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149 Cards in this Set
- Front
- Back
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Ependymal cells |
Form choroid plexus Line the ventricles |
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Choroid plexus |
Manufactures 500 ml of clear CSF daily External & internal shock absorber Removes waste & maintains ion balance |
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How many neurons and glial cells are in an adult brain? |
100-200 neurons and 900 glial cells |
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Cerebrum |
Largest portion of the brain Five lobes |
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What are the five lobes of the cerebrum? |
Frontal, parietal, occipital, temporal, insula |
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What are the functions of the frontal lobe? |
Thought, speech, motor control |
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What are the functions of the parietal lobe? |
General sense perception/integration |
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What is the function of the occipital lobe? |
Vision |
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What are the functions of the temporal lobe? |
Hearing, smell, learning, memory, & emotion |
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What are the functions of the insula? |
Taste, visceral sense, speech comprehension |
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Broca's area |
Located in the frontal lobe Function: motor speech |
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Wernicke's area |
Located in the parietal lobe Function: sensory speech |
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Cerebral lateralization |
Movements/vision are controlled by the contralateral side of the brain |
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What tasks are performed better by the right hemisphere? |
Visuospatial tasks, recognizing faces, composing music |
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What tasks are performed better by the left hemosphere |
Language, speech, calculations |
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Gray matter |
Unmyelinated cell bodies and dendrites make up the surface |
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White matter |
Vast tracts which associate with deeper islands of cell clusters called nuclei Myelinated axons |
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Association neurons |
Connect various brain areas Predominate in the CNS |
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Sulcus (Sulci) |
Depressed grooves in the brain Help increase surface area |
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Gyrus (gyri) |
Elevated folds between sulci Increases surface area |
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Fiber tracts |
White matter |
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Association fibers |
Connect different areas of the same hemisphere |
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What are the three types of fiber tracts? |
Commissural fibers (corpus callosum), association fibers, projection fibers |
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What is the 'emotional brain'? |
Limbic system + hypothalamus |
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What is the function of the Prefrontal cortex |
Conscious experience of pleasure |
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Limbic system |
Phylogenetically older than cerebral cortex Little conscious control of emotions |
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Amygdala |
Greatly I handed memories with emotional content Stimulation produces rage and aggression Lesions impair ability to recognize fear and anger in others |
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What emotions does the limbic system control? |
Aggression, fear, reward, hunger/satiety, sex drive |
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Mirror neurons |
Frontal and parietal lobes Integrate sensory and motor activity Connected through insula and cingulate gurus to emotion centers |
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What ability are mirror neurons involved in? |
The ability to learn social skills and language |
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What disorder do mirror neurons possibly play a part in? |
Autism |
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Capgras delusion |
Causes a person to believe that a person they recognize is an imposter |
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How is the limbic system involved in Capgras delusion |
The face recognition of the brain is damaged, causing the signal to move to the emotional center of the brain. The emotional recognition is lacking, resulting in the imposter feeling. |
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Basal nuclei |
Islands of cell bodies deep within the cerebral white matter |
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What is the function of the basal nuclei? |
They receive excitatory motor axons from the cortex Possess motor excitatory and inhibitory pathways back to cortex via thalamus |
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Cerebellum |
Acts to ensure that the desired movements occur smoothly in accordance with motor programs |
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How many neurons does the cerebellum have? |
50+ billion |
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Purkinje cells |
Project only inhibitory feedback to the cortex |
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Broca's aphasia |
Slow, poorly articulated speech |
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Wernicke's aphasia |
Clear/rapid speech with no meaning |
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Thalamus |
2 ovoid masses at the superior end of the brain stem just under the cerebral hemispheres The gateway for all sensory input to the cerebral cortex |
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Hypothalamus |
Essential for: autonomic regulation, emotion, thermal regulation, thirst, hunger/satiety, birthing/lactating, sleep cycles, endocrine control |
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Melanopsin |
Responsible for pupil light reflex and is related to the suprachiasmatic nuclei of hypothalamus |
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Pineal gland |
'The 3D eye' |
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Suprachiasmatic nuclei |
Contains 20,000 neurons called clock cells |
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'Clock cells' |
Establish 24 hour rhythms but must be synchronized by light input arriving via out optic Bertie at the optic chiasm |
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Pons |
Site of major ascending and descending tracts Site of many nuclei |
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Medulla |
Site where most motor and sensory tracts decussate Site of vital centers |
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What vital centers are in the medulla? |
Vasomotor, cardiac control, respiratory |
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What nuclei are located in pons? |
CN V-XIII |
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What nuclei are present in the medulla? |
CN IX-XII |
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Midbrain + pons + medulla compose what? |
Brain stem and area spanned by the reticular formation (RF) |
