NERVOUS SYSTEM

-
The nervous system is a complex network of nerves and cells that carry messages to and from the brain and spinal cord to various parts of the body.


DIVISION  OF THE NS
➡️ Central NS
➡️ Peripheral NS

CENTRAL NS
The central NS is responsible for the regulation and coordination of the activities of the body. They are however known as the control centers. They are divided into the
➡️ Brain
➡️ Spinal Cord

PERIPHERAL NERVOUS SYSTEM
The peripheral NS consist of the specialised cells that  carries information to and from the central nervous system.

The peripheral NS is further divided into
➡️ Afferent Divisions: this Afferent neurons carries signal to the brain and spinal cord. 

➡️ Efferent Divisions: why the Efferent neurons carry signals away from the brain and spinal cord.

NOTE: Afferent neurons  provide  sensory  input  to  modulate  the  function  of  the  efferent  division through reflex arcs or neural pathways that mediate a reflex action.

The Efferent division of the Peripheral NS is further divided into
➡️ Autonomic NS
➡️ Somantic NS

AUTONOMIC NS

The autonomic nervous system controls specific body processes, such as circulation of blood, digestion, breathing, urination, heartbeat, etc. The autonomic nervous system is named so, because it works autonomously, i.e., without a person’s conscious effort.

The primary function of the autonomic nervous system is homeostasis. Apart from maintaining the body’s internal environment, it is also involved in controlling and maintaining the following life processes:

  • Digestion
  • Metabolism
  • Urination
  • Defecation
  • Blood pressure
  • Sexual response
  • Body temperature
  • Heartbeat
  • Breathing rate
  • Fluid balance
➡️It has both the Afferent and the Efferent neurons 

EFFERENT NEURONS :  The ANS carries nerve impulses from the CNS to the effector organs by way of two types of efferent neurons:  the preganglionic neurons and the postganglionic neurons. 

The cell body of the first nerve cell, the preganglionic neuron, is located within the CNS.  

The  ganglia  function  as  relay  stations between the preganglionic neuron and the second nerve cell, the postganglionic  neuron. 

The  cell  body  of  the postganglionic  neuron originates  in  the  ganglion.  It  is  generally  nonmyelinated  and  terminates on effector organs, such as smooth muscles of the viscera, cardiac muscle, and the exocrine glands.

AFFERENT NEURONS :  The afferent neurons (fibers) of the ANS are important in the reflex regulation of this system  and in signaling the CNS to influence the efferent branch of the system to respond.

The Autonomic NS is composed of the sympathetic and parasympathetic neurons

➡️ SYMPATHETIC NEURONS
The sympathetic neurons originated from the thoracic and Lumbar segment of the spinal cord. ( T1 to L2).

➡️ PARASYMPATHETIC NEURONS 
The parasympathetic preganglionic fibers arise from cranial nerves III (oculomotor),  VII (facial), IX (glossopharyngeal), and X (vagus), as well  as from the sacral region (S2 to S4) of the spinal cord and synapse in ganglia near or on the effector organs.

➡️ ENTERIC NEURONS :  
The enteric nervous system is the third division of  the  ANS.  It  is  a  collection  of  nerve  fibers  that  innervate  the  gastrointestinal (GI) tract, pancreas, and gallbladder, and it constitutes the  “brain of the gut.”  This system functions independently of the CNS  and  controls  the  motility,  exocrine  and  endocrine  secretions, and  microcirculation  of  the  GI  tract.  It  is  modulated  by  both  the sympathetic and parasympathetic nervous systems.

SOMATIC NERVOUS SYSTEM 
The efferent somatic nervous system differs from the ANS in that a single  myelinated  motor  neuron,  originating  in  the  CNS,  travels  directly to skeletal muscle without the mediation of ganglia.  As noted earlier, the somatic nervous system is under voluntary control, whereas the ANS is involuntary.  Responses in the somatic division are generally faster than those in the ANS.

Comments

Post a Comment

Popular posts from this blog

ANATOMY OF THE EYE

-
Image
Special senses  [ EYE] These are organs in the body that performs specialised functions. They contain sensory receptors which receives sensory impulses and pass them to the appropriate centers in the brain for interpretation.   ➡️ Types of Sensory Receptors - based on the type of stimuli they detect: 1. Mechanoreceptors - pressure receptors, stretch receptors, and specialized mechanoreceptors involved  in movement and balance.  2. Thermoreceptors - skin and viscera, respond to both external and internal temperature.  3. Pain receptors - stimulated by lack of O2, chemicals released from damaged cells and inflammatory  cells.  4. Chemoreceptors - detect changes in levels of O2, CO2, and H+ ions (pH) as well as chemicals that  stimulate taste and smell receptors  5. Photoreceptors - stimulated by light ➡️ Distribution of Receptors in the body: Special Senses • mediated by relatively complex sense organs of the head, innervated by cranial ...
Read more

VENTRICLES OF THE BRAIN

-
Image
 The ventricular system is a set of communicating cavities within the brain. These structures are responsible for the production, transport and removal of cerebrospinal fluid, which bathes the central nervous system. FUNCTIONS OF CEREBROSPINAL FLUID  Cerebrospinal fluid is an ultrafiltrate of plasma that surrounds the brain and spinal cord. It serves three main functions : ➡️ Protection : acts as a cushion for the brain, limiting neural damage in cranial injuries. ➡️Buoyancy : by being immersed in CSF, the net weight of the brain is reduced to approximately 25 grams. This prevents excessive pressure on the base of the brain. ➡️Chemical stability : the CSF creates an environment to allow for proper functioning of the brain, e.g. maintaining low extracellular K+ for synaptic transmission. VENTRICLES OF THE BRAIN  The ventricles are structures that produce cerebrospinal fluid, and transport it around the cranial cavity. They are lined by ependymal cells, which fo...
Read more

FLORENCE NIGHTINGALE

-
Image
Born: May 12, 1820 Florence, Italy Died: August 13, 1910 London, England English nurse The English nurse Florence Nightingale was the founder of modern nursing and made outstanding contributions to the knowledge and improvement of public health. EARLY YEARS AND STUDY  Florence Nightingale was born in Florence, Italy, on May 12, 1820; she was named after the city of her birth. Her father, William E. Nightingale , was a wealthy landowner who had inherited an estate in Derbyshire, England. Like many members of the wealthy class, he and Florence's mother, Fanny , dedicated themselves to the pursuit of active social lives. Florence and her sister, Parthenope , were tutored by their father in languages, mathematics, and history. Though Florence was tempted by the idea of a brilliant social life and marriage, she also wanted to achieve independence, importance in some field of activity, and obedience to God through service to society. In 1844 Nightingale decided that she want...
Read more