PSIO Block 4 Study Guide PDF

4.1 1. List the divisions of the nervous system. What are the two major cell types within the nervous system and their basic functions? Central nervous system -brain and spinal cord Peripheral nervous system -cranial and spinal nerves 2 cell types: - Nerve cells (neurons) - invol...

4.1 1. List the divisions of the nervous system. What are the two major cell types within the nervous system and their basic functions? Central nervous system -brain and spinal cord Peripheral nervous system -cranial and spinal nerves 2 cell types: - Nerve cells (neurons) - involved in generation and interpretation of ‘electrical signals’ - Process information - Senses environmental and internal changes - Communicates changes to other neurons - Commands body responses - Glial cells (neuroglia) - supports neuronal cell activity - Insulates, supports, and nourishes neurons - Allows action potentials to travel 4 types of neuroglial cells in the CNS Astrocytes -maintain environment around neurons -keep neurons in place -form the blood brain barrier Oligodendrocytes -form processes that form myelin sheaths around axons in the CNS ( increased AP speed) Microglia -engulf invading microbes, debris, necrotic tissue Ependymal cells -line the 4 ventricles of the brain + the central canal of the spinal cord -form and circulate cerebrospinal fluid (CSF) 2 types of neuroglial cells in the PNS Satellite cells -covers sensory neuron cell bodies, maintains neurons environment Schwann cells -entire cell forms myelin sheath around a segment of an axon in the PNS (increases AP speed) Dendrites -collect information (inputs) Cell body -process information Axon -propagate information to output site Synapses -transmit information to other parts of the nervous system Structural classifications Unipolar- sensory receptors Multipolar- most neurons in the brain Bipolar-retina, inner ear, olfaction) Functional classifications- PNS Afferent (sensory) neurons - conduct APs to CNS, unipolar or bipolar Efferent (motor) neurons- conduct APs to target organs, multipolar CNS Interneurons- makes up 90% of neurons in CNS, multipolar Membrane potential -Resting membrane potential- relatively steady voltage across the membrane -Graded voltage changes occur in response to sensory stimuli or synaptic inputs -Action potentials- transient, “all or none” changes in this voltage which allow transmission of information 2. List the four major structures of the brain. Brain- center of intelligence, behavior, memory, and emotion -influences activity of visceral organs and glands Processing center- Interpretation of sensory information is based on a path traveled and destination in the brain Plasticity- anatomical changes in the brain. New synapses form and new pattern of activity develops, also neurogenesis (new neurons) Cerebrum- vast majority Cerebellum- little brain Diencephalon -thalamus -hypothalamus -Epithalamus Brain stem -pons -medulla oblongata -midbrain 3. Describe the organization of the cerebrum in terms of gyri, sulci, hemispheres, lobes, and gray and white matter. 2 cerebral hemispheres Right= music, face recognition, visual imagery, spatial abilities Left= language,logic, reason Lobes Frontal-reasoning, planning, part of speech and movement, emotions, problem solving  Parietal- perception of stimuli related to touch, pressure, temperature, pain Temporal- perception and recognition of auditory stimuli and memory Occipital- many aspects of vision Insula- integrates autonomic information, associated to visceral function Gray matter -most superficial, Usually outside White matter - axons, fatty myelinated axon Gyri(gyrus), sulci (sulcus) 4. Describe the organization of the cerebellum in terms of hemispheres and white and gray matter. 2 cerebellar hemispheres Cerebellar cortex (gray matter) Arbor vitae (white matter) 5. List and describe the meningeal layers and spaces, in order from superficial to deep. Include a list of the dural folds as described in lecture. Meninges - connective tissue coverings that surround the brain and spinal cord -functions- protect underlying neural tissues, anchor the brain in cranial cavity and spinal cord in vertebral cavity Dura mater - Subdural space - Most superficial layer - Outer layer fuses with periosteum of skull - Inner layer folds into parts of cranial cavity forming sinuses Major dural folds - Falx cerebri (separates left+right) - Flax cerebelli - Tentorium cerebelli Arachnoid mater -subarachnoid space - includes arachnoid villus (which returns CSF back to venus blood) Pia mater -Deepest Ventricles of the brain -Fluid filled (CSF-filled) chambers within the brain -CSF is produced within them -numbered according to CSF flow -from the 4th ventricle, CSF empties into the central canal of spinal cord and into the subarachnoid space through apertures 6. Describe the functions, formation, and flow of cerebrospinal fluid. FUNCTIONS - Cushioning and