3 Functions of the cerebrospinal fluid (csf)
1. buoyancy
2. protection
3. chemical stability
Cerebrospinal fluid is secreted by the _________ by ________ cells
choroid plexus; ependymal
A clear, colorless liquid that fills the ventricles and canals of the CNS and bathes its external surface
Cerebrospinal fluid
Flow of Cerebrospinal Fluid (8 Steps)
1. CSF is secreted by choroid plexus in lateral ventricle
2. CSFflows through interventricular foramina into third ventricle
3. Choroid plexus is third ventricle adds more CSF
4. CSF flows down cerebral aqueduct to fouth ventricle
5. Choroid plexus in for
Strictlly regulates what substances can get from the bloodstream into the tissue fluid of the brain
Brain barrier system
Stops most blood-born wastes, drugs, and removes excess K+, and allows passage of nutrients (glucose, amino acids) fat soluble molecules
Brain barrier systems
At the choroid plexuses, the brain is protected by a ___________ formed by tight junctions between the ependymal cells
Blood-CSF barrier
Consists of tight junctions between the endothelial cells that form the capillary walls
blood-brain barrier (BBB)
Circumventricular organ of ___ and ____ ventricle have no barrier system. This allows brain to monitor blood variables and ________ (Gives HIV access to brain)
3rd & 4th; make adjustments via pumps
3 parts of the Hindbrain
1. Medulla oblongata
2. Pons
3. Cerebellum
Mass of neurons in gray matter
Nuclei
Adjusts rate and force of heart beat
Cardiac center
Nerve fiber connecting the brain to the spinal cord that pass through the medulla that are ascending - used for taste, thoracic, and abdominal viscera
Sensory nuclei - Medulla Oblongata
Nerve fiber connecting the brain to the spinal cord that pass through the medulla that are descending (include cardiac center, vasomotor center, respiratory centers, and reflex centers)
Motor nuclei - Medulla Oblongata
Adjusts blood vessel diameter
Vasomotor center
Sets rate of depth of breathing
Respiratory centers
For coughing, sneezing, swallowing, vomiting, salivation, sweating
Reflex centers
Pathways in and out of cerebellum (ascending sensory tracts, descending motor tracts)
Pons
Medulla Oblongata cranial nerves
IX, X, XI, XII
Pons cranial nerves
V, VI, VII, and VIII
Hearing, taste, facial sensations
Sensory - Pons
Facial expressions, urination, and secretion of saliva
Motor - Pons
Monitors muscle contractions, helps motor coordination, Evaluation of sensory input, Timekeeping, hearing, planning and scheduling tasks
Cerebellum
A short segment of brainstem that connects the hindbrain and forebrain
Midbrain
Two stalks that anchor the cerebrum to the brainstem - tracts for fine motor control of limbs
Cerebral peduncles
Collaborates fine motor control
Tegmentum
Relays inhibitory motor signals to stabilize muscle
Substantia nigra
Degeneration of dopamine-releasing neurons in a portion of the brain called the substantia nigra
Parkinson Disease
Involved with the reticulospinal tracts in controlling awareness of pain
Central Gray Matter
Visual attention and tracking
Tectum
Loosely organized web of gray matter that runs through midbrain, pons, and medulla
Reticular Formation
Reticular Formation functions that include balance, posture, gaze center, central pattern generators
Somatic motor control
The reticular formation includes the cardiac and vasomotor centers of the medulla oblongata
Cardiovascular control
The reticular formation that is the origin of the descending analgesic pathways (blocks pain signals)
Pain modulation
The reticular formation that act as general anesthetics block transmission
Sleep and consciousness
Process in which the brain learns to ignore repetitive, inconsequential stimuli while remaining sensitive to others
Habituation
The 4 parts of the Forebrain
1. Thalamus
2. Hypothalamus
3. Epithalamus (pineal gland)
4. Cerebrum
The 'gateway to the cerebral cortex'
Thalamus
Role in motor control by relaying signals from cerebrum to cerebellum; memory and emotional functions of the limbic system, nearly all sensory input passed to cerebrum
Thalamus
8 roles of the Hypothalamus
1. Hormone secretion
2. autonomic n.s. integration
3. thermoregulation
4. hunger and satiety center
5. thirst center
6. rhythm of sleep and waking
7. memory
8. emotional behavior
A very small mass of tissue composed mainly of the pineal gland
Epithalamus
An endocrine gland that produces melatonin (sleep inducing hormone)
Pineal gland
Lies immediately behind the frontal bone, superior to the eyes. Voluntary motor functions and deals with personality and memory
Frontal lobe
5 parts of the Cerebrum
1. Frontal lobe
2. Parietal lobe
3. occipital lobe
4. temporal lobe
5. insula
Receives and integrates sensory information (forms the uppermost part of the brain and underlies the parietal bone)
Parietal lobe
The principal visual center of the brain
Occipital lobe
Concerned with hearing, smell, learning, memory, and some aspects of vision and emotion
Temporal lobe
Small mass of cortex deep to the lateral sulcus that integration role in understanding spoken language, taste
Insula
4 Cerebrum components
1. Cerebral white matter - (axons, connections)
2. Cerebral cortex - outside layer (gray, integrated)
3. Basal Nuclei
4. Limbic System
