Brain

brain

The mass of nerve tissue that is the main control center of the nervous system. composed of 100 billion neurons & 10 to 15 trillion neuroglia

cranial cavity

contains the brain

15-20% of blood pumped by heart
consumes 80% of glucose
15% of O2 that body uses

receives how much blood, glucose, and oxygen from the body

brain stem, cerebellum, diencephalon, cerebrum

4 major parts of the brain

Brainstem

The oldest part and central core of the brain, responsible for automatic survival functions. continuous with the spinal cord and inferior to diencephalon

medulla oblongata, pons, midbrain & reticular formation

parts of the brainstem

Diencephalon

located above the brain stem & consists mostly of the thalamus & hypothalamus

Cerebrum

forms the bulk of the brain, supported on the diencephalon & brain stem

Cerebellum

the "little brain" at the rear of the brainstem; functions include processing sensory input and coordinating movement of skeletal muscles, and regulates posture and balance

cranium (skull)

bony structure protecting the brain

cerebrospinal fluid

a clear, colorless liquid w/c contains small amounts of glucose, proteins, lactic acid, urea, cations in the space between the meninges and acts as a shock absorber that protects the central nervous system.

ventricles of the brain

canals or chambers in the brain that contain cerebrospinal fluid

lateral ventricles

A set of paired ventricles lying within the cerebral hemispheres.

third ventricle of brain

found inferior to lateral ventricles

fourth ventricle of brain

found bet. brain stem & cerebellum inferior to third ventricle

choroid plexus

specialized networks of capillaries in the walls of the ventricles lined w/ ependymal cells where CSF is produced from blood plasma

arachnoid villi

fingerlike extensions of arachnoid mater that gradually absorbs CSF

Cranial venous sinuses

large veins w/in dura mater where CSF drains & becomes blood plasma again

hydrocephalus

abnormal accumulation of fluid (CSF) in the brain

medulla oblongata

the continuation of the spinal cord within the skull, forming the lowest part of the brainstem. its gray matter contains several nuclei. within its white matter are all ascending & descending tracts where most sensory & motor fibers decussate

Decussation

The anatomical crossing over of neurons from left to right

Cardiac center, Vasomotor center, Medullary respiratory center, Reflex centers, Nuclei of cranial nerves.

Nucleis of medulla

cardiac center

adjusts the force & rate of heart beat

vasomotor center

adjusts blood vessel diameter for blood pressure regulation

Medullary respiratory center

adjusts the basic rhythm & rate of breathing

Reflex centers

for coughing, sneezing, gagging, swallowing, vomiting, salivation, sweating, movements of tongue and head

Nuclei of cranial nerves

pairs of cranial nerves VIII to XII

Pons

The bulging center part of the brain stem. Includes nuclei involved in the control of breathing. contains nuclei for pairs of cranial nerves V to VIII. bridge whose white matter contains tracts w/c connect parts

Midbrain

A small part of the brain above the pons that integrates sensory information and relays it upward. connects the pons to the diencephalon. Startle (auditory) reflex visual reflex. cranial nerves III & IV

reticular formation

group of nuclei scattered throughout brain stem. damage causes coma

reticular activating system

the part of the brain that is involved in attention, sleep, and arousal

Thalamus

egg-shaped structure. the relay station for all sensations except smell. groups sensory impulses & transmits them to the cerebrum for localization & processing

Hypothalamus

A neural structure lying below the thalamus; major regulator of homeostasis. produces hormones. regulates emotional & behavioral patterns. acts as biological clock that regulates circadian rhythms

cerebral cortex

gray matter that forms the outer rim of the cerebrum. contains several nuclei divided into functional areas. "executive suite" of the nervous system and the home of the "conscious mind"

Gyri

the convolutions or "folds " of the cerebral cortex. increase the surface area of the cortex

Sulci

shallow grooves that separate gyri

fissures

deep grooves in the brain

Longitudinal fissure

separates left and right hemispheres

Corpus callosum

broad band of white matter containing axons that connect the two cerebral hemispheres internally

Central sulcus

separates frontal and parietal lobes

Precentral gyrus

major gyrus located immediately anterior to the central sulcus. contains the primary motor area of the cerebral cortex

Postcentral gyrus

immediately posterior to the central sulcus. contains the primary somatosensory area of the cerebral cortex

Cerebral white matter

located internal to the cerebral cortex (gray matter). made of myelinated nerve fibers that connect the lobes. transmit impulses

basal nuclei (ganglia)

collective term for the nuclei that lie deep within each cerebral hemisphere. regulates movement, muscle tone, and subconscious contractions of skeletal muscles

Parkinson's disease

A disorder of the central nervous system that affects movement, often including tremors.

limbic system

a ring of structures on inner border of cerebrum & floor of diencephalon. the "emotional brain" plays a primary role in a range of emotions

Hippocampus

A neural center located in the limbic system that helps process explicit memories for storage.

