BIOL 223 Lecture 3 Flashcards
Components of the Central Nervous System (CNS)
Brain & Spinal Cord. Contains Nucleus (cluster of nerve cell bodies) and Tracts (bundles of axons also known as nerve fibers)
Components of the Peripheral Nervous System (PNS)
Nerves & Ganglia (collection of nerve cell bodies outside CNS). Nerves bundles of axons also known as nerve fibers
Grey Matter
Primarly comprised of neurosomas (nerve cell bondies) and dendrites.
White Matter
Possesses Myelin that’s why it is white.
Myelin
lipid rich material that surrounds the nerve cell axons to insulate them.
Structures of a Neuron
Composed of dendrites (extension that receives information), Soma (cellbody), and Axon (transmits information from soma to another cell via action potentials)
Compare Nucleus and Ganglion
Essentially same thing just different locations
Compare Tract and nevrves
Essential same thing just different locations
Briefly describe the three basic functions of the nervous system
Sensation - Receiving information (stimulus)
Response - Motor function (voluntary or involuntary)
Integration - Information processing
Somatic Nervous System
Conscious perception and voluntary motor responses. Body Moving Skeletal tissue
Autonomic Nervous System
Visceral Motor System. Involuntary control of the body. Maintains homeostasis.
Enteric Nervous System
Can function without other nervous input. Smooth muscle and glandular tissue of the digestive system
Describe the Structure of the nerve cell body
Large nucleus and nucleolus. Perikaryon (Cytoplasm). Mitochondria (produce energy)
Describe the structure of dendrites
Short and highly branched processes extending from the cell body.
Describe the function of denderites
Dendritic spines receive information from other neurons. 80-90 percent of neuron surface area.
Describe the structure of axons
Single, long cytoplasmic process
Describe the function of axons
Propagates electrical signals - action potentials
Axoplasm
plasma membrane of the axon. Specialized to conduct electrical activity
Axolemma
Plasma membrane of the axon. Specialized to conduct electrical activity
pseudo-unipolar neurons
sensory neurons. Cell bodies found in ganglia
Bipolar Neurons
Olfactory epithelium and retinal cells - smell and vision
Multipolar neurons
majority of neurons
Glial Cell Function
Because neurons are so specialized they are not very good at other things and need help from glial cells. Support and protect neurons. Make up half the volume of the nervous system.
Astrocytes
In the CNS. Have large star shaped cell bodies with many processes that come from the cell body
Astrocytes function
Maintain Blood Brain Barrier. Create three-dimensional framework for CNS. Repair damaged nervous tissue. Guide Neuron Development. Control interstitial environment
oligodendrocytes
In the CNS. have small cell bodies with few processes. Many cooperate to form a myelin sheath around the axons in the CNS
Ependymal Cells
In the CNS. Form epithelium that lines central canal of spinal cord and ventricles of brain. Produce and monitor Cerebrospinal Fluid(CSF)
Microglia
In the CNS. Smallest and least numerous glia. Migrate through nervous tissue. Clean up cellular debris, waste and pathogens
Satellite cells
In the PNS. Surround ganglia. Regulate interstitial fluid around neurons. Help with limited repair
Schwann Cells
in the PNS. Form myelin sheath around axons. Neruolemma - Outer surface of schwann cell.
Steps of Temperature senstation
Sensation, intergration, response.
Non-specific ion channels
Allows for diffusion down the concentration gradient.
Ligand-Gated Ion Channels
Chemically gated. Opens only when a ligand binds to them
Mechanically Gated ion channels
Responds to a physical distortion of the plasma membrane
Voltage Gated Ion Channels
Open and close at specific voltages
Leak channels
resting membrane potential. Open and close randomly
Explain how resting membrane potential is and how it is set up/maintenance
Charge difference across the membrane surface. High concentration of sodium and chloride in extracellular fluid. High concentration of potassium and negatively charged proteins in intracellular fluid. Set up by a sodium potassium pump.
Explain the all-or-none principle
Any stimulus that changes the membrane potential to threshold causes an action potential
Generation of an action potential
Rapid voltage changes in membrane affects the entirety of the excitable membrane. Begins at initial segment (Axon hillock) of the axon.
Absolute refractory period
Membrane cannot generate another action potential. All voltage-gated sodium channels are already open or inactiviated
Relative refractory period
A strong stimulus can initiate another action potential. Begins when sodium channels regain resting condition. Continus until membran potential stabalizes.
Graded potentials
A graded potential is a change in the membrane potential that does not spread far from the site of stimulation
Temporal Summation
Rapid, repeated stimuli at a single synapse.
Spatial Summation
Simultaneous stimuli arrive at multiple syanpses
List the for regions of the brain
Cerebrum, Cerebellum, Diencephalon, Brainstem
Functions of the Cerebrum
Controls higher mental functions. Concious thoughts, intellect, memory.
Function of Basal Nuclei
Cognitive processing, planning movements
Basal Forebrain
Learning and Memory
Limbic Cortex
Portion of the limbic system, emotion, memory, and behavior
Describe the anatomy of the cerebral cortex
Highly folded increases surface area. Gyri, ridges or hills. Sulci, Groves
Premotor cortex
Also called somatic motor association area. Coordinates learned movements
Visual Association area
Monitors patterns of activity in the visual cortex
Auditory Association Area
Word recognition
Describe the function of cerebral integrative centers
In loves and cortical areas of both cerebral hemispheres. Receive information from association areas. Directs complex motor activities. Perform analytical functions.
Wernicke’s Area
Language and comprehension. Primarily associated with left cerebral hemisphere. Receives information from sensory association. Coordinates access to visual and auditory memories.