Majority of cerebrum; non-integrative centers (no decision making); consists of 'tracks' of fibers interconnecting cerebrum with lower brain centers
Cerebral white matter
Gray matter; integrative centers; 90% is 'neocortex'
Cerebral cortex
Gray matter nuclei found deep within white matter; receives signals from midbrain and cerebral cortex, integrates, and send back for motor control
Basal Nuclei
'Ring of tissue'; role in emotion and learning; eg. nuclei in amygdala (emotion) and hippocampus (memory); gratification, aversion centers
Limbic system
Amygdala = _______; hippocampus = _________
emotion; memory
Useful in studying normal brain functions such as sleep and consciousness, and in diagnosing degenerative brain diseases, metabolic abnormalities, brain tumors, trauma, and so forth
Electroencephalogram (EEG)
Awake, resting, eyes closed
Alpha waves
Eyes open, mental activity
Beta waves
children and sleeping adults
Theta waves
infants and adults in deep sleep
Delta waves
_____ waves indicate emotional distress and mental disorders
Theta waves
_____ waves indicate brain damage
Alpha waves
Sleep occurs in cycles known as
Circadian rhythms
Sleep is controlled by the __________ and __________
hypothalamic; brain stem nucleii
4 Stages of sleep
1. drowsy (alpha waves)
2. light sleep (EEG irregular, sleep spindles)
3. moderate sleep (theta and s waves) vital signs fall
4. slow wave sleep, difficult to awaken, vital signs low (mostly s and alpha waves absent)
About ____ times a night, a sleeper backtracks from stage 3 or 4 to stage 2 and exhibits bouts of ______
5; rapid eye movement (REM) sleep
nightmares occur in stages ____ & ____
3 & 4
Why do we need to sleep
Aids in critical restorative functions. eg. immunity, brain metabolism, glycogen and ATP, GH & protein synthesis increase
The range of mental processes to acquire and use knowledge
Cognition
Such functions are widely distributed over regions of cerebral cortex called ________, which constitute about 75% of all brain tissue
association areas
Contralateral recognition - people become unaware of objects, or even their own limbs (shaving only half the face)
Parietal lobe
The inability to recognize, identify, and name familiar objects
Temporal lobe
Response planning & personality
Frontal lobe
Ability to tie your shoes
Procedural memory
The ability to recall information
Declarative memory
Defects in declarative memory
Amnesia
Organizes sensory and cognitive information
Hippocampus
'teaches' cerebral cortex to form and store long-term memory
memory consolidation
Vocabulary and familiar faces are stored in the __________
temporal lobe
Plans and social roles are stored in the ________
prefrontal cortex
Helps learn motor kills
Cerebellum
Emotional memory
amygdala
Pathway through brain '_________';
Memory; 'memory trace'
Memory is a result of ______
Synaptic plasticity
Existing synapses are modified in 2 ways:
1. make transmission easier (remember)
2. make transmission more difficult (forget)
Potential problems with synaptic potentiation and reverberating circuits result in ______
epilepsy
Reverberating circuits (memory type)
Immediate, 'working memory'
seconds to hours (memory type)
Short term
3 types of memory
1. Immediate
2. Short term
3. Long term
Long term memory requires molecular changes known as _____
synaptic remodeling
Seat of judgment and control over emotions
Prefrontal cortex
Store feelings of love, fear
hypothalamus & amygdala
_____ receives sensory input and output goes to _______
amygdala; hypothalamus
General sensations (________)
somesthetics
Touch, stretch, temp, pain; thalamus processes input
General (somesthetics)
right post central gyrus receives input from left side of body (and visa versa)
Decessation
Primary central gyrus, becomes ' conscious' of stimulus; association areas nearby process and interpret sensory information
Post Central Gyrus
Visual signals are received by the ________
primary visual cortex
Auditory signals are received by the _______
primary auditory cortex
Visual primary cortex and association area are located in _____
Occipital lobe
Primary auditory cortex and association area are located in the _______ & ________
temporal lobe & Insula
Signals project to cerebellum and brainstem nuclei
equilibrium
Gustatory _____ signals are received by the __________
taste; primary gustatory cortex
Olfactory ______ signals are received by the _________
smell; primary olfactory cortex
Gustatory signals are received by _________ & ______
parietal lobe and insula
Olfactory signals are received by ______ & ______
temporal and frontal lobe
Maps out amount of cerebral tissue and innervation devoted to various body regions
Sensory Homunculus (pg. 545)
Intent to move planned in motor association area of frontal lobes
Motor Control (pg. 545)
The most posterior gyrus of the frontal lobe, immediately anterior to the central sulcus that intentions are transmitted to in motor control
Pre central gyrus
Feedback circuit for planning and executing movements
Basal Nuclei
Coordination (compare muscle movements with stored info about learned skills)
Cerebellum
Two areas of language (often left hemisphere)
1. Wernicke Area
2. Broca Area
Recognition of spoken and written language, formulates speech; transmits plan
Wernicke Area
Generates and transmits motor program for muscles of larynx, tongue, ...