shock absorption - Chemical protection  - Exchange of nutrients and wastes FORMATION - Glucose and nutrients - Ions (Na+, CI-, Mg+2 and others) - Oxygen - Other metabolic substrates - WBCs FLOW Choroid plexuses in the lateral ventricles produce CSF. CSF flows from the lateral ventricles into the third ventricle through the interventricular foramen. From the third ventricle, CSF moves into the fourth ventricle via the cerebral aqueduct. CSF exits the fourth ventricle into the subarachnoid space through the foramina of Magendie and Luschka. CSF circulates around the brain and spinal cord, providing protection and nutrient exchange. Arachnoid villi absorb CSF into the venous circulation (superior sagittal sinus). Hydrocephalus - Buildup of CSF in the ventricles - Excess fluid increases the size of the ventricles and puts pressure on the surrounding brain tissues BBB(BLOOD BRAIN BARRIER) - Protective mechanism that maintains stable environment for the brain - Capillaries of the brain are least permeable of any capillaries in the body - Capillaries are selectively partly due to presence of astrocytes (type of neuroglia) Formation Astrocytes form and maintain a bbb for the purpose of isolating the brain from - “Foreign substances” in the blood -Hormones and neurotransmitters that are traveling in the blood to the rest of the body Structure -astrocytes extend foot processes to contact the endothelial cells of blood capillaries in the brain -in response, endothelial cells form and maintain highly impermeable tight junctions between each other (they are the least permeable of all capillaries) Weaker BBB- in the pineal body, posterior pituitary, vomiting center…) Function - BBB capillaries permit O2, CO2, lipid-soluble molecules to cross - Large lipid-soluble molecules (fatty acids) move slowly - Nutrients like glucose, amino acids have to be transported Nervous system functions- 1) Sensory function (afferent neurons) -Information goes to the brain and spinal cord via cranial and spinal nerves 2) Integrative function (interneurons) -Integrates sensory information by analyzing and storing it 3) Motor function (efferent neurons) -Information from the brain and spinal cord is sent out to muscles or glands (effectors) 4.2 1. Describe the location and function of the specific functional areas of the cortex as described in lecture. Cerebral Cortex (gray matter) 1) Sensory areas 2) Motor areas 3) Association areas Primary motor area Location- precentral gyrus in frontal lobe Function- voluntary activation of skeletal muscles Premotor area Location- anterior to primary motor area in frontal lobe Function- communicates with primary motor area and thalamus to coordinate complex learned movements Primary somatosensory area Location-post central gyrus in parietal lobe Function- receives sensory impulses from sensory receptors responding to touch, temperature, and proprioception Primary visual cortex Location- medial portion of occipital lobe Function- nervous signals travel along the optic nerve and provide information about color, shape, and movement of visual stimuli Visual Association Area Location- occipital lobe, anterior to the primary visual area Function- receives sensory impulses from the primary visual area for recognition of visual stimuli (visual memory) Primary Auditory area Location- superior portion of temporal lobe Function- receives impulses arising from the vestibulocochlear nerve which provides information on the basic characteristics of sound (pitch, rhythm, loudness) Auditory Association Area Location- temporal lobe, inferior and posterior to the primary auditory area, found on left temporal lobe ONLY Function- Interpretation and recognition of sound, determines if sound is speech, music, or noise Wernicke area  Location- temporal lobe, posterior to primary auditory area on left lobe Function- Interprets the meaning of speech (translates words into languages) Broca's area Location- frontal lobe, usually left side Function- controls the activity of muscles of the vocal cords to facilitate speech Aphasia -communication disorder that impairs a person’s ability to process language but does not affect intelligence (common cause is stroke) Broca's aphasia (non-fluent- aphasia) Wernicke’s aphasia (fluent aphasia) 2. Describe the general location and function of the basal nuclei centers of cell bodies deep in the cortex (gray matter) -help initiate and terminate movements -suppress unwanted movements -regulate muscle tone -control subconscious contractions of skeletal muscles 3. Describe the location and function of the cerebral white matter Myelinated axons that are bound into large tracts -responsible for communication between cerebral areas and other parts of the brain Association tracts -contain axons that conduct nerve impulses between gyri in the same hemisphere Commissural tracts -conduct nerve impulses between corresponding gyri from one hemisphere to