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Synergists and Fixators Synergists— assist prime mover in accomplishing a movement Example = Brachioradialis and Brachialis during flexion of elbow Fixators-stabilize insertion points during a movement Interactions of Skeletal Muscles in the Body Muscles may have multiple site...

Synergists and Fixators Synergists— assist prime mover in accomplishing a movement Example = Brachioradialis and Brachialis during flexion of elbow Fixators-stabilize insertion points during a movement Interactions of Skeletal Muscles in the Body Muscles may have multiple sites of attachments Tendons attach muscle to bone Tendons pull on periosteum causing bone to move Origin-point of attachment that does not move Insertion-point of attachment that moves Prime mover-principal muscle involved in an action Other muscles may be involved in the movement as well Example-Biceps brachii is prime mover for flexion of elbow Agonists and Antagonists Agonist-primarily responsible for an action; also known as the prime mover Antagonist-muscle that produces the opposite movement of an agonist Triceps brachii is the antagonist of the biceps brachil Alternately, the biceps brachil is the antagonist of the triceps brachil Connective Tissue Wrapping of Skeletal Muscle Endomysium - around single muscle fiber Perimysium - around a fascicle (bundle) of fibers Patterns of Fascicle Organization Fascicle-a bundled group of muscle fibers Surrounded by perimysium Fascicle arrangement-arrangement of fascicles in skeletal muscle Influences force generated and range of motion of muscle Muscles of the Anterior Neck Assist in swallowing (deglutition) and speech Suprahyoid muscles-originate above hyoid bone Digastric, stylohyoid, mylohyoid, geniohyoid Infrahyoid muscles-originate below hyoid bone Omohyoid, sternohyoid, thyrohyoid, sternothyroid Interactions of Skeletal Muscles, Their Fascicle Arrangement, and Their Lever Systems Muscles That Move the Toes Sole supported by plantar aponeurosis Dorsal group Extensor digitorum brevis Plantar group Flexor digitorum brevis, abductor hallucis, abductor digiti minimi, quadratus plantae, lumbricals, flexor digiti minimi brevis, flexor hallucis brevis Shoulder Movements Movements possible at the shoulder include: Retraction Protraction Flexion Extension Abduction Adduction Internal rotation External rotation Synergists and Fixators * Synergists— assist prime mover in accomplishing a movement Example = Brachioradialis and Brachialis during flexion of elbow Fixators-stabilize insertion points during a movement Characteristics Used to Name Skeletal Muscle shape-named for their resemblance to a shape Muscle size-muscles in a group are sometimes named for their size relative to other muscles in the group Location-named for the region where they are located Orientation of fibers-orientation of the muscle fibers and fascicles is used to describe some muscles Muscles of the Thorax Diaphragm-divides abdominal and thoracic cavities Major muscle involved in breathing Intercostal muscles  External, internal, and innermost Located between ribs Assist in breathing Muscles That Move the Feet Posterior compartment - plantar flexion of foot Gastrocnemius, soleus, plantaris, popliteus, flexor digitorum longus, flexor hallucis longus, tibialis posterior Superficial muscles insert on calcaneal tendon Thigh Muscles That Move the Femur, Tibia, and Fibula Medial compartment - adduct the femur Adductor longus, adductor brevis, adductor magnus, pectineus, gracilis Anterior compartment - flex thigh, extend knee Quadriceps femoris = Rectus femoris, vastus lateralis, vastus medialis, vastus intermedius Posterior compartment - extend thigh, flex knee Hamstrings = Semitendinosus, semimembranosus, biceps femoris Muscles of the Pelvic Floor Pelvic diaphragm forms base of pelvic cavity Levator ani Consists of pubococcygeus and iliococcygeus Forms anal and urethral sphincters Ischiococcygeus Muscles That Move the Tongue Aid in speech, mastication, and swallowing Extrinsic muscles-originate outside of tongue Genioglossus, styloglossus, palatoglossus, hyoglossus Intrinsic muscles-originate inside tongue Muscles That Move the Wrist, Hand, and Fingers Superficial muscles Anterior muscles—most cause flexion of the hand or fingers Flexor carpi radialis, palmaris longus, flexor carpi ulnaris, flexor digitorum superficialis Posterior muscles-most cause extension of the hand or fingers Extensor radialis longus, extensor carpi radialis brevis, extensor digitorum, extensor digiti minimi, extensor carp ulnaris Muscles of the Posterior Neck and the Back Lateral flexion, extension, and rotation of head Splenius capitis, splenius cervicis Extension of vertebral column Erector spinae group-Iliocostalis, longissimus, spinalis Transversospinalis muscles Quadratus lumborum muscles Intrinsic Muscles of the Hand Originate and insert within hand Allow precise movements of fingers Thenar muscles-abductor pollicis brevis, opponeus pollicis, flexor pollicis brevis, adductor pollicis Hypothenar muscles-abductor digiti minimi, flexor digiti minimi brevis, opponens digiti minimi Intermediate muscles-lumbricalis, palmar interossei, dorsal interossei Gluteal Region Muscles That Move the Femur Most originate on pelvis and insert on femur Iliopsoas group-psoas major, iliacus Gluteus maximus, gluteus medius, gluteus minimus Tensor fascia latae Adductor longus, adductor brevis, adductor magnus Pectineus The Carpal Tunnel Many extrinsic muscles of the hand originate on the humerus Long tendons pass through carpal tunnel to connect to hand Retinacula surround tendons at wrist Flexor retinaculum on palmar surface- Extensor retinaculum on dorsal surface Muscles of the Perineum Perineum-space between pubic symphysis and coccyx Urogenital triangle - anterior of perineum  Includes external genitalia Anal triangle-posterior perineum Includes anus Muscles That Move the Forearm Allow flexion and extension of the elbow, supination, and pronation Elbow flexion-biceps brachii, brachialis, brachioradialis Elbow extension-triceps brachii, anconeus Muscles That Move the Head Head is balanced, moved, and rotated by neck muscles Sternocleidomastoid Lateral flexion and rotation of head Scalenes Synergists of sternocleidomastoid Movements of the Forearm, Wrist, and Fingers Forearm: Flexion, extension, pronation, and supination Wrist: Radial and ulnar deviation, flexion, extension, pronation, and supination Fingers: Flexion, extension, hyperextension, abduction, adduction, circumduction Posterior Muscles of the Abdomen Help form posterior wall of the abdomen Stabilize body and maintain posture Psoas major Iliacus Quadratus lumborum Muscles That Move the Humerus Muscles that originate on scapula Deltoid, subscapularis, supraspinatus, infraspinatus, teres major, teres minor, coracobrachialis Rotator cuff-formed by tendons of subscapularis, supraspinatus, infraspinatus, and teres minor Give structure and stability to shoulder joint Shoulder Muscles Anterior shoulder muscles Subclavius, pectoralis minor, serratus anterior Pull scapula forward (protract) Posterior shoulder muscles Trapezius, rhomboid major, rhomboid minor Pull scapula back (retract) Muscles That Move the Lower Jaw Allow for mastication (chewing) Masseter Temporalis Pterygoid muscles Muscles That Move the Humerus Pectoralis major and latissimus dorsi Prime movers of the humerus Convergent muscles Function of the muscles Produce movement Maintain posture Stabilize joints Generate heat Microscopic anatomy of skeletal muscle Sarcolemma - specialized plasma membrane " Sarcoplasmic reticulum - specialized smooth endoplasmic reticulum Tranmission of nerve impulse to muscles " Sodium rushing into the cell generates an action potential Once started, muscle contraction, cannot be stopped Skeletal