A&P Exam 4
15-3 Identify the receptors for the general senses, and describe how they function.
3 types of nociceptors in the body provide info on pain as related to extreme temps, mechanical damage, and dissolved chemicals. Myelinated Type A fibers cary fast pain. Unmyelinated Type C fibers carry slow pain. Thermoceptors are found in dermis. Mechanoreceptors are sensitive to distortion of their membranes and include tactile receptors, baroreceptors, and proprioceptors. There are 6 types of tactile receptors in the skin, three kinds of proprioceptors. Chemoreceptors include carotid bodies and aortic bodies
13-4 Describe the major components of a spinal nerve, and relate the distribution pattern of spinal nerves to the regions they innervate
31 pairs of spinal nerves each has an epineurium (outer most layer), perineurium, and endoneurium (inner most layer). Each pair of spinal nerves monitors a region of the body surface called a dermatome. A spinal nerve has a white ramus communicans, a gray ramus communicans, a posterior ramus (provides sensory and motor innervation to the skin and muscles of the back ), and an anterior ramus (supplies the ventrolateral body surface, structures in the body wall and the limbs). The 4 large plexuses are the cervical plexus, brachial plexus, lumbar plexus, and the sacral plexus
15-5 Describe the components, processes, and functions of the somatic motor pathways, and the levels of information processing involved in motor control.
Somatic motor (descending) pathways always involve upper motor neuron (whose cell body lies in a CNS processing center) and a lower motor neuron (whose cell body is located in a nucleus of the brain stem or spinal cord). Cortiicobulbar tracts synapse on lower motor neurons in the anterior horn of the spinal cord. The corticospinal tracts are visible along the medulla oblongata as a pair of thick bands. Corticospinal pathway provides a rapid direct mechanism for controlling skeletal muscles. Medial pathway controls gross movements of the neck, trunk, and proximal limbs. Vestibulospinal tracts carry info related to maintaining balance and posture. Commands carried by the tectospinal tracts change the position of the head, neck, and upper limbs in response to bright lights, sudden movements, or loud noises. Rubrospinal tracts control muscle tone and movements of the distal muscles of upper limbs.
13-5 Discuss the significance of neuronal pools, and describe the major patterns of interaction among neurons within and among these pools
The body has sensory neurons which deliver information to the CNS; motor neurons which distribute commands to peripheral effectors and interneurons which interpret info and coordinate responses. A neuron pool is an organized functional group of interconnected interneurons. The neural circuit patterns are divergence, convergence, serial processing, parallel processing, and reverberation
13-8 Explain how higher centers control and modify reflex responses
The brain can facilitate or inhibit reflex motor patterns based in the spinal cord. Motor control involves a series of interacting levels. Monosynaptic reflexes form the lowest level at the highest level are the centers in the brain that can modulate or build on reflexive motor patterns. Facilitation can produce an enhancement of spinal reflexes known as reinforcement. Spinal reflexes many also be inhibited as when the plantar reflex in adults replaces the Babinski reflex in infants
15-1 Specify the components of the afferent and efferent divisions of the nervous system, and explain what is meant by the somatic nervous system.
The brain, spinal cord, and peripheral nerves continuously communicate with each other and with the internal and external environments. Info arrives by sensory receptors and ascends within the afferent division, while motor commands descend and are distributed by the efferent division.
14-6 List the main components of the midbrain, and specify the functions of each.
The cerebellum adjusts postural muscles and programs and tunes ongoing movements. The 2 cerebellar hemispheres consist of anterior and posterior lobes, the vermis, and the flocculondular lobe. The superior, middle, and inferior cerebellar peduncles link the cerebellum with brainstem, diencephalon, cerebrum, and spinal cord and interconnect the two cerebellar hemispheres.
14-2 Explain how the brain is protected and supported, and discuss the formation, circulation, and function of cerebrospinal fluid.
The cranial meninges dura mater, arachnoid mater, and pia mater are continuous with the meninges of the spinal cord. Folds of dura mater include falx cerebru, tentorium cerebri, and falx cerebelli, stabilize the position of the brain. CSF protects delicate neural structures, supports brain, transports nutrients, chemical messengers, and waste products. CSF is produces at the choroid plexus, reaches the subarachnoid space through lateral and median aperture and diffuses across the arachnoid granulations into the superior sagittal sinus. Blood brain barrier isolates nervous tissue from general circulation. Blood brain barrier is incomplete in parts of hypothalamus, pituitary gland, pineal gland and choroid plexus.
13-2 Discuss the structure and functions of the spinal cord, and describe the three meningeal layers that surround the central nervous system pt.2
The three spinal meninges provide physical stability and shock absorption for nervous tissues of the spinal cord; the cranial meninges surround the brain. The dura mater, the outer meningeal layer covers the spinal cord and tapers to the coccygeal ligament. Interior to the inner surface the arachnoid mater (2nd layer) and the subarachnoid space which contains CSF which is a shock absorber for dissolved gases, nutrients, chemical messengers, and waste products. The pia mater is a meshwork of elastic and collagen fibers (the inner most layer).
15-4 Identify the major sensory pathways, and explain how it is possible to distinguish among sensations that originate in different areas of the body.
3 major somatic sensory pathways carry sensory info from the skin and musculature of the body wall, head, neck, and limbs: the spinothalamic pathway, posterior column pathway, and spinocerebellar pathway. Spinothalamic pathway carries poorly localized sensations of touch, pressure, pain, and temp. Posterior column pathway carries fine touch, pressure, and proprioceptive sensations. Spinocerebellar pathway including posterior and anterior spinocereballar tracts, carries sensations to the cerebellum concerning the position of muscles, tendons, and joints.
14-1 Name the major brain regions, vesicles, and ventricles, and describe the locations and functions of each.
4 main regions in the adult brain are the cerebrum, cerebellum, diencephalon, and brain stem. The brainstem is made up of the midbrain (mesencephalon), pons, and medulla oblongata. Brain contains extensive ares of cortex, a layer of gray matter on the surfaces of the cerebrum and the cerebellum. Brain forms 3 swellings at the superior tip of the nerual tube: prosencephalon, mesencephalon, and the rhombencephalon. The prosencephalon (forebrain) forms the telencephalon (becomes cerebrum) and diencephalon; the mesencephalon becomes midbrain; rhombencephalon (hindbrain) forms metencephalon (cerebellum and pons) and myelencephalon (medulla oblongata)
13-6 Describe the steps in a neural reflex, and classify the types of reflexes
A reflex arc is the neural "wiring" of a single reflex. The 5 steps involved in neural reflex are 1. the arrival of a stimulus and activation of a receptor, 2. the activation of a sensory neuron, 3. information processing in the CNS, 4. the activation of a motor neuron, 5. a response by an effector.
15-2 Explain why receptors respond to specific stimuli, and how the organization of a receptor affects its sensitivity.
A sensory receptor is a specialized cell or cell process that monitors specific conditions within the body or in the external environment. Arriving info in a sensation; awareness of a sensation is perception. General senses are our sensitivity to temp, pain, touch, pressure, vibration, and proprioception. Receptors for these senses are distributed throughout the body. Special senses located in specific sense organs are structurally more complex. Each cell monitors a specific receptive field. Transduction begins when a large enough stimulus depolarizes the receptor potential or generator potential to the point where action potentials are produced.
16-10 Summarize the effects of aging on the nervous system and give examples of interactions between the nervous system and other organ systems.
Age related changes in the nervous system include reduction of brain size and weight, reduction in the number of neurons, decrease in blood flow to the brain, changes un the synaptic organization of the brain, intracellular and extracellular changes in the CNS neurons. Nervous system monitors all other systems and issues commands that adjust their activities. Efficiency of these activities typically decrease with aging.
16-5 Describe the mechanisms of parasympathetic neurotransmitter release and their effects on target organs and tissues.
All parasympathetic preganglionic adn postganglionic fibers release ACh. Effects are short lived because ACh is inactivated by AChE and the tissue cholinesterase. Postsynaptic membranes have 2 types of ACh receptors. Stimulation of muscarinic receptors produce a longer lasting effect than does the stimulation of nicotinic receptors
13-7 Distinguish among the types of motor responses produced by various reflexes, and explain how reflexes interact to produce complex behaviors
All polysynaptic reflexes 1. involve pools of interneurons 2. are intersegmental in distribution 3. involve reciprocal inhibition 4. have reverberating circuits which prolong the reflexive motor response 5. can cooperate to produce a coordinated response
14-9 Identify the major anatomical subdivisions and functions of the cerebrum, and discuss the origin and significance of the major types of brain waves seen in an electroencephalogram.
Brain activity is measured using an electroencephalogram. Alpha waves appear in healthy resting adults; beta waves occur when adults are concentrating; theta waves appear in children; delta waves are normal during sleep
14-10 Describe representative examples of cranial reflexes that produce somatic responses or visceral responses to specific stimuli.
Cranial reflexes are monsynaptic and polysynaptic reflex arcs that involve sensory and motor fibers of cranial nerves
16-9 Describe some of the ways in which the interactions of neurotransmitters influence brain function.
Higher order functions 1. performed by cerebral cortex and involve complex interactions among areas of cerebral cortex and between the cortex and other areas of the brain 2. involve conscious and unconscious info processing 3. subject to modification and adjustment over time.
13-6 Describe the steps in a neural reflex, and classify the types of reflexes
Innate reflexes result from the genetically determined connections that form between neurons during development Acquired reflexes are learned and typically are more complex Somatic reflexes control skeletal muscles Visceral reflexes control activities of other systems Monosynaptic reflex the simplest reflex arc a sensory neuron synapses directly on a motor neuron Polysynaptic reflex has at least one interneuron between the sensory afferent and the motor efferent and there is a longer delay between stimulus and response. Cranial reflex are reflexes processed in the brain Spinal reflexes are reflexes that process events in the spinal cord
13-7 Distinguish among the types of motor responses produced by various reflexes, and explain how reflexes interact to produce complex behaviors
Intersegmental reflexs in which spinal segments interact to produce a coordinated motor response. Stretch reflex is a monosynaptic reflex that automatically regulates skeletal muscles length and muscle tone. The sensory receptors involved are muscle spindles. Postural reflex maintains a persons normal upright posture. Tendon reflex ( monitors the tension produced during muscular contractions and prevents damage to tendons) Withdrawal reflexes (move affected portions of the body away from a source of stimulation). Flexor reflex is a withdrawal reflex affecting muscles of a limb. Crossed extensor reflex complements withdrawal reflexes.
14-3 Describe the anatomical differences between the medulla oblongata and the spinal cord, and identify the main components and functions of the medulla oblongata.
Medulla oblongata connects brain and spinal cord. Contains relay stations as the olivary nuclei, and relfex centers including the cardiovascular and respiratory rhythmicity centers. The reticular formation begins in the medulla oblongata and extends into more superior portions of the brainstem.
16-4 Describe the structures and functions of the parasympathetic division of the autonomic nervous system.
Parasympathetic division includes preganglionic neurons in the brainstem and sacral segments of the spinal cord, and ganglionic neurons in the peripheral ganglia located within or next to target organs. Preganglionic fibers leave the brain as components of cranial nerves III, VII, IX, and X. Those leaving the sacral segments form the pelvic nerves. Effects produced by the parasympathetic division center on relaxation, food processing, and energy absorption.
16-7 Describe the hierarchy of interacting levels of control in the autonomic nervous system, including the significance of visceral reflexes.
Parasympathetic division innervates only visceral structures that are serviced by cranial nerves or enclosed by the thoracic abdominopelvic cavities . Organs with dual innervation receive input from both divisions. Parasympathetic and sympathetic nerves intermingle in the thoracic and abdominopelvic cavities to form a series of characteristic autonomic plexuses. the cardias, pulmonary, esophageal, celiac, inferior mesenteric, and hypogastric plexuses.
16-3 Describe the mechanisms of sympathetic neurotransmitter release and their effects on target organs and tissues.
Stimulation of the sympathetic division has 2 distinctive results; release of wither ACh at specific locations and the secretion of epinephrine and norepinephrine into the general circulation. 2 types of sympathetic receptors are alpha and beta receptors. Sympathetic division includes 2 sympathetic chain ganglia, 3 collateral ganglia, and 2 adrenal medullae.
16-2 Describe the structures and functions of the sympathetic division of the autonomic nervous system.
Sympathetic division consists of preganglionic neurons between T1-L2, ganglionic neurons in ganglia near the vertebral column and specialized neurons in the adrenal glands. 2 types of sympathetic ganglia and sympathetic chain ganglia, and collateral ganglia. Preganglionic fibers run between the sympathetic chain ganglia and interconnect them. Celiac ganglion innervates the stomach, liver, gallbladder, pancreas, and spleen, superior mesenteric ganglion innervates small and large intestine; inferior mesenteric ganglion innervates kidneys, urinary bladder, terminal portions of the large intestine, and sex organs.
16-6 Discuss the functional significance of dual innervation and autonomic tone.
Sympathetic division has widespread influence on visceral and somatic structures. Parasympathetic division innervates areas serviced by cranial nerves and organs in the thoracic and abdominopelvic cavitites.
14-5 List the main components of the cerebellum, and specify the functions of each.
Tectum roof of the midbrain contains the corpora quadrigemina (superior and inferior colliculi) the tementm contains the red nucleus the substantia nigra the cerebral peduncles and the headquarters of the reticular activating systems
14-8 Identify the main components of the limbic system, and specify the locations and functions of each.
Th limbic system or motivational system includes the amygdaloid body, cingulate gyrus, dentate gyrus, parahippocampal gyrus, hippocampus, and fornix. The functions of the limbic system involve emotional states, behavioral drives, and memory
13-1 Describe the basic structural and organizational characteristics of the nervous system
The CNS consists of the brain and spinal cord; the PNS includes cranial nerves and spinal nerves
13-2 Discuss the structure and functions of the spinal cord, and describe the three meningeal layers that surround the central nervous system
The adult spinal cord has two localized enlargements called cervical enlargement (supplies nerves to the shoulders and upper limbs) and the lumbosacral enlargement (innervates structures of the pelvis and lower limbs) the spinal cord has 31 segments.
16-1 Compare the organization of the autonomic nervous system with that of the somatic nervous system.
The autonomic nervous system coordinates cardiovascular, respiratory, digestive, urinary, and reproductive functions. Preganglionic neurons in the CNS send axons to synapes on ganglionic neurons in the autonomic ganglia outside the CNS. Preganglionic fibers from the thoracic and lumbar segments form the sympathetic division (fight or flight) of the ANS. Preganglionic fibers leaving the brain and sacral segments form the parasympathetic division or the (rest and digest) system.
14-7 List the main components of the diencephalon, and specify the functions of each.
The diencephalon is composed of the epithalamus, the thalamus, and the hypothalamus. The thalamus is the final relay point for ascending sensory information and coordinates the activites of the basal nuclei and cerebral cortex. Hypothalamus can 1. secrete certain hormones 2. regulate body temp 3. control autonomic function 4. coordinate voluntary and autonomic functions 5. coordinate activities of the nervous and endocrine systems 6. regulate circadian cycles of activity 7. control skeletal muscles contractions at the subconscious level 8. produce emotions and behavioral drives
14-9 Identify the major anatomical subdivisions and functions of the cerebrum, and discuss the origin and significance of the major types of brain waves seen in an electroencephalogram.
The longitudinal cerebral fissure separates the two cerebral hemispheres. The central sulcus separates the frontal and parietal lobes. Other sulci form the boundaries of the temporal and occipital lobes. White matter of the cerebrum contains association fibers, commissural fibers, and projection fibers. Basal nuclei include caudate nucleus, globus pallidus, and putamen; they control muscle tone and coordinate learned movement patterns and other somatic motor activities. Primary motor cortex of the precentral gyrus directs voluntary movements. Primary somatosensory cortex of the postcentral gyrus receives somatic sensory info from touch, pressure, pain, vibration, taste and temp receptors. Association areas, somatic sensory association area, visual association area, premotor cortex, control our ability to understand sensory info and coordinate motor response.
16-8 Explain how memories are created, stored, and recalled, and distinguish among the levels of consciousness and unconsciousness.
Visceral reflex arcs perform simplest functions of the ANS and can be either long or short reflexes. Parasympathetic reflexes govern respiration, cardiovascular functions, and other visceral activities. Levels of activity in the sympathetic and parasympathetic divisions of the ANS are controlled by centers in the brainstem and regulate specific visceral functions.The SNS ANS are organized in parallel. Integration occurs at the level of the brainstem and higher centers.
15-4 Identify the major sensory pathways, and explain how it is possible to distinguish among sensations that originate in different areas of the body.
Visceral sensory pathways carry info collected by interoceptors. Sensory info from the cranial nerves V, VII, IX, and X is delivered to the solitary nucleus in the medulla oblongata. Posterior roots of spinal nerves T1-L2 carry visceral sensory info from organs between the diaphragm and the pelvic cavity. Posterior roots of spinal nerves S2-S4 carry sensory info from more inferior structures.
13-3 Explain the roles of white matter and gray matter in processing and relaying sensory information and motor commands
White matter can be divided into six columns where they each contain a tract. Ascending tracts relay info from the spinal cord to the brain and the descending tracts carry info from the brain to the spinal cord. Gray matter contains cell bodies of neurons and neuroglia and unmyelinated axons , its projections toward the outer surface of the spinal cord are called horns. Posterior horns contain somatic and visceral sensory nuclei; nuclei in the anterior horns function in the somatic motor control. Lateral horns contain visceral motor neurons.
14-4 List the main components of the pons, and specify the functions of each.
pons contains 1. sensory info and motor nuclei for 4 cranial nerves 2. nuclei that help control respiration 3. nuclei and tracts linking cerebellum with the brain stem, cerebrum, and spinal cord and 4. ascending, descending, and transverse tracts
