Cerebrum

1. Cerebrum • Largest part of brain • “Thinking”; voluntary muscles • 2 halves • Right – Abstract thoughts • Left – Analytical thoughts • Gyri and Sulci allow for more surface area • Increased amount of neurons Cerebrum

2. Cerebellum • Back of brain • Balance, movement, and coordination • Contains 50% of neurons in brain, but 1/10 its size • Evolutionary – came before cerebrum

3. Medulla Oblongata • Middle portion of brainstem • Controls autonomic functions • Relays nerve signals between spinal cord and brain

4. Functional Lobes of the Cerebrum • Cerebrum is divided into 2 hemispheres, each containing 5 discrete lobes. • Frontal Lobe • Temporal Lobe • Parietal Lobe • Occipital Lobe

5. Frontal Lobe • Associated with reasoning, planning, parts of speech, movement, emotions and problem solving. • 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

7. Parietal Lobe • Associated with movement, orientation, recognition and perception of stimuli. • Areas posterolateral to the postcentral gyrus generates visual-spatial relationships and integrates these perceptions with other sensations to create awareness of the path of moving objects. • Parts of mid-parietal lobe of the dominant hemisphere involve in calculation, writing, left-right orientation and finger naming • Non-dominant parietal lobe enables people to be aware of the environment space, and is important for abilities such as drawing.

8. Temporal Lobe and Occipital Lobe • Temporal Lobe • Associated with perception and recognition of auditory stimuli, memory and speech. • Occipital Lobe • Associated with visual processing • Contains the primary visual cortex.

9. Neuron • Definition:Neuronsare responsive cells in the nervous system that process and transmit information by electrochemical signalling. • It is a structural and functional unit of nervous tissue, which is specialized to conduct nerve signals.

10. Nueron • 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. • Neurons have a large number of extensions called dendrites. It is primarily the surfaces of the dendrites that receive chemical messages from other neurons. • 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. • Electro-chemical signals are converted into a chemical message in the axon ending. • Between the axon ending and the dendrite of the next neuron is a tiny gap called the synapse.

12. Three types of Neuron • Three major classes of neurons – • Sensory neurons - Run from 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.

13. 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. • A nerve impulse travels through the axon to reach the presynaptic membrane. On reaching, neurotransmitters are picked up by receptors. • Once it is picked, the molecule is internalized in the neuron and the impulse continues.

14. The Action Potential • 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 • This effect runs across the cell’s membrane to the axon • On reaching the axon, it initiates the action potential • Surface of ion contains ion channels(voltage gated sodium channel and volted gated potassium channel) • When charge enters axon, the channels let the positive charged ions enter • Causes the next group of ion channels to do the same, while other channels return positive ions to the outside.

15. The Action Potential • Neurons pump out positively charged sodium ions. • Pump in positively charged potassium ions. • High concentration of sodium ions present outside the neuron ; and potassium ions present inside.

17. Head Injuries • Skull Fractures • Any break in bone surrounding brain • 3 types • Linear • Depressed • Basilar • Intracranial Hemorrhages • Any type of bleeding within skull • Subdural/Epidural Hematoma • Cerebral Contusion

18. Head Injuries cont. • Causes • 2 types of trauma • Penetrating trauma • Usually requires surgery • Blunt head trauma • Symptoms • Blunt head trauma • Loss of consciousness, seizures, sensory impairments, death • Penetrating trauma • Usually similar, but more serious

19. Head Injuries cont. • Treatments • Surgery • Reduce pressure in skull • Craniotomy, Burr holes, Bone flap removal • Medication • Prevent seizures • Decrease pressure

20. Brain Abcesses • 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,. Because the skull cannot expand, the mass may put pressure on delicate brain tissue. Infected material can block the blood vessels of the brain.

21. What causes brain abscesses? • 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. • 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

22. What are the symptoms of a brain abcess? • 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

23. Treatment for a brain abcess: • 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. • Medication, not surgery, is recommended if you have: • Several abscesses (rare) • A disease that makes surgery dangerous • 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.

24. Treatment for a brain abcess: • Surgery is needed if: • Pressure in the brain continues or gets worse • Brain abcess contains gas • 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. • Surgery consists of opening the skull, exposing the brain, and draining the abscess.

25. Diseases • Alzheimer’s Disease • Atrophy of the brain • Destruction of brain cells • No cure, but there are treatments (pharmacological) • Cholinesterase inhibitors • Namenda • Multiple Sclerosis • Autoimmune disease; attacks nervous system • Immune systems eats away at myelin sheaths • Treatments • Natalizumab

26. Diseases Alzheimer’s Disease Multiple Sclerosis