Body Tissues PDF

BODY TISSUES Group of cells that are similar in structure and function. 4 Primary Tissue Types 1. Epithelium (covering) 2. Connective tissue (support) 3. Nervous tissue (control) 4. Muscle tissue (movement) Epithelial Tissues Pseudostratified columnar epithelium Transitional Epithe...

BODY TISSUES Group of cells that are similar in structure and function. 4 Primary Tissue Types 1. Epithelium (covering) 2. Connective tissue (support) 3. Nervous tissue (control) 4. Muscle tissue (movement) Epithelial Tissues Pseudostratified columnar epithelium Transitional Epithelium Glandular Epithelium Connective Tissues Bone Tissue Hyaline cartilage Fibrocartilage Elastic Cartilage Dense Connective Tissues: Dense Collagenous Dense Fibrous/Dense Elastic Loose Connective Tissues: Areolar Adipose Tissues Reticular Tissues Fluid Connective Tissue: Blood Bone Marrow Muscle Tissues Cardiac Muscle Tissue Smooth Muscle Tissue Skeletal Muscle Tissue Nucleus at the periphery Skeletal Muscle Nervous Tissue Muscular System Muscle Names 1. Location – pectoralis, brachialis, gluteus 2. Size – maximus, minimus; longus, brevis 3. Shape – deltoid, quadratus, teres 4. Orientation of fascicles – rectus, oblique 5. Origin of insertion – sternocleidomastoid 6. Number of heads – biceps, triceps 7. Function – flexor, extensor Muscle Shapes Muscle Movements Types of Movement a. Gliding Movements -simplest of all types of movement -occur in plane joints between two flat or nearly flat surface that slide or glide over each other -allow only slight movement e.g. between carpal bones Types of Movement b. Angular Movements -one part of linear structure bends relative to another part of the structure, changing the angle between the two parts FLEXION – decreases angle, closer together, bending EXTENSION – increases angle, straightening -HYPEREXTENSION – extension beyond 180 degrees Angular movement of the foot: PLANTAR FLEXION – foot toward the plantar surface DORSIFLEXION – foot toward the shin Types of Movement b. Angular Movements ABDUCTION – to take away; away from midline ADDUCTION – to bring together; toward the midline LATERAL FLEXION of the neck – abduction of the head LATERAL FLEXION of the vertebral column – abduction of the waist Types of Movement c. Circular Movements -involves rotation around an axis or movement in an arc ROTATION – turning of a structure around its long axis - MEDIAL ROTATION of the arm - LATERAL ROTATION of the arm PRONATION – rotation of the forearm with the palm faces posteriorly or the palm faces down SUPINATION - rotation of the forearm with the palm faces anteriorly or the palm faces up CIRCUMDUCTION – combination of flexion, extension, abduction and adduction; e.g. shoulder Types of Movement d. Special Movements ELEVATION – moves a structure superiorly DEPRESSION – moves a structure inferiorly PROTRACTION – motion that moves a structure in an anterior direction RETRACTION - motion that moves a structure in a posterior direction LATERAL EXCURSION – moving the mandible either the right or the left away from the midline MEDIAL EXCURSION – mandible to the midline position Types of Movement d. Special Movements OPPOSITION – unique to the thumb, the thumb and another finger brought toward each other across the palm REPOSITION – returns the thumb to the neutral position INVERSION – turns the ankle medially towards the opposite foot EVERSION – turns the ankle laterally away from the opposite foot Types of Movement e. Combination Movements - most movements that we perform in the course of normal activities Neck Muscles Facial Muscles Mastication Tongue Movements Eyeball Movement Muscles moving the vertebra Thoracic Muscles Abdominal Wall Pelvic Floor and Perineum Scapular Movements Arm Movements Forearm Movements Wrist, Hand, and Finger Leg Movements Ankle, Foot and Toe Muscle Tissue 1 Icebreaker Have you ever stopped to think about how the body is able to move? Muscles generate movement of the body. Muscle also helps move molecules and other substances through the human body. In this chapter we will discuss: The anatomy of muscle tissue. The physiology of muscle contraction. Functions of Muscle Tissue Movement Movement of the body and movement of internal materials Posture maintenance