Anatomy Exam 4
4. Define Afferent and Efferent. What 2 subdivisions do each have (what they consists of and what they are responsible for)? Label Figure 12.1
- Afferent division • Carries sensory information • From receptors in peripheral tissues and organs to CNS - Efferent division • Carries motor commands • From CNS to muscles, glands, and adipose tissue ▪ Efferent division of PNS - Somatic nervous system (SNS) • Controls skeletal muscle contractions • Both voluntary and involuntary (reflexes) - Autonomic nervous system (ANS) • Controls subconscious actions, contractions of smooth andcardiac muscle, and glandular secretions • Sympathetic division has a stimulating effect new• Parasympathetic division has a relaxing effect
10. Define 4 structural classifications of neurons (define processes). Label Figure 12.3
- Anaxonic neurons • Small • All cell processes look similar • Found in brain and special sense organs - Bipolar neurons • Small and rare • One dendrite and one axon • Found in special sense organs (sight, smell, hearing) - Unipolar neurons (pseudounipolar neurons) • Axon and dendrites are fused • Cell body to one side • Most sensory neurons of PNS - Multipolar neurons • Have one long axon and two or more dendrites • Common in the CNS • All motor neurons that control skeletal muscles
17. What is meant by the "All of none" principle.
- Any stimulus that changes the membrane potential to threshold • Will cause an action potential - All action potentials are the same • No matter how large the stimulus - An action potential is either triggered (100%) or not (0%)
14. Define 3 types of neuron to neuron synapses.
- Axodendritic • The axon of one neuron and thedendrite of another neuron - Axosomic • The axon of one neuron and thesoma of another neuron - Axoaxonic • The axon of one neuron and theaxon of another neuron
3. Define PNS (what it consists of and what it is responsible for).
- Includes all nervous tissue outside CNS - Delivers sensory information to the CNS - Carries motor commands to peripheral tissues - Nerves (peripheral nerves) • Bundles of axons with connective tissuesand blood vessels • Cranial nerves connect to brain • Spinal nerves attach to spinal cord
12. Define: action potential. Describe the events involved in generating and propagating an action potential. Figure12.13 (Lots of information and terminology here!)
- Is an electrical impulse - Produced by graded potential that reaches threshold (-55mV) - Propagates along surface of axon to synapse - Propagated changes inmembrane potential - Affect an entire excitablemembrane - Begin at initial segment of axon - Do not diminish as they moveaway from source - Stimulated by a graded potential that depolarizes the axolemma to threshold Generation of action potentials: Step 1: • Depolarization to threshold-55mV Step 2: • Activation of voltage-gated Na+ channels • Na+ rushes into cytosol • Inner membrane surface changes from negative to positive • Results in rapid depolarization Step 3: • Inactivation of Na+ channels and activationof K+ channels • At +30 mV, inactivation gates of voltage-gated Na+ channels close • Voltage-gated K+ channels open • K+ moves out of cytosol • Repolarization begins Step 4: • Voltage-gated K+ channels begin to close • As membrane reaches normal resting potential • K+ continues to leave cell • Membrane is briefly hyperpolarized to -90 mV Step 5: • After all voltage-gated K+ channels finishclosing • Resting membrane potential is restored • Action potential is over Propagation •Moves an action potential along an axon in a series of steps •Types of propagation -Continuous propagation -Saltatory propagation Continuous propagation of action potentials -Occurs in unmyelinated axons -Affects one segment of an axon at a time -Step 1: Action potential develops at initial segment •Depolarizes membrane to +30 mV -Step 2: Local current develops •Depolarizes second segment to threshold -Step 3: Action potential occurs in second segment •Initial segment begins repolarization -Step 4: Local current depolarizes next segment -Cycle repeats •Action potential travels in one direction (1 m/sec) Saltatory propagation of action potentials -Occurs in myelinated axons -Faster than continuous propagation •Requires less energy -Myelin prevents continuous propagation -Local current "jumps" from node to node -Depolarization occurs only at nodes 1. an action potential has occurred at the initial segment 2. a local current produces a graded depolarization that brings the axon membrane (axolemma) at the next node to threshold 3. An action potential develops at node 2 4.a local current produces a graded depolarization that brings the axolemma at node 3 to threshold
What 2 cell types make up neural tissue?
- Nervous tissue contains two kinds of cells: • Neurons for intercellular communication • Neuroglia (glial cells) - Essential to survival & function ofneurons - Preserve structure of nervous tissue
1. Define 5 types of neuronal pools and explain how they process information. Label Figure 13.14
1. Divergence 2. Convergence 3. Serial processing 4. Parallel processing 5. Reverberation Divergence - The spread of information from oneneuron to several neurons - Permits broad distribution of aspecific input - Information enters the CNS and thenspreads to the brain and spinal cordat the same time • Especially common in sensory pathways Convergence- Information going from severalneurons to a single neuron • Example: subconscious andconscious control of thediaphragm in breathing—twoneuronal pools synapse withthe same motor neurons Serial Processing - Information going from one neuronto the next in a sequence - Information going to one part ofthe brain, then to another part,and then to another part, etc .• Example: pain signals passsequentially through twoneuronal pools to reachconscious brain Parallel Processing - Several neurons are processing the information at the same time • Example: If you step on a nail, you typically move your foot, shout "ouch," and dance a bit, all at the same time Reverberation - Collateral axons extend back towardthe origin of the impulse to cause anenhancement or a continuation of theimpulse • Forms positive feedback loop; continues until synaptic fatigue or inhibition occurs • Examples: may maintain consciousness, breathing, muscle coordination