another -corpus callosum- one of three important groups of commissural tracts (the two being the anterior and posterior commissures) its a thick axons that connects corresponding areas of the 2 hemispheres -right and left hemispheres communicate via corpus callosum Projection tracts -convey impulses to lower parts of the CNS (thalamus, brain stem, or spinal cord) or visa versa 4. Describe hemispheric lateralization -symmetrical on right and left sides and shares performance of many functions -less pronounced in females Right -Music, face recognition, visual imagery, spatial abilities -emotional content of language, different smell discrimination, mental images of sight, sound, touch and taste Left -language, logic, reason -numerical and scientific skills, ability to use + understand sign language 4.3 1. Describe the location and function of the: – Diencephalon - Thalamus (relay station for sensory and motor information) -crude interpretation of touch, temperature, pain, pressure -forms 3rd ventricle -organized into 7 groups of nuclei (clusters of cell bodies in the CNS) - Hypothalamus -Located inferior to thalamus -Contains 12 nuclei in 4 major regions -controls and integrates activity of autonomic nervous systems and pituitary gland →controls HOMEOSTASIS -link between nervous system and endocrine system -Main control center for visceral function -receives info from cerebrum and from brain stem and spinal cord -regulates emotions- pleasure, pain, aggression -regulates diurnal rhythms with help from pineal gland (melatonin) day= energy up night= sleep -Epithalamus -located superior and posterior to the thalamus 1)pineal gland (melatonin)- contributes to setting the biological clock 2)habenular nuclei- emotional responses to odors – Cerebellum -receives input from proprioceptors in muscles and tendons about movement -sends signals to motor cortex to improve and coordinate movements -receives input from visual and equilibrium receptors and sends input to motor cortex to aid in regulation of posture and balance Organization - Cerebellar cortex (gray matter) - Arbor vitae (white matter) - Two cerebellar hemispheres – Brain stem Pons - Bridge between the medulla oblongata, cerebellum and higher brain centers in the cerebral cortex  Pontine nuclei- gray matter centers connecting the cerebral cortex and cerebellum → coordinate voluntary motor output RESPIRATORY CONTROL 1) Apneustic area- controls depth of breathing 2) Pneumotaxic area- controls rate of breathing Medulla Oblongata -connects brain to spinal cord - involves all nerve tracts that ascend (sensory) to or descend (motor) from the brain, axons cross over from one side to the other of the brain stem -contains cardiovascular center (control of heart rate and force, blood pressure -control of respiratory rhythmicity -control of vegetative functions- swallowing, coughing, sneezing, vomiting -midbrain Located between the pons and the diencephalon -contains nuclei and tracts Superior colliculi- reflexes for certain visual activities and movement of the head and trunk in response to visual stimuli Inferior colliculus- part of the auditory pathway and startle reflex Contains several other nuclei -darkly pigmented substantia nigra Neurons that release dopamine, extending from the substantia nigra, help control subconscious muscle activities Red Nucleus -helps control voluntary movement of the limbs 2. Briefly describe the limbic system Cingulate gyrus- plays role in emotion Hippocampus- involved in learning and memory Amygdala- involved in emotion and memory - Functional system composed of parts of cerebral cortex, diencephalon, and midbrain - Emotional brain → plays primary role in promoting a range of emotions, including pleasure, pain, docility, affection, fear, and anger - Functions in memory together with parts of the cerebrum - Connects motivation to action 4.4 1. Draw and label an accurate representation of the gross anatomy of the spinal cord. Cervical enlargement- at C4-T1- nerves that exit here supply the shoulder girdle and upper limbs Lumbar enlargement- at T9-T12- nerve that exit here supply the pelvis and lower limbs Cauda Equina- extension of nerves exiting from end of spinal cord. 2. Draw a cross section through the spinal cord and label the internal anatomy as discussed in class.  