Stabilization of joints Protection of internal organs Temperature regulation  Excitability—responds to Involuntary—unconsciously controlled changes in electrical Smooth and cardiac muscle potentials across cell Voluntary—consciously controlled Skeletal muscle membrane Extensibility—can stretch or extend Characteristics of Muscle Tissue Elasticity—can stretch and return to original shape Contractility—can pull on attachment site and shorten Muscle Tissue Cells Skeletal muscle Cardiac muscle Smooth muscle Long, One or two One nucleus multinucleated nuclei Spindle- cells Shorter, shaped Cylindrical branching cells (appearance shape Striated like a football) Striated Non-striated  Three Types of Muscle Tissue Skeletal muscle is associated with bones Smooth muscle is found within the walls of internal organs Cardiac muscle is found in the walls of the heart Think, Pair, Share Activity Compare and contrast the three types of muscle tissue. Think, Pair, Share Activity Answer Cardiac muscle Skeletal muscle One or two nuclei Long, multinucleated cells Cylindrical shape Shorter, branching cells Striated Striated Voluntary Involuntary Smooth muscle One nucleus Spindle-shaped (appearance like a football) Non-striated Involuntary Matching Activity: Match the muscle tissue to its characteristic. A. Multinucleated 1. Skeletal muscle B. Located in internal organs 2. Cardiac muscle C. Branching cells 3. Smooth muscle D. Non-striated E. Single nucleus F. Cylindrical shape Matching Activity Answer A. Multinucleated Skeletal muscle—A, F B. Located in internal organs C. Branch-shaped cells Cardiac muscle—C D. Non-striated Smooth muscle—B, D, E E. Single nucleus F. Cylindrical shape Connective Tissue (CT) Coverings of Skeletal Muscle Epimysium— Fuses with tendons to link muscle to bone for surrounds entire movement muscle Fascia = additional layer of CT external to epimysium Perimysium— Fascicles—bundles of muscle cells surrounds fascicles Endomysium— surrounds individual muscle cells  Structure of Skeletal Muscle Cells Sarcolemma = cell membrane Sarcoplasm = cytoplasm Sarcoplasmic reticulum (SR) = endoplasmic reticulum that stores calcium Transverse tubules (T-tubules)— extensions of sarcolemma Myofibrils—cylinders of contractile proteins Muscle Cell Components Specialized terms for muscle cell components: Sarcolemma Sarcoplasm Sarcoplasmic reticulum Many are rooted in the Greek prefix sarco- meaning “flesh”  Anatomy of a Skeletal Muscle Cell Endomysium covers individual muscle cells Sarcolemma is the plasma membrane of the muscle cell Skeletal muscle cells have multiple nuclei Multiple mitochondria produce ATP (adenosine triphosphate) for muscle contraction Contractile proteins are arranged into myofibrils  The Sarcomere Contractile unit of skeletal muscle Thick filament made of myosin Thin filament made of actin Associated with regulatory proteins troponin and tropomyosin Arrangement of proteins gives skeletal and cardiac muscle striated appearance Z discs anchor thin filaments Sarcomere spans Z disc to Z disc  Anatomy of the Sarcomere Myofibrils run the length of the muscle fiber and attach to sarcolemma Sarcomeres contract and the myofibrils shorten to contract the muscle Components and regions of a sarcomere: A band – region spanning the length of the thick filament I band – region containing only thin filament M line – horizontal line in center of sarcomere H zone – space where only thick filament can be found; extends laterally from M line The Neuromuscular Junction Point of contact between skeletal muscle and motor neuron that controls it Motor end plate = region of sarcolemma at the NMJ Excitatory signals from motor neuron leads to skeletal muscle contraction Think, Pair, Share Activity Diagram the sarcomere structure. Label the components and proteins that compose them. Think, Pair, Share Activity Answer The diagram should resemble Figure 11.3B. The proteins mentioned should include: Myosin that makes up the thick filament. Actin that makes up the thin filament. Troponin and tropomyosin that make up the regulatory proteins associated with the thin filament. Matching Activity Match the structure to its description Sarcolemma A. Cell membrane of skeletal muscle Epimysium B. Surrounds fascicles