Sensory Areas

receive sensory information from the various receptors & sensory/ascending tracts. conscious awareness of a sensation called "perception"

Primary somatosensory area

parietal lobe (postcentral gyrus). perception of touch, pressure, vibration, proprioception, pain, itching, tickle & temp. allows one to discriminate where sensations originate

Primary visual area

occipital lobe, visual perception

Primary auditory area

part of the temporal lobe in which auditory information is first registered

Primary gustatory area

parietal lobe, perception & discrimination of taste

Primary olfactory area

temporal lobe, perception & discrimination of smell

Motor Areas

control the execution of voluntary movements

Primary motor area

frontal lobe (precentral gyrus). contraction of specific skeletal muscles on contralateral or opposite side of the body

Broca's motor speech area

frontal lobe. translates thoughts into speech. impairment causes nonfluent, expressive or Broca's aphasia

Broca's aphasia

condition resulting from damage to Broca's area, causing the affected person to be unable to speak fluently, to mispronounce words, and to speak haltingly

Association Areas

Makes associations bet. various kinds of sensory information. associates new sensory inputs w/ memories of past experiences & plans appropriate motor responses

Somatosensory association area

parietal lobe. integrates & interprets what is felt such as the exact shape & texture of an object

Visual association area

occipital lobe. interprets what is being seen, relates present & past visual experiences

Auditory association area

temporal lobe. allows one to realize whether a sound is speech, music, or noise

Wernicke's area

temporal lobe. interprets the meaning of speech by recognizing spoken words

Wernicke's aphasia

condition resulting from damage to Wernicke's area, causing the affected person to be unable to understand or produce meaningful language

Facial recognition area

temporal lobe. allows one to store information and recognize people by faces

premotor area

frontal lobe. carries out learned motor skills by allowing different muscles to contract in a specific sequence

Prefrontal area

frontal lobe. personality, intuition, reasoning, planning actions, critical thinking, mood, etc

Alzheimer's disease

a progressive and irreversible brain disorder characterized by gradual deterioration of memory, reasoning, language, and, finally, physical functioning

Hemispheric lateralization (split-brain theory)

premise that human brain is divided into two distinct cerebral hemispheres that operate together, but "specialize" in processing different types of cognitions

Left Hemisphere

receives sensory signals from and controls the right side of the body. more important for spoken & written language, numerical & scientific skills, ability to use & understand sign language & reasoning.

Right Hemisphere

controls the left side of the body; creative, intuitive, spacial.

cranial nerves

part of PNS. innervate specific areas of the body & function could be sensory, motor or both

12 pairs of cranial nerves

How many pairs of cranial nerves are there?

olfactory nerve (I)

sensory function: the nerve that carries smell impulses from the nose to the brain

optic nerve (II)

sensory function: the nerve that carries neural impulses from the eye to the brain

Oculomotor Nerve (III)

motor function: moves eyelid & eyeball constricts pupil

Trochlear Nerve (IV)

motor function: eye movement

Trigeminal Nerve (V)

sensory function: corneal reflex facial sensations. motor function: mastication

motor function: mastication

Abducens Nerve (VI)

Motor: lateral eye movement

strabismus

Crossed eyes resulting from a weakness in eye muscles

Facial Nerve (VII)

sensory function: taste (anterior 2/3 of tongue) motor function: facial expression

Vestibulocochlear Nerve (VIII)

sensory function: hearing balance/equilibrium

Glossopharyngeal Nerve (IX)

sensory function: taste (posterior 1/3 of tongue), detects changes in BP & pH of blood. motor function: swallowing, speaking

motor function: swallowing, speaking

Vagus Nerve (X)

sensory function: detects changes in BP & pH of blood. Motor function: swallowing, speaking, coughing.

motor function: swallowing, speaking, coughing, decreases heart rate, peristalsis, increases, digestive secretions

dysphagia

condition in which swallowing is difficult or painful

Accessory Nerve (XI)

motor function: moves head & shoulder (innervates trapezius & sternocleidomastoid muscles)

Hypoglossal Nerve (XII)

motor function: moves tongue

autonomic nervous system

part of the PNS, consists of cranial & spinal nerves whose motor & sensory fibers innervate smooth & cardiac muscles & glands

Preganglionic neuron

first neuron in the autonomic motor pathway. cell body in the CNS. axon extends from the CNS via cranial or a spinal nerve to an autonomic ganglion, where it synapses with the second neuron

Postganglionic neuron

second neuron in the autonomic motor pathway. lies entirely in the peripheral nervous system. cell body is located in an autonomic ganglion, and its axon extends from the ganglion to the effector

thoracolumbar division

another name for sympathetic division

sympathetic division

nerve impulses from this division stimulate the organ to increase its activity through the release of norepinephrine to effectors

craniosacral division

another name for parasympathetic division

Parasympathetic Division

nerve impulses from this division decrease activity of effectors through the release of acetylcholine

Sympathetic Effects

fight or flight activities. dilates pupils, inhibit saliva, accelerates heartbeat, dilates bronchi, inhibits peristalsis, conversion of glycogen to glucose, inhibits bladder contractions

Parasympathetic Effects

rest & digest activities. opposite of sympathetic effects. Constricts Pupils, Stimulate saliva, slows heartbeat, constricts bronchi, stimulates peristalsis, stimulate bile, contracts bladder

frontal lobe

A region of the cerebral cortex that has specialized areas for movement, abstract thinking, planning, memory, and judgement

parietal lobe

A region of the cerebral cortex whose functions include processing information about touch.