Nervous System and Endocrine System - Human Anatomy PDF

Human Anatomy and Physiology with Pathophysiology CHAPTER 8: NERVOUS SYSTEM OUTLINE Division of PNS: I. Functions of the Nervous System Sensory division II. D...

Human Anatomy and Physiology with Pathophysiology CHAPTER 8: NERVOUS SYSTEM OUTLINE Division of PNS: I. Functions of the Nervous System Sensory division II. Divisions of the Nervous System III. Cells of the Nervous System A. Neurons or afferent division (toward); conducts action potentials B. Glial Cells from sensory receptors to the CNS C. Myelin Sheaths sensory neurons -neurons that transmit action potentials D. Organization of Nervous Tissue from the periphery to the CNS IV. Electrical Signals and Neural Pathways A. Resting Membrane Potential Motor division B. Action Potentials C. The Synapse or efferent division (away); conducts action potentials D. Reflexes from the CNS to effector organs, such as muscles and E. Neuronal Pathways glands V. Spinal Cord motor neurons -neurons that transmit action potentials VI. Spinal Nerves from the CNS toward the periphery VII. Brain Motor division can be subdivided into: A. Brainstem o somatic nervous system -transmits action potentials B. Cerebellum from the CNS to skeletal muscles C. Diencephalon o autonomic nervous system (ANS) -transmits action D. Cerebrum potentials from the CNS to cardiac muscle, smooth VIII. Sensory Functions muscle, and glands IX. Somatic Motor Functions X. Other Brain Functions ‣ sympathetic division XI. Meninges, Ventricles, and Cerebrospinal Fluid ‣ parasympathetic division XII. Cranial Nerves Enteric nervous system (ENS) - unique subdivision of PNS; has XIII. Autonomic Nervous System both sensory and motor neurons contained wholly within the XIV. Effects of Aging on the Nervous System digestive tract; can function w/o input from CNS or other parts XV. Diseases of PNS I. FUNCTIONS OF THE NERVOUS SYSTEM 1. Receiving sensory input 2. Integrating information 3. Controlling muscles and glands 4. Maintaining homeostasis 5. Establishing and maintaining mental activity II. DIVISIONS OF THE NERVOUS SYSTEM A. Central nervous system (CNS) consists of the brain and spinal cord o connect with each other at the foramen magnum of the skull III. CELLS OF THE NERVOUS SYSTEM B. Peripheral nervous system (PNS) Two types of cells of nervous system: consists of all the nervous tissue outside the CNS, neurons including nerves and ganglia glial cells @medtech.files | by MAPB Chapter 8: Nervous System A. Neurons Pseudo-unipolar neurons -have a single process extending from the cell body; appears to have an axon and ‑ or nerve cells no dendrites; most sensory neurons ‑ receive stimuli, conduct action potentials, and transmit signals to other neurons or effector organs ‑ require oxygen and glucose Three Parts cell body -or soma; contains a single nucleus; processes stimulus dendrites -are short, often highly branching cytoplasmic extensions that receives stimulus for other neurons or sensory receptors axons -a single long cell process extending from the neuron cell body; transmits stimulus to a gland, muscle, organ, or other neuron B. Glial Cells o axon hillock - cone-shaped projection of the soma; area where the axon leaves the neuron cell body ‑ or neuroglia o collateral axons -another branch of axon attached to ‑ supportive cells of the CNS and PNS; do not conduct action the main axon potentials o axoplasm -cytoplasm of an axon ‑ carry out different functions that enhance neuron o axolemma -plasma membrane of axon function and maintain normal conditions within nervous tissue ‑ more numerous than neurons; can divide to produce more cells Glial Cells of the CNS Astrocytes -star-shaped; serve as the major supporting cells in the CNS; provide structural support; regulate neuronal signaling; contribute to blood-brain barrier; help with neural tissue repair o blood-brain barrier -a permeability barrier formed when astrocytes participate with the blood vessel endothelium Types of Neurons Ependymal cells -epithelial-like; line the fluid-filled cavities (ventricles and canals) within the CNS; some form According to function: choroid plexuses, which produce CSF Microglia -act as immune cells of the CNS; small, mobile Sensory neurons (afferent neurons) -conduct action cells; protect CNS from infection; become phagocytic in potentials toward the CNS response to inflammation Motor neurons (efferent neurons) -conduct action Oligodendrocytes -provide an insulating material that potentials away from the CNS toward muscles or glands surrounds axons; cell processes form myelin sheaths Interneurons -conduct action potentials within the CNS around axons or enclose unmyelinated axons in the CNS from one neuron to another According to structure: Glial Cells of the PNS Multipolar neurons -many dendrites and a single axon; Schwann cells -single cells surrounding axons; form most motor neurons and most CNS neurons myelin sheaths around axons or enclose unmyelinated Bipolar neurons -have two processes: one dendrite and axons in the PNS insulating > cell material around body one axon; found in special sense organs, such as eye and Satellite cells -surround neuron cell bodies in sensory and nose autonomic ganglia provide support 3 > nutrition > protect neurons from heavy metal poisons @medtech.files | by MAPB Chapter 8: Nervous System  Oligodendrocyte Schwann cells IV. ELECTRICAL SIGNALS AND NEURAL PATHWAYS produce myelin sheath produce myelin sheath in CNS in PNS A. Resting Membrane Potential mom positive collection of axons: collection of axons: outside of cell is more + (Na+) nerve tracts nerves inside of cell is more – (K+) cell bodies: nuclei cell bodies: ganglion more negative The resting membrane potential is generated by three main C. Myelin Sheaths factors: Myelin sheaths -specialized