Broca’s Area
Speech Production
Functions of prefrontal cortex
Coordinates information related from all critical association areas. Performs abstract intellectual functions, Predict consequences of actions
Functions of the limbic system
Establishes emotional states. Links conscious functions of cerebral cortex with autonomic functions. Facilitates memory storage and retrieval.
Limbic lobe
Cingulate, dentate and parahippocampal gyri
Amygdala
Acts as interface between the limbic system, cerebrum and various sensory systems
Fornix
Connects hippocampus with hypothalamus
Anterior Nuclei of Thalamus
Gatekeeper to the cerebrum
Reticular Formation
Alertness, excitement, lethargy and sleep
Basal Nuclei Function
Subconscious control of skeletal muscle tone. Coordinate learned movement patterns
Components of the Diencephalon
Thalamus, Hypothalamus, Epithalamus
Discuss the funtions of the pineal gland
in posterior portion of epithalamus. Secretes melatonin
Melatonin
Hormone regulates circadian rhythms
Thalamus
Filters and relays sensory information from spinal cord and cranial nerves to cerebral cortex.
Hypothalamas
Produces ADH (antidiuretic Hormone) and oxytocin
Regulates body temperature
Controls autonomic function
coordinates voluntary and autonomic functions
coordinates nervous and endocrine systems
Regulates circadian rhythms
subconscious control of skeletal muscles
produces emotions and behavioral drives
List the three components of the brain stem
Midbrain, Pons, Medulla oblongata
Tectum
Two pairs of sensory nuclei
Tegmentum
Red nucleus and substantia nigra
Function of the pons
Sensroy and motor nuclei of cranial nerves. Rate and depth of repsiration. Major relay center to the cerebelum
Functions of the Medulla Oblongata
Coordinates complex autonomic reflexes.
Cerebellum
Cerebral cortex comprised of grey matter.
Describe the arterial blood supply to the brain
Internal carotid arteries enter cranium through carotid canal, Vertebral arteries pass through the transverse foramina and foramen magnum, Branches of these vessels supplies blood to the brain
Describe venous return of blood from the brain to the internal jugular veins
Dural Venous sinuses, Absorb cerebrospinal fluid,Collect blood for return to circulation
List the different physical protections of the brain and spinal cord
Physical protection of the brain: Bones of the cranium
Cranial Meninges: Connecive tissue layers
Cerebralspinal fluid (CSF)
Biochemical isolation: Blood brain barrier -astrocytes
Describe the flow of cerebrospinal fluid through the ventricles, central canal, and subarachnoid space
Two large lateral ventricles. Third ventricle in diencephalon - interventricular foramen. Fourth ventricle Joins ventral canal of spinal cord, connects with third ventricle, median aperture and lateral apertures connect to subarachnoid space
Discuss the functions of cerebrospinal fluid
Surrounds all exposed surfaces of the CNS. Support brain - physically, the brain is floating in the CSF. If it wasn’t floating it would crush itself.
Cushion delicate neural structures
Transport nutrients, chemical messengers, and wastes
cerebrospinal fluid formation and absorption
Specialized ependymal cells surround capillaries
Secrets about 500 mL of CSF into ventricles per day
The same amount is absorbed daily
Removes waste products from CSF
Adjust composition of CSF
Sympathetic chain ganglia
rows of ganglia along vertebral column
paravertebral ganglia
Superior to the chain ganglia, in the cervical region, neck
prevertebral ganglia
Outside of the chain
terminal ganglia
near their target, parasympathetic nervous system;
Enteric plexus
Gastric plexus
Esophageal plexus
Epineurium
Network of collagen fibers
surrounds entire nerve
Perineurium
Middle Layer
Surrounds nerve Fascicles
Endoneurium
inner most layer
Surrounds individual axons
Nerve I
olfactory nerves - Sensory - Nucleus in Brainstem
Primary function is smell
Nerve II
Optic Nerves - Sensory - Nucleus in Brainstem
Primary Function is vision
Nerve III
Oculomotor Nerves - Motor - nucleus in midbrain
Primary function is eye movement and pupillary constriction
Nerve IV
Trochlear Nerves - motor - nucleus in midbrain
Primary function is eye movement
Nerve V
Trigeminal Nerve - Mixed - Nucleus in Pons
Primary function is sensory and motor to face
Nerve VI
Abducens Nerves - Motor - Nucleus in Pons
Primary function is eye movement
Nerve VII
Facial Nerves - Mixed - Nucleus in pons
Primary function is motor face, sensory taste
Nerve VIII
Vestibulocochlear nerves - Sensory - Nucleus found in Pons and medulla oblongata
Function is hearing and balancing
Nerve IX
Glossopharyngeal nerves) - Mixed nerves - Nucleus found in Medulla
Function motor throat, taste, swallowing
Nerve X
Vagus - Mixed - found in medulla
Function Motor/sensory viscera
Nerve XI
Accessory Nerves - Motor - Medulla
Also called spinal accessory nerves
Nerve XII
Hypoglossal - Motor - Medulla
Function Motor lower throat
Explain why all spinal nerves are mixed nerves
Spinal nerves are formed by junctions of anterior (motor function) and posterior roots (sensory function). Because the nerve forms by the joining of the nerve roots it makes all spinal nerves mixed
Dermatome
Specific bilateral region of skin supplied by a single pair of spinal nerves
Cervical plexus (C1-C5)
Phrenic Nerve: Controls diaphragm and breathing
Brachial plexus (C5 - T1)
Musculocutaneous Nerve
Median Nerve
Ulnar Nerve
Radial Nerve
Lumbar plexus (T12-L4)
Femoral Nerve
Sacral plexus (L4 - S4)
Sciatic Nerve
Carpal tunnel syndrome
compression of median nerve