Gray matter -Central canal- small opening in center of SC, contains CSF -Posterior horns- cell bodies of somatic and visceral sensory neurons -Gray commissure- connects posterior horns -Anterior horns- cell bodies of somatic motor neurons -lateral horns- cell bodies of visceral motor neurons, found only in thoracic, lumbar and sacral regions of spinal cord. White matter -Posterior columns- sensory tracts (ascending) -lateral columns- motor and sensory tracts -anterior columns- motor tracts (descending) -anterior white commissure- connects white matter on the left and right of SC 3. Trace the path taken by sensory information entering the spinal cord and motor information exiting the spinal cord Dorsal root of spinal nerve- carries afferent (sensory) information Dorsal root ganglion- cluster of (sensory) cell bodies outside the CNS Ventral root- carries motor (efferent) information from the anterior portion of the cloud Spinal nerves- joining of dorsal and ventral roots -only -2cm long -mixed nerves (they contain both sensory and motor information) -31 pairs of spinal nerves exit the cord Spinal meninges Dura mater is not attached to the bony vertebral column – creates epidural space (anesthesia) CSF flows in subarachnoid space – same as cranial meninges Spinal tap -Collect CSF for diagnostic purposes 4.5 1. Define reflex and list the five components of a reflex arc. Reflex- a rapid automatic response to a stimulus (help you maintain homeostasis by responding to changes in the environment) Reflex arc- the “wiring: of a particular reflex 1) Sensory receptors- responds to a stimulus by producing a generator by a producing a generator or receptor potential 2) Sensory neuron- axon conducts impulses from receptor to integrating center 3) Integrating center- one or more regions within the CNS that relay impulses from sensory to motor neurons 4) Motor neuron- axon conducts impulses from integrating center to effector 5) Effector- muscle or gland that responds to motor nerve impulses 2. Differentiate between ipsilateral and contralateral, somatic and autonomic, monosynaptic and polysynaptic reflexes.  Ipsilateral- same side of the body Contralateral- Opposite sides Somatic- (Somatic nervous system) controls voluntary movement and skeletal muscles, sensory input that results in muscle contraction Autonomic- (Autonomic nervous system ANS) controls involuntary functions like heart rate, digestion, and glandular secretion. (involving smooth muscle, cardiac muscle, or glands Monosynaptic- stretch reflex (lacks interpretive center) 1 synapse (sensory to motor neuron) Polysynaptic- autonomic nervous system 2 or more synapses (involving interneurons) 3. Diagram and describe the 4 representative reflex arcs discussed in lecture. 1) stretch reflex -purpose is to prevent injury from over- stretching a muscle -results in contraction of the muscle that was stretched -stretch sensed by muscle spindle(sense changes in muscle tissue/strength) -monosynaptic, ipsilateral, spinal, somatic (affects muscle) reflex. 2) Tendon reflex (protective reflex) -prevent damage from development of too much tension in a muscle -results is inhibition of the muscle that is contracting -Tension sensed by the Golgi tendon organ (sensitive to the amount of force) (located within the tendon. -polysynaptic (integrating neuron), ipsilateral (relaxation of muscle that was produces forces (same side of body), spinal, somatic reflex 3) Flexor reflex (protective mechanism) -Protect body from further pain/damage -Purpose is to protect body part from further injury -results in flexion of affected limb -Pain sensed by nociceptors (sometimes the threat of pain can stimulate the reflex) -Polysynaptic (extensive interneuron, ipsilateral (same side of body), spinal, somatic reflex (skeletal muscle) 4) Crossed extensor reflex (base of support) -purpose is to stabilize body position when a painful stimulus results in flexion of opposite limb -usually paired with flexor reflex -results is extension of opposite limbs -pain sensed by nociceptors -polysynaptic, contralateral (opposite side of body extends), spinal, somatic reflex. 4.6 1. Describe the main differences that exist between the somatic and autonomic nervous systems. - Somatic  - Effectors- skeletal muscle - Control- voluntary - Output- 1 efferent neuron exists CNS -Somatic and special sensory receptors and somatic sensory neurons (sensory input) -the lower motor (efferent) neuron that stimulates the skeletal muscle exits the spinal cord (CNS) at the anterior horn - Autonomic - Effectors- cardiac muscle, smooth muscle and glands - Control- Involuntary (self- governing), operates without conscious control via reflex arcs (sympathetic and parasympathetic divisions) - Output- 2 efferent neurons exit CNS (pre ganglion- inside, post ganglion- outside) - Controlled by centers in the hypothalamus and brainstem -One efferent neuron exits the spinal cord @ the lateral horn and synapses with another efferent neuron in a ganglion (cell bodies in the PNS) -1st efferent neuron is called the preganglionic neuron -2nd one is postganglionic neuron 2. Differentiate between the parasympathetic and sympathetic nervous systems in terms of anatomy and function. Sympathetic Division- - “Fight or flight” - Prepares body for stress - Dual intervention (balance between the two) - “Thoracolumbar” - preganglionic neurons begin in the thoracic (T1) and lumbar (L2) regions of the spinal cord - Most ganglia located near the spinal cord (reaches out to ganglia chain Location of SNS ganglia -sympathetic