layers that wrap around the 1. a higher concentration of K+ immediately inside the cell axons of some neurons; formed by the cell processes of membrane glial cells; specifically, oligodendrocytes in the CNS and 2. a higher concentration of Na+ immediately outside the Schwann cells in the PNS cell membrane o myelinated axons 3. greater permeability of the cell membrane to K+ than to ‑ conduct axon potentials more quickly (3-15 Na+ meters/sec) than unmyelinated due to nodes of Ranvier o unmyelinated axons Two basic types of ion channels: Leak channels -are always open; ions can “leak” across the membrane down their concentration gradient; K+ channels Gated channels -closed until opened by specific signals; Na+ channels o Chemically gated channels -opened by Nodes of Ranvier -gaps in myelin sheath where action neurotransmitters or other chemicals potentials develop o Voltage-gated channels -opened by a change in Saltatory conduction -jumping of action potentials from membrane potential one node to another Multiple sclerosis -disease of myelin sheath that causes sodium-potassium pump - required to maintain the greater loss of muscle function concentration of Na+ outside the cell membrane and K+ inside D. Organization of Nervous Tissue B. Active Potentials Gray matter ‑ electricity that cause depolarization and repolarization ‑ change resting membrane potential by activating gated -consists of groups of neuron cell bodies and their dendrites, ion channels where there is very little myelin local current -movement of Na+; causes the inside of the cortex -gray matter on the surface of the brain cell membrane to become positive nuclei -clusters of gray matter located deeper within the depolarization -the inside of the cell membrane become brain positive; results in local potential ganglion -a cluster of neuron cell bodies in the PNS o If depolarization is not strong enough, the Na+ channels close again, and the local potential White matter disappears without being conducted along the nerve cell membrane. -consists of bundles of parallel axons with their myelin sheaths, o If depolarization is large enough, Na+ enters the cell which are whitish in color so that the local potential reaches a threshold value. nerve tracts -or conduction pathways; formed by white This threshold depolarization causes voltage-gated matter of the CNS; propagate action potentials from one Na+ channels to open. area of the CNS to another hyperpolarization -condition that the charge on the cell nerves -formed by white matter of PNS consisting of membrane briefly becomes more negative than the bundles of axons and associated connective tissue resting membrane potential @medtech.files | by MAPB Chapter 8: Nervous System  continuous conduction -action potential is conducted Reflex arc -neuronal pathway by which a reflex occurs; along the entire axon cell membrane basic functional unit of the nervous system because it is saltatory conduction - action potentials “jump” from one the smallest, simplest pathway capable of receiving a node of Ranvier to the next along the length of the axon stimulus and yielding a response Five basic components of reflex arc: C. The Synapse 1. Stimulus to sensory receptor creates receptor potential Synapse 2. Sends signals (nerve conduction) to sensory/afferent neuron Junction where the axon of one neuron interacts with 3. Sent centrally to the CNS (spinal cord) where the another neuron or with cells of an effector organ interneurons are located Three major components: 4. Sends action potential to motor/efferent neuron o Presynaptic terminal -forms the end of the axon 5. Effector muscle or gland responds to motor nerve o Postsynaptic terminal -membrane of the dendrite of impulses effector cell o Synaptic cleft -space separating the presynaptic and postsynaptic membranes Neurotransmitters a chemical substances stored in synaptic vesicles in the presynaptic terminal acetylcholine (ACh) and norepinephrine -best known neurotransmitters acetylcholinesterase -an enzyme that breaks down the E. Neuronal Pathways acetylcholine converging pathway -two or more neurons synapse with Substance Site of release Effect the same postsynaptic neuron; allows information Acetylcholine CNS synapses, ANS Excitatory or transmitted in more than one neuronal pathway to (ACh) synapses, inhibitory converge into a single pathway and neuromuscular diverging pathway -the axon from one neuron divides and junctions synapses with more than one other postsynaptic neuron; Norepinephrine Selected CNS Excitatory allows information transmitted in one neuronal pathway (NE) synapses to diverge into two or more pathways and some ANS synapses summation -allows integration of multiple subthreshold local Serotonin CNS synapses Generally potentials inhibitory Dopamine Selected CNS Excitatory or spatial summation -occurs when the local potentials synapses inhibitory originate from different locations on the postsynaptic and some ANS neuron synapses temporal summation -occurs when local potentials Gamma- CNS synapses Inhibitory overlap in time; can occur from a single input that fires aminobutyric rapidly, which allows the resulting local potentials to acid (GABA) overlap briefly Glycine CNS synapses Inhibitory Endorphins Descending Inhibitory pain pathways V. SPINAL CORD ‑ part of the CNS; extends from the foramen magnum at the D. Reflexes base of the skull to the 2nd lumbar vertebra ‑ protected by vertebral column Reflex -an involuntary reaction in response to a stimulus ‑ allows movement; if damage, paralysis can occur applied to the periphery and transmitted to the CNS; allow ‑ ends at the conus medullaris which is the cone-shaped a person to react to stimuli more quickly than is possible if tapered end conscious thought is involved @medtech.files | by MAPB Chapter 8: Nervous System  