Fail's Exam 1 Flashcards by AE G

functions of the cerebrum

consciousness, perception, voluntary movements, and executive functions

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brainstem general function

homeostatic functions, cranial nerves have sensory/motor function, arousal and sleep, neuronal pathways to/from cerebrum

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cerebellum general function

motor coordination, timing and planning of complex movements

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where are the paleocortex and archicortex found in the brain?

cerebral cortex “old cortex”
includes the hippocampus, limbic cortex, and olfactory regions

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where is the neocortex found in the brain? what distinguishes it from other kinds of cerebral cortex?

found in the cerebral cortex
regional (perception, motor, executive functions, auditory cortex, motor cortex, visual cortex)
histological specialization (6 distinct layers)

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Distinguish between an ion channel receptor and a receptor that works through second messengers. How are they similar? How are they different?

ion channel - iontropic, fast response

GPCR - metabotropic, slow response, acts by 2nd messengers

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What are some of the consequences of activating G-protein linked receptors (what cellular effects might they have)?

there is a possibility of many possible behaviors

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Distinguish between a ligand-gated ion channel and a voltage-gated ion channel.

ligand-gated - requires ligand (NT) to open channel
voltage-gated - requires change in membrane potential to open channel

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By what mechanisms are neurotransmitters removed from the synaptic cleft? Which are most important*?

diffusion
*uptake by surrounding cells
*enzymatic degradation

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effect of Fluoxetine (Prozac)

prevents the reuptake of serotonin at serotonergic synapses
antidepressant –> keeps serotonin in the synapse = happy

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effect of organophosphates

inhibit AChE
Ach not being taken back up = increased activity at cholinergic synapses = constant muscle contraction

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Describe the relative concentrations of Na+, K+, and Ca2+ in the intraneuronal versus extracellular fluid.

Intraneuronal fluid: high concentrations of Na+ and Ca2+

Extracellular fluid: high concentrations of K+

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Define “excitatory” in a neurotransmitter sense. What happens at an excitatory synapse that makes a neuron more likely to produce an action potential?

excitatory: depolarization due to influx of Na+ that allows initiation of action potential

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What is the most common excitatory neurotransmitter in the central nervous system?

glutamate

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Define “inhibitory” in a neurotransmitter sense. What happens at an inhibitory synapse that makes a neuron less likely to produce an action potential?

inhibitory: hyperpolarization due to influx of K+, no action potential

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What is the most common inhibitory neurotransmitter in the brain?

GABA

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What is the most common inhibitory neurotransmitter in the spinal cord?

glycine

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Neurotransmitter: ACh
Iontropic/Metabotropic
Predominant Effect on Postsynaptic Membrane:

found at the NMJ
iontropic (nAChR) - conductance for Na & Ca
metabotropic (mAChR) - M2 inhibitory & M3 excitatory

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Neurotransmitter: Dopamine
Iontropic/Metabotropic
Predominant Effect on Postsynaptic Membrane:

metabotropic (GPCR)
excitatory & inhibitory
motor behavior & mood

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Neurotransmitter: GABA
Iontropic/Metabotropic
Predominant Effect on Postsynaptic Membrane:

ionotropic (Cl- ion channel)
inhibitory only in the brain

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Neurotransmitter: Glutamate
Iontropic/Metabotropic
Predominant Effect on Postsynaptic Membrane:

iontropic (AMPA)
iontropic (NMDA) - admits both Na & Ca
metabotropic (GPCR)
excitatory only in CNS

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Neurotransmitter: Glycine
Iontropic/Metabotropic
Predominant Effect on Postsynaptic Membrane:

ionotropic (Cl- channel)
inhibitory only to the spinal cord

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Neurotransmitter: Norepinephrine
Iontropic/Metabotropic
Predominant Effect on Postsynaptic Membrane:

adrenergic receptors (GPCR)
alpha 1, 2 and beta 1 and 2
sympathetic neurons associated with mood, attention, sleep-wake cycles

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alpha 1 receptor

constriction of smoth m.