11. Define 3 connective tissue layers found in peripheral nerves. Label Figure 14.5a.
1. Epineurium—outermost;network of collagen fibers 2. Perineurium—middle layer;separates nerve into fascicles(axon bundles) 3. Endoneurium—innermost;surrounds individual axons
18. Describe the steps by which an impulse crosses vesicular and non-vesicular synapses.
1. action potential triggers release of neurotransmitter from secretory vesicles (exocytosis); 2. neurotransmitter diffuses across synaptic cleft and binds to receptor on postsynaptic membrane; 3. binding results in change in permeability of postsynaptic membrane (excitatory or inhibitory); 4. if degree of excitation is sufficient, binding may lead to action potential in axon or sarcolemma. since the post/presynaptic neurons are bound together and communicating, junctions permit passage of ions between cells, can move in either direction and no ventricles needed Vesicular synapse- chemical synapse involving a neurotransmitter (most common) Nonvesicular synapse- electrical synapse with direct contact between cells
8. How is the suprarenal medulla innervated by the sympathetic division? Where is its general location, the origin of its preganglionic fibers, its general functions? Label Figure 16.2
Adrenal medulla - Modified sympathetic ganglion at center of each adrenal gland - Innervated by preganglionic fibers that synapse oncells that secrete • Epinephrine (adrenaline) • Norepinephrine (noradrenaline) - Epinephrine makes up 75-80 percent of secretory output - Center of each adrenal gland - Modified sympathetic ganglion - Ganglionic neurons have very short axons - When stimulated, they release neurotransmitters into bloodstream (not at synapse) • Function as hormones to affect target cells throughout body Fibers in sympathetic division - Preganglionic fibers • Relatively short • Ganglia located near spinal cord - Postganglionic fibers • Relatively long, except at adrenal medullae
16. Explain how membrane potential is determined and how it can change (review chapter 3 on membranes).
All plasma (cell) membranes produce electrical signals by ion movements - Membrane potential is particularly important to neurons ▪ Resting membrane potential - The membrane potential of a resting cell - The extracellular fluid (ECF) andintracellular fluid (cytosol) differ greatly inionic composition • Extracellular fluid contains highconcentrations of Na+ and Cl- • Cytosol contains high concentrationsof K+ and negatively charged proteins - Cells have selectively permeablemembranes - Membrane permeability varies by ion Resting membrane potential -The membrane potential of a resting cell Graded potential -Temporary, localized change in resting potential -Caused by a stimulus Action potential -Is an electrical impulse -Produced by graded potential -Propagates along surface of axon to synapse Passive processes acting across cell membrane -Current •Movement of charges to eliminate a potential difference -Resistance •How much the membrane restricts ion movement •If resistance is high, current is small
13. What 2 factors do impulse speed depend on?
Axon diameter affects propagation speed of action potentials - The larger the diameter, the lower the resistance and faster the speed Myelin insulates myelinated axons • Increases speed of action potentials
5. Define the Blood-Brain Barrier.
Blood brain barrier (BBB) - Isolates CNS from general circulation - Formed by network of tight junctions • Between capillary endothelial cells in CNS - Generally, only lipid-soluble compounds like O2, CO2,steroids, prostaglandins, and small alcohols • Can diffuse into interstitial fluid of CNS - Astrocytes regulate blood brain barrier by • Releasing chemicals that control permeability ofendothelium
2. Define CNS (what it consists of and what it is responsible for).
Brain and spinal cord - Consists of nervous tissue, connective tissue, and blood vessels - Functions to process and coordinate sensory data from inside andoutside body - Motor commands control activities of peripheral organs (e.g., skeletalmuscles) - Higher functions of brain include intelligence, memory, learning, and emotion
What two anatomical subdivisions does the nervous system have?