C. Cytoplasm of skeletal muscle Sarcoplasm D. Surrounds individual muscle cells E. Surrounds entire skeletal muscle Perimysium Endomysium Matching Activity Answer Sarcolemma—A A. Cell membrane of skeletal muscle Epimysium—E B. Surrounds fascicles C. Cytoplasm of skeletal muscle Sarcoplasm—C D. Surrounds individual muscle cells E. Surrounds entire skeletal muscle Perimysium—B Endomysium—D  The Sliding Filament Model of Muscle Contraction Describes how a sarcomere shortens Thin filaments slide past thick filaments toward M line 1. Calcium released from SR binds to troponin 2. Shape change moves tropomyosin 3. Myosin heads on thick filament bind to thin filament Results in cross-bridge formation The Sliding Filament Model of Muscle Contraction 4. Myosin heads use power of ATP to pull thin filament toward M line 5. Myosin heads will “re-cock” Continue to pull as long as ATP is available and binding sites are exposed 6. Z discs move closer together and sarcomere shortens Muscle Contraction Troponin and tropomyosin regulate cross-bridge formation between thick and thin filaments Tropomyosin wraps around the thin (actin) filament and covers myosin (thick filament) binding sites Troponin moves tropomyosin to expose myosin binding sites on the actin filament Occurs when calcium ions bind to troponin  Excitation-Contraction Coupling Connects muscle action potential and the muscle fiber contraction Leads to release of calcium ions from sarcoplasmic reticulum (SR) Nervous system uses membrane potentials to control skeletal muscle Membrane potentials—differences in electrical charge across cell membrane Created by movement of ions across sarcolemma Resting membrane potential—difference across the membrane when cell is at rest Action potential—change in membrane potential that activates muscle cell Leads to contraction Measuring Membrane Potential Voltmeter can be used to measure membrane potential Inside of cell is usually more negatively charged than outside Due to activities of sodium/potassium pumps Membrane potential changes as ions move Events at the Neuromuscular Junction Action potential of motor neuron causes release of the neurotransmitter acetylcholine (ACh) from motor neuron ACh diffuses across synaptic cleft and binds to receptors on motor end plate of muscle fiber Receptors open and sodium ions (Na+) enter muscle cell Resting membrane potential becomes positive As depolarization occurs the membrane potential becomes positive  Electrical Sequence of an Action Potential Resting membrane potential is −90 mV Sodium channels open and sodium enters cell Membrane potential becomes +30 mV This is depolarization When slow potassium channels open, potassium diffuses out of cell and membrane potential becomes more negative This begins repolarization PISO Potassium In Sodium Out  Events Along the Sarcolemma Voltage-gated channels respond to changes in membrane potential Voltage-gated sodium channels Open quickly in response to depolarization at motor end plate Sodium ions continue to flow into cell Conducts muscle action potential throughout entire muscle Voltage-gated potassium channels Open more slowly Allow potassium ions (K+) to exit cell Involved in repolarization of skeletal muscle cell  End Plate Potential Muscle action potential begins when sodium ions enter through receptors at end plate Adjacent voltage-gated sodium channels open in response to change in membrane potential Action potential spreads along entire sarcolemma and down T- tubules Potassium voltage-gated channels slowly open to allow potassium to diffuse out of cell Leads to repolarization Events at the Sarcomere Muscle action potential Calcium binds to travels through T-tubules troponin, causing shape Causes release of calcium from change Cross-bridge formation SR Shape change exposes myosin occurs binding sites on thin filaments Power of ATP used to pull Continues as long as ATP thin filament across thick and calcium are available filament  Steps in Muscle Contraction 1. Action potential arrives at motor neuron axon terminal 2. Acetylcholine is released and binds to receptors on motor end plate 3. Sodium ions enter muscle cell, resulting in depolarization to generate a muscle action potential 4. Depolarization spreads along the