Broca Area
Any language deficits from lesions
Aphasia
Motor nervous system for controlling glands, cardiac, & smooth muscle. AKA ______
Autonomic Nervous System (ANS); viscera motor divsion
Unconscious, automatic, stereotyped responses to stimulate involving visceral receptors and effectors
Visceral reflexes
Homeostatic negative feedback loop
Visceral reflex to high BP
fight, flight, or freeze
Sympathetic
rest and digest
Parasympathetic
An example of balance between the sympathetic and parasympathetic activity ______; These exhibit _______
heart rate; autonomic tone
Which activity shows only vasomotor tone
Sympathetic
Somatic vs. Autonomic
Effectors
Control
Efferent pathways
Neurotransmitters
Effect on target cells
Effect of denervation
Effectors: Skeletal muscle; glands, smooth muscle, cardiac muscle
Control: usually voluntary; usually involuntary
Efferent pathways: One nerve fiber from CNS to effectors (no ganglia) ; Two nerve fibers from CNS to effector; synapse at a ganglion
Neurotra
Preganglionic sympathetic fibers follow 3 routes:
1. End in ganglion that they enter and synapse with postgangionic fibers (T8 to skin)
2. Travel up and down chain ganglia and synapse with other levels (T1-T5 to heart)
3. T5-T12 pass through chain without synapsing and continue as splanchnic nerves to co
Fibers exit a T1 through a L2
Efferent Pathways
Divergence that predominates
Neuronal
Modified postganglionic neurons (no axons or dendrites); stimulated by preganlionic sym. neurons
Inner Medulla
Secretes Catecholamines (85% epinephrine, 15% norepinephrine) into blood
Inner medulla
Long preganglionic neurons from: cranial nerves of midbrain, pons, and medulla; Sacral spinal cord segments S2-S4
Parasympathetic Division
Narrows pupil and focuses lens
Oculomotor nerve (III)
Tear, nasal and salivary glands
Facial nerve (VII)
Parotid salivary gland
Glossopharyngeal nere (IX)
Cardiac, pulmonary and esophageal plexus; proximal half of colon
Vagus nerve (X)
Of the spinal cord (pelvic splanchnic nerves)
S2-S4
Form pelvic nerves to distal half of colon, rectum, urinary bladder, and reproductive organs
S2-S4
Separate reflex areas, innervate smooth muscle and glands of GI tract; does not arise from the brainstem or spinal cord
Enteric Nervous system
Regulates motility of esophagus, stomach, and intestines and secretion of digestive enzymes and acid; but normal digestive function also requires regulation by sym and parasym systems
Enteric Nervous System
Most viscera receive innervation from both parasym and dym divisions
Dual Innervation
Heart Rate, Parasym decreases, sym increases (eg. Pupil diameter; sym dilates pupil while parasym constricts pupil) (Part of dual innervation)
Antagonistic
Two divisions produce a unified effect
Cooperative
_______ increase salivary serous cell secretion
parasympathetic
_____ increase salivary mucous cell secretion
sympathetics
Adrenal medulla, sweat glands, and most blood vessels receive only _____
sympathetic
The sympathetic fibers to a blood vessel have a baseline sympathetic tone, which keeps the vessels in a state of partial constriction
vasomotor tone
Sympathetic division alone can have opposite effects on target organ through _________ (eg stress)
blood vessel control
State of awareness of external or internal body conditions
Sensation
Conscious interpretation of a sensory stimulus
Perception
Sensation receptors transmit 4 kinds of information:
1. Modality
2. Location
3. Intensity
4. Duration
Refers to the "type" of stimulus or the sensation it produces. Vision, hearing, and taste are examples
Modality
Is encoded by which nerve fibers are issuing signals to the brain. Sense of touch is an example
Location
Increased firing frequency, intense stimuli, or weak stimuli. Refers to whether a sound is loud or soft, a light is bright or dim, a pain is mild or excruciating , and so forth.