CNS, PNS
6. List and describe the functions, locations and steps in the circulation of cerebrospinal fluid (CSF). LabelFigures 14.4
Cerebrospinal fluid (CSF) - Surrounds all exposed surfaces of CNS - Functions to • Support brain • Cushion delicate neural structures • Transport nutrients, chemical messengers, and wastes Choroid plexus produces CSF - Specialized ependymal cells surround capillaries - Secretes about 500 mL of CSF into ventricles per day - Removes waste products from CSF - Adjusts composition of CSF CSF circulates - From choroid plexus - Through ventricles - To central canal of spinal cord - Into subarachnoid space • Via two lateral apertures and one median aperturein roof of fourth ventricle • To surround brain, spinal cord, and cauda equina Arachnoid villi - Extensions of arachnoid membrane - Extend through meningeal layer of dura mater intosuperior sagittal sinus Arachnoid granulations - Large clusters of arachnoid villi in adults - Absorb CSF into venous circulation
2. Identify the main brain regions and their functions (Medulla oblongata, Pons, Cerebellum,Mesencephalon, Epithalamus, Thalamus, Hypothalamus, and Telencephalon. Label Figure 14.1
Cerebrum (telenephalon) - Largest part of adult brain - Controls higher mental functions • Conscious thoughts, intellect, memory, etc. - Divided into left and right cerebral hemispheres Cerebellum - Second-largest part of brain - Coordinates repetitive body movements - Two hemispheres - Covered by gray matter (cerebellar cortex) Midbrain (mesencephalon) - Processes sight, sound, and associated reflexes - Maintains consciousness Pons - Connects cerebellum to brainstem - Contains • Tracts (collections of CNS axons) • Relay centers • Nuclei for somatic and visceral motor control Medulla oblongata - Connects brain to spinal cord - Inferior portion has a narrow central canal - Relays sensory information - Regulates autonomic functions • Heart rate, blood pressure, and digestion Diencephalon - Located under cerebrum and cerebellum - Epithalamus (pineal gland) • Produces melatonin - Thalamus • Relays and processes sensory information - Hypothalamus is involved with • Emotions • Autonomic function • Hormone production
19. Describe the major types of neurotransmitters and neuromodulators and discuss their effects on postsynaptic membranes.
Classes of neurotransmitters: - Excitatory neurotransmitters • Cause depolarization of postsynaptic membranes • Promote action potentials - Inhibitory neurotransmitters • Cause hyperpolarization of postsynaptic membranes • Suppress action potentials The effect of a neurotransmitter on postsynaptic membrane -Depends on the properties of the receptor -Not on the nature of the neurotransmitter Major classes of neurotransmitters include -Biogenic amines -Amino acids -Neuropeptides -Dissolved gases Neuromodulators -Chemicals released by axon terminals that alter •Rate of neurotransmitter release •Or response by postsynaptic cell -Effects are long term and slow to appear -Responses involve multiple steps and intermediary compounds -Affect presynaptic membrane, postsynaptic membrane, or both -Released alone or with a neurotransmitter
7. Describe the collateral ganglia general location, origin of preganglionic fibers, target tissue, general function,basic anatomy). Use the notes as a guideline for the level of detail expected. Label Figure 16.2, 16.3
Collateral ganglia - Anterior to vertebral bodies - Contain ganglionic neurons that innervate abdominopelvic tissues and viscera - Originate as paired ganglia (left and right) • Typically unpaired in adults due to fusion - Preganglionic fibers • Pass through sympathetic chain without synapsing • Form splanchnic nerves • In posterior wall of abdominal cavity Collateral ganglia - Postganglionic fibers • Leave collateral ganglia • Extend throughout abdominopelvic cavity • Innervate visceral tissues and organs • Function to - Reduce blood flow and energy use by organs notvital to short -term survival - Release stored energy Collateral ganglia - Preganglionic fibers from seven inferior thoracic spinal segments • End at celiac ganglion or superior mesentericganglion - Preganglionic fibers from lumbar segments • Form splanchnic nerves • End at inferior mesenteric ganglion - All three ganglia are named after nearby arteries
14. What is a plexus?
Complex, interwoven networks of nerve fibers - Formed from blended fibers of anterior rami of adjacent spinal nerves - Allows multiple spinal nerves to supply the same structures
4. Describe the 3 cranial meninges that surround the brain. How do the compare to the spinal meninges?What are the 4 locations were the dura matter extends into the cranial cavity and what names are used? Label Figure 14.3
Cranial meninges - Have three layers • Dura mater • Arachnoid mater • Pia mater - Continuous with spinal meninges - Dura mater • Inner fibrous layer (meningeal cranial dura) • Outer fibrous layer (periosteal cranial dura) - Fused to periosteum Cranial meninges - Arachnoid mater • Covers brain • In life, it attaches to dura mater - May be separated by subdural space • Subarachnoid space lies between arachnoid materand pia mater - Pia mater • Attached to brain surface by astrocytes Dural folds - Extensions of meningeal cranial dura into cranial cavity - Stabilize and support brain - Contain collecting veins (dural venous sinuses) - Three largest dural folds • Falx cerebri • Tentorium cerebelli • Falx cerebelli Falx cerebri - Projects between cerebral hemispheres - Contains superior sagittal sinus and inferior sagittalsinus Tentorium cerebelli - Separates cerebrum from cerebellum - Contains transverse sinus Falx cerebelli - Divides cerebellar hemispheres below the tentorium cerebelli DIAPHRAGMA SELLAE: lines the sella trucica of the sphenoid bone,
13. Please explain what is meant by the term dual innervation in the ANS
Dual innervation - Most vital organs are innervatedby both divisions of ANS - Commonly opposing (antagonistic) effects Anatomy of dual innervation - Autonomic plexuses • Nerve networks in the thoracic and abdominopelvic cavities •Formed by mingled sympathetic postganglionic fibers andparasympathetic preganglionic fibers • Travel with blood and lymphatic vessels that supply visceralorgans Autonomic tone (baseline firing frequency) - Autonomic motor neurons have resting level of activity • Even without stimulation - Important aspect of ANS function - Because nerves maintain background level of activity,they can increase or decrease activity • Provides greater range of control - Significant where dual innervation occurs • More important where it does not occur