Muscle Attachments * Epimysium blends into a connective tissue attachment Tendon - cord-like structure  Aponeuroses - sheet-like structure Sites of muscle attachment Bones Cartilages Connective tissue coverings Microscopic Anatomy of Skeletal Muscle Myosin filaments have heads (extensions, or cross bridges) Myosin and actin overlap somewhat " At rest, there is a bare zone that lacks actin filaments Sarcoplasmic reticulum (SR) - for storage of calcium Cells are multinucleate Nuclei are just beneath the sarcolemma Sarcomere Contractile unit of a muscle fiber " Organization of the sarcomere Thick filaments = myosin filaments Composed of the protein myosin " Has ATPase enzymes Myofibril * Bundles of myofilaments Myofibrils are aligned to givé distinct bands I band = light band A band = dark band Muscles of Facial Expression Originate on bones of skull and insert on skin Orbicularis oculi Orbicularis oris Occipitofrontalis Buccinator  Zygomaticus major Zygomaticus minor Nerve stimulus to muscles " Synaptic cleft - gap between nerve and muscle Nerve and muscle do not make contact Area between nerve and muscle is filled with interstitial fluid Skeletal muscles must be stimulated by a nerve to contract Motor unit One neuron Muscle cells stimulated by that neuron Characteristics Used to Name Skeletal Muscles Number of origins-number of origins a muscle has can differentiate it from other nearby muscles Action-named for the action the muscle achieves Attachment-attachment location can appear in a muscle name Origin is always first Grouping-some muscles exist in groups Neuromuscular junctions - association site of nerve and muscle the Sliding Filament theory of muscle Contraction " Activation by nerve causes myosin heads (crossbridges) to attach to binding sites on the thin filament Myosin heads then bind to the next site of the thin filament Cardiac Muscle Characteristics Has striations  Usually has a single nucleus Joined to another muscle cell at an intercalated disc (b) Involuntary Found only in the heart Smooth Muscle Characteristics. Has no striations Spindle-shaped cells Single nucleus Involuntary - no conscious control Found mainly in the walls of hollow organs Skeletal muscle Characteristics Most are attached by tendons to bones Cells are multinucleate Striated - have visible banding Voluntary - subject to conscious control Cells are surrounded and bundled by connective tissue Some Muscles are Named for Their Shape (Figure 12.5) Rhomboid muscles of back resemble the shape of a rhombus Deltoid muscle of the shoulder resembles an upside-down Greek letter delta Matching Activity i Match the term to the correct description.. Origin - D. Agonist - = Muscle that produces the opposite movement Attachment site that moves 3. Synergist - C C. Muscle that assists in 4. Antagonist - A accomplishing a movement 5. Insertion - B D. Attachment site that does not move E. Muscle that is primarily responsible for a movement Prefixes That Indicate Number (Table 12.2) Greek and Latin prefixes that indicate number: Uni = 1. Bi/Di = 2 Tri = 3 Quad = 4 Multi = many Anatomy of a Muscle Name Biceps brachii "Bi" = Latin for 2 "Ceps" derived from Latin for "head" Brachii refers to the brachium region Flexor carpi ulnaris Flexor derived from action; flexes the wrist Carpi derived from wrist Ulnaris due to location on ulna Characteristics if Muscles Muscle cells are elongated (muscle cell = muscle fiber) Contraction of muscles is due to the movement of microfilaments " All muscles share some terminology Prefix myo refers to muscle Prefix mys refers to muscle Prefix sarco refers to flesh Properties of Skeletal Muscle Activity Irritability - ability to receive and respond to a stimulus Contractility - ability to shorten when an adequate stimulus is received Origins of Skeletal Muscle Names Many skeletal muscles names are derived from Greek and Latin root words Names were based on easily observable characteristics of muscles Shape Size comparison Orientation of fibers  Number of origins Action of muscle Attachment location Grouping of muscle Microscopic Anatomy of Skeletal Muscie Myosin filaments have heads (extensions, or cross bridges) Myosin and actin overlap somewhat Movements of the Hip Movements of the thigh that occur at the hip include: Abduction Adduction Flexion Extension - Muscle Bellies Muscle bellies of fusiform muscles enlarge when the muscle contracts Forms an even larger muscle belly The Functions of the Nervous System Sensation-receiving information Integration-combining sensory information with higher cognitive functions Association areas accomplish this function Response—motor functions carried out by effectors Both conscious and unconscious nervous pathways exist Ganglia Groups of cell bodies in the peripheral nervous system (PNS) May be sensory or autonomic ganglia Posterior root ganglia-contain cell bodies of sensory (afferent) neurons Autonomic ganglia (discussed in Chapter 16) There are no motor ganglia Cross Sectional Anatomy of the Spinal Cord  Anterior median fissure-deep groove on anterior surface Posterior median sulcus—shallow groove on posterior surface Dorsal (posterior) nerve root Posterolateral sulcus Ventral (anterior) nerve root The Peripheral Nervous System The Cerebrum Left hemisphere Sulcus Makes up most of the mass of the brain Longitudinal fissure Gyrus Superficial cerebral cortex Gyri-folds (singular = gyrus) Sulci-grooves between folds (singular - sulcus) Fissures-deep grooves Cerebrum is divided into left and right hemispheres by longitudinal fissure The Central and Peripheral Nervous Systems Central Nervous System (CNS) Brain and spinal cord Housed within cranial cavity and vertebral cavity Peripheral Nervous System (PNS) Nerves outside of brain and spinal cord Outside of bony protection CNS and PNS are made of nervous tissue Neurons = cells capable of communication Glial cells = cells that provide structure and support to neurons The Brain Controls conscious experiences Regulates homeostasis Controls muscle movements Four major regions:. Cerebrum. Diencephalon. Brainstem. Cerebellum Nerves from what level of the spinal cord do not participate in plexuses? B. Thoracic Brainstem The three regions of the brainstem from superior to inferior are:. Midbrain. Pons. Medulla oblongata Brain Functions Primary areas-receive input or control output Association areas-link sensory information to memories Precentral gyrus-primary motor cortex Moves skeletal muscles Premotor area helps plan movements Postcentral gyrus-primary somatosensory cortex Processes sensation from skin and proprioception Nerves Cranial nerves Attach directly to brain 12 pairs in total May be purely motor, purely sensory, or a mixture of sensory and motor axons Spinal nerves Attach to the spinal cord 31 pairs in total Mixture of sensory and motor axons Functional Divisions of the Nervous System Sensory-sends information toward CNS Afferent (sensory) neurons Integration-occurs in brain and spinal cord  Interneurons Response-communicates with effectors Effector = muscle or organ that responds Achieved via efferent (motor) neurons The spinal cord extends the entire length of the vertebral column. B. False The Cerebral Cortex Lateral sulcus separates temporal lobe from other regions Central sulcus separates parietal lobes from frontal lobe Responsible for memory, emotion, language, and consciousness Hemispheres receive input from and control the opposite side Divided into lobes by fissures and Frontal lobe sulci: Frontal lobe Parietal lobe Temporal lobes Occipital lobe Insula The Spinal Cord Divided into regions that correspond to vertebral column Cervical, thoracic, lumbar, and sacral Intact spinal cord ends at first lumbar vertebrae (L1) Forms conus medullaris Continues as bundle of nerves called cauda equina Enlargements-occur where