sarcolemma into the T- tubules leading to calcium release 5. Calcium release into the cytosol leads to exposure of myosin binding sites on actin resulting in cross-bridge formation 6. Sarcomere shortening (contraction) leads to muscle contraction ATP and Muscle Contraction Cross-bridge forms ADP and phosphate release leads to power stroke New ATP molecule binds Myosin heads detach Myosin heads remain attached if amount of ATP is insufficient leading to rigor mortis ATPase breaks down ATP, releasing energy Myosin head returns to ready position  Sarcomere Shortening Length of myofilaments will remain the same There is an increase in the overlap between the myofilaments I band and H zone eliminated because of increase overlap during sarcomere shortening Skeletal Muscle Cell Relaxation Motor neuron stops releasing Ach and acetylcholinesterase breaks down ACh at NMJ Without ACH, ACh receptors close Calcium ions are pumped back into SR Tropomyosin moves back into original position Covers myosin binding sites Prevents cross-bridge formation and muscle relaxes Knowledge Check Which ions enter skeletal muscle, causing it to depolarize? A. Potassium B. Sodium C. Calcium D. Phosphate Knowledge Check Answer Which ions enter skeletal muscle, causing it to depolarize? B. Sodium Breakout Group Activity List the steps of skeletal muscle contraction on several sheets of paper or note cards. Take turns placing the steps in their correct order while your group members check your work. Breakout Group Activity Answer Muscle cell contraction begins when acetylcholine, released by the motor neuron, depolarizes the end plate. As the sarcolemma and T-tubules depolarize, calcium is released into the cell, triggering the movement of troponin and tropomyosin on the thin filaments. Myosin heads, now able to form cross-bridges with actin, contract the sarcomere, the whole muscle cell, and the entire muscle. Sources of ATP Creatine phosphate Glycolysis Lactic acid Aerobic respiration Creatine Phosphate Resting muscle builds up stores of creatine phosphate Donates phosphate to ADP Quickly regenerates ATP Short-lived source of ATP Only lasts about 15 seconds Glycolysis Breaks down glucose to yield ATP and pyruvate Energy from bonds in glucose used to bind phosphate to ADP Generates ATP slower than creatine phosphate If oxygen is available, pyruvate used for aerobic respiration If oxygen not available, pyruvate converted to lactic acid Lactic acid can be broken down by liver Produces ATP for approximately 1 minute of muscle activity Aerobic Respiration Occurs in mitochondria and produces large quantities of ATP Requires oxygen Myoglobin stores oxygen in muscle cells for use by mitochondria Glucose is also stored by muscle cells as glycogen for use by mitochondria Pyruvate is broken down to generate approximately 36 ATP Supplies the majority of ATP used by muscle cells Muscle Fatigue Occurs when muscle can no longer contract Multiple causes: 1. Depletion of ATP 2. Lactic acid and ADP buildup 3. Impaired ion movement 4. Inadequate release of calcium from sarcoplasmic reticulum  Muscles are a blend of three different types of muscle fibers Three Types of 1. Slow oxidative (SO) Muscle Fibers 2. Fast glycolytic (FG) 3. Fast oxidative (FO) Differ in speed of contraction and ATP production  Contract slowly Weakest strength of contraction of the three types Slow of muscle fibers Oxidative Produce ATP via aerobic respiration (SO) Muscle Fibers Red due to presence of myoglobin Fatigue slowly Maintain posture and stabilize joints  Fast contractions Fast Produce strongest contractions Glycolytic (FG) Muscle Produce ATP via glycolysis - Store glycogen in higher amounts Fibers Fatigue quickly Used for fast, powerful movements  Also known as intermediate fibers Possess characteristics of both SO and FG fibers Fast Contract quickly Oxidative (FO) Muscle Produce ATP via glycolysis and aerobic respiration Fibers More fatigue-resistant than FG fibers Used for movements like walking Think, Pair, Share Activity List the muscle fiber types in order from the strongest to the weakest in strength of contraction. Next, list the muscle fiber types in order from those that fatigue the quickest to those that fatigue the slowest. Think, Pair, Share Activity Answer Strongest to weakest: fast glycolytic, fast oxidative, and slow oxidative Fatigue: fast glycolytic, fast oxidative, and slow oxidative This pattern illustrates how the strongest fibers fatigue the fastest and the weakest fibers fatigue the slowest.  