Cauda equina -inferior end of the spinal cord and the VI. SPINAL NERVES spinal nerves exiting; resemble a horse’s tail Spinal Nerves White matter -composed of white fibers/myelinated axons; outside of spinal cord ‑ arise along the spinal cord from the union of the dorsal Gray matter -composed of unmyelinated axons; shaped as roots and ventral roots letter H or butterfly; center of spinal cord ‑ contain axons of both sensory and somatic motor Central canal -fluid-filled space in center of spinal cord neurons; mixed nerves Ventral root -where the spinal nerve rootlets on the ‑ communicate between the spinal cord and the body; ventral aspect combine categorized by region of vertebral column from which it Dorsal root -where the spinal nerve rootlets on the dorsal emerges aspect combine ‑ 31 pairs Ganglion -ovoid structures containing cell bodies of cervical (C) C1 – C8 neurons and glial cells supported by connective tissue thoracic (T) T1 – T12 lumbar (L) L1 – L5 sacral (S) S1 – S5 coccygeal (Co) Co dermatome -area of skin supplied with sensory innervation by a pair of spinal nerves plexuses -where neurons of several spinal nerves come together and intermingle coccygeal plexus -originates from S5 and Co; supplies motor White matter innervation to the muscles of the pelvic floor and sensory cutaneous innervation to the skin over the coccyx composed of 3 columns: dorsal, ventral, lateral Ascending tracts -consists of axons that conduct action potential toward brain Descending tracts -consists of axons that conduct action potentials away from brain Gray matter Posterior horns -contain axons which synapse with interneurons Anterior horns -contain somatic neurons Lateral horns -contain autonomic neurons A. Spinal Cord Reflexes Knee-Jerk Reflex ‑ or patellar reflex ‑ example of stretch reflex stretch reflex -simplest reflex; occurs when muscles contract in response to a stretching force applied ‑ stretching of quadriceps femoris muscle ‑ used by clinicians to determine if the higher CNS centers that normally influence this reflex are functional Withdrawal Reflex ‑ or flexor reflex ‑ the function is to remove a limb or another body part from a painful stimulus @medtech.files | by MAPB Chapter 8: Nervous System Three Major Plexuses: VII. BRAIN Cervical Plexus Part of the CNS; occupies most of the cranial cavity within the skull -originates from spinal nerves C1 to C4; branches from this Different parts: plexus innervate several of the muscles attached to the hyoid o Brainstem bone o Cerebellum phrenic nerve -innervates the diaphragm o Diencephalon o Cerebrum Covered by meninges and CSF Brachial Plexus A. Brainstem -originates from spinal nerves C5 to T1; five major nerves emerge from the brachial plexus to supply the upper limb and connects the spinal cord to the rest of the brain shoulder composed of: medulla oblongata, pons, midbrain axillary nerve -innervates two shoulder muscles and the skin over part of the shoulder radial nerve -innervates all the muscles in the posterior arm and forearm o crutch paralysis -dysfunction of the radial nerve; paralysis of the posterior arm and forearm muscles and loss of sensation over the back of the forearm and hand musculocutaneous nerve -innervates the anterior muscles of the arm and the skin over the radial surface of the forearm ulnar nerve -innervates two anterior forearm muscles and most of the intrinsic hand muscles Medulla Oblongata median nerve -innervates most of the anterior forearm muscles and some of the intrinsic hand muscles; also most inferior portion; continuous with the spinal cord innervates the skin over the radial side of the hand it regulates heart rate, blood vessel diameter, breathing, swallowing, vomiting, hiccupping, coughing, sneezing, balance Lumbosacral Plexus pyramids -two prominent enlargements that extend the length of the medulla oblongata; involved in conscious -originates from spinal nerves L1 to S4; four major nerves exit control of skeletal muscle the lumbosacral plexus to supply the lower limb obturator nerve -innervates the muscles of the medial Pons thigh and the skin over the same region femoral nerve -innervates the anterior thigh muscles and above medulla the skin over the anterior thigh and medial side of the leg functional bridge between the cerebrum and cerebellum tibial nerve -innervates the posterior thigh muscles, the it controls breathing, chewing, salivation, swallowing, anterior and posterior leg muscles, and most of the relay station between cerebrum and cerebellum intrinsic foot muscles; innervates the skin over the sole of the foot Midbrain common fibular nerve -innervates the muscles of the lateral thigh and leg and some intrinsic foot muscle above pons; smallest region of the brainstem sciatic nerve -tibial and common fibular nerves that are it coordinated eye movement, pupil diameter, turning bound together within a connective tissue head toward noise culliculi -four mounds in the dorsal part of midbrain substantia nigra -black nuclear mass in midbrain which is part of the basal nuclei; involved in regulating general body movements @medtech.files | by MAPB Chapter 8: Nervous System Reticular formation -group of nuclei that are scattered Hypothalamus throughout the brainstem; involved in regulating cyclical motor functions such as respiration, walking, and chewing below thalamus controls homeostasis, body temp, thirst, hunger, fear, Reticular activating system -plays a role in arousing and rage, sexual emotions maintaining consciousness and in regulating the sleep-wake infundibulum -funnel-shaped stalk that extends from the cycle floor of the hypothalamus to the pituitary gland mammillary bodies -externally visible swellings on the posterior portion of the hypothalamus; involved in B. Cerebellum emotional responses to odors and in memory