heart rate, breathing, sleeping and eating.
Upper motor neurons originate in the Brainstemβs vestibular, red, tectal,& reticular nuclei.
Are there any other functions of the Brainstem, you know?
The Brainstem has integrative functions including cardiovascular system control, respiratory control, pain sensitivity, alertness, awareness and consciousness.
Talk about the Pons
Pons (named after the Latin word for Bridge) is a relay Station between the forebrain and cerebellum that passes sensory information from the periphery to the thalamus. It has a length 2.5cm in adults.
It is above the medulla, below the Midbrain and anterior to the cerebellum.
What connects the cerebellum to the Pons and midbrain?
Cerebellar peduncles
Mention the different types of Nociceptors
- Mechanical nociceptors
- Chemical nociceptors
- Thermal & mechano-thermal
- Polymodal
What is central pontine myelinosis
Central pontine myelinosis is a demyelination disease that causes difficulty with sense of balance, walking, sense of touch, swallowing and speaking. If not diagnosed and treated, it can lead to death or locked in syndrome (a condition in which a person is conscious but cannot move or communicate)
What is the substantiae nigra and itβs role?
It is a structure located in the brain, closely associated with motor system pathways of the basal ganglia. It produces dopamine and plays a role in motivation & habituation
Briefly talk on Reticular formation
Reticular formation assist in regulation of sleep cycle and detecting sensory salience. It is a region in the Pons involved in regulation the sleep-wake cycle and filtering incoming stimuli to discriminate irrelevant background stimuli.
What are the divisions of reticular formation
- Raphe nuclei (medium column)
- Magnocellular red nucleus (medial zone)
- Parvocellular reticular nucleus
What are the functions of the reticular formations?
- Pain modulation
- Cardiovascular control
- Sleep & consciousness
- Somatic motor control
- Habituation
What is Pain?!
Pain is the perception of unpleasant sensory and emotional experiences associated with actual or potential tissue damage.
What are the components of pain?
- Motor reaction : reflex withdrawal from pain
- Emotional r types of subeactions: e.g anxiety, anguish, crying and depression.
- Autonomic reaction
What are the types of pain?
- Acute pain
- Chronic pain
- Nociceptive pain
- Visceral pain
- Somatic pain
- Neuropathic pain
- Referred pain.
What are Nociceptors?
Are receptors for noxious stimuli
What is the role of the brain in pain?
When the secondary neuron is activated by neurotransmitters released from the primary adherent fibres, it generates an electrical signal, which it transmits its axon to a number of areas in the brain.
The brain then;
1. Locates the pain and determine itβs intensity (through somatosensory cortex).
2. The signal allows is to decide what pain means and what to do about it (undertaken by the prefrontal cortex)
3. The body responds by increasing the heart rate and blood pressure (through the amygdala) and preparing for fight or flight (using the hypothalamus)
4. There is also emotional response, perhaps fear (controlled by cingulate cortex).
5. The brain integrates & coordinates responses to all these experiences (using the thalamus & insula)
Upon tissue damage, activation of nociceptors occur and release of factors such as?
- Arachidonic acid
- Potassium
- 5-HT
- Histamine
- Bradykinin
- Lactic acid
- ATP
Many of these factors are also proinflammatory & lead to acute inflammation in the area of damage