Discussion Activity Do you think there is a difference in the muscle fiber makeup of a powerlifter versus a marathon runner? Describe the muscle fiber makeup you think is present in each athlete.  Discussion Activity Answer Yes, there is a difference. A powerlifter trains to develop fast glycolytic (FG) muscle fibers that produce quick, powerful movements. A marathon runner trains for endurance. This type of training helps develop slow oxidative (SO) muscle fibers.  Muscle Tension Force generated by contraction of muscle Tension can be used to move an object (load) Isometric contraction—muscle contracts, but does not move a load Isotonic contraction—moves a load Concentric contraction—muscle shortens to move load Eccentric contraction—muscle lengthens to move load  Concentric isotonic contraction Types of Muscle shortens and moves a load Eccentric isotonic contraction Muscle Muscle lengthens and moves a load Contractions Isometric contraction Muscle contracts but does not move load Length-Tension Range of a Sarcomere Thick and thin filaments must overlap for sarcomere to shorten Amount of overlap influences strength of contraction Insufficient or excessive overlap = weaker contractions Sufficient overlap optimizes strength of contraction Myogram of a Muscle Twitch Twitch—singular contraction of a muscle cell Myogram—displays the amount of tension produced by a twitch over a period of time Latent period Contraction phase Relaxation phase Phases of Muscle Fiber Contraction 1 2 3 Latent phase Contraction phase Relaxation phase Action potential is Cross-bridges have formed Calcium ions are pumped propagated along and sarcomeres shortened back into SR and cross- sarcolemma and calcium Peak of tension bridge cycling stops ions released from SR Tension decreases No contraction occurs during this phase  Summation and Tetanus Each action potential produces a singular twitch contraction Summation is a series of action potentials that sustain muscle contraction Tetanus occurs when action potentials occur quickly and lead to sustained maximal contraction Muscle Tone Skeletal muscles are rarely fully relaxed (flaccid) Muscle tone is maintained by a small amount of contraction within the muscle fiber Nervous system activates a few groups of muscle at a time Rotating muscle groups prevents fatigue Control of motor units helps maintain muscle tone  Motor Units A motor unit consists of a motor neuron and all the skeletal muscle fibers it controls Each motor unit consists of only one fiber type All muscle fibers in motor unit contract at the same time Additional motor units can be recruited if more strength is required Referred to as recruitment Breakout Group Activity Have each group member perform either an isometric, eccentric, or concentric contraction while the other members of the group try to guess which type of contraction is being performed. Think, Pair, Share Activity Can you think of any advantages to having larger motor units in a muscle? Can you think of any advantages to having smaller motor units within a muscle? Think, Pair, Share Activity Answer Larger motor units would allow the muscle to generate greater force when it contracts. Large motor units are seen in powerful muscles like those around the femur. Smaller motor units allow for greater control of fine motor movements. Smaller motor units are seen in the muscles that move the eyes and fingers.  