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Reticular formation |
Part of the arousal system called the reticular activating system |
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Reticular activating system |
Projects chili ethic neurons to thalamus to enhance sensory thru-put to cortex |
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Peripheral nervous system |
Nerves entering and leaving the spinal cord |
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'Mixed nerves' |
All spinal nerves Have motor and sensory components as well as contributions from the autonomic NS |
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Where does the spinal cord begin and end? |
Begins: for amen magnum of the skull Ends: extends about 10 inches to level of first lumbar (L1) before tapering |
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Where do sensory neurons have their cell body? |
In the dorsal root ganglion |
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Efferent System |
Somatic + autonomic NS "Motor" system |
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Autonomic nervous system |
Regulates involuntary effectors Cardiac muscle, smooth muscle & glands |
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How many neurons are involved in autonomic motor control? |
2 neurons |
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Preganglionic fibers |
Originate in brain stem, thoracic cord and sacral cord segments |
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Preganglionic fibers |
Originate in brain stem, thoracic cord and sacral cord segments |
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Postganglionic fibers |
Have cells bodies in the ganglia which may be remote to the effector organ or incorporated into it |
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What are the general features of the ANS? |
1. Many involuntary effectors can function somewhat independently of innervation 2. Normally AN maintain a basal firing rate that may be increased or decreased -> baseline of function 3. ACh release may stimulate or inhibit 4. Two arms -> sympathetic and parasympathetic 5. Axons of postganglionic neurons have varicosities that release NT along length of axon |
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Sympathetic division of ANS |
Accelerator 'Fight or flight' 'E division' (exercise, excitement, emergency, embarrassment) |
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Parasympathetic division of the ANS |
Decelerator 'Rest & digest' 'D division' (digestion, defecation, diuresis)
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Variocosities |
Swellings in postganglionic neurons Release NT along length of axon |
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Synapses en passant |
Formed by varicosities 'Synapses in passing' Analogous to many synaptic knobs on various telodendeia |
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White rami communicantes |
Where myelinated fibers split away to form synapses with postganglionic fibers |
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Gray rami communicantes |
Where most fibers synapse in the ganglia and send return, unmyelinated fibers back to the spinal nerve to be distributed to the body's surface effectors |
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Paravertebral ganglia |
a linked chain where myelinated fibers form synapses with postganglionic fibers
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Ganglionic divergence |
fibers from rami communicantes ascend and descend with the sympathetic chain |
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Convergence |
occurs when a postganglionic dendrite receives input from multiple preganglionic fibers |
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Mass activation |
When the sympathetics activate as a unit |
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Splanchnic nerves |
Presynaptic fibers that pass through the ganglia without synapsing |
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Visceral plexes |
"mesh overlay" of splanchnic nerves over the abdominal aorta where they synapse with post-ganglionic fibers in collateral ganglia |
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What CNs carry preganglionic fibers from the brain stem? |
CNs III, VII, IX, & X |
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In the parasympathetic division, where do synapses occur? |
With the postganglionic fibers lying near or in the organs they innervate in terminal ganglia |
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Vagus nerve |
Fills the gap between cranial & sacral roots Originates in the medulla and is extremely long territorially, extends from neck to mid colon and all the viscera in between |
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What does the vagus nerve do? |
Protects our airways, slows our heart, revs up our GI motility |
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What is acetylcholine the NT for? |
all preganglionic fibers all post ganglionic parasympathetic fibers sympatheitc fibers to sweat glands & vessels supplying our muscles |
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What is norepinephrine the NT for? |
Most postganglionic fibers
Chemically related to other catecholamines (epinephrine & dopamine) |
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Cholinergic responses |
Parasympathetic Always stimulatory for motor neurons in the somatic NS & in the ganglionic synapses of the autonomic NS Usually stimulatory at postganglionic effector sites |
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What are the two receptors of cholinergic response actions? |
Nicotinic Muscarinic |
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Nicotinic |
found in muscle and ganglia blocked by curare |
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Muscarinic |
found in visceral organs blocked by atropine |
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Nicotinic receptor |
Each receptor protein a channel which opens by binding 2 ACh Bidirectional down gradient flow of Na+ > K+ Depolarization (EPSP) |
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Muscarinic receptors |
Receptor and K+ channels are separate proteins Binding indirectly leads to channel response via G-protein interface |
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What are the two types of adrenergic receptors? |
Alpha receptors (1&2)
Beta receptors (1-3) |
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What is an example of an alpha receptor? |
Binding of norepinephrine to alpha receptor in the smooth muscle of blood vessels is stimulating, causing vasoconstriction
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What is an example of a beta receptor? |
Binding of norepinephrine to beta receptor in the smooth muscle of the bronchioles & coronary blood vessels in inhibitory, causing dilation/relaxation
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Propranolol |
Beta receptor blocker (antagonist). Used to lower blood pressure by reducing heart rate (B1). It also blocks B2 receptors to block bronchodilation triggering asthma in susceptible people |
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Atenolol |
Selective B1 blocker that doesn't bother B2. Provides all the benefits of propranolol without the downside |
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Phenylephrine |
In many cold medicines Its a1 effects cause vasoconstriction in the nasal mucosa to reduce congestion |
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Clonidine |
