Block 2 Exam Flashcards
What makes up the Central nervous system
Brain
Spinal cord
What are the three membranes of the CNS
Dura mater
Arachnoid
Pia mater
What makes up the Peripheral Nervous system
Sensory nerves
Motor nerves
Peripheral ganglia
Sensory nerves
Afferent nerves
Periphery to CNS
Motor nerves
Efferent nerves
CNS to periphery
Peripheral ganglia
Nerve cells concentrated outside the CNS
Autonomic nervous system (ANS)
Regulates and controls visceral functions
Four domains of typical neuron
Cell body
Dendrites
Axon
Presynaptic terminals
Vertebrate embryo layers
Endoderm
Mesoderm
Ectoderm
Notochord
Direct ectoderm to form neural tube in a complex process called neurulation
What does the ectoderm become?
Nervous system
Skin
Two categories of defects of neural tube closure
Brain defects
Spina Bifida defects
Three brain defect examples
Anencephaly
Cephalocele
Meningocele
Anencephaly
Absence of brain, with massive defects in the skull, meninges, and scalp
Cephalocele
Partial brain herniation through a skull defect (cranium bifidum)
Meningocele
Meningeal herniation through a skull or spine defect
Three Spina bifida defect examples
Spina bifida occulta
Spina bifida cystica
Myelomeningocele
Spina bifida occulta
Vertebral arch defect only
Spina bifida cystica
Herniation of the dura and arachnoid through a vertebral defect
Myelomeningocele
Herniation of the spinal cord and meninges through a vertebral defect
Regional specialization
Prosencephalon
Mesencephalon
Rhombenecephalon
What does the prosencephalon divide into
Telencephalon
Diencephalon
Telencephalon Neural tissue
Central hemispheres
Diencephalon Neural tissue
Thalamus
Subthalamus
Hypothalamus
Neuropituitary
What does the Rhombencephalon divide into
Metencephalon
Myelencephalon
Metencephalon Neural tissue
Pons
Cerebellum
Myelencephalon Neural tissue
Medulla
Basal plate
Ventral horn
Motor neurons leave to innervate “efferent”
Alar plate
Dorsal horn
Receives sensory input “afferent”
Nuclei
Aggregates of neurons
What 4 things do progenitor cells produce?
Neurons
Oligodendrocytes
Astrocytes
Ependymal cells
What 5 things are stem cells able to do?
Proliferate
Renew themselves over the life of the organism
Create fully differentiated cells through progenitor cells
Retain their multilineage potential throughout life
Replace cells lost to injury or disease
Stem cell asymmetrical cell division
Create one stem cell and one progenitor cell
Progenitor cell
Cell that begins path to terminal differentiation
Stem cell symmetrical division
Create two new stem cells
What do stem cells produce
Neurons
Astrocytes
Oligodendrocytes
Wallerian degeneration
Loss of axonal structure distal to lesion
Chromatolysis
ER degenerates
Retrograde transneuronal degeneration
The retrograde neuron’s terminals retract and the neuron degenerates
Anterograde transneuronal degeneration
The anterograde neuron degenerates
Five major areas of CNS
Telencephalon Cerebellum Diencephalon Brainstem Spinal cord
Parts of the brainstem
Midbrain
Pons
Medulla
Vestibulocerebellum
maintain body’s balance
Spinocerebellum
Regulates muscle tone
Cerebrocerebellum
Coordinates motor behavior
Midbrain
Control eye movement
What nerves control eye movement
CN III and CN IV
What does the Pons control
Mastication
Eye movement
Facial muscles
What nerve controls mastication
CN V
What nerve controls facial muscles
CN VII
What nerve is responsible for sensory input from face, scalp, mouth and nose
CN V
What nerve is responsible for processing hearing and equilibrium
CN VIII
What muscles does the Medulla inervate?
Muscles of neck and tongue
What nerve innervates muscles of neck
CN XI
What nerve innervates muscles of tongue
CN XII
What nerves control blood pressure, heart rate, respiration, and digestion
CN IX and X
Ascending tracts
Mediate synaptic interactions within the spinal cord and convey information to more rostral areas of the CNS
Descending tracts
Control motor neurons whose cell bodies are in the ventral horn
PNS 4 main purposes
Transduces stimuli into raw sensory information through receptors
Conveys sensory information to CNS
Conveys motor signals from CNS to target organs
Converts motor signals to chemical signals at synapses on target tissues
Peripheral nerves
Organization of axons in the PNS
Endoneurium
Loose connective tissue surrounding individual axons
Perineurium
Connective tissue sheath surrounding small groups of fascicles
Epineurium
Matrix of connective tissue that surrounds a group of fascicles
Three divisions of ANS
Sympathetic
Parasympathetic
Enteric
Sympathetic and Parasympathetic
Innervate most visceral organs and have a yin yang relationship with one another
Enteric
Regulates rhythmic contraction of intestinal smooth muscle
Regulates secretory functions of intestinal epithelial cells
Receives afferent input from gut and is subject to modulation by Sympathetic and Parasympathetic
Neuronal microenvironment
Extracellular fluid
Capillaries
Glial cells
Adjacent neurons
Brain extracellular fluid (BECF)
Solute concentrations fluctuate with neural activity
Control of composition of BECF
Blood brain barrier (BBB) protects BECF from fluctuations in blood composition
CSF influences composition of BECF
Glial cells “condition” BECF
Where are choroid plexuses present?