more axons are associated with the limbs Cervical enlargement-associated with the upper limb Lumbar enlargement-associated with the lower limb Amino Acid Neurotransmitters Include glutamate, GABA (gamma-aminobutyric acid) and glycine Released by glutamatergic, GABAergic, and glycinergic neurons Each has its own receptors  Eliminated from synapse by reuptake GABA leads to IPSPs Receptors are Cl- channels that hyperpolarize membrane Medulla Oblongata Most inferior structure of brain Houses fourth ventricle Pyramidal tracts-tracts decussate (cross over) leading to contralateral control of muscles Nuclei Cardiovascular center-regulates heart rate and blood pressure Respiratory center-responsible for ability to breathe Abdominal and thoracic motor centers-coordinate swallowing, coughing, sneezing Cranial Nerves CN I-olfactory nerve Sensory for smell CN Il-optic nerve Sensory for vision CN Ill-oculomotor nerve Motor nerve for eye movement CN IV-trochlear nerve Motor nerve for eye movement CN V- trigeminal Nerve CN IX-glossopharyngeal nerve Motor to pharynx; sensory for taste CN X-vagus nerve Sensory and motor functions of thoracic and abdominal viscera CN XI— accessory nerve Motor to sternocleidomastoid and trapezius CN XII-hypoglossal nerve Motor to tongue Gray Horns Gray matter of spinal cord resembles the letter H Posterior gray horns— contain axons of sensory neurons Anterior gray horns-contain cell bodies of motor neurons Lateral gray horns-contain autonomic neurons (sympathetic division) Only in thoracic, upper lumbar, and sacral regions Basal Nuclei  Basal nuclei in cerebrum connect to nuclei in brainstem Help form a motor pathway Influences likelihood of movement taking place Hippocampus and amygdala involved in long-term memory and emotional responses Occipital Lobe Located on posterior of cerebrum Processes visual information Responsible for visual memories Functions of CSF Functions of CS include: Delivers some nutrients Carries away some wastes Provides cushioning and protection to brain and spinal cord Volume of CS is regulated to prevent excess intracranial pressure Arachnoid membrane absorbs excess and returns it to blood The Diencephalon Connects cerebrum to rest of nervous system Regions of the diencephalon: Thalamus Hypothalamus Epithalamus Contains pineal gland Secretes melatonin, regulates sleep-wake cycles Subthalamus Contains subthalamic nuclei Thalamus Collection of nuclei Relays information between cerebral cortex, periphery, spinal cord, and brainstem Two egg-shaped masses connected by interthalamic adhesion Major sensory integration and processing area Involved in processing all sensations except smell (olfaction) Left and Right Temporal Lobes Located on the lateral/inferior regions of the brain Involved with hearing (auditory) and smelling (olfactory)  Insula are deep to temporal lobes Involved with taste (gustatory) sensations Spinal Nerves Connected to spinal cord Contain sensory and motor axons Sensory axons enter via posterior root Motor axons exit via anterior root 31 spinal nerves Named for level where they exit spinal cord C1-C8, T1-T12, L1-L5, S1-S5, one pair of coccygeal nerves Four Spinal Nerve Plexuses Spinal nerves from different levels combine to form plexuses T2-11 spinal nerves do not form plexuses Four spinal nerve plexuses Cervical plexus Brachial plexus Lumbar plexus Sacral plexus Pons Visible as bulge on anterior of brain stem Lies between midbrain and medulla oblongata Bridge between cerebellum and brain stem White matter on surface Deep gray matter Continuation of midbrain nuclei Controls rate of involuntary respiration Blood and the Nervous System Primary delivery mechanism of nutrients Blood vessels found between fascicles of peripheral nerves Cell bodies are highly protected Satellite cells provide additional protection to cell bodies in PNS Astrocytes form blood brain barrier (BBB) in CNS Most impermeable capillaries in body The Corpus Callosum Corpus callosum—white matter tract that bridges the cerebral hemispheres  Allows for communication between the two hemispheres The Limbic System Structures collectively process emotion Consists of hippocampus, amygdala, olfactory bulbs, cingulate gyrus, parahippocampal gyrus, fornix, mammillary bodies, and several nuclei Hippocampus-involved in memory formation and navigation Amygdala-processes the fear response Spinal Nerve Plexuses Spinal nerves emerge separately from spinal cord They quickly weave together to form plexuses Combinations of axons from multiple different spinal nerves Named for the regions they innervate Development of the Nervous System Neural tube forms along posterior of embryo Neural crest cells surround neural tube Will differentiate into neurons Neural tube becomes brain, eyes, and spinal cord Neural crest cells will become peripheral nerves Endoneurium covers: D. An individual axon Biogenic Amine Neurotransmitters Made from amino acids Serotonin, dopamine, norepinephrine and epinephrine Each has its own membrane receptors Elimination from synapse by reuptake Serotonin reuptake can be blocked by selective serotonin reuptake inhibitors (SSRIs) Used in treatment of depression and anxiety Development of the Central Nervous System Telencephalon becomes the cerebrum of the brain Diencephalon becomes retinas of the eyes, thalamus, and hypothalamus  Mesencephalon becomes midbrain Metencephalon becomes the pons and cerebellum Myelencephalon becomes the medulla oblongata Hypothalamus Collection of nuclei involved in regulating homeostasis Regulatory center of the autonomic nervous system (ANS) Regulates blood pressure, cardiac and smooth muscle contractions, and many activities of internal organs The "master" endocrine gland Regulates hormone secretion of the pituitary gland Regulates body temperature Regulates hunger and thirst Development of the Central Nervous System Neural tube forms three vesicles during first stage of development Called primary vesicles Forebrain, midbrain, hindbrain Primary vesicles become five secondary vesicles Forebrain becomes telencephalon and diencephalon Midbrain becomes the mesencephalon Hindbrain becomes the metencephalon and myelencephalon Basal Nuclei Located within white matter tracts Help control intensity and appropriateness of muscle movements Maybe involved regulation of emotions as well Striatum is composed of: Caudate Putamen Globus pallidus External and internal segments Classification Based on Innervation Based on type of location nerve innervates Somatic nervous system (SNS) Responsible for conscious perception and voluntary motor responses Innervates skeletal muscle Autonomic nervous system (ANS) Responsible for involuntary control of body Helps maintain homeostasis  Innervates smooth muscle, cardiac muscle, and glands White Columns White matter of spinal cord arranged into columns Ascending tracts send sensory info to CNS Descending tracts send motor info to muscles Posterior white columns Anterior white columns Lateral white columns Cholinergic Neurotransmitters Acetylcholine is released by cholinergic neurons Acts on two types of receptors: Nicotinic receptors - found at NMJ, adrenal medulla, and some autonomic synapses Muscarinic receptors - found at autonomic synapses Elimination by acetylcholinesterase Enzyme that breaks down acetylcholine Midbrain Cerebral peduncles-white matter tracts in midbrain Corpora quadrigemina-four "bumps" on midbrain Inferior colliculi-aid in processing auditory stimuli Superior colliculi-combine sensory information with motor output Red nucleus Substantia nigra-inhibits motor neurons to help control smooth motor movements Red nuclei-contribute to reticular formation to help control attention and state of wakefulness Graded Potentials Small changes in resting membrane potential Can vary in size Caused by mechanically-gated