Intensity
How long a stimulus lasts, is encoded by changes in the firing frequency of a nerve fiber with the passage of time. All receptors exhibit the property of sensory adaptation and neuronal firing slows
Duration
If the stimulus is prolonged, the firing of the neuron gets slower over time, and with it, we become less aware of the stimulus
Sensory adaptation
Recalling the ability to tie one's shoelaces is
Procedural memory
Mass of gray matter inside the brain is called
Nuclei
4 ;kinds of information sensation receptors transmit:
1. Thermoreceptors
2. Photoreceptors
3. Nociceptors
4. Chemoreceptors
5. Mechanoreceptors
Pain receptors that respond to tissue injury or situations that threaten to damage a tissue
Nociceptors
Respond to physical deformation of a cell or tissue caused by vibration, touch, pressure, stretch, or tension
mechanoreceptors
Fast, sharp pain
myelinated fibers
slow, dull pain
non-myelinated fibers
_____ stimulate by tissue damage, brady kinin, prostaglandins, histamine, neurotransmitters
Nociceptors
Pain from skin, muscles, joints- projected to orgin
Somatic Pain
Pain from organs: brain may mistake location ; referred pain
Visceral pain
The eyes, respond to light
photoreceptors
Respond to heat and cold
Thermoreceptors
Respond to chemicals, including odors, tastes, and body fluid composition
Chemoreceptors
The CNS has ______ mechanisms that help in pain-relieving
analgesic
Oligopeptides with 200X the potency of morphine, and named them ______
enkephalins
Larger analgesic neuropeptides
Endorphins and dynorphins
Normal route of pain transmission (1-3)
1. A nociceptor stimulates a second-order nerve fiber. The neurotransmitter at this synapse is called substance P
2. The second-order nerve fiber transmits signal up the spinothalamic tract to the thalamus
3. The thalamus relays the signals through a thir
Pathway for pain blocking, or modulation (4-8)
4. Signals from the hypothalamus and cerebral cortex feed into the central gray matter of midbrain, allowing both autonomic and conscious influences on pain perception
5. The midbrain relays signals to certain nuclei in the reticular formation of the medu
When you hit your elbow, rubbing it releases
enkephlins
Rod and cone cells are most of
photoreceptors
Ganglion cells have sensory pigment called
melanopsin
Rods and cones synapse on ______ cells
bipolar
Bipolar cells synapse on _____ cells
ganglion
3 functions of ganglion cells
1. Detect light intensity
2. axons form optic nerve (II)
3. transmit signals to brainstem
____ million rods and ____ million cones in the retina
130; 6.5
1.2 million nerve fibers in ________
optic nerve
Neuronal convergence and information processing take place in the _____ before signals reach brain
retina
There are multiple rod or cone cell synapses on ______ cell
one bipolar cell
Multiple bipolar cell synapse on ________
one ganglion cell
Rods contain
rhodopsin
Protein embedded in disc membrane of rods outer segment
Opsin
Vitamin A derivative
Retinal
2 components of Rhodopsin
Opsin & retinal
Cones contain
photopsin
____ contains different amino acid sequences that absorb 3 different wavelengths of light (color vision)
Opsin
Trans-retinal configuration is ______
bleached
______ absorbs light; Cis-retinal converted to trans-retinal
rhodopsin
Retinal dissociates from opsin in a process called
bleaching
___ minutes to regenerate 50% of bleached rhodposin
5
____ regenerate photopsin faster; how fast?
cones; 50% in 90 secs
Generating visual signals in the dark
1. Second messenger cGMP keeps Na+ gates open, exciting rod cells
2. rod cells release glutamate
3. bipolar cell inhibited (ISPS hyperpolarization)
Generating visual signals in light:
1. trans-retinal allows opsin to degrade cGMP, Na+ gates close, glutamate release stops, bipolar cells excited
2. bipolar cells sensitive to on/off pulses of glutamate
3. Some bipolar cells inhibited by glutamate excited when secretion stops with rising l
Dark adaptations
pupils dilate
rod pigment was bleached by lights
rhodopsin regenerates faster than it bleaches
after 20-30 minutes the amount of regenerated rhodopsin is sufficient for your eyes to reach max sensitivity
Light adaptations
pupil constriction, pain from overstimulated retinas
color vision and acuity below normal (5-10 min)
time needed for pigment bleaching to adjust retinal sensitivity to high light intensity
rod vision nonfunctional (totally bleached)
Why do we have rods and cones?
Duplicity Theory
600 rods converge on 1 bipolar cell; many bipolar converge on each ganglion cell
Scotopic (Night Vision)
Results from cones
Color Vision Photopic System (Day Vision)
Contains 4000 tiny cone cells ; finest image acuity
fovea
Each foveal cone cell has a _________
private line to brain
_______ have well developed color vision
Primate
Nocturnal vertebrates have only ______
rods
Three types of cones, named for absorption peaks of their photopsins
(S, M, L)
Hereditary alteration or lack of one photopsin or another
Color Blindness
Most common color blindness
red/green color blindness