Human Physiology Exam 3

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


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)


Medulla Oblongata cranial nerves


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


A short segment of brainstem that connects the hindbrain and forebrain


Two stalks that anchor the cerebrum to the brainstem - tracts for fine motor control of limbs

Cerebral peduncles

Collaborates fine motor control


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


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


The 4 parts of the Forebrain

1. Thalamus
2. Hypothalamus
3. Epithalamus (pineal gland)
4. Cerebrum

The 'gateway to the cerebral cortex'


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


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


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


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


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


Organizes sensory and cognitive information


'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


Emotional memory


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 ______


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 (________)


Touch, stretch, temp, pain; thalamus processes input

General (somesthetics)

right post central gyrus receives input from left side of body (and visa versa)


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


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)


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


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


rest and digest


An example of balance between the sympathetic and parasympathetic activity ______; These exhibit _______

heart rate; autonomic tone

Which activity shows only vasomotor tone


Somatic vs. Autonomic
Efferent pathways
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

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


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)


Form pelvic nerves to distal half of colon, rectum, urinary bladder, and reproductive organs


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)


Two divisions produce a unified effect


_______ increase salivary serous cell secretion


_____ increase salivary mucous cell secretion


Adrenal medulla, sweat glands, and most blood vessels receive only _____


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


Conscious interpretation of a sensory stimulus


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


Is encoded by which nerve fibers are issuing signals to the brain. Sense of touch is an example


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.


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


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


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


Respond to physical deformation of a cell or tissue caused by vibration, touch, pressure, stretch, or tension


Fast, sharp pain

myelinated fibers

slow, dull pain

non-myelinated fibers

_____ stimulate by tissue damage, brady kinin, prostaglandins, histamine, neurotransmitters


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


Respond to heat and cold


Respond to chemicals, including odors, tastes, and body fluid composition


The CNS has ______ mechanisms that help in pain-relieving


Oligopeptides with 200X the potency of morphine, and named them ______


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


Rod and cone cells are most of


Ganglion cells have sensory pigment called


Rods and cones synapse on ______ cells


Bipolar cells synapse on _____ cells


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


There are multiple rod or cone cell synapses on ______ cell

one bipolar cell

Multiple bipolar cell synapse on ________

one ganglion cell

Rods contain


Protein embedded in disc membrane of rods outer segment


Vitamin A derivative


2 components of Rhodopsin

Opsin & retinal

Cones contain


____ contains different amino acid sequences that absorb 3 different wavelengths of light (color vision)


Trans-retinal configuration is ______


______ absorbs light; Cis-retinal converted to trans-retinal


Retinal dissociates from opsin in a process called


___ minutes to regenerate 50% of bleached rhodposin


____ 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


Each foveal cone cell has a _________

private line to brain

_______ have well developed color vision


Nocturnal vertebrates have only ______


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