NERVOUS SYSTEM: The Brain

100 billion neurons 100 billion neurons Weighs 3 pounds Weighs 3 pounds Gray and white matter Gray and white matter Cerebrum = 85% of total mass of brain Cerebrum = 85% of total mass of brain Brain Factoids…

4 main areas of brain 1. Brain stem 2. Cerebellum 3. Diencephalon 4. Cerebrum –2 halves (hemispheres –4 lobes Highly-wrinked part = cerebral cortex Highly-wrinked part = cerebral cortex

Covered by Meninges

CEREBRAL CORTEX Sensory perception Sensory perception Willed movements Willed movements Consciousness Consciousness Memory Memory Subcortical= Subcortical= subconscious subconscious

Lobes of the Brain

1. Frontal Lobe Associated with Associated with –Reasoning –Planning –Parts of speech –Movement –Emotions –Problem solving –Personality You are who you are because of this lobe. This area determines personality and emotions. It's also involved in controlling judgment, impulses, sexual behavior, language and movement.

2. Temporal Lobe Associated with Associated with –Perception and recognition of auditory stimuli –Memory –Speech This region controls your hearing and the ability to recognize words. It can also affect memory. Damage to the left side of this lobe can cause problems remembering what people said. Damage to the right side might stop you from recalling music or pictures.

Damage to… Broca’s Area>> expressive aphasia – –Know what you want to say, but can’t get the words out properly – –Yes... ah... Monday... er... Dad and Peter H... (his own name), and Dad.... er... hospital... and ah... Wednesday... Wednesday, nine o'clock... and oh... Thursday... ten o'clock, ah doctors... two... an' doctors... and er... teeth... yah. Wernicke’s Area:>> receptive aphasia – –No problem getting the words out, but the sentences don’t make sense – –“I called my mother on the television and did not understand the door. It was too breakfast, but they came from far to near. My mother is not too old for me to be young.”

3. Parietal Lobe Associated with Associated with –Movement –Orientation –Recognition –Perception of stimuli This region of the brain helps people understand what they see and feel. It also controls how they understand and process information about the environment around them, such as distance and position of objects.

4. Occipital Lobe Associated with Associated with –visual processing Call this the visual center. This area determines if you understand what you're looking at. Damage to the occipital lobe could cause hallucinations, make objects appear larger or smaller then they are or make the colors look abnormal.

Check out brain lobe function Check out brain lobe function Check out brain lobe function Check out brain lobe function Brain video: The work of neurons Brain video: The work of neurons Brain video Brain video

CORPUS CALLOSUM Broad band of white matter Broad band of white matter Contains axons that connect the right and left cerebral hemispheres Contains axons that connect the right and left cerebral hemispheres

Brain Stem & Associated Structures Cerebellum Cerebellum Brainstem Brainstem –Midbrain –Pons –Medulla Oblongata Spinal Cord Spinal Cord

CEREBELLUM Regulates muscle coordination Regulates muscle coordination Maintains equilibrium Maintains equilibrium Stores movement patterns Stores movement patterns Posture Posture

Histology of the cerebellum

Cerebellum & Brainstem

BRAINSTEM Relay Station Relay Station –Connects brain to the spinal cord Runs from the thalamus Runs from the thalamus to the spinal cord Composed of 3 parts Composed of 3 parts –Midbrain –Pons –Medulla Oblongata Life center- controls Life center- controls –breathing –heart rate –blood pressure

A. Midbrain Superior portion of the brainstem Superior portion of the brainstem Contains relays for visual and auditory impulses Contains relays for visual and auditory impulses 1. Midbrain 2. Cerebellum 3. Pons 4. Medulla oblongata 5. Inferior colliculus 6. Superior medullary velum 7. Fourth ventricle

B. Pons Middle portion of the brainstem Middle portion of the brainstem Is a conduction pathway from body to thalamus/cerebrum/ cerebellum Is a conduction pathway from body to thalamus/cerebrum/ cerebellum Regulates respiration Regulates respiration

C. Medulla Oblongata Inferior portion of the brainstem that controls Inferior portion of the brainstem that controls –Cardiac function –Respiratory function –Vasomotor centers

SPINAL CORD Carries messages to and from the brain and the rest of the body Carries messages to and from the brain and the rest of the body Mediates reflexes Mediates reflexes

Describe a reflex arc.

Two-neuron reflex arc: Impulse from sensory neuron  dendrite  cell body in dorsal root ganglion, near SC (Ganglion: group of hundreds of nerve cell bodies located in the PNS.)  axon  synapse To motor neuron To motor neuron –  dendrite  cell body (in gray matter of SC) –  axon which runs through the ventral root of a spinal nerve To effector To effector

Limbic System & Associated Structures Limbic System Limbic System –Hippocampus –Amygdala –Thalamus –Hypothalamus Pituitary Gland Pituitary Gland Pineal Gland Pineal Gland thalamus pineal gland

LIMBIC SYSTEM: emotional brain Hippocampus Hippocampus Amygdala Amygdala Thalamus Thalamus Hypothalamus Hypothalamus

A. Hippocampus Plays a role in long term memory Plays a role in long term memory

B. Amygdala Plays a key role in processing emotion Plays a key role in processing emotion Linked to Linked to –fear response –pleasure

Perceive, integrate, respond

C. Thalamus Sensory relay station from various areas of the body to the cerebral cortex Sensory relay station from various areas of the body to the cerebral cortex Involved with Involved with –emotion –alerting mechanisms –arousal mechanisms

D. Hypothalamus Maintains Homeostasis Maintains Homeostasis Releases hormones to the pituitary gland Releases hormones to the pituitary gland Regulates Regulates –body temperature –water balance –sleep-wake cycle –sexual arousal –aggression/pleasure –eating/drinking

Hypothalamus  Pituitary  Target Glands/Organs

Pituitary Gland Releases sex and growth hormones Releases sex and growth hormones Stimulates lactation Stimulates lactation Stimulates uterine contractions Stimulates uterine contractions Regulates urine output Regulates urine output

Pineal Gland Involved in the body’s sleep/wake cycle Involved in the body’s sleep/wake cycle