Two lateral ventricles
Third ventricle
Fourth ventricle
Special neurons
Transmit information to or from a “special” subset of visceral or somatic structures
General neurons
Transmit information to or from visceral or somatic structures that are not in the special group
Special visceral neurons
Information travels to or from structures derived from the branchial arch region of the embryo
Special somatic neurons
Handle only sensory information, the neurons arise from the organs of special sense
Visceral neurons
Transmit information to or from internal organs or regions that arise embryologically from the branchial arch
Somatic neurons
Transmit information to or from all non-visceral parts of the body, including skin and muscle
What type of nerve is not possible?
Special somatic efferent
Two directions of transport
Anterograde
Retrograde
Anterograde transport
Carried down the axon
Retrograde transport
Carried back up the axon
Fast anterograde
Transport speed ~400mm/day
Transports mitochondria and vesicles via microtubules
Kinesin
Slow anterograde
Moves cyoskeletal elements soluble proteins of intermediary metabolism, actin
Limiting factor when dealing with damage in PNS
Fast retrograde
Dynein protein
Moves degraded vesicles and absorbed exogenous materials
Mesencephalon Neural tissue
Midbrain
Telencephalon cavities
Lateral ventricles
Diencephalon cavities
Most of third ventricle
Mesencephalon cavities
Central aqueduct
Metencephalon cavities
Rostral fourth ventricle
Myelencephalon cavities
Caudal fourth ventricle
Spinal cord cavities
Central canal
Arachnoid granulations
Pressure sensitive one-way valves, which clear CSF into the venous blood supply via transcytosis
Na+ Plasma concentration
153 mM
K+ Plasma concentration
4.7 mM
Ca2+ Plasma concentration
1.3 mM (ionized)
Mg2+ Plasma concentration
0.6 mM (ionized)
Cl- Plasma concentration
110 mM
HCO3- Plasma concentration
24 mM
H2PO4- and HPO42- Plasma concentration
0.75 mM (ionized)
pH Plasma
7.4
Amino acids Plasma concentration
2.6 mM
Proteins Plasma concentration
7 g/dL
Osmolality (mOsm) Plasma
290
Na+ CSF concentration
147 mM
K+ CSF concentration
2.9 mM
Ca2+ CSF concentration
1.1 mM (ionized)
Mg2+ CSF concentration
1.1 mM (ionized)
Cl- CSF concentration
113 mM (ionized)
HCO3- CSF concentration
22 mM
H2PO4- and HPO42- CSF concentration
0.9 mM
pH CSF
7.33
Amino acids CSF concentration
0.7 mM
Proteins CSF concentration
0.03 g/dL
Osmolality (mOsm) CSF
290
Na+ CSF/Plasma Ratio
0.96
K+ CSF/Plasma Ratio
0.62
Ca2+ CSF/Plasma Ratio
0.85
Mg2+ CSF/Plasma Ratio
1.8
Cl- CSF/Plasma Ratio
1.03
HCO3- CSF/Plasma Ratio
0.92
H2PO4- and HPO42- CSF/Plasma Ratio
1.2
Amino acids CSF/Plasma Ratio
0.27
Proteins CSF/Plasma Ratio
0.004
Osmolality CSF/Plasma Ratio
1.00
What is secreted in the brain?
Na+
Cl-
HCO3-
H2O
What is absorbed in the brain?
K+
Where is the Na+/K+ ATPase in the brain
Apical membrane
How is absorption impaired in Hydrocephalus?
Arachnoid villi damaged from infection, inflammation of meninges, or irritating blood
What will testing for Hydrocephalus show?
Spinal tap shows normal pressures
Imaging shows enlarged ventricles
What are the signs of Hydrocephalus?