Characteristics of Cardiac Muscle Located in the walls of the heart Striated fibers like skeletal muscle Sarcomere is functional unit Shorter, branching fibers Intercalated discs attach fibers Allow for fast communication between cells Involuntarily controlled  Cardiac Muscle Cells Branching shape Striated in appearance Cells connected by intercalated discs Desmosomes firmly attach cardiac muscle cells to each other Gap junctions allow for action potential to move from one cell to another  Found in internal organs Non-striated Characteristics Thick and thin filaments present, but not regularly arranged of Smooth Spindle-shaped cells Muscle Wide in the middle and tapered at each end Single nucleus Involuntary  Contraction of Smooth Muscle Thin filaments anchored by dense bodies Dense bodies connected by intermediate filaments Calcium comes from sarcoplasmic reticulum and extracellular fluid Binds to calmodulin and activates myosin kinase Activated myosin heads bind to and pull thin filaments Ends of cell are pulled toward center as it contracts Corkscrew motion  Smooth Muscle Innervation Innervated by singular neurons with multiple varicosities Varicosities = bulges that store/release neurotransmitters Single-unit smooth muscle = multiple cells that contract as a unit Contain gap junctions Stress-relaxation response Multi-unit smooth muscle = cells contract individually Think, Pair, Share Activity Compare and contrast the processes of skeletal and smooth muscle contraction. Think, Pair, Share Activity Contraction of skeletal and smooth muscle requires depolarization of the muscle cells. Depolarization of skeletal muscle is voluntary and caused by motor neurons. Depolarization of smooth muscle is involuntary and is caused by local neurons or the autonomic nervous system. For both muscle tissues, calcium binds to a regulatory protein. Calcium binds to the troponin/tropomyosin complex in skeletal muscle and calmodulin in smooth muscle. Sarcomere shortening in skeletal muscle leads to contraction. Contraction of smooth muscle occurs when the cell as a whole shortens in a corkscrew motion. Discussion Activity Would a disease that inhibits the flow of sodium ions affect the functioning of the heart? (Hint: Cardiac muscle is striated like skeletal muscle.) Discussion Activity Yes, it would. An influx of sodium ions leads to depolarization of striated muscle. If sodium ions no longer flow into cardiac muscle, the muscle would not depolarize. Without depolarization, cardiac muscle would not contract.  At the end of this chapter, you should be able to: Discuss the anatomy of muscle tissue. List characteristics of the three types of muscle tissue. Discuss the gross and microscopic Summary structure of skeletal muscle. Discuss contraction of skeletal muscle. Discuss contraction of smooth muscle. The Muscular System Icebreaker Many of our daily activities require the use of skeletal muscles. Have you ever been curious about how a baseball player throws a ball or how the human body breathes? In this chapter we will explore the arrangement and names of skeletal muscles and investigate their actions. 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  Synergists and Fixators Synergists—assist prime Fixators—stabilize mover in accomplishing insertion points during a a movement movement Example = Brachioradialis and Brachialis during flexion of elbow  Agonists and Antagonists Agonist—primarily Antagonist—muscle that responsible for an action; also produces the opposite known as the prime mover movement of an agonist Triceps brachii is the antagonist of the biceps brachii Alternately, the biceps brachii is the antagonist of the triceps brachii  Patterns of Fascicle Organization Fascicle—a bundled group of muscle fibers Surrounded by perimysium Fascicle arrangement— Influences force generated arrangement of fascicles in skeletal and range of motion of muscle muscle  Parallel—fascicles arranged in same direction as long axis of muscle Fusiform—parallel arrangement with large muscle belly in the middle and narrowing ends Patterns of Circular—fibers wrap in a circle Fascicle Organization Convergent—fascicles unite on singular, narrow insertion point  Muscle Bellies Muscle bellies of fusiform muscles enlarge when the muscle contracts Forms an even larger muscle belly  Patterns of Fascicle Organization Pennate—fascicles blend into tendon in center of muscle Unipennate—fascicles on one side of tendon Bipennate—fascicles on both sides of tendon Multipennate—muscle branches within muscle to resemble many feathers arranged together Matching Activity Match the term to the correct description. A. Muscle that produces the opposite 1. Origin movement 2. Agonist B. Attachment site that moves 3. Synergist C. Muscle that assists in accomplishing a 4. Antagonist movement 5. Insertion D. Attachment