and ligand-gated membrane channels Occur along dendrites and cell body Membrane channels open to allow Nations to enter neuron Depolarization occurs as inside of neuron becomes more positively charged White Matter Tracts  Deep to gray matter of cerebral cortex White matter tracts Association tracts Arcuate fibers Longitudinal fasciculi Commissural tracts Projection tracts Connective Tissue Protection of CNS Cranium protects brain Vertebral column protects spinal cord Membranes Meninges protect the brain and spinal cord Dura mater, Arachnoid mater, Pia mater Meningeal Spaces Subarachnoid space Contains cerebrospinal fluid (CSF) CS cushions brain and spinal cord Potential spaces Not normally present, but may form Subdural space Between dura mater and arachnoid mater Epidural space Between dura mater and cranial or vertebral bones Cerebrospinal Fluid Cerebrospinal Fluid (CSF) Derived from blood Produced by ependymal cells in ventricles Choroid plexus-tangle of capillaries that are surrounded by a lining of ependymal cells Circulates through ventricles and down into central canal to protect spinal cord Glial Cells Supportive cells found throughout nervous system Can multiply and divide Glial cells of the CNS  Astrocytes, oligodendrocytes, microglia, ependymal cells Glial cells of the PNS Satellite cells, Schwann cells The Action Potential Begins at axon hillock and travels toward axon terminals Membrane channels in dendrites and cell body respond to stimuli Produce graded potentials Depolarizing graded potentials allow positively charged sodium ions (Nat) to enter neuron Depolarization occurs as sodium ions make interior of neuron more positively charged Summation Spatial summation-graded potentials occurring at several different synapses over short timeframe Temporal summation— graded potentials occur at one synapse over short timeframe Neurotransmitters Effect depends on receptor Same neurotransmitter can have different effects on different cells Mechanically-Gated lon Channels Mechanically-gated channels— open and close in response to pressure Detected by distortions in cell membrane Ligand-Gated Channels Ligand-gated channels-open and close due to binding of an extracellular messenger molecule (ligand) Voltage-Gated Channels Voltage-gated channels-open and close in response to changes in electrical potential A change in membrane potential can open or close voltage-gated channels Anatomical Patterns of Nervous Tissue Anatomical patterns of the PNS Ganglion-collection of neuron cell bodies Nerve-bundle of axons May refer to the same tract of the CNS  Difference is location The Na+/K+ Pump Plays critical role in resting membrane potential of neurons Pumps 3 Nations out of cell and 2 K+ ions into cell using energy from ATP Builds chemical and electrical gradient across membrane Communication between Neurons Types of Graded Potentials Postsynaptic potential (PSP)— graded potentials occurring in neuron that received signals Excitatory (EPSP)-moves membrane toward threshold Depolarizes membrane Inhibitory (IPSP)-moves membrane away from threshold Hyperpolarizes membrane Anatomical Classification of Neurons Unipolar neuron-only one process from cell body that splits into an axon and dendrites Most sensory neurons Bipolar neuron-two processes, one dendrite and one axon, extend from cell body Sensory for smell and vision Multipolar neuron-many dendrites and one axon Majority of neurons in body Resting Membrane Potential Resting membrane potential of neuron is -70 mV Established by: Unequal distribution of Nat and K+ ions across cell membrane From activities of sodium/potassium pumps Negatively charged proteins inside of cell Make interior of neuron more negative Exit of K+ ions due to leak channels Further loss of positive charges from interior of cell Classes of Membrane Channels Ligand-gated channels-open and close due to binding of a molecule (ligand)  Mechanically-gated channels-open and close in response to pressure Voltage-gated channels-open and close in response to changes in electrical potential Leak channels-always open or randomly open and close No single stimulus influences their activity Connective Tissue Protection of PNS Epineurium-covers outer surface of entire nerve Perineurium-covers fascicles Fascicles-bundles of axons Endoneurium-covers individual axons Glial Cells of the PNS Satellite cells-regulate extracellular environment Cluster around cell bodies  Similar in function to astrocytes of CNS Schwann (neurilemma) cells - myelination Similar in function to oligodendrocytes of CNS Glial Cells of the CNS Astrocytes—regulate extracellular environment Make up blood-brain barrier (BBB) Oligodendrocytes-myelination Microglia-immune defense and waste removal Ependymal cells-produce cerebrospinal fluid (CSF) Circulation of CSF CS is produced in the ventricles Lateral ventricles located within each cerebral hemisphere Interventricular foramen drains CSF to third ventricle Cerebral aqueduct drains CSF to fourth ventricle CSF from fourth ventricle drains into central canal of spinal cord Graded Potentials Graded potentials are additive-smaller graded potentials can add together; this is called summation Depolarization of graded potentials-move membrane toward threshold Nat or Ca++usually enters neuron Hyperpolarization graded potentials-move membrane away from threshold K+ may exit or Cl- enters neuron If threshold is reached, action potential is guaranteed to move down axon Threshold value is -55 mV The Meninges of the CNS Dura mater is most superficial Thick and collagen-rich Separates into two layers in certain locations Arachnoid mater is deep to dura mater Encases brain, spinal cord, and CSF Pia mater is tightly adhered to surface of the brain The value of the threshold voltage is: C. -55 mV Dural Venous Sinuses Cerebral vern. Thin-walled veins located between layers of dura mater Collect venous blood from brain to heart. Superior sagittal sinus. Inferior sagittal sinus. Occipital sinus. Straight sinus:. Transverse sinuses Cholinergic Neurotransmitters Acetylcholine is released by cholinergic neurons Acts on two types of receptors: Nicotinic receptors - found at NMJ, adrenal medulla, and some autonomic synapses Muscarinic receptors - found at autonomic synapses Elimination by acetylcholinesterase Enzyme that breaks down acetylcholine Anatomical Patterns of Nervous Tissue Anatomical patterns of the CNS Gray matter-unmyelinated regions with mainly cell bodies and dendrites Nucleus—collection of cell bodies White matter —myelinated regions with mainly axons Also called a trac Infections of the central nervous system are difficult to treat. How do the glial cells contribute to the difficulty of treating central nervous system infections? Astrocytes make up the blood brain barrier (BBB). The blood brain barrier protects the central nervous system by preventing the entry of various molecules including antimicrobials that are used to treat infections. Neurotransmitters Each neuron only releases one neurotransmitter Categories of Neurotransmitters: Cholinergic Acetylcholine Amino acids Glutamate, GABA (inhibitory), glycine Biogenic amines  Serotonin, dopamine, epinephrine, norepinephrine Refractory Periods The period after an action potential is generated and before another can retractory period begin Absolute refractory period-no action potential possible Relative refractory period-second action potential possible with strong stimulus Membrane potential must be between -55 mV and -70 mV Myelin Insulation for axons Allows axon to conduct electrical signals faster Oligodendrocytes in CNS Multiple processes myelinate different areas Schwann (neurilemma) cells in PNS Singular cells myelinate each section Changes in Resting Membrane Potential As ions flow into and out of neurons, membrane potential changes