6. What makes up gray matter? White matter?
Gray matter—cell bodies of neurons, neuroglia, and unmyelinated axons White matter—myelinated and unmyelinated axons
2. What are gross anatomical characteristics of the spinal cord? Please review Figure 14.1a
Gross anatomy of the spinal cord - ~18 in. (45 cm) long, 1/2 in. (14 mm) wide - From brain to vertebrae L1 and L2 - 5 regions (cervical, thoracic, lumbar,sacral, coccygeal) - Has bilateral symmetry - Grooves divide spinal cord into left and right
11. Describe the parasympathetic ganglia (general location, origin of preganglionic fibers, target tissue). Use thenotes as a guideline for the level of detail expected. Label Figure 16.2
If sympathetic division causes excitation, the parasympathetic causes inhibition • Autonomic nuclei are in all parts of brainstem and lateral horns of S2-S4 - Ganglionic neurons in peripheral ganglia within oradjacent to target organs - Short postganglionic fibers in or near target organs Organization of parasympathetic division - Parasympathetic preganglionic fibers leave brain in cranial nerves • III (oculomotor) • VII (facial) • IX (glossopharyngeal) • X (vagus) - Control visceral structures in head - Synapse in ciliary, pterygopalatine, submandibular, andotic ganglia Vagus nerve - Provides 75 percent of all parasympathetic outflow - Innervates structures in • Neck • Thoracic and abdominopelvic cavities including distal portion of large intestine - Branches intermingle with fibers of sympathetic division Preganglionic fibers in sacral segments of spinal cord - Carry sacral parasympathetic output - Do not join anterior roots of spinal nerves - Form pelvic nerves • Innervate intramural ganglia in kidneys, urinarybladder, portions of large intestine, and sex organs Major effects of parasympathetic division - Constriction of pupils and focusing on near objects - Secretion by digestive glands - Absorption and use of nutrients by peripheral cells - Changes associated with sexual arousal - Increased smooth muscle activity in digestive tract - Stimulation and coordination of defecation - Contraction of urinary bladder during urination - Constriction of respiratory passageways - Reduction in heart rate and force of contraction
13. What is unique about the thoracic spinal nerves as compared to the other regions in terms of distribution to target muscles?
In the thoracic region they remain distinct from each other and each innervates a narrow strip of muscle and skin along the sides, chest, ribs, and abdominal wall. These rami are called the intercostal nerves. In regions other than the thoracic, anterior rami converge with each other to form networks of nerves called nerve plexuses.
4. List 2 general statements about the synapses and neurotransmitters in the ANS
Increased neurotransmitter release - A frequently active synapse increases amount of neurotransmitter it stores - Releases more on each stimulation - The more neurotransmitter released, the greater the effect on postsynaptic neuron Facilitation at synapses - A repeatedly activated neural circuit results incontinuous release of neurotransmitters - Neurotransmitter binds to receptors on postsynapticmembrane - Produces graded depolarization that brings membranecloser to threshold - Resulting facilitation affects all neurons in circuit Sympathetic Division - Ganglion fibers release ACh at synapse with ganglionic neurons Parasympathetic Division - All preganglionic and postganglionic fibers release ACh at their synapses and neuroeffector junctions
10. What are the general components and functions of the basal ganglia and limbic system?
Limbic system - Functional grouping that • Establishes emotional states • Links conscious functions of cerebral cortex withautonomic functions of brainstem • Facilitates memory storage and retrieval Components of the limbic system - Limbic lobe of cerebral hemisphere • Cingulate gyrus • Dentate gyrus • Parahippocampal gyrus • Hippocampus - Amygdaloid body • Acts as interface between the limbic system,cerebrum, and various sensory systems Components of the limbic system - Fornix • Tract of white matter • Connects hippocampus with hypothalamus - Anterior nuclei of thalamus • Relay information from mammillary body tocingulate gyrus - Reticular formation • Alertness, excitement, lethargy, and sleep Basal nuclei - Masses of gray matter - Embedded in white matter of cerebrum - Direct subconscious activities Functions of basal nuclei - Subconscious control of skeletal muscle tone - Coordination of learned movement patterns (walking,lifting) Basal nuclei - Caudate nucleus • Large head and slender, curving tail - Lentiform nucleus • Putamen (lateral) • Globus pallidus (medial) - Claustrum • Thin layer of gray matter close to putamen
10. List and briefly describe the 2 major components of the parasympathetic division. Label Figure 16.2
Long preganglionic fibers in brainstem and sacral segments of spinal cord
3. Define 3 specialized membranes and associated "spaces" that surround the spinal cord (include general histology and function of each). Label Figure 14.2c
Made of three layers • Dura mater • Tough, fibrous outermost layer - Tough with dense collagen fibers - Continuous with cranial dura mater and fuses with periosteum ofoccipital bone - Distal end tapers to dense cord of collagen fibers; joins filumterminale in coccygeal ligament - Epidural space • Between vertebrae and dura mater (superficial to dura mater) • Contains loose connective and adipose tissue - Subdural space = potential space deep to dura mater • Arachnoid mater • Middle layer - Two components • Arachnoid membrane—weblike layer of simple squamous epithelia • Arachnoid trabeculae—network of collagen/elastic fibers between arachnoid membrane • Subarachnoid space - Space with arachnoid trabeculae, between arachnoid mater and pia mater - Filled with cerebrospinal fluid (CSF) that carries dissolved gases,nutrients, wastes - Lumbar puncture or spinal tap withdraws CSF from subarachnoid space • Pia mater • Innermost layer - Is a mesh of collagen and elastic fibers - Firmly attached to underlying neural structures it surrounds - Blood vessels for spinal cord are on surface of the pia mater, withinsubarachnoid space - Paired denticulate ligaments • Anchor pia mater to dura mater • Prevent lateral movement of spinal cord