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alpha 2 receptor

primarily inhibitory

beta 1 receptor

increase cardiac function (strength of contract & speed of conduction)

beta 2 receptor

smooth m. relaxation (e.g. bronchial walls)

Describe the arterial blood supply to the canine brain.

vertebral a. internal carotid aa.

what does the cerebral arterial circle surround

optic nn. & chiasm & pituitary on base of brain

Rete mirabile

modified intracranial parts of internal carotid a.; NOT in dogs or horses; speculations with brain cooling

what arteries make up the cerebral arterial circle

rostral cerebral aa. middle cerebral aa. internal carotid aa. caudal communicating aa. caudal cerebral aa. rostral cerebellar aa.

what does the rostral cerebral aa. supply

medial aspect of hemisphere

what does the middle cerebral aa. supply

lateral aspect of cerebrum

what does the caudal cerebral aa. supply

occipital region (medial & lateral) of cortex

what arteries come off the basilar a.

labyrinthine aa. caudal cerebellar aa.

main supply to the spinal cord

ventral spinal a.

what does the central branch of the ventral spinal a. supply what is its clinical significance

gray matter of spinal cord fibrocartilagenous embolism (FCE)

what do the dorsal spinal aa. supply

white matter

what do the vertebral aa., intercostal aa., lumbar aa., median sacral a. give rise to

spinal brr --> radicular brr

Name the layers of the meninges and describe their relationships to one another.

dura mater - superficial/tough arachnoid - middle layer, subarachnoid space, connected to dura via fibroblasts and to pia via arachnoid trabeculations pia mater - deepest laye

Describe the anatomical differences between spinal and cranial meninges.

Cranial meninges have the two dura mater layers (periosteal and meningeal layers) that are fused except at the dural sinuses Cranial meninges dural reflections create broad dividing sheets w/in braincase Cranial epidural space is potential space only Subarachnoid space has expanded regions “cisternae” in cranial meninges

Epidural space of spinal cord

real space

Subdural space

potential

Subarachnoid space

real

epidural space of the cranium

normally no epidural space of cranium but can have a epidural hematoma potential

components of choroid plexus

capillaries + c.t. + simple cuboidal epithelium with tight junctions

why is the choroid plexus endothelium leaky

lack of tight junctions

difference between the blood-brain barrier and blood-CSF barrier

BBB has tight junctions on endothelial cells blood-CSF barriers endothelium is leaky, no astrocytes, but has has tight junctions in choroid epithelium

how is CSF produced

produced by ependymal of choroid plexus via active secretion and by ependymal which line ventricles

Trace CSF’s circulation through the ventricular system to the subarachnoid space and to its ultimate reabsorption back into the circulatory system.

CSF circulate through ventricles and central canal CSF passes through subarachnoid space (high P) via lateral apertures of 4th ventricle CSF absorption at arachnoid granulations → into venous sinuses (low P) → internal jugular v. -passive, one-way, dependent on pressure gradient (CSF > venous)

Describe how changes in blood osmotic pressure can affect CSF production.

CSF production influenced by blood osmotic pressure (Increase in blood osmotic pressure decreases CSF production)

what is CSF not influenced by

blood pressure or pressure of CNS w/in ventricles

Describe how changes in hydrostatic pressure in the venous system can affect CSF reabsorption, with reference to the function of specific anatomical elements.

Reabsorption of CSF is dependent on presence of hydrostatic pressure between subarachnoid space (high P) and venous sinus (low P) - Increase in hydrostatic pressure increases CSF reabsorption - Increase in venous pressure will decrease CSF reabsorption CSF reabsorbed by arachnoid granulations into venous sinuses which drain into internal jugular v.

Define hydrocephalus. Describe conditions under which it might develop.

Hydrocephalus: dilation of ventricular system, “water head” Obstruction to the outflow of CSF can occur at the arachnoid granulations (e.g., as a consequence of meningitis) or somewhere more proximal in the circulation of CSF (e.g., a mass in the midbrain compressing the mesencephalic aqueduct).

What is the blood-brain barrier? what does it protect the CNS from? ______ makes up tight junctions where is it found?

-barrier between blood and ECF of CNS - protects CNS from dangerous blood constituents (K, glutamate, albumin) -astrocytic end feet/pericytes with tight junctions in CNS endothelial cells -brain & spinal cord

What is the blood-CSF barrier?

between blood & CSF tight junctions in epithelium, not endothelium

what can pass through the BBB

gases, substances with specific transporters (e.g. glucose/AA), lipid-soluble substances, very small molecules

major dural sinuses... falx cerebri has ____ & _____ tentorium cerebelli has ______ diaphragma sellae has _______

dorsal sagittal sinus straight sinus transverse sinuses cavernous sinuses

what are the dural reflections

falx cerebri tentorium cerebelli diaphragma sellae

what is the clinical significance of the tenorial incisure (notch)

increase intracranial pressure can cause the brain to herniate through the notch compressing the brainstem

needle placement for CSF collection in small animals

cerebellomedullary cistern (cisterna magna - between cerebellar & medulla)

needle placement for CSF collection in large animals

cerebellomedullary cistern or lumbar cistern

needle placement for epidural anesthesia in small animals

L7-S1 epidural space

needle placement for epidural anesthesia in large animals

Cd1-2 more common than S5-Cd1 epidural space

Fail's Exam 1 Flashcards

(64 cards)