trunk (chain)- paired ganglia near spinal cord… postganglionic neuron innervates visceral organs in thoracic cavity -3 cervical, 11 thoracic, 4 lumbar, 4 sacral -prevertebral ganglia (collateral)- anterior to vertebral bodies…postganglionic neurons innervate abdominopelvic organs -celiac, superior mesenteric, inferior mesenteric -adrenal medulla- acts as a modified sympathetic ganglion..postganglionic neurons are short and release norepinephrine (20%) and epinephrine (80%) into the bloodstream -chromaffin cells act as postganglionic neurons and the adrenal medulla acts as a modified ganglion Catecholamines -NE is a neurotransmitter when it is released from sympathetic nerve endings directly at target tissues (short lived effects) -NE is a hormone when it is released from the adrenal gland into the bloodstream (longer lasting effects)  -Epinephrine is a hormone because it is released from the adrenal gland into the blood Sweat Glands -Preganglionic neurons ACh (same as other SNS organs) ; -postganglionic neurons release ACh instead of NE at the effector tissue; ACh binds to muscarinic cholinergic receptors at sweat gland Parasympathetic Division- - “Rest and digest” - Promotes digestion and storage of nutrients - Salivation - Lacrimation - Urination - Defecation Responses to PSNS -Increased digestive enzyme/hormone secretion -Increased smooth muscle activity of the GI tract -Constriction of pupils for near vision -Decreased heart rate, contractility, blood pressure -Contraction of muscular wall of bladder and intestine, promotes urination/ defecation -Increased secretion of the lacrimal glands 3. Describe the neurotransmitters used and the effects of the sympathetic nervous system Neurotransmitters of the SNS -preganglionic neurons release Acetylcholine (ACh) → binds to nicotinic cholinergic receptors on postganglionic cell body -Post ganglionic neurons release Norepinephrine (NE) → binds to adrenergic receptors on effector cells Adrenergic receptors -bind epinephrine (adrenaline) and norepinephrine (noradrenaline) at effector tissues 1) Alpha adrenergic receptors- found in smooth muscle of arterioles, bladder, result in constriction when activated 2) Beta adrenergic receptors- found in heart, bronchioles, liver, cause Increase metabolism Responses to SNS -Mobilize (break down) fuels -redistribution of blood flow -decreased urinary output and digestive functions -increase heart rate and blood pressure -increase activity of sweat glands -increase diameter of bronchioles (bronchodilation) -dilation of pupils 4.7 1. Differentiate between the parasympathetic and sympathetic nervous systems in terms of anatomy, neurotransmitters used, and the effects produced by each system. Description Sympathetic N.S. Parasympathetic N.S. Neurotransmitter released ACh ACh by preganglionic neurons Neurotransmitter released NE / ACh @ sweat gland by postganglionic neurons Location of preganglionic NE neuron cell bodies (within ganglia) Names of ganglia Type of receptors on postganglionic cell bodies within ganglia Types of receptors on effector organs Effect on heart rate General effect on urinary system activity General effect on digestive system activity (secretion of enzymes, smooth muscle activity) Effect on pupil diameter 2. Describe syncope and its relationship to the parasympathetic nervous system Syncope = fainting = vasovagal reaction - Transient loss of consciousness resulting from insufficient supply of oxygen to the brain - Insufficient cerebral perfusion from hypotension because of failure of ANS to maintain blood pressure - Can be avoided by laying down in supine position, elevating feet, contracting leg and arm muscles to bring more blood back to the heart and increase circulation of blood back to the brain - EX: seeing a needle Cholinergic receptors (PSNS) Respond to acetylcholine 1) Nicotinic receptors- found on sympathetic and parasympathetic cell bodies and dendrites of postganglionic neurons (within the ganglion) ….can only generate excitatory postsynaptic potentials (EPSP) 2) Muscarinic receptors- found on membrane of target tissues innervated by parasympathetic post ganglionic axons- can generate both EPSP and inhibitory postsynaptic potentials (IPSP) Anatomy of PSNS Cranial nerves 1) Oculomotor (III)- mixed cranial nerve responsible for eye ball movement stimulates the lacrimal gland (tears) 2) Facial (VII)- mixed cranial nerve stimulates salivation 3) Glossopharyngeal (IX)- mixed cranial nerve involved in swallowing and salivation 4) Vagus (X)- mixed cranial nerve, carries 80% of parasympathetic outflow to heart, airways, liver, gallbladder, stomach, small intestine, and part of large intestine Cranial portion 1) Preganglionic neurons found in pons or medulla 2) Information carried by 4 cranial nerves: III,VII, IX,X 3) 80% of PSNS information carried by Vagus (X) Sacral portion 1) Preganglionic neurons in sacral region (S2-S4) exit via pelvic nerves