17. Define spinal reflexes: stretch (stimulus, receptor, response, effector).
Monosynaptic reflexes - Stretch reflex • Regulates skeletal muscle lengththroughout the body • Very rapid (large myelinated fibers) - Example: patellar reflex Steps in a stretch reflex 1. Stimulus = muscle stretching 2. Distortion of receptor sends actionpotential through sensory neuron 3. Sensory neuron synapses with motorneurons in spinal cord 4. Motor neurons send signals to motorunits; triggers reflexive contraction ofstretched muscle
11. Know the cranial nerves by name, number. What are their primary functions? Do they carry Sensory,Motor or Both (sensory and motor) neurons. Label Figure 14.8
Olfactory nerves (I) - Primary function • Special sensory (smell) - Origin • Receptors of olfactory epithelium - Pass through • Olfactory foramina in cribriform plate of ethmoid - Destination • Olfactory bulbs Optic nerves (II) - Primary function • Special sensory (vision) - Origin • Retina of eye - Pass through • Optic canals of sphenoid - Destination • Diencephalon via optic chiasm Oculomotor nerves (III) - Primary function • Motor (eye movements) - Origin• Midbrain - Pass through • Superior orbital fissures of sphenoid Oculomotor nerves (III) - Destination • Somatic motor - Superior, inferior, and medial rectus muscles - Inferior oblique - Levator palpebrae superioris • Visceral motor - Intrinsic eye muscles Trochlear nerves (IV) - Primary function • Motor (eye movements) - Origin • Midbrain - Pass through • Superior orbital fissures of sphenoid - Destination • Superior oblique muscle Trigeminal nerves (V) - Primary function • Mixed (sensory and motor) of face - Origin • Ophthalmic nerve (V1) (sensory) - Orbital structures - Nasal cavity - Skin of forehead, upper eyelid, and eyebrow - Part of nose Abducens nerves (VI) - Primary function • Motor (eye movements) - Origin • Pons - Pass through • Superior orbital fissures of sphenoid - Destination • Lateral rectus muscle Facial nerves (VII) - Primary function • Mixed (sensory and motor) of face - Origin • Sensory - Taste receptors on anterior 2/3 of tongue • Motor - Motor nuclei of pons - Pass through • Internal acoustic meatus to stylomastoid foramina Vestibulocochlear nerves (VIII) - Primary function • Special sensory - Vestibular nerve • Balance and equilibrium - Cochlear nerve • Hearing Glossopharyngeal nerves (IX) - Primary function • Mixed (sensory and motor) of head and neck - Origin • Sensory - Posterior 1/3 of tongue - Part of pharynx and palate - Carotid arteries • Motor - Motor nuclei of medulla oblongata Glossopharyngeal nerves (IX) - Primary function • Mixed (sensory and motor) of head and neck - Origin • Sensory - Posterior 1/3 of tongue - Part of pharynx and palate - Carotid arteries • Motor - Motor nuclei of medulla oblongata Accessory nerves (XI) - Primary function • Motor to muscles of neck and upper back - Origin • Motor nuclei of spinal cord and medulla oblongata Hypoglossal nerves (XII) - Primary function • Motor (tongue movements) - Origin • Motor nuclei of medulla oblongata - Pass through • Hypoglossal canals of occipital bone - Destination • Muscles of tongue
5. List and briefly describe the 3 major components of the sympathetic division. Label Figure 17.2
Preganglionic neurons between T1 and L2, neuronal cell bodies in ganglia near vertebral column, specialized neurons in interior of suprarenal gland
1. Compare and contrast the SNS and the ANS.
Somatic nervous system (SNS) - Voluntary control of skeletal muscles Autonomic nervous system (ANS) - Involuntary control of visceral effectors • Smooth muscle, cardiac muscle,glands, adipocytes - Hypothalamus contains integrativecenters - Motor neurons of CNS synapse on visceral motor neurons in autonomic ganglia
10. Define spinal nerve (make up, location, #).
Spinal nerves - Pairs—one from each side at each vertebral level - Each has a white ramus communicans (pre-ganglionic) and a gray ramus communicans (post ganglionic) that innervate glands and smooth muscle (Somatic or visceral?) (Found T1-L2 = Sym. NS) There are 31 pairs of spinal nerves - 8 cervical nerves - 12 thoracic nerves - 5 lumbar nerves - 5 sacral nerves - 1 coccygeal nerve
9. What is the difference between spinal nerves and peripheral nerves?
Spinal nerves (part of PNS) - Pair of spinal nerves emergeslaterally from each spinal cordsegment - Form by junction of anterior andposterior roots - All spinal nerves are mixed nerves (sensory and motor) Peripheral nerves - Form from branching and re-sorting of spinal nerves. - All are mixed nerves - Same connective tissue layers as spinal nerves (continuous with each other)
12. What is unique about the thoracic spinal nerves as compared to the other regions in terms of number of branches? Define each branch (information carried). Label Figure 14.6a&b.