translates as “small brain” located at the postero-inferior portion of the cerebrum D. Cerebrum and dorsal to the brainstem controls balance, muscle tone, and fine motor movements largest and most prominent part of the brain cerebellar peduncles -large connections attached to the brainstem C. Diencephalon between the brainstem and cerebrum composed of: thalamus, hypothalamus, epithalamus Divisions: Left hemisphere -controls the right side of the body, responsible for science and logic Right hemisphere -controls the left side of the body, responsible for music and art Cerebrum Components Cerebral cortex -gray matter on the outer surface of the cerebrum; controls thinking, communicating, remembering, understanding, and initiates voluntary movements Thalamus Cerebral medulla -white matter of the brain between the largest portion of diencephalon cortex and the nuclei influences moods and detects pain Longitudinal fissure -divides left and right hemisphere Corpus callosum -mass of white fibers that connects the left and right hemispheres Epithalamus Gyri -convoluted folds on the cerebral cortex that increases the surface area above thalamus Sulci -shallow indentions emotional and visceral response to odors Fissure -deep indentations pineal gland -an endocrine gland that may influence the Central sulcus -separates the frontal and parietal lobe onset of puberty and may play a role in controlling some Lateral fissure -separates the temporal lobe from the rest long term cycles that are influenced by the light-dark cycle of the cerebrum Transverse fissure -separates cerebrum and cerebellum @medtech.files | by MAPB Chapter 8: Nervous System Lobes of the Cerebrum IX. SOMATIC MOTOR FUNCTIONS Frontal lobe -control of voluntary motor functions, Motor Areas of Cerebral Cortex motivation, aggression, mood, and smell Parietal lobe -principal center for receiving and Primary motor cortex -frontal lobe; control voluntary consciously perceiving most sensory information; touch, motor movement pain, temperature, and balance Premotor area -frontal lobe; where motor functions are Occipital lobe -receiving and perceiving visual input organized before initiation Temporal lobe -involve in smell (olfactory), hearing Prefrontal area -motivation and foresight to plan and (auditory), and memory initiate movement Insula -fifth lobe, functions for desires, cravings, and addiction Descending Tracts ‑ project from upper motor neurons in cerebral cortex to lower motor neurons in spinal cord and brainstem ‑ control different types of movements Pathway Function VIII. SENSORY FUNCTIONS Direct Lateral corticospinal Muscle tone and skilled Ascending Tracts movements, especially of hands ‑ pathways in brain and spinal cord Anterior corticospinal Muscle tone and movement of ‑ transmit information via action potentials from periphery trunk muscles to brain Indirect ‑ each tract has limited type of sensory input (temp, touch, Rubrospinal Movement coordination pain, etc.) ‑ tracts are named that indicated origin and termination Reticulospinal Posture adjustment, especially during movement ‑ made of 2-3 neurons in sequence Pathway Function Vestibulospinal Posture and balance Spinothalamic Pain, temperature, light touch, pressure, tickle, and itch sensations Tectospinal Movement in response to visual Dorsal column Proprioception, touch, deep reflexes pressure, and vibration Spinocerebellar Proprioception to cerebellum Basal Nuclei group of functionally related nuclei Sensory Areas of Cerebral Cortex plan, organize, coordinate motor movements and posture Primary sensory area -where ascending tracts project; Two primary nuclei: where sensations are perceived o Corpus striatum -deep in cerebrum Primary somatic sensory cortex -general sensory area; in o Substantia nigra - group of darkly pigmented cells in parietal lobe; sensory input such as pain, pressure, the midbrain temperature @medtech.files | by MAPB Chapter 8: Nervous System  X. OTHER BRAIN FUNCTIONS Memory Communication Between the Right and Left Hemispheres Encoding -brief retention of sensory input received by brain while something is scanned, evaluated, and acted Right cerebral hemisphere -receives sensory input from up; also called sensory memory; in temporal lobe; lasts and controls muscular activity in the left half of the body. less than a second Left cerebral hemisphere -receives input from and Consolidated -data that has been encoded; temporal controls muscles in the right half of the body lobe; short term memory Commissures -connections between the two hemispheres Storage -long term memory; few minutes or permanently Corpus callosum -a broad band of nerve tracts at the base (depends on retrieval) of the longitudinal fissure Retrieval -how often information is used Speech Types Of Memory ‑ mainly in left hemisphere Working memory - task-associated memory; information is retained for a few seconds or minute; bits of info 2 major cortical area: (usually 7) Short-term memory -few minutes to a few days; Sensory speech (Wernicke’s area) -parietal lobe; where susceptible to brain trauma, drugs words are heard and comprehended Long-term memory -can last for a few minutes or Motor speech (Broca’s area) -frontal lobe; where words permanently; length of time memory is stored may are formulated; controls the movement necessary for depend on how often it is retrieved and used speech Declarative/explicit memory - retention of facts, such as aphasia -absent or defective speech or language names, dates, and places, as well as related emotional comprehension undertones Procedural memory/reflexive memory -development of motor skills Brain Waves and Consciousness Electroencephalogram (EEG) -monitors brain waves Limbic System and Emotions Brainwaves -a summation of the electrical activity of the brain Limbic System Alpha waves -observed