Cerebrumo Largest part of braino “Thinking”; voluntary

muscleso 2 halves

– Right – Abstract thoughts– Left – Analytical thoughts

o Gyri and Sulci allow for more surface area– Increased amount of

neurons

Cerebrum

Cerebellum

o Back of braino Balance, movement,

and coordinationo Contains 50% of

neurons in brain, but 1/10 its size

o Evolutionary – came before cerebrum

Medulla Oblongata

o Middle portion of brainstem

o Controls autonomic functions

o Relays nerve signals between spinal cord and brain

Functional Lobes of the Cerebrum

o Cerebrum is divided into 2 hemispheres, each containing 5 discrete lobes.

Frontal Lobe Temporal Lobe Parietal Lobe Occipital Lobe

Frontal Lobe

o Associated with reasoning, planning, parts of speech, movement, emotions and problem solving.

o Functionally distinct areas: Primary motor cortex – Controls all moving parts Medial frontal cortex – Arousal and motivation Orbital frontal cortex – Modulate Social behaviors Left Postero inferior frontal cortex – Expressive language

function Dorsolateral frontal cortex – Working memory

Parietal Lobe

o Associated with movement, orientation, recognition and perception of stimuli.

o Generates visual-spatial relationships and integrates these perceptions with other sensations to create awareness of the path of moving objects.

o Parts of mid-parietal lobe of the dominant hemisphere involve in calculation, writing, left-right orientation and finger naming

o Non-dominant parietallobe enables people to be aware of the environment space, and is important for abilities such as drawing.

Temporal Lobe and Occipital Lobe

o Temporal Lobe Associated with

perception and recognition of auditory stimuli, memory and speech.

o Occipital Lobe Associated with visual

processing Contains the primary

visual cortex.

Neuron

• Definition: Neurons are responsive cells in the nervous system that process and transmit information by electrochemical signalling.

Nuerono The main portion of the cell is called the soma or cell body.  It

contains the nucleus, which in turn contains the genetic material in the form of chromosomes.

o Neurons have a large number of extensions called dendrites. It is primarily the surfaces of the dendrites that receive chemical messages from other neurons.

o One extension is different from all the others, and is called the axon. The purpose of the axon is to transmit an electro-chemical signal to other neurons, sometimes over a considerable distance.

o  Longer axons are usually covered with a myelin sheath, a series of fatty cells which have wrapped around an axon many times. They serve a similar function as the insulation around electrical wire.

Impulse Transmission

o A nerve impulse travels through the axon to reach the presynaptic membrane. On reaching, neurotransmitters are picked up by receptors.

o Once it is picked, the molecule is internalized in the neuron and the impulse continues.

Types of Neuronso Three major classes of neurons – Sensory neurons

- Stimulus receptors to the brain and spinal cord Motor neurons

- Transmit impulses from the central nervous system to

the muscles and glands Interneurons

- They provide connections between sensory and

motor neurons.

The Action Potentialo When chemicals contact the surface of a neuron, they change the

balance of ions (electrically charged atoms) between the inside and outside of the cell membrane

o This effect runs across the cell’s membrane to the axono On reaching the axon, it initiates the action potentialo Surface of ion contains ion channelso When charge enters axon, the channels let the positive charged

ions entero Causes the next group of ion channels to do the same, while other

channels return positive ions to the outside.

The Action Potential

o Neurons pump out positively charged sodium ions.o Pump in positively charged potassium ions.o High concentration of sodium ions present outside the

neuron ; and potassium ions present inside.

Neurons in Impulse Transmission

• The brain’s great computational abilities are derived from the communication among its billions of nerve cells. But

the process of neural conduction that lets a nerve impulse propagate down a neuron would serve no

purpose if it were not coupled with another mechanism: the synaptic transmission that lets the impulse pass from

one neuron to the next.

Head Injuries

o Skull FracturesAny break in bone

surrounding brain3 types

• Linear• Depressed• Basilar

o Intracranial HemorrhagesAny type of bleeding

within skull• Subdural/Epidural

Hematoma• Cerebral Contusion

Head Injuries cont.

o Causes2 types of trauma

• Penetrating trauma– Usually requires

surgery

• Blunt head trauma

o SymptomsBlunt head trauma

• Loss of consciousness, seizures, sensory impairments, death

Penetrating trauma• Usually similar, but

more serious

Head Injuries cont.

o TreatmentsSurgery

• Reduce pressure in skull• Craniotomy, Burr holes, Bone flap removal

Medication• Prevent seizures• Decrease pressure

Brain Abcesses

o Definition: A brain abscess is a collection of immune cells, pus, and other material in the brain, usually from a bacterial or fungal infection.

• Brain abscesses commonly occur when bacteria or fungi infect part of the brain. Swelling and irritation (inflammation) develops in response. Infected brain cells, white blood cells, and live and dead bacteria and fungi collect in an area of the brain. A membrane forms around this area and creates a mass.

• While this immune response can protect the brain by isolating the infection, it can also do more harm than good. The brain swells. Because the skull cannot expand, the mass may put pressure on delicate brain tissue. Infected material can block the blood vessels of the brain.

What causes brain abscesses?

o The more common causes of a brain abscess include viruses and bacteria. There are three ways a virus or bacteria can enter the body and infect the brain, including the following:

1. Infection is spread from another area of infection in the body. This accounts for the majority of brain abscess cases.

2. Infection is spread through the blood stream from the lung or chest area.

3. Viral or bacterial germs enter directly into the brain through an open wound in the head.

o Risk factors for developing a brain abscess include the following: congenital (present at birth) heart disease head injury or skull fracture infections of the face or scalp

What are the symptoms of a brain abcess?

o Symptoms may develop slowly, over a period of 2 weeks, or they may develop suddenly.

In babies and younger children• Fever• Sleepiness or less alert than usual• Poor feeding In older children• Changes in speech• Problems walking• Nausea and vomiting

Treatment for a brain abcess:

o A brain abscess is a medical emergency. Pressure inside the skull may become high enough to be life-threatening. You will need to stay in the hospital until the condition is stable. Some people may need life support.

o Medication, not surgery, is recommended if you have: Several abscesses (rare) A disease that makes surgery dangerouso You will get antibiotics. Antibiotics that work against a

number of different bacteria (broad spectrum antibiotics) are most commonly used. You may be prescribed several different types of antibiotics to make sure treatment works.

Treatment for a brain abcess:

o Surgery is needed if: Pressure in the brain continuesor gets worse Brain abcess contains gaso Surgery consists of opening the skull, exposing the

brain, and draining the abscess. Laboratory tests are often done to examine the fluid. This can help identify what is causing the infection, so that more appropriate antibiotics or anti-fungal drugs can be prescribed.

o Surgery consists of opening the skull, exposing the brain, and draining the abscess.

Diseaseso Alzheimer’s Disease

Atrophy of the brainDestruction of brain

cellsNo cure, but there are

treatments (pharmacological)

• Cholinesterase inhibitors

• Namenda

o Multiple SclerosisAutoimmune disease;

attacks nervous system

Immune systems eats away at myelin sheaths

Treatments• Natalizumab

Diseases

Alzheimer’s Disease Multiple Sclerosis