Spinal nerves originate from two branches (dorsal ramus and ventral ramus) Spinal nerves from T1 to L2 have two additional branches (white ramus and gray ramus) - Each spinal nerve quickly divides into rami • Posterior (dorsal) ramus supplies skin/muscles of back • Anterior (ventral) ramus supplies most of body wall, skin, limbs
16. Define the 5 steps of a reflex arc. Please review Figure 14.13.
Step 1: Stimulus activates a receptor •Step 2: With enough stimulation, action potential is generated in sensory neuron. Axon enters spinal cord via posterior root •Step 3: Information processing in spinal cord usually occurs at one or more interneurons •Step 4: Interneurons stimulate action potentials in motor neuron; its axon leaves via anterior root •Step 5: Motor neuron stimulates effector (muscle/gland) Five components of a reflex arc 1. Sensory receptor 2. Sensory neuron 3. Information processing in CNS 4. Motor neuron 5. Effector
9. List and describe the locations and main functions of the precentral and postcentral gyrus. Label Figure14.13
Structures of the cerebrum - Gyri of cerebral cortex • Increase surface area available for cortical neurons - Central sulcus divides • Anterior frontal lobe from posterior parietal lobe -Precentral gyrus of frontal lobe • Forms anterior border of central sulcus - Postcentral gyrus of parietal lobe • Forms posterior border of central sulcus Central sulcus separates motor and sensory areas Motor areas - Primary motor cortex • Surface of precentral gyrus - Pyramidal cells • Neurons of primary motor cortex Sensory areas - Primary somatosensory cortex • Surface of postcentral gyrus
6. Describe the sympathetic ganglia chain (general location, origin of preganglionic fibers, target tissue, general function, basic anatomy). Use the notes as a guideline for the level of detail expected. Label Figure 16.2
Sympathetic chain ganglia - On either side of vertebral column - One preganglionic fiber synapses on many ganglionic neurons - Fibers interconnect sympathetic chain ganglia, making the chain look like a string of pearls - Each ganglion innervates a particular body organ or group of organs Ganglionic neurons synapse in three locations - Sympathetic chain ganglia - Collateral ganglia - Adrenal medullae Sympathetic chain ganglia - On both sides of vertebral column - Control effectors in • Body wall • Thoracic cavity • Head • Neck • Limbs Sympathetic chain ganglia - 3 cervical - 10-12 thoracic - 4-5 lumbar - 4-5 sacral - 1 coccygeal ganglion Preganglionic neurons are limited to spinal cord segments T1-L2 - These spinal nerves have • White rami (myelinated preganglionic fibers) • Gray rami (unmyelinated postganglionic fibers) - Preganglionic fibers innervate cervical, inferior lumbar,and sacral sympathetic chain ganglia - Chain ganglia provide postganglionic fibers • Through gray rami • To cervical, lumbar, and sacral spinal nerves Summary of sympathetic chain ganglia - Cervical, inferior lumbar, and sacral chain ganglia receive preganglionic fibers from T1-L2 - Only thoracic and superior lumbar ganglia (T1-L2) receive preganglionic fibers from white rami - Every spinal nerve receives a gray ramus from a ganglion of the sympathetic chain
9. Describe the types of sympathetic synapses and their neurotransmitter release. Label Figure 16.5
Sympathetic chain ganglia - On either side of vertebral column - One preganglionic fiber synapses on many ganglionicneurons - Fibers interconnect sympathetic chain ganglia, making the chain look like a string of pearls - Each ganglion innervates a particular body organ or group of organs Stimulation of sympathetic preganglionic neurons - Releases acetylcholine (ACh) at synapses withganglionic neurons - Effect is always excitatory Ganglionic neurons - Release neurotransmitters at target organs - Telodendria form branching networks - Each swollen segment is a varicosity • Packed with neurotransmitter vesicles • Membrane receptors scattered across target cells Most sympathetic ganglionic neurons - Release NE at varicosities - Called adrenergic neurons Some ganglionic neurons release ACh - Called cholinergic neurons - Located in body wall, skin, brain, and skeletal muscles Majority of sympathetic postganglionic fibers release NE (adrenergic) - A few release ACh (cholinergic) • Stimulate sweat glands and dilate blood vessels ofskeletal muscles and brain - Others release nitric oxide (NO) • Nitroxidergic synapses • Neurons innervate smooth muscles in blood vesselwalls (e.g., in skeletal muscles and brain) • Produce vasodilation and increased blood flow
Compare and contrast the sympathetic and parasympathetic nervous systems
Sympathetic division has widespread effects - Two sets of sympathetic chain ganglia, three collateralganglia, and two adrenal medullae - Short preganglionic fibers, long postganglionic fibers - Extensive divergence - Preganglionic neurons release ACh; most post ganglionic fibers release NE - Effector response depends on second messengers Parasympathetic division has specific effects - Visceral motor nuclei are associated with cranialnerves III, VII, IX, and X, and with S2-S4 - Ganglionic neurons are located in ganglia within or next to target organs - Innervates regions serviced by cranial nerves and organs in thoracic and abdominopelvic cavities - One-fifth the divergence of sympathetic division - All neurons are cholinergic - Effects are generally brief and restricted
12. Describe the types of parasympathetic synapses and their neurotransmitter release. Label Figure 16.5
Synapse in ciliary, pterygopalatine, submandibular, andotic ganglia All parasympathetic neurons release ACh - Effects on postsynaptic cell vary widely • Due to different types of receptors • Or nature of second messenger involved - Effects of parasympathetic stimulation of cholinergic receptors are localized and short lived • Most ACh is inactivated at synapse byacetylcholinesterase (AChE) • ACh that diffuses into surrounding tissues is inactivated by tissue cholinesterase
15. What spinal nerves make up the cervical, brachial, lumbosacral plexuses? What major peripheral nerves emerge from the brachial and lumbosacral plexuses? Label Figures 14.9, 14.10 a,b,c and 14.12a,b,c,d.