in a normal person who is awake ‑ located in deep cortical structures but in a quiet, resting state with the eyes closed ‑ influences long term declarative memory, emotions, Beta waves -have a higher frequency than alpha waves visceral response to emotions, motivation and mood and occur during intense mental activity ‑ responds to olfactory stimulation by initiating response Delta waves -occur during deep sleep, in infants, and in necessary for survival patients with severe brain disorders ‑ voracious appetite; increase sexual activity; loss of fear and anger response Theta waves -usually observed in children, but they can also occur in adults who are experiencing frustration or who have certain brain disorders XI. MENINGES, VENTRICLES, AND CEREBROSPINAL FLUID A. Meninges ‑ protective wrapping around brain and spinal cord ‑ three connective tissue membranes Dura mater -tough, skin-like outermost covering; thickest layer subdural space -space between the dura mater and the arachnoid mater; space containing a very small amount of serous fluid @medtech.files | by MAPB Chapter 8: Nervous System Arachnoid mater -deep to the dura mater and is a much thinner layer and appears spidery Subarachnoid space -space under the arachnoid mater and is filled with CSF Pia mater -thin, vascular membrane adhering to the surface C. Cerebrospinal Fluid (CSF) bathes the brain and spinal cord, providing a protective cushion around CNS choroid plexus -produce the CSF hydrocephalus -accumulation of CSF in the ventricles Flow of CSF 1. Lateral ventricle 2. Third ventricle 3. Cerebral aqueduct/Aqueduct of Sylvius 4. Fourth ventricle 5. Central canal of the spinal cord XII. CRANIAL NERVES 12 pair of cranial nerves named by roman numerals 2 Categories of Functions Sensory functions -vision, touch, pain Motor functions o Somatic motor cranial nerves innervate skeletal muscles in the head and neck o Parasympathetic cranial nerves innervate glands, Epidural space -in vertebral column between dura and smooth muscle throughout the body, and cardiac vertebra; injection site for epidural anesthesia muscle of the heart Spinal block -to inject anesthetic into the area Spinal tap -take a sample of cerebrospinal fluid B. Ventricles cavities in CNS that contain fluid lateral ventricle -large cavity in each cerebral hemisphere third ventricle -a smaller, midline cavity located in the center of the diencephalon fourth ventricle -base of cerebellum; continuous with central canal of spinal cord o connected to the third ventricle by a narrow canal, called the cerebral aqueduct @medtech.files | by MAPB Chapter 8: Nervous System Cranial Nerves and Their Functions Number Name General Functions* Specific Function I Olfactory S Smell II Optic S Vision III Oculomotor M, P Motor to four of six extrinsic eye muscles and upper eyelid; parasympathetic: constricts pupil, thickens lens IV Trochlear M Motor to one extrinsic eye muscle V Trigeminal S, M Sensory to face and teeth; motor to muscles of mastication (chewing) VI Abducens M Motor to one extrinsic eye muscle VII Facial S, M, P Sensory: taste; motor to muscles of facial expression; parasympathetic to salivary and tear glands VIII Vestibulocochlear S Hearing and balance IX Glossopharyngeal S, M, P Sensory: taste and touch to back of tongue; motor to pharyngeal muscles; parasympathetic to salivary glands X Vagus S, M, P Sensory to pharynx, larynx, and viscera; motor to palate, pharynx, and larynx; parasympathetic to viscera of thorax and abdomen XI Accessory M Motor to two neck and upper back muscles XII Hypoglossal M Motor to tongue muscles *S, sensory; M, somatic motor; P, parasympathetic XIII. AUTONOMIC NERVOUS SYSTEM XV. DISEASES Divisions oof Autonomic Nervous System Condition Description CNS Disorders 1. Sympathetic Encephalitis Inflammation of the brain caused by a virus and less often by bacteria or other activated during times of stress agents part of flight or flight response Meningitis Inflammation of meninges caused by viral prepares you for physical activity by: or bacterial infection o increasing heart rate, blood pressure, and breathing Multiple Autoimmune condition; inflammation in rate sclerosis brain and spinal cord with demyelination o sending more blood to skeletal muscles and sclerotic (hard) sheaths results in poor o inhibiting digestive tract conduction of action potentials Parkinson Caused by a lesion in basal nuclei; 2. Parasympathetic disease characterized by muscular rigidity, resting tremor, general lack of movement, and a housekeeper slow, shuffling gait activated under normal conditions Alzheimer Mental deterioration, or dementia; rest and digest disease usually affects older people; involves loss stimulates involuntary activities of the body at rest of neurons in cerebral cortex involved in digestion, urine production, and PNS Disorders dilation/constriction of pupils, etc. Herpes Family of diseases characterized by skin lesions due to herpes viruses in sensory ganglia Poliomyelitis Viral infection of the CNS; damages XIV. EFFECTS OF AGING ON THE NERVOUS SYSTEM somatic motor neurons, leaving muscles In general, sensory and motor functions decline with age. without innervation, and leads to paralysis Mental functions, including memory, may decline with and atrophy age, but this varies from person to person. Myasthenia Autoimmune disorder affecting gravis acetylcholine receptors; makes the neuromuscular junction less functional; muscle weakness and increased fatigue lead to paralysis @medtech.files | by MAPB Chapter 8: Nervous System  specialized > endocrine system Human Anatomy and Physiology with Pathophysiology - endocrine glands CHAPTER 9: ENDOCRINE SYSTEM messengers) - hormones (chemical - Grand through blood OUTLINE II. FUNCTIONS OF THE ENDOCRINE SYSTEM I. Principles of Chemical Communication