Changes that cause the charge difference to decrease are called depolarizing Changes that cause the charge difference to increase are called hyperpolarizing Repolarization occurs if depolarization is followed by a return to a polarized state Changes can be caused by ions channels that allow ions to move Some channels are open and allow ions to freely move Some channels open and close in response to various stimuli Propagation of an Action Potential down an Unmyelinated Axon "All or nothing" event Propagation in unmyelinated axon is continuous conduction Nations gather at axon hillock Nat voltage-gated channels open and Nations flow into neurón Each section of axon depolarizes in sequence Speed of Action Potential Propagation Speed of action potential movement is influenced by  Myelination Faster conduction in myelinated versus unmyelinated axons Size of electrochemical gradient Diameter of axon Faster in larger axons Larger axons have less resistance to ion movement The Term "Nucleus" "Nucleus" is used in a variety of ways The nucleus of an atom contains protons and neutrons The nucleus of a cell contains DNA Nucleus in the brain is a cluster of unmyelinated tissue Inactivation of Nat Voltage-Gated Channels Na voltage-gated channels close when the membrane potential reaches +30 mV Inactivation gates stop inflow of Nat Stops depolarization Inactivation gates not required on K+ voltage-gated channels K+ exits cell leading to repolarization Synaptic Events Neurotransmitter binds to receptors on postsynaptic neuron Causes graded potential Neurotransmitter eliminated from synapse by:. Diffusion. Reuptake. Breakdown Which of the following is not a method for eliminating neurotransmitters from a synapse? Exocytosis Synapses Areas where neurons communicate Chemical synapses—release neurotransmitters Electrical synapses-direct connections where ions move from one cell to another Less common in the human nervous system Anatomy of a Synapse Events of chemical synaptic transmission Anatomy of Neurons Synapses - junctions where neurons communicate with other cells Axons may be wrapped in myelin Gaps in myelin create neurofibril nodes Multiple axonal branches (axon terminals) allows a single neuron to communicate with multiple cells Membrane Potentials The cell membrane is a barrier to ionic movement Different charges can build up inside and outside of neurons Sodium/potassium (Na*/K*) pumps play a key role Pumps three sodium ions out of cell and two potassium ions into cell Creates a relatively negative internal environment of neuron Membrane becomes polarized Inside and outside of cell have different charges Communication Within the Nervous System Once a stimulus is detected, communication depends on electrical signaling Occurs due to the movement of ions lon movement generates action potentials Action potentials lead to release of neurotransmitters Chemicals that relay messages from neurons Functional Classification of Neurons Sensory neurons-collect and send information to CNS Interneurons-integrate and process information from sensory neurons Motor neurons-communicate with effectors to make them perform an action Action Potential Propagation down a Myelinated Axon Propagation in myelinated axons is saltatory conduction Faster than continuous conduction Na+ions gather at axon hillock Na+ions move toward axon terminals Only depolarize neurofibril nodes  Myelinated areas lack voltage-gated channels Myelin insulates sections of axon, preventing loss of Na+ions Anatomy of Sensory Information Painful stimulus causes nerve to send information to CNS Interneuron in spinal cord synapses with neuron in thalamus Thalamus relays information to primary somatosensory area where it is interpreted as pain Cranial Dural Septa Dura mater folds to separate and stabilize brain within cranial cavity Falx cerebri - separates right and left sides of brain Tentorium cerebelli - forms "roof" over cerebellum Falx cerebelli - separates 2 halves of cerebellum  Diaphragma sellae- forms "roof" over sella turcica Anatomy of Neurons Responsible for communication within nervous system Cell body-houses organelles like nucleus, nucleolus, ribosomes, and endoplasmic reticulum Dendrites—receive signals from other neurons Axon—begins at axon hillock Sends signals to other neurons Each neuron has one axon Brain Functions Primary visual and visual association areas-located in occipital lobe Primary auditory and auditory association areas-located in temporal lobes Primary olfactory and olfactory association areas —located in temporal lobes Primary gustatory and gustatory association areas-located in insula Brain Functions Language and Speech Mainly located on left side of cerebrum Broca's area-plans movements and regulates breathing for speech Wernicke's area-recognition and understanding of writing or speech Intellect and personality Involves prefrontal cortex One of last areas to mature The Nervous System Anatomy of Spinal Nerves Spinal nerves divide soon after leaving the spinal cord Dorsal rami - serve the skin and muscles of the posterios trunk Ventral rami - forms a complex of networks (plexus) for the anterior Spinal Nerves There is a pair of spinal nerves at the level of each vertebrae for a total of 31 pairs Spinal nerves are formed by the combination of the ventral and dorsal roots of the spinal cord - Spinal nerves are named for the region from which they arise- Autonomic Nervous System The involuntary branch of the nervous system Consists of only motor nerves Divided into two divisions Sympathetic division – Parasympathetic division Differences Between Somatic and Autonomic Nervous Systems Nerves Somatic - one motor neuron Autonomic - preganglionic and postganglionic nerves Effector organs Somatic - skeletal muscle Autonomic - smooth muscle, cardiac muscle, and glands Differences Between Somatic and Autonomic Nervous Systems Neurotransmitters Somatic - always use acetylcholine Autominic - use acetylcholine, epinephrine, or norepinephrine Pineal Gland Found on the third ventricle of the brain Secretes melatonin Helps establish the body's wake and sleep cycles May have other as-yet-unsubstantiated functions Anatomy of the Sympathetic Division * Originates from I, through L2 Ganglia are at the sympathetic trunk (near the spinal cord) * Short pre-ganglionic neuron and long postganglionic neuron transmit impulse from - CNS to the effector  Norepinephrine and epinephrine are neurotransmitters to the effector organs Hormonal Stimuli of Endocrine Glands Endocrine glands are: activated by other hormones Parathyroid Glands Tiny masses on the posterior of the thyroid Secrete parathyroid hormone Stimulate osterclasts to remove calcium from bone Stimulate the kidneys and intestine to absorb more calcium Raise calcium levels in the blood Mechanisms of Hormone Action Hormones affect only certain tissues or organs (target cells or organs) Target cells must have specific protein receptors Hormone binding influences the working of the cells Control of Hormone Release Hormone levels in the blood are maintained by negative feedback A stimulus or low hormone levels in the blood triggers the release of more hormone Hormone release stops once an appropriate level in the blood is reached Developmental Aspects of the Endocrine System Most endocrine organs operate smoothly until old age Menopause is brought about by lack of efficiency of the ovaries Problems assogiated with reduced estrogen are common Growth hormone production declines with age Many endocrine glands decrease output with age Anatomy and Physiology Chapter 15: The Somatic Nervous System Sensory Pathways * Sensory information is processed through a series of neurons – Sensory receptor/Primary neuron – seconcary neuron  – Tertiary neuron " May result in conscious sensation or motor response Motor Pathways Motor responses are carried out by a series of neurons also Secondary neuron Primary neuron Decussates/crosses over to the opposite side of the body Decussation leads to many brain injuries affecting the apposite side a the body Reflexes Connections between sensory and motor neurons * Synapse between neurens occurs within. CNS Do not include higher brain centers Do not include involvement of conscious or voluntary aspects of movement Categorizing Reflexes Spinal-synapse within spinal cond Cranial-involve the brain Intrinsic-develop before birth Learned-develop after birth Somatic-effector is skeletal muscle Visceral-effector is smooth or cardiao muscle Ipsilateral-begins and ends on same side of body Contralateral- begins and ends on opposite sides of the body Simple Spinal Reflex Arc * Reflex starts with sensory receptor Stimulus brings recepton to threahole Action potentials travel along the axon the sensory nerve and synapse with a motor neuron in the spinal cord No nigher brain centers involved Neurotransmnitters are reueased by the sensory neuron and bind to the cell Body of the motor neuran Directly leads to an action potentiall in motor neuran  Muscle contraction occurs Ipsilateral versus Contralateral Reflexes Ipsilateral-begins and ends on same side of body * Contralateral- begins and ends on opposite sides of the body Functional Classifications of Reflexes * Withdrawal - painful stimuli directly cause contraction of skeletal muscle Stretch - activation of muscle spindles prevents overstretching of muscles * Tendon - Golgi tendon organs prevent overstretenne of tencons Crossed-extensor - acTiatos tho opposite (contralateral) side of the body Withdrawal Reflexes (Figure 15.4) Painful stimuli directly cause contraction of skeletal muscle Causes the body to withdraw from the painful stimulus Polysynaptic sensory neuron Interneuron within spina, cord * Motor neuron Stretch Reflexes (Figure 15.5) Stretching of skeletal muscle causes activation of muscle spindle Muscle contracts in response to prevent overstretching Monosynaptic Sensory neuron synapses with motor neuron in spina. cord Stretch Reflexes (Figure 15.5 Stretching of skeletal muscle causes activation of muscle spindle Muscle contracts in response to prevent overstretching Monosynaptic † Sensory neuron synapses with motor neuron in spinal cord Crossed-extensor Reflexes (Figure 15.3B) – Reflexes activate the opposite of the body  Usually in response to painful stimuli Polysynaptic Sensory neuron synapses wich interneurons Interneurons may synapse at different levels within spinal cord Multiple motor neurons involved What advantages do reflexes offer the body? Can you think of any disadvantages of reflexes? Reflexes offer the advantage of being able to respond quickly to stimuli in a manner that protects the body from injury or damage Reflexes are primarily advantageous because they protect the body They may become a cisadvantage if the response is extreme and causes harm to the body. Sensory Receptors Anatomy of a Sensation * Receptors can detect a variety of stimuli/sensations Different stimuli/sensations activate different receptors Primary somatosensory cortex Interprets (processes) signals Determines location of stimulus Intensity of stimulus determined by frequency of action potentials Characteristics of Sensory Receptors Transduce stimuli into an electrical charge interpreted by your brain Results in a sensation Adaptation allows receptors to become less sensitive to stimuli over time Phasic receptors can adapt quickly Tonic receptors adapt slowly/not at all. Receptors are found all over your body in different forms Adaptation (Figure 15.7) Adaptation allows receptors to become less sensitive to stimuli over time Action potential generation slows down Phasic receptors adapt quickly Tonic receptors do not adapt or do so slowly Types of Receptors (1 of 2) * Based on type of stimuli, source of stimuli, or distribution  Type of stimuli * Chemoreceptors-detect chemical stimuli Osmoreceptors-detect solute concentrations in bodily fluids Thermoreceptors - detect temperature Mechanoreceptors-detect physical stimuli like pressure and vibration Baroreceptors- detect pressure Nociceptors-detect pain Photoreceptors detect photons of light - Only found in the eye Types of Receptors (2 of 2) Source of Stimuli Exteroceptors-stimuli from external environment Interceptors-stimuli from internal organs and tissues Proprioceptors-moving body parts Distribution General sense receptors-found all over the body Special sense receptors-limited to the head Used for vision, taste, hearing, olfaction, and balance Categories of General Senses Can be detected everywhere in/on the body Pressure, vibration, light touch, tickle, itch, temperature, pain, and proprioception Receptors are throughout the body (skin, muscles, tendons, joints, organs) Unencapsulated receptors Dendrites enmeshed by surrounding tissue Encapsulated receptors Dendrites wrapped to enable function Categories of General Senses Can be detected everywhere in/on the body Pressure, vibration, light touch, tickle, itch, temperature, pain, and proprioception Receptors are throughout the body (skin, muscles, tendons, joints, organs) Unencapsulated receptors Dendrites enmeshed by surrounding tissue Encapsulated receptors Dendrites wrapped to enable function Unencapsulated Receptors Free nerve endings detect pain and temperature Merkel cells in skin used for discriminatory touch Hair follicle receptors in the skin detect movement of hair Thermoreceptors detect temperature Also respond to chemicals Capsaicin activates thermoreceptors Interpreted as increase in temperature Encapsulated Receptors Lamellated corpuscles in dermis detect deep pressure Tactile corpuscles in dermis detect light pressure Bulbous corpuscles detect stretching of skin Each receptor has a receptive field Tissue space it receives information from Higher density of small receptive fields leads to more acuity Acuity—how accurately brain interprets stimulus Receptive Fields (Figure 15.9) Each receptor has a receptive field Tissue area where sensory receptors are distributed Fewer receptors with a larger receptive field decreases acuity Fewer signals sent to CNS Greater number of receptors with smaller receptive fields increases acuity More signals sent to CNS Pain Prevents further damage to tissues and cells of the body Detected by nociceptors Somatic pain and visceral pain can share the same pathway Referred pain occurs when the brain becomes confused as to the origin of the pain Phantom pain occurs when a limb is lost  Pathway remains intact and CNS continues to interpret signals Referred Pain (Figure 15.10) Somatic pain is perceived when stimulus is visceral Pain originating in heart may cause pain in left arm Occurs because somatic pain and visceral pain can share same pathway Brain lacks acuity to distinguish origin of pain Opioids and Pain Nociceptors release substance P to a secondary neuron to communicate pain An inhibitory neuron synapses at the nociceptor to release natural endorphins that bind to opioid receptors on the nociceptor Decreases release of substance P and decreases pain Opioids mimic effect of endorphins to decrease pain Opioid receptors also found in brain centers for addiction and respiration Which of the following types of receptors is used to detect deep pressure? B. Lamellated corpuscles Vision Accomplished by photoreceptors located within eye Light is transduced into electrical signals interpreted by the brain Light passes through cornea of eye Iris regulates size of pupil to adjust amount of light entering eye Lens focuses light where it is received with most acuity Photoreceptors transduce photons of light into electrical signals Eye Anatomy (Figure 15.11) Orbit, eyelashes, and eyebrows protect the eye Conjunctiva Stratified columnar epithelium Helps protect and keeps eye moist Lacrimal glands Produce tears to keep eye moist Cengage Orbit Eyebrow Conjunctiva Eyelashes Cornee Tunics of the Eye ge 15.923  Fibrous layer contains sclera and cornea Vascular layer Rich blood vessels Iris is smooth muscle around pupil Controls size of pupil and amount of light entering eye Ciliary body alters shape of lens for better visual acuity Neural layer (retina) Nervous tissue for photoreception Cavities of the Eye Anterior chamber Between cornea and lens Contains aqueous humor (watery fluid) Posterior chamber Behind the lens, extends to retina Contains vitreous humor (jellylike) Retina Contains cells that transduce light Rods and cones in posterior layer of retina transduce light Release neurotransmitters onto bipolar cells Bipolar cells form synapses with ganglion cells Axons of ganglion cells form optic nerve Comparison of Color Sensitivity (Figure 15.14) Rods contain rhodopsin Sensitive to a variety of wavelengths Only detects white and black Cones contain pigments called opsins Sensitive to specific wavelengths of light Used to detect red, green, and blue Dark and Light Adaptation Dark adaptation Decreased vision when moving from a brightly lit environment to a dark environment In bright light, rods are highly active and store rhodopsin Rods take a few moments to activate in dark space Light adaptation Decreased vision when moving from a dark environment to a brightly lit environment Rods and cones send signals initially leading to a glare  Signals adjust and rods turn off while cones refine their signal Density of Cones in Retina Periphery of retina has higher density of rods Proportion of cones in retina increases posteriorly Macula lutea has a high density of cones Fovea centralis is center of macula lutea with highest density of cones Lens focuses light on fovea centralis for greatest visual acuity Pathway of Visual Information (Figure 15.15) Lateral geniculate nucleus of thalamus edits visual information Info then sent to primary visual cortex in occipital lobe Some axons of optic nerve cross to opposite of brain at optic chiasm Right visual field processed by left side of occipital lobe Left visual field processed by right side of occipital lobe Taste (Gustation) (Figure 15.16) A chemical special sense Recognized tastes include: Sweet, salty, sour, bitter, umami, and fat Papillae on tongue contain taste buds Taste buds contain taste receptors Transduce chemicals in food into taste Basal epithelial cells replace damaged taste receptors Detection of Tastes Saliva dissolves molecules so more chemicals reach taste receptor cells Salty is detected when Na+ ions activate taste cell receptors Sour is detected when H+ ions activate taste cell receptors Sweet is detected when glucose activates taste cell receptors Other monosaccharides and artificial sweeteners can activate sweet receptors Bitter is detected by 23 different taste receptors Varies with each individual Umami is detected when L-glutamate activates taste cell receptors Monosodium glutamate (MSG) can also activate umami receptors Pathway of Taste Information (Figure 15.17) 57) Taste information travels to the CNS along cranial nerves Glossopharyngeal, Facial, and  Vagus nerves Nerves converge at medulla oblongata Information is next sent to thalamus Thalamus sends information to insula to be processed Smell (Olfaction) (Figure 15.18) A chemical special sense Odorant molecules bind to olfactory receptors in olfactory epithelium Olfactory neurons pass through cribriform plate to form olfactory bulb Axons gather to form olfactory tract Olfactory tract projects to different regions of the brain Primary olfactory cortex in temporal Lobe, limbic system, and hypothalamus External Ear (Figure 15.19) * Hearing is the transduction of sound waves into electrical signals interpreted by brain Auricle, ear canal, and tympanic membrane make up external ear * Auricle and auditory canal (external acoustic meatus) funnels the sound waves toward the tympanic membrane Tympanic membrane vibrates in response Auricle, ear canal, and tympanic membrane make up external ear Middle Ear (Figure 15.19) * The middle ear contains the ossicles: Malleus, incus, and stapes Ossicles attached to tympanic membrane amplify vibrations Stapes rests against oval window Oval window is door to inner ear Middle Ear connects to pharynx via auditory (Eustacian) tube The Inner Ear (Figure 15.19) The inner ear is within the temporal bone Consists of cochlea, vestibule. and semicircular canals Cochlea involved in hearing Vestibule and semicircular canals involved in balance The Inner Ear (Figure 15.19) The inner ear is within the temporal bone Consists of cochlea, vestibule. and semicircular canals Cochlea involved in hearing Vestibule and semicircular canals involved in balance The Function of the Ossicles (Figure 15.20) Ossicles amplify vibrations Middle ear is air filled space Inner ear is fluid filled space – Vibrations must have more force to move fluid through The cochlea Components of The Inner Ear (Figure 15.21) The malleus, incus, and stapes amplify vibrations of tympanic grane Oval window receives amplified vibrations Vibrations are transduced into electrical signals by cochlea Scala vestibuli, scala tympani, and cochlear duct are the tubular portions of the cochlea The Cochlea (Figure 15.22) * Three separate tubes that are rolled together Scala vestibuli - filled with perilymph – Scala tympani - filled with perilymph Cochlear duct - filled with t endolymph Contains spiral organs that transduce movement of scala Cympani and scaa vestibuli The Basilar Membrane (Figure 15.23) * Width of basilar membrane varies Causes different locations to move in response to different sound wave frequencies Higher pitched sounds move region close to base of cochlea – Lower pitched sounds mave region close to tip of cochlea – Alows us to aetect differenees In sound like volume, pitch, and Lone Pathway for Auditory Information (Figure 15.24) Axons of hair cells form cochlear branch of vestibulacochlear nerve * Synapses with cochlear nucleus in medulle pblongata – Axons from medulla synapse in the superior olivary nucleus of the pons – Signal then carried to miabrain and thalamus – Primary auditory cortex in temporal labe ultimately processes information Equilibrium (Balance) (Figure 15.25)  Maintained by hair cells of vestibule and semicircular canals Sensitive to head movement and body position Static equilibrium Sense of head position and acceleration Maintained by vestibule Pathway for Equilibrium * Axons of hair cells form vestibular branch of vestibulocochlear nerve Axons of vestibulocochlear nerve terminate in nuclei within pons and medulla – Nuclei relay information throughout CNS Endocrine System Second messenger system of the body Uses chemical messages (hormones) that are released into the blood Hormones control several major processes Reproduction Growth and development Mobilization of body defenses Maintenance of much of homeostasis Regulation of metabolism Hormone Overview Hormones are produced by specialized cells Cells secrete hormones into extracellular fluids Blood transfers hormones to target sites These hormones regulate the activity of other cells Humoral Stimuli of Endocrine Glands Changing blood levels of certain ions stimulate hormone release Other Hormone-Producing Tissues and Organs Parts of the small intestine Parts of the stomach Kidneys Heart Many other areas have scattered endocrine cells Development Aspects of the Nervous System The nervous system is formed during the first month of embryonic development Any maternal infection can have extremely harmful effects The hypothalamus is one of the last areas of the brain to develop Thymus Located posterior to the sternum Largest in infants and children Produces thymosin Matures some types of white-blood cells * Important in developing the immune system Nonsteroid Hormone Action Hormone binds to a membrane receptor « Hormone does not enter the cell Sets off a series of reactions that activates an enzyme * Catalyzes a reaction that produces a second messenger molecule Oversees additional intracellular changes to promote a specific response Autonomic Functioning Parasympathetic - housekeeping activites Conserves energy Maintains daily necessary body functions Remember as the "D" division - digestion, defecation, and diuresis Development Aspects of the Nervous System No more neurons are formed after birth, but growth and maturation continues for several years The brain reaches maximun weight as a young adult Hormones of the Adrenal Cortex Sex hormones Produced in the inner layer of the adrenal cortex Androgens (male) and some estrogen (female) Growth Hormone (GH) General metabolic hormone * Major effects are directed to growth of skeletal muscles and long bones Causes amino acids to be built into proteins Causes fats to be broken down for a source of energy Endocrine. Function of the Placenta Produces hormones that maintain the pregnancy " Some hormones play a part in the delivery of the baby Produces HCG in addition to estrogen, progesterone, and other hormones Hormones of the Ovaries Estrogens Produced by Graafian follicles or the placenta Stimulates the development of secondary female characteristics Matures female reproductive organs Helps prepare the uterus to receive a fertilized egg Helps maintain pregnancy Prepares the breasts to produce milk Functions of Other Anterior Pituilary Hormones Gonadotropic hormones (continued) Luteinizing hormone (LH) Triggers ovulation Causes ruptured follicle to become the corpus luteum Stimulates testosterone production in males Referred to as interstitial cell-stimulating hormone (ICSH) Functions of Other Anterior Pituitary Hormones Gonadotropic hormones Regulate hormonal activity of the gonads Follicle-stimulating hormone (FSH) Stimulates follicle development in ovaries Stimulates sperm development in testes Hormones of the Adrenal Cortex  Mineralocorticoids (mainly aldosterone) Produced in outer adrenal cortex Regulate mineral content in blood, water, and electrolyte balance Target organ is the kidney Production stimulated by renin and aldosterone Production inhibited by atrial natriuretic peptide Calcitonin Decreases blood calcium levels by causing its deposition on bone, Antagonistic to parathyroid hormone Produced by C (parafollicular) cells Neural Stimuli of Endocrine Glards Nerve impulses stimulate hormone release Most are under control of the sympathetic nervous system Steroid Hormone Action * Diffuse through the plasma membrane of target cells Enter the nucleus Bind to a specific protein within the nucleus Bind to specific sites on the cell's DNA Activate genes that result in synthesis of new proteins Hormones of the Adrenal Medulla Produces two similar hormones (catecholamines) Epinephrine Norepinephrine These hormones prepare the body to deal with short-term stress Thyroid Gland Found at the base of the throat Consists of two lobes and a connecting isthmus Produces two hormones Thyroid hormone Calcitonin Pancreatic Islets The pancreas is a mixed gland The islets of the pancreas produce hormones * Insulin - allows glucose to cross plasma membranes into cells from beta cells Glucagon - allows glucose to enter the blood from alpha cells These hormones are antagonists that maintain blood sugar homeostasis Hormones of the Posterior Pituitary Oxytocin Stimulates contractions of the uterus during labor Causes milk ejection Antidiuretic hormone (ADH) Can inhibit urine production In large amounts, causes vasoconstriction leading to increased blood pressure (vasopressin) Hormones. of the Ovaries Progesterone Produced by the corpus luteum *Acts with estrogen to bring about the menstrual cycle Helps in the implantation of an embryo in the uterus Effects Caused by Hormones Changes in plasma membrane permeability or electrical state Synthesis of proteins, such as enzymes Activation or inactivation of enzymes Stimulation of mitosis Hormones of the Adrenal Cortex Glucocorticoids (including cortisone and cortisol) Produced in the middle layer of the adrenal cortex Promote normal cell metabolism Help resist long-term stressors Released in response to increased blood levels of ACTH Hormones of the Anterior Pituitaly Six anterior pituitary hormones Two affect non-endocrine targets Four stimulate other endocrine glands (tropic hormones) Characteristics of all anterior pituitary hormones Proteins (or peptides) Act through second-messenger systems Regulated by hormonal stimuli, mostly negative feedback Adrenal Glands Two glands Cortex - outer glandular region in three layers Medulla - inner neural tissue region Sits on top of the kidneys Pituitary Gland Size of a grape Hangs by a stalk from the hypothalamus Protected by the sphenoid bone Has two functional lobes *Anterior pituitary - glandular tissue Posterior pituitary - nervous tissue Thyroid Hormone Major metabolic hormone Composed of two active iodine-containing hormones Thyroxine (T4) - secreted by thyroid follicles Triiodothyronine (Ts) - conversion of T, at target tissues Pituitary - Hypothalamus Relatiohship Release of hormones is controlled by releasing and inhibiting hormones produced by the hypothalamus Hypothlamus produces two hormones that are transorted to neurosecretory cells-of the posterior pituitary The poterior pituitary is not strictly an endocrine gland, but does release hormones Functions of Other Anterior Pituitary-Hormones Prolactin (PRL) Stimulates and maintains milk production following childbirth. * Function in males is unknown Adrenocorticotropic hormone (ACTH) Regulates endocrine activity of the adrenal cortex Thyroid-stimulating hormone (TSH) * Influences growth and activity of the thyroid Anatomy of the Parasympathetic Division * Originates from the brain stem and S, through Terminal ganglia are at the effector organs Always uses acetylcholine as a neurotransmitter The Chemistry of Hormones Amino acid-based hormones " Proteins Peptides Amines Steroids - made from cholesterol * Prostaglandins - made from highly active lipids Autonomic Functioning Sympathetic -"fight-or-flight" * Response to unusual stimulus Takes over to increase activities Remember as the "E" division = exercise, excitement, emergency, and embarrassment Hormones of the Testes * Interstitial cells of testes are hormone- producing Produce several androgens Testosterone is the most important androgen Responsible for adult male secondary sex characteristics Promotes growth and maturation of males reproductive system Required for sperm cell production Pineal Gland Found on the third ventricle of the brain Secretes melatonin Helps establish the body's wake and sleep cycles May have other as-yet-unsubstantiated functions Hormones of the Adrenal Cortex Sex hormones  Produced in the inner layer of the adrenal cortex Androgens (male) and some estrogen (female) Hormones of the Adrenal Cortex Glucocorticoids (including cortisone and cortisol) Produced in the middle layer of the adrenal cortex Promote normal cell metabolism Help resist long-term stressors Released in response to increased blood levels of ACTH Hormones of the Ovaries Estrogens Produced by Graafian follicles or the placenta Stimulates the development of secondary female characteristics Matures female reproductive organs Helps prepare the uterus to receive a fertilized egg Helps maintain pregnancy Prepares the breasts to produce milk Hormones of the Adrenal Medulla Produces two similar hormones (catecholamines) Epinephrine * Norepinephrine These hormones prepare the body to deal with short-term stress