The cervical plexus - Includes anterior rami of spinalnerves C1-C5 - Innervates scalp behind ear,neck, and diaphragm Major cervical plexus nerves- Phrenic nerve—from C3-C5 • controls diaphragm The Brachial Plexus (C5-T1) - Innervates the pectoral girdle and upper limbs - Roots - Trunks - Divisions - Cords - Nerves • "Really Tired Drink Coffee Now" The Brachial Plexus (C5-T1) - The ventral rami (root) formthe trunks • Superior trunk • Middle trunk • Inferior trunk - The trunks form the divisions • Anterior • Posterior - The divisions form the cords • Posterior • Lateral • Medial - The cords form the branches of spinal nerves Major brachial plexus nerves - Musculocutaneous nerve (lateral cord) - Median nerve (lateral and medial cords) - Ulnar nerve (medial cord) - Axillary nerve (posterior cord) - Radial nerve (posterior cord) The lumbar plexus - Includes anterior rami of spinal nerves T12-L4 - Major nerve (can you find it?) • Femoral nerve (L2-L4) The sacral plexus - Includes anterior rami of spinal nerves L4-S4 - Major nerves (can you find them?) • Sciatic nerve (L4-S3) • Superior and inferior gluteal nerves • Pudendal nerve - Two branches of the sciatic nerve 1. Fibular nerve (common fibular nerve) 2. Tibial nerve
3. What are the 2 subdivisions of the ANS? Briefly describe where the preganglionic fibers originate, the names ofthe ganglia they may synapse in.
Two divisions of ANS - Sympathetic division "Fight or flight" • Prepares the body to deal withemergencies • Increases alertness, metabolic rate,and muscular abilities • Most active during times of stress,exertion, or emergency • Also called the thoracolumbar division - Parasympathetic division "Rest and digest" • Conserves energy and maintains resting metabolic rate • Most active during resting conditions • Also called the craniosacral division
6. Define Neuroglia found in PNS and CNS (name, location, function). Label Figures 12.4, 12.5
Types of neuroglia in the CNS - Astrocytes - Ependymal cells - Oligodendrocytes - Microglia Astrocytes - Have large cell bodies with many processes - Function to • Nourish neurons • Control interstitial environment - maintain ion concentration • Maintain blood brain barrier (BBB) • Create three-dimensional framework for CNS • Repair damaged nervous tissue • Guide neuron development & synapse formation Ependymal cells - Form epithelium that lines central canal of spinal cord and ventriclesof brain - Produce and monitor cerebrospinal fluid (CSF) - Have cilia that help circulate CSF Oligodendrocytes - Have small cell bodies with few processes - Many cooperate to form a myelin sheath • Myelin insulates myelinated axons • Increases speed of action potentials • Makes nerves (tracts) appear white - Internodes—myelinated segments of axon - Nodes (nodes of Ranvier) lie between internodes Microglia - Smallest and least numerous neuroglia - Have many fine-branched processes - Migrate through nervous tissue - Phagocytes that engulf & remove invading organisms - Clean up cellular debris, wastes, and pathogens Neuroglia of the PNS - Insulate neuronal cell bodiesand most axons - Two types: • Satellite cells • Schwann cells - Satellite cells • Surround ganglia (clusters of neuronal cell bodies) • Regulate interstitial fluid around neurons - Schwann cells (neurolemmocytes) • Form myelin sheath around axons • Neurolemma—outer surface of Schwann cell • A myelinating Schwann cell sheaths only one axon - Many Schwann cells sheath entire axon