II. Functions of the Endocrine System 1. Metabolism III. Characteristics of the Endocrine System 2. Control of food intake and digestion IV. Hormones 3. Tissue development V. Control of Hormone Secretion 4. Ion regulation VI. Hormone Receptors and Mechanisms of Action 5. Water balance VII. Endocrine Glands and Their Hormones 6. Heart rate and blood pressure regulation A. Pituitary and Hypothalamus 7. Control of blood glucose and other nutrients B. Thyroid Gland 8. Control of reproductive functions C. Parathyroid Glands 9. Uterine contractions and milk release D. Adrenal Glands 10. Immune system regulation E. Pancreas, Insulin, and Diabetes F. Testes and Ovaries G. Thymus H. Pineal Gland III. CHARACTERISTICS OF THE ENDOCRINE SYSTEM VIII. Other Hormones IX. Effects of Aging on the Endocrine System Endocrine System X. Diseases consists of ductless glands that secrete hormones into the interstitial fluid I. PRINCIPLES OF CHEMICAL COMMUNICATION endo – within; krino – secrete Endocrine glands -secrete their product directly on Chemical Messengers bloodstream ‑ allows cells to communicate with each other to regulate Hormones -chemical messengers; derived from Greek body activities word hormone, which means to set into motion Endocrinology -study of the endocrine system Classes of Chemical Messenger Autocrine -secreted by cells in a local area; influences the activity of the same cell or cell type from which it was secreted Paracrine -produced by a wide variety of tissues and secreted into extracellular fluid; has a localized effect on other tissues Neurotransmitter -produced by neurons; secreted into a synaptic cleft by presynaptic nerve terminals; travels short distances; influences postsynaptic cells Endocrine -secreted into the blood by specialized cells; travels some distance to target tissues; results in coordinated regulation of cell function Types of Chemical Signals Intracellular -produce in one part a cell and move to another part of same cell Intercellular -released from one cell and bind to receptors on another cell Exocrine glands -have ducts that carry their secretions to the outside of the body, or into a hollow organ @medtech.files | by MAPB Chapter 9: Endocrine System  IV. HORMONES Regulation of Hormone Levels in the Blood \ How Does Hormones Work? Negative feedback 1. Hormones are secreted by endocrine glands directly into the increase in concentration of hormone in the blood will bloodstream send negative signals to the endocrine gland to slow down 2. Hormones travel to all parts of body or stop its secretion 3. Hormones (key) bind to receptor site (lock) on target more commonly observed tissue self-limiting system 4. Response occurs Positive feedback Chemical Nature of Hormones less commonly observed increase in blood level hormone will further increase of Lipid-soluble hormones the hormone being released nonpolar; include steroid hormones, eicosanoids, thyroid self-propagated system hormones, and fatty acid derivative hormones small molecules that are insoluble in water-based fluids (plasma and blood); attached to binding proteins VI. HORMONE RECEPTORS AND MECHANISMS OF ACTION Example: LH, FSH, androgens Receptor site -location on a cell where hormone binds Water-soluble hormones (lock) Target tissues -group of cells that respond to specific polar molecule; include protein hormones, peptide hormones hormones, and most amino acid derivative hormones Specificity -specific hormones bind to specific receptor most common; can be dissolved in blood; circulate as free sites hormones; delivered directly to their target tissue without attaching to a binding protein Example: growth hormone, ADH, prolactin, etc. Classes of Receptors 1. Lipid-soluble hormones bind to nuclear receptors Nonpolar molecules can freely cross the cell V. CONTROL OF HORMONE SECRETION membrane Stimulation of Hormone Release 2. Water-soluble hormones bind to membrane-bound receptors Control by Humoral Stimuli Polar molecules and cannot pass through the cell membrane Some hormones are secreted in direct response to changes in certain blood-borne chemicals Ex: blood glucose levels (insulin) VII. ENDOCRINE GLANDS AND THEIR HORMONES Control by Neural Stimuli A. Pituitary and Hypothalamus Some hormone secretion is due to a stimulus from a neurotransmitter. Pituitary gland Example: epinephrine and fight or flight response ‑ aka hypophysis; extension of hypothalamus; small gland releasing hormones -hormones from hypothalamus about the size of a pea located in the Sella turcica (sphenoid bone) Control by Hormonal Stimuli ‑ master gland of the body (produces hormones that Some hormone secretion is due to a stimulus from control other endocrine organs) another hormone. Hypothalamus tropic hormones -hormones from the anterior pituitary gland; hormones that stimulate the secretion of another ‑ an important autonomic nervous system and endocrine hormone control center of the brain located inferior to the thalamus ‑ Hypothalamus controls the pituitary gland in two ways: hormonal control and direct innervation @medtech.files | by MAPB Chapter 9: Endocrine System infundibulum -connects the hypothalamus and the pituitary Adrenocorticotropic hormone (ACTH) gland increases secretion of glucocorticoid hormones, such as cortisol; increases skin pigmentation at high concentrations increases the secretion of a hormone from the adrenal cortex called cortisol, also called hydrocortisone Melanocyte-stimulating hormone (MSH) increases melanin production in melanocytes to make skin darker in color Luteinizing hormone (LH) or interstitial cell–stimulating hormone (ICSH) promotes ovulation and progesterone production in ovary; promotes testosterone synthesis and support for sperm cell production in testis Anterior pituitary made up of epithelial cells derived from the embryonic