Progressive dementia
Urinary incontinence
Gait disturbance
Obstructive hydrocephalus
CSF outflow from ventricles obstructed resulting in enlarged ventricles
BECF
Route by which important molecules such as oxygen, glucose, and amino acids reach brain cells and by which the products of metabolism, including CO2 and catabolized neurotransmitters, leave the brain
Waste-management
What areas of the brain lack the BBB
Median Eminence Area Postrema Subfornical Organ Subcommissural Organ Posterior Pituitary Organum Vasculosum Laminae Terminalis (OVLT) Pineal Gland
Components of the BBB
Astrocytes
Astrocyte end feet
Pericyte
Endothelial cell
CNS Glial Cells
Astrocytes
Oligodendrocytes
Microglial Cells
PNS Glial Cells
Satellite Cells
Schwann Cells
Enteric Glia
Six Astrocyte Functions
Supply fuel to neurons through lactic acid
Regulate [K+]o
Modulate cerebral blood flow
Secrete trophic factors that promote neuronal survival and synaptogenesis
Make neurotransmitters
Communicate via gap junctions
Oligodendrocytes
Make and support myelin sheath in the CNS
Control pH regulation through carbonic anhydrase and iron metabolism
Schwann cells
Make and support myelin sheath in the PNS
Microglial cells
Activated by injury to the brain
Macrophages of the CNS
Dendritic spines
Protrusions from dendrite membrane where contact with neighboring axons is formed in order to receive synaptic input
Initial Segment
Initiation of axon potentials
Interneurons
Connect motor and sensory neurons
Dysraphism
Disturbance in the process of neural tube closure
Apoptosis
Programmed cell death
Initiates in nucleus
Protein synthesis
Necrosis
Ca2+ entry
Energy failure
Loss of cell membrane integrity
Forms of cell death
Apoptosis
Necrosis
Fibrillation
Individual muscle fibers twitch spontaneously
Fasciculation
simultaneous involuntary contraction of groups of muscle fibers within the motor unit innervated by a single motor neuron
Paresthesia
Tingling sensation
Projection neurons
Neurons whose axons extend from the neuronal cell body within the central nervous system
Modality category that refers to the direction of information flow
Afferent vs. efferent
Modality category that defines the anatomical distribution of the information flow
Visceral vs. Somatic
Modality category that defines the information flow on the basis of embryological origin of structure being innervated
General vs. Special
Where are bipolar neurons found?
Retina
What structure secretes CSF?
Choroid plexus
Which solutes have similar compositions in CSF as compared to plasma?
Na+
Ca2+
Cl-
HCO3-
Lipid solubility and BBB
Solubility increases and diffusion across BBB increases
Molecular mass and BBB
Mass increases and diffusion across BBB decreases
Plasma proteins and BBB
Molecule bound to plasma protein and diffusion across BBB decreases
Charge and BBB
Uncharged leads to higher diffusion across BBB
Water solubility and BBB
Water solubility increases and diffusion across BBB decreases
OVLT
Temperature control centers
Involved in fever induction
Subfornical organ
Circulating levels of Ang II
Median eminence
Neurohormonal control of autonomic system
Pineal gland
Circadian rhythm
Area postrema
Circulating toxins
Initiates vomiting reflex
Cerebrospinal Fluid (CSF)
Cushions brain and spinal cord
Picks up needed supplies from blood
Gets rid of waste products from brain cells
Pia mater
Glia limitans
Pia-glial membrane
Pia-glial membrane
Does not restrict diffusion of substance between BECF and CSF
Arachnoid mater
Composed of layers of cells linked by tight junction
Blood-CSF barrier
Blood-CSF barrier
Isolates CSF in arachnoid space from blood on overlying vessels of dura mater
Dura mater
Intracranial venous sinuses
Blood vessels are outside blood brain barrier
Queckenstedt test
Used to detect a block in circulation of CSF in spinal canal
Transcytosis
Formation of giant fluid-containing vacuoles
Tortuosity
Reduces rate of diffusion by 60% compared with movement in free solution
Cell swelling
Water moves from BECF into cells
Blood Brain Barrier (BBB)
Prevents some blood constituents from entering brain extracellular space
Features of cerebral capillaries
Tight junctions Apical Na+/K+ ATPase Carriers for glucose and amino acids Proteolytic enzymes Basal lamina
Pericytes
Regulate blood-brain barrier
Astrocytes
Essential for formation and maintenance of the BBB
Thrombospondins
Astrocyte-secreted proteins that promote CNS Synaptogenesis
Where does the Pons receive sensory input from?
Face
Scalp
Mouth
Nose
What does the Pons process
Hearing and equilibrium
What does the medulla control?
Blood pressure
Heart rate
Respiration
Digestion