Activates (agonist) CNS a2 receptors to diminish norepinephrine release Suppresses the sympathoadrenal system (decreases epi & NE release) centrally Lowers BP |
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Adrenal medulla |
Part of the sympathetic division Functional equivalent of a post-synaptic cell Releases the hormones epinephrine (85%) & norepinephrine (15%) directly into the blood Epinephrine augments the action of norepinephrine |
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Where does most sensory info come from? |
The vagus a mixed nerve (motor + sensory) |
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Where does sensory control come from? |
The medulla, with significant input from the cerebellum, cortex, & hypothalamus |
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Phasic |
Stimulation persists but firing rate decreases Fast adapting |
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Tonic |
Stimulus persists & so does firing rate (until stimulation stops) Slow adapting |
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How many neurons are there between the receptor and the post central gyrus sensory strip? |
3 neurons |
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1st order neuron |
receptor on one end pseudounipolar may be extremely long (medulla to foot) |
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2nd order neuron |
Cross over (decussate) in cord or in medulla & ascend to thalamus
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3rd order neuron |
from thalamus to post-central gyrus
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Free nerve endings |
the most numerous receptor heat, cold, pain, light touch |
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Merkel endings |
Merkel's disc
fine touch-texture |
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Meissner's corpuscle |
hairless areas pressure, vibration |
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Ruffini's corpuscle |
Ruffini's ending fine touch, skin stretch "thread in jello mold" |
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Pacini's corpuscle |
pressure, vibration
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Root hair plexus |
fine touch |
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Krause's end bulb |
vibration, cold lips, tongue, penis, clitoris |
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Nociceptors |
respond to pain, stimuli sufficient enough to cause tissue injury
two types (A and C fibers) |
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A fibers |
acute (A-delta) sharp, intense, localizing myelinated fibers with phasic response rapid adaptation |
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C fibers |
chronic fibers
less intense, aching & dull, more persistent pain unmyelinated fibers with a tonic response |
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Capsaicin Receptor |
dendritic membrane receptor responsive to heat & capsaicin |
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Capsaicin |
makes chilis hot a ligand that opens NA+ and CA+2 channels used medicinally as a cream to abate neurogenic pain |
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Menthol receptor |
Responsive to cold and menthol
Either open Ca+2 or Na+ channels Below 15C, cold also activates pain receptors More cold receptors than heat receptors |
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Olfactory neurons |
responsible for smell
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Gustatory neurons |
responsible for taste
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What are the types of papillae? |
Filiform, fungiform, circumvallate, foliate
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What papillae do not have taste buds? |
Filiform Sense texture of food |
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What papillae have taste buds?
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fungiform, circumvallate, foliate
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Is taste regionalized? |
No. Any taste can be perceived anywhere there are taste buds |
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What are the 5 primary tastes? |
sweet, sour, bitter, salty, umami
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Differential stimulation |
What produces the perception of a specific taste
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Gustatory cells |
50-100 chemoreceptors in each of the 10,000 taste buds |
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Gustatory hairs |
Cilia extend from each cell and project into a space called the taste pore, which is bathed in saliva |
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What categories of taste are depolarized by ions? |
Salty (Na+) Sour (H+) |
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What categories of taste are depolarized through the use of G-proteins and secondary messengers? |
Sweet (sugars)
Umami (amino acids) Bitter (quinine) |
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Where are olfactory neuron cell bodies found? |
interposed between epithelial cells
Cilia project into the mucous of one end overlying the epithelium in which odor molecules dissolve |
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Glomeruli |
the points of synapse with the dendrites of 2nd order neurons |
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How many odor genes are there? |
350
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How many odor receptors do each odor gene code for? |
Each gene codes for one odor receptor in the ciliary membrane
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What are the structures found in the middle ear? |
Malleus, incus, stapes, external auditory meatus, oval window, round window, auditory (eustachian tube)
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Malleus |
hammer
vibrates from tympanic membrane |
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Incus |
anvil
bridges malleus & stapes |
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Stapes |
stirrup
vibrates against the oval window |
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External auditory meatus |
covered by the tympanic membrane
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Oval window |
opening into inner ear; stapes fits here
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Round window |
opening from inner ear; membrane covered
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Auditory (eustachian) tube |
swallowing opens the eustachian tube; this equalizes pressure on both sides of drum
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Tensor tympani |
contracts to open eustachian tube |
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Stapedus |
muscles dampen stapes with loudness |
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Inner ear |
mechanisms for hearing and balance
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The bony labyrinth |
complex space in temporal bone Cochlea, semicircular canals, utricle & saccule |
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Cochlea |
Hearing element of inner ear Snail shaped |
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Where are the balance organs housed? |
semicircular canals, utricle & saccule
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Membranous labyrinth |
lies within bony labyrinth separated from bony labyrinth by perilymph filled with K+ rich endolymph provides a soft tissue skeleton for the organs of hearing & balance |