15. Define 2 other types of synapses (neuron and effector).
Types of synapses - (A) Electrical synapses • Direct physical contact between cells (gap junctions) - (B) Chemical synapses • Signal transmitted across a synaptic cleft by neurotransmitters
3. Define and identify the 4 ventricles of the brain. Label Figure 14.2
Ventricles of the brain - In the embryo, neural tube encloses neurocoel • Neurocoel expands to form chambers (ventricles)lined with ependymal cells - Each cerebral hemisphere contains one large lateralventricle • Separated by medial partition (septum pellucidum) - Third ventricle in diencephalon • Communicates with each lateral ventricle • Via interventricular foramen - Fourth ventricle • Extends into medulla oblongata • Joins central canal of spinal cord • Connects with third ventricle - Via narrow canal in midbrain (cerebral aqueduct)
2. Define preganglionic and ganglionic neurons. How do they differ from preganglionic and postganglionic fibers?
Visceral motor neurons - Preganglionic neurons in brainstem and spinal cord - Preganglionic fibers—axons of preganglionic neurons • After leaving CNS, they synapse on ganglionic neurons(postganglionic neurons) - Autonomic ganglia • Contain many ganglionic neurons that innervate visceral effectors • Postganglionic fibers—axons of ganglionic neurons
14. Describe the events of a visceral reflex. Figure 16.7
Visceral reflex arc consists of - Receptor - Sensory neuron - Processing center (one or more interneurons) - Two visceral motor neurons - Long reflexes • Autonomic equivalents of polysynaptic reflexes • Visceral sensory neurons deliver information to CNSalong posterior roots of spinal nerves - Within sensory branches of cranial nerves - Within autonomic nerves that innervate visceraleffectors • ANS carries motor commands to visceral effectors • Coordinate activities of entire organ Short reflexes • Bypass CNS entirely • Involve sensory neurons and interneurons whosecell bodies lie in autonomic ganglia • Interneurons synapse on postganglionic neurons • Postganglionic fibers distribute motor commands • Control simple motor responses with localizedeffects • Control activity in one small part of target organ
8. Identify/Label five main lobes of the brain and describe what they perceive. Label Figure 14.13
frontal lobe = Emontional control, self awareness, motivation, judgement, problem solving, talking, movement, and initiation, matured, personality parietal lobe = Sense of touch, awareness of spatial relationships and academic functions such as reading, touch, temperature, pressure, pain temporal lobe = Memory, hearing, understanding language, and processing information, Broncos-speech ability occipital lobe = Vision, memory cerebellum = Balance, coordination, skilled motor activity movement, muscle coordination
8. What are groups of cell bodies also called?
ganglia (PNS) nuclei (CNS)
1. What are inside the nuclei of CNS?
gray matter
7. What are groups of myelinated or unmyelinated axons also called?
nerves (PNS) tracts (CNS)
7. Where the pineal gland located and what is its function?
posterior portion of epithalamus in diencephalon secretes melatonin
9. What are anatomical characteristics of a representative Neuron? Label Figure 12.2
• Cell body (soma) - Large nucleus and nucleolus - Perikaryon (cytoplasm) - Mitochondria (produce energy) - RER and ribosomes (synthesize proteins) Dendrites - Short and highly branched processes extending from cell body - Dendritic spines • Fine processes on dendrites • Receive information from other neurons • 80-90 percent of neuron surface area Axon - Single, long cytoplasmic process - Propagates electrical signals (action potentials) - Axoplasm - Cytoplasm of axon • Contains neurofibrils, neurotubules, enzymes, and organelles
5. What are the general cross sectional anatomical characteristics of the spinal cord? Label Figure 14.4b.
• Features of the Spinal Nerves • Formed by union ofposterior and anterior roots • Classified as mixed nerves • Sensory nerves(afferent nerves) • Transmit impulsestoward the spinal cord • Motor nerves (efferentnerves) • Transmit impulses away from the spinal cord
7. In the PNS, what makes up ganglia?
• Ganglia are collections of neuron cell bodies in the PNS
8. In the PNS, what makes up peripheral nerves?
• Nerves - Bundles of axons in the PNS
4. What is cerebrospinal fluid (function) and where is it found
• Subarachnoid space in arachnoid mater - Space with arachnoid trabeculae, between arachnoid mater and pia mater - Filled with cerebrospinal fluid (CSF) that carries dissolved gases,nutrients, wastes - Lumbar puncture or spinal tap withdraws CSF from subarachnoid space
11. Define 3 functional classifications of neurons. Label them on Figure 12.3
▪ Sensory neurons (afferent neurons) - Unipolar - Cell bodies grouped in sensory ganglia - Processes (afferent fibers) extend from sensoryreceptors to CNS - Somatic sensory neurons • Monitor external environment - Visceral sensory neurons • Monitor internal environment ▪ Motor neurons (efferent neurons) - Carry instructions from CNS to peripheral effectors • Via efferent fibers (axons) - Somatic motor neurons of SNS • Innervate skeletal muscles - Visceral motor neurons of ANS • Innervate all other peripheral effectors - Smooth and cardiac muscle, glands, adipose tissue ▪ Interneurons - Located between sensory andmotor neurons - Responsible for • Distribution of sensoryinformation • Coordination of motoractivity - Involved in higher functions • Memory, planning, learning