site that does not move E. Muscle that is primarily responsible for a movement Matching Activity Answer Match the term to the correct description. A. Muscle that produces the opposite 1. Origin—D movement 2. Agonist—E B. Attachment site that moves 3. Synergist—C C. Muscle that assists in accomplishing a 4. Antagonist—A movement 5. Insertion—B D. Attachment site that does not move E. Muscle that is primarily responsible for a movement  Knowledge Check Activity The principal muscle involved in accomplishing an action is called: A. Antagonist B. Origin C. Prime mover D. Synergist  Knowledge Check Activity Answert The principal muscle involved in accomplishing an action is called: C. Prime mover 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 Characteristics Used to Name Skeletal Muscles 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 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  Words that Pertain to Muscle Size Greek and Latin words that describe muscle size include: Maximus Medius Minimus Brevis Longus Major Minor Longissiumus  Some Muscles are Named for Their Shape Rhomboid muscles of back resemble the shape of a rhombus Deltoid muscle of the shoulder resembles an upside-down Greek letter delta Prefixes That Indicate Number 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  Muscle actions are predictable based on their location Lateral side of joint Muscle Abduction of limbs Lateral flexion of trunk or neck Medial side of joint Actions Adduction Anterior portion of joint Flexion Posterior portion of joint Extension  One of the muscles of the human body is the orbicularis oculi. Using your knowledge of Think, Pair, anatomical terms, where do you Share think this muscle is located? What shape does this muscle Activity have?  Oculi is a derivative of ocular, so this muscle is located near the eye. Think, Pair, Orbicularis is a derivative of orbit. Share Activity The term orbit implies a circular path of movement, so the muscle Answer has circular in shape.  In your group, research the names of muscles found in the human body. Write down the Breakout Group names of the muscles in a list. Activity After finding the names of several muscles, try to determine how the muscles most likely got their names. Muscles of Facial Expression Originate on bones of skull and insert on skin Orbicularis oculi Orbicularis oris Occipitofrontalis Buccinator Zygomaticus major Zygomaticus minor Muscles That Move the Eyes Originate outside of eye and insert on outer surface of eye Superior and inferior obliques Lateral, medial, inferior, and superior rectus Muscles of the eye and movements that they allow Muscles of Facial Expression Originate on bones of skull and insert on skin Orbicularis oculi Orbicularis oris Occipitofrontalis Buccinator Zygomaticus major Zygomaticus minor Muscles That Move the Lower Jaw Allow for mastication (chewing) Masseter Temporalis Pterygoid muscles Muscles of Mastication (Table 12.5)  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 Tongue (Table 12.6)  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  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 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 Anterior Muscles of the Abdomen External oblique Internal oblique Transversus abdominis Rectus abdominis Enclosed by rectus sheaths of linea alba  Posterior Muscles of the Abdomen Help form posterior wall of the abdomen Stabilize body and maintain posture Psoas major Iliacus Quadratus lumborum  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 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 of the Perineum Perineum—space between pubic symphysis and coccyx Urogenital triangle – anterior of perineum Includes external genitalia Anal triangle—posterior perineum Includes anus Breakout Group Activity Make a list of common facial expressions such as smiling or closing your eyes. After you make your list, add the names of the muscles responsible for each expression.  Breakout Group Activity Answer Smiling—zygomaticus major Closing eyes—orbicularis oculi Pursing lips—orbicularis oris Raising eyebrows—frontalis Think, Pair, Share Activity The diaphragm moves up and down to allow for breathing. What direction does the diaphragm move during inhalation? What direction does the diaphragm move during exhalation? Think, Pair, Share Activity During inhalation, the diaphragm moves downward. During exhalation, the diaphragm moves upward.  