Neuroscience module 1

Major parts of the nervous system

central nervous system and peripheral nervous system

Central Nervous System (CNS)

consists of the brain and spinal cord

all parts of the brain except cranial and spinal nerves

Peripheral Nervous System (PNS)

Composed of cranial nerves and spinal nerves that relay information to and from the CNS

Four lobes of the brain

frontal, parietal, occipital, temporal

Fissures of the brain

deep grooves in the brain

Commissural Fibers

connect regions of the right and left hemispheres of the cerebrum

* corpus callosum
* anterior commissure
* posterior commissure

The brain stem

Consists of three parts

* midbrain
* pons
* medulla oblongata

\
controls:

* respiration
* heartbeat
* arousal
* reflexes
* sound localization

Brain stem: control of respiration

o **Medulla Oblongata and the Pons within the brain stem are**

 **responsible for autonomic control of respiration**

o **Respiration is under both autonomic and somatic control**

Medulla oblongata

* **Registers the changes in oxygen and carbon dioxide levels within the blood**
* **Medulla oblongata is responsible for the rate and depth of breathing.**
* **Involuntary impulses (nerve activation) from the medulla oblongata are sent to the diaphragm to contract.**

Cells of the nervous system

Neuron

* **Communicate by transmitting signals between neurons and**

**between neurons and muscles**
* behavior is controlled by neurons working in large bundles (10,000 neurons firing simultaneously)

A sensory-motor neuron

* Sensory neurons bring signals to the CNS, motor neurons carry signals out of the CNS
* **Signals in sensory-motor neurons travel in one direction;**

**dendrites receive signals and axons send signals**

\

facts about neurons

* neurons = building blocks
* human brain = 100 billion neurons
* specialized function = communication
* communication = “electrochemical”

Neurons compared to other cells in the body

similar:

* have a membrane
* have a nucleus
* have a cytoplasm, mitochondria, and other organelles

\
differences:

* have specialized projections
* communicate with each other through an electrochemical process
* can be long, several feet at times

Gila

Other types of cells in the nervous system

Gila consists of:

\
* radical cells
* oligodendrocytes
* Schwann cells
* astrocytes

Astrocytes

control levels of neurochemical in extracellular space

Radical cells

* scaffold for neurogenesis
* may support neurogenesis

Oligodendrocytes

Forms the myelin sheath in the CNS

Schwann cells

Forms the myelin sheath in the PNS

Support systems of the brain

Vascular system

Brain cells

Meninges

Vascular system

arteries and veins

Brain cells require oxygen

* as do all cells in the body
* the brain is small relative to the body; the brain consumes 20% of the body’s oxygen supply
* when brain cells divide, they do not rejuvenate
* 3 - 5 minutes without oxygen will result in cell death

Meninges

* protective coverings of the brain
* pia mater (thin membrane cover that follows convolutions of the brain)
* arachnoid mater (spider mother)
* dura mater (tough mother)
* dura and pia mater fuse to form a sheath surrounding and protecting the cranial and spinal nerves

Meninges within the CNS

Layers offer protection to sensitive brain tissue

* contains blood vessels that transport blood to and from brain tissue and remove cerebrospinal fluid from the ventricles.

\

subdural hematoma

blood between brain and outermost covering

* causing pressure on the brain


* acute subdural hematoma (head trauma)
* chronic subdural hematoma (more common in elderly)

Ventricles

spaces within the brain

* protection for the brain
* fluid is created in them

Cerebrospinal fluid (CSF)

* **CSF surrounds the brain and the spinal cord traveling within the subarachnoid space of the meninges**
* **CSF is created in the choroid plexus of the ventricles, mainly the lateral ventricles.**
* **It is absorbed back into the bloodstream by way of the dural venous sinuses**
* the brain floats in CSP providing protection and less weight
* contains glucose, proteins, lipids, and electrolytes.
* provides nutrients to the brain and removes toxic waste

 

Hydrocephalus  

The buildup of the cerebral spinal fluid in the ventricles because it is not being reabsorbed by the veins 

Can be caused because of a tumor blocking the fluid, or a hemorrhage  

Treatment of hydrocephalus  

* Treatment – a shunt – goes into the brain to rectify the path of the fluid – stretches from the brain to the belly – many complications with this because it needs to be followed up with  


* ETV – endoscopic third ventriculostomy - put an opening in the third ventricle, a camera is attached and put inside the brain, corrects the flow of fluid - it is more successful than shunts and is recommended because it doesn’t require as many surgeries  

Sensory motor systems

five senses and motor responses

35% of the brain is devoted to sensory-motor systems

General processing systems

* Attention
* Memory
* Prediction
* Emotion

65% of the brain is devoted to general processing systems that act on and influence sensory and motor systems

The anatomical position

* arms forward
* palms out
* face forward
* body erect

Body sections

* coronal
* sagittal
* transverse

Sagittal section

* lateral
* splits structure into right and left portions
* think apple

Coronal section

* frontal
* splits structure into front and back sections
* think how bread is sliced

Transverse section

* horizontal
* splits section into upper and lower sections
* like the layers of a hamburger

Superior

(cranial)

from a high position

Inferior

(caudal)

from a low position

Anterior

(ventral) towards the stomach

Posterior

(dorsal) towards the back

Lateral

away from body’s midline

Medial

towards the body’s midline

Proximal

point nearest limb’s attachments

Distal

points farthest from limb’s attachments

Peripheral

towards the outer surface

Central

towards the center

Ipsilateral

on the same side

Contralateral

on the opposite side