Follicle-stimulating hormone (FSH) oral cavity synthesizes hormones, whose secretion is under the promotes follicle maturation and estrogen secretion in control of the hypothalamus ovary; promotes sperm cell production in testis hormonal control Gonadotropins -regulate the growth, development, and hypothalamic-pituitary portal system -capillary beds and functions of the gonads (LH AND FSH) veins that transport the releasing and inhibiting hormones Prolactin Hormones of Anterior Pituitary stimulates milk production and prolongs progesterone Growth hormone secretion following ovulation and during pregnancy in women; increases sensitivity to LH in males ‑ increases gene expression, breakdown of lipids, and release of fatty acids from cells; increases blood glucose Posterior pituitary levels ‑ stimulates the growth of bones, muscles, and other organs extension of the brain and is composed of nerve cells regulated by neural input pituitary dwarfism -a young person suffering from a storage location for two hormones synthesized by special deficiency of growth hormone remains small, although neurons in the hypothalamus normally proportioned direct innervation giantism -abnormally tall; excess growth hormone is present before bones finish growing in length; exaggerated bone growth occurs Hormones of Posterior Pituitary acromegaly -facial features and hands become Antidiuretic hormone (ADH) abnormally large; excess hormone is secreted after growth in bone length is complete; growth continues in aka vasopressin bone diameter only conserves water; constricts blood vessels increases water reabsorption in kidney tubules Thyroid-stimulating hormone (TSH) Diabetes insipidus -low ADH; kidneys to produce large amount of dilute (watery urine); lead to dehydration and increases thyroid hormone secretion (thyroxine and thirst triiodothyronine) @medtech.files | by MAPB Chapter 9: Endocrine System Oxytocin Disorders: increases uterine contractions goiter – loss of negative feedback will result in excess TSH, increases milk letdown from mammary glands causing the thyroid gland to enlarge Pitocin -commercial preparations of oxytocin; given under hypothyroidism -lack of thyroid hormones; results in certain conditions to assist in childbirth and to constrict cretinism in infants; results in decreased metabolic rate in uterine blood vessels following childbirth adults cretinism -in infants; characterized by mental retardation, short stature, and abnormally formed skeletal structures myxedema -in adults; accumulation of fluid and other B. THYROID GLAND molecules in the subcutaneous tissue of the skin ‑ butterfly-shaped located on the anterior aspect of the hyperthyroidism -elevated rate of thyroid hormone trachea inferior to the larynx secretion; an increased metabolic rate, extreme ‑ composed of 2 lobes connected by the isthmus nervousness, and chronic fatigue ‑ one of the largest glands and is highly vascular Grave disease -an autoimmune disease that causes ‑ requires iodine to function hyperthyroidism; occurs when the immune system; ‑ main function is to produce thyroid hormones as produces abnormal proteins that are similar in structure stimulated by the thyroid stimulating hormone (TSH) and function to TSH, which overstimulates the thyroid gland exophthalmia -bulging of the eyes Calcitonin decreases rate of bone breakdown; prevents large increase in blood Ca2+ levels following a meal; secreted by parafollicular cells C. Parathyroid Gland Thyroid follicle -glandular formation where thyroid -embedded in the posterior wall of the thyroid gland hormones are synthesized and stored; small spheres with walls composed of simple cuboidal epithelium; filled with Chief cells -primary producers of PTH; appear denser with the protein thyroglobulin to which thyroid hormones are larger nucleus attached Oxyphil cells -scattered among the chief cells and are Colloid -pinkish content of the follicle which contains the considered as back-up hormone producers; have more thyroid hormones; stored form of hormones cytoplasm with an overall lighter appearance Follicular cells -simple cuboidal epithelium Parafollicular cells/C cells -network of loose connective tissue between the follicles; secrete the hormone called Parathyroid hormone calcitonin -increases rate of bone breakdown by osteoclasts; increases vitamin D synthesis, essential for maintenance of normal blood calcium levels Hormones of Thyroid Gland hyperparathyroidism -abnormally high rate of PTH Thyroid hormones (thyroxine, triiodothyronine) secretion hypoparathyroidism -abnormally low rate of PTH -increase metabolic rates, essential for normal process of secretion growth and maturation If Ca2+ is low, osteoclasts break down bone matrix and less Ca2+ thyroxine (T4) -aka tetraiodothyronine; contains four is lost in urine. iodine atoms triiodothyronine (T3) -contains three iodine atoms If Ca2+ is high, osteoclasts don’t break down bone matrix and more Ca2+ is lost in urine. @medtech.files | by MAPB Chapter 9: Endocrine System D. Adrenal Glands Glucocorticoids (cortisol) aka suprarenal gland -increase blood nutrient levels; inhibit inflammation and 2 small glands located superior to each kidney immune response cone-shaped gland located on top of the kidneys composed of two layers: adrenal medulla (inner part) and cortisol -major glucocorticoids hormone; increase lipid adrenal cortex (outer part) and protein breakdown; increase glucose synthesis from amino acids Adrenal androgens -insignificant in males; increase female sexual drive, growth of pubic and axillary hair hypoadrenalism -failure of adrenal cortex to produce adrenocortical hormones Addison’s disease -signs and symptoms: hyponatremia, hyperkalemia, sluggishness, weak muscles hyperadrenalism Adrenal medulla Cushing’s syndrome -abnormal secretion of cortisol and androgens; too much intake of steroid; buffalo torso Chromaffin cells -makeup the medulla and secrete (deposition of fat in the thoracic and upper abdominal epinephrine and norepinephrine region); moon face (edematous face) Epinephrine -aka adrenaline; principal hormone released from adrenal medulla Norepinephrine E. Pancreas, Insulin, and Diabetes Epinephrine mostly, some norepinephrine both an exocrine and endocrine gland long, narrow mass of glandular tissue cradled in the increases cardiac output; increases blood flow to skeletal duodenum muscles and heart; increases release of glucose and fatty consists of pancreatic islets (islets of Langerhans) acids into blood; in general, prepares body for physical activity fight-or-flight hormones Adrenal cortex Zona glomerulosa -outermost region; secretes mineralocorticoids; arranged in balls and loops Zona fasciculata -secretes glucocorticoids; straight rows Acinar cells -exocrine cells; secrete pancreatic Zona reticularis -innermost layer; secretes androgen juice/digestive juice called amylase Islets of Langerhans -endocrine cells; dispersed throughout the exocrine portion of pancreas; 3 types: Mineralocorticoids (aldosterone) o alpha cells -secrete glucagon o beta cells -secrete insulin -increase rate of sodium transport into body; increase rate of o delta cells -secrete somatostatin potassium excretion; secondarily favor water retention aldosterone -major mineralocorticoids hormone Insulin renin -a protein molecule from the kidney that are released because of low blood pressure; act as enzyme -increases uptake and use of glucose and amino acids; released that causes angiotensinogen to be converted to when blood glucose levels are elevated angiotensin I angiotensin-converting enzyme -a protein that causes satiety center -area of the hypothalamus that controls angiotensin I to be converted to angiotensin II appetite @medtech.files | by MAPB Chapter 9: Endocrine System  diabetes mellitus -the body’s inability to regulate blood ‑ functions both as an endocrine gland and lymphatic organ glucose levels within the normal range ‑ sites for the development of T lymphocytes o type 1 diabetes mellitus -occurs when too little insulin is secreted from the pancreas o type 2 diabetes mellitus -cause by either too few insulin receptors on target cells or defective receptors on target cells hyperglycemia -a condition where blood glucose levels become very high insulin shock -blood glucose become very low because of too much insulin injection or has not eaten after insulin injection Thymosin Glucagon promotes immune system development and function aids the development of WBC called T cells increases breakdown of glycogen and release of glucose into the circulatory system; released when blood glucose levels are low H. Pineal Gland Somatostatin ‑ small, pinecone-shaped structure located superior and posterior to the thalamus of the brain released in response to food intake; inhibits secretion of insulin and glucagon and inhibits gastric tract activity F. Testes and Ovaries Testes Testosterone Melatonin aids in sperm cell production, maintenance of functional reproductive organs, secondary sex characteristics, sexual sleep-inducing hormone behavior inhibits secretion of gonadotropin-releasing hormone, growth of body hair, voice changes, and male sexual drive thereby inhibiting reproduction Ovaries VIII. OTHER HORMONES Estrogens and Progesterone Prostaglandins -mediate inflammatory responses; -aid in uterine and mammary gland development and function, increase uterine contractions and ovulation; widely external genitalia structure, secondary sex characteristics, distributed in tissues of the body; function as intercellular sexual behavior, menstrual cycle signals Atrial natriuretic hormone (ANH or ANP) -secreted by estrogen -primary female sex hormone; female right atrium of the heart in response to elevated blood reproductive organ development pressure progesterone -thickens the lining of the uterus to nourish Erythropoietin -secreted by kidney in response to reduced the fertilized egg oxygen levels in the kidney; act on bone marrow to increase the production of RBC Human chorionic gonadotropin (HCG) -produces by the G. Thymus chorion of the embryo during early development; increases during pregnancy and is the bases of pregnancy ‑ located in the upper thoracic cavity test ‑ can only be found in children @medtech.files | by MAPB Chapter 9: Endocrine System  IX. EFFECTS OF AGING ON THE ENDOCRINE SYSTEM Age-related changes include a gradual decrease in o GH in people who do not exercise o melatonin o thyroid hormones (slight decrease) o reproductive hormones o thymosin Parathyroid hormones increase if vitamin D and Ca2+ levels decrease. There is an increase in type 2 diabetes in people with a familial tendency. X. DISEASES Condition Description Diabetes insipidus due to a lack of ADH from the posterior pituitary; results in excessive urination Hashimoto autoimmune disease in which thyroiditis thyroid hormone secretion can be decreased; metabolic rate is decreased, weight gain is possible, and activity levels are depressed Primary 90% of cases due to adenoma of the hyperparathyroidism parathyroid gland; causes blood PTH levels to increase above normal; elevated blood Ca2+ levels, weakened bones and possible muscular weakness Addison disease low levels of aldosterone and cortisol from the adrenal cortex; low blood Na+ levels, low blood pressure, and excessive urination Gestational diabetes develops in pregnant women due to actions of the placental hormone, human placental lactogen (HPL); in some women, HPL overly desensitizes the woman’s insulin receptors; causes elevated blood glucose levels in the mother and, if left untreated, excessive fetal growth @medtech.files | by MAPB Chapter 9: Endocrine System