The muscles located between the ribs are called: Knowledge A. The diaphragm Check B. Scalene muscles Activity C. Intercostal muscles D. Sternocleidomastoid muscles Knowledge The muscles located between Check the ribs are called: C. Intercostal muscles Activity  Shoulder Muscles Subclavius, pectoralis minor, serratus Anterior shoulder muscles anterior Pull scapula forward (protract) Trapezius, rhomboid major, rhomboid Posterior shoulder muscles minor Pull scapula back (retract)  Movements possible at the shoulder include: Retraction Protraction Flexion Shoulder Extension Abduction Movements Adduction Internal rotation External rotation Muscles That Move the Humerus Pectoralis major and latissimus dorsi Prime movers of the humerus Convergent muscles Muscles That Move the Humerus Rotator cuff—formed by Muscles that originate on tendons of subscapularis, scapula supraspinatus, infraspinatus, and teres minor Deltoid, subscapularis, Give structure and stability supraspinatus, to shoulder joint infraspinatus, teres major, teres minor, coracobrachialis  Muscles That Move the Forearm 1 2 3 Allow flexion and Elbow flexion— Elbow extension— extension of the biceps brachii, triceps brachii, elbow, supination, brachialis, anconeus and pronation brachioradialis Muscles That Move the Forearm Pronation—pronator teres, pronator quadratus Supination—supinator 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 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 Muscles That Move the Wrist, Hand, and Fingers Superficial muscles Anterior muscles— Flexor carpi radialis, palmaris longus, flexor carpi most cause flexion of ulnaris, flexor digitorum superficialis the hand or fingers Posterior muscles— Extensor radialis longus, extensor carpi radialis most cause extension brevis, extensor digitorum, extensor digiti minimi, of the hand or fingers extensor carpi ulnaris Muscles That Move the Hand, Wrist, and Fingers Deep muscles Anterior muscles—cause flexion of fingers Flexor pollicis longus, flexor digitorum profundus Posterior muscles—cause extension and abduction of thumb Abductor pollicis longus, extensor pollicis brevis, extensor pollicis longus, extensor indicis  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  Movements of the thigh that occur at the hip include: Movements of Abduction the Hip Adduction Flexion Extension  Most originate on pelvis and insert on femur Gluteal Region Iliopsoas group—psoas major, iliacus Muscles That Gluteus maximus, gluteus medius, Move the gluteus minimus Femur Tensor fascia latae Adductor longus, adductor brevis, adductor magnus Pectineus  Medial compartment – adduct the femur Adductor longus, adductor brevis, adductor magnus, pectineus, gracilis Thigh Muscles That Move the Anterior compartment – flex thigh, extend knee Femur, Tibia, Quadriceps femoris = Rectus femoris, and Fibula vastus lateralis, vastus medialis, vastus intermedius Posterior compartment – extend thigh, flex knee Hamstrings = Semitendinosus, semimembranosus, biceps femoris  Anterior compartment – dorsiflex foot Tibialis anterior, extensor hallucis longus, extensor digitorum longus Muscles That Superior extensor retinaculum and inferior extensor retinaculum anchor Move the Feet tendons during contraction Lateral compartment – eversion and plantar flexion of foot Fibularis longus, fibularis brevis  Posterior compartment – plantar flexion of foot Gastrocnemius, soleus, plantaris, Muscles That popliteus, flexor digitorum longus, Move the Feet flexor hallucis longus, tibialis posterior Superficial muscles insert on calcaneal tendon  Sole supported by plantar aponeurosis Dorsal group Extensor digitorum brevis Muscles That Plantar group Move the Toes Flexor digitorum brevis, abductor hallucis, abductor digiti minimi, quadratus plantae, lumbricals, flexor digiti minimi brevis, flexor hallucis brevis  What are advantages to grouping appendicular muscles into compartments? Are there any Think, Pair, disadvantages to grouping Share appendicular muscles into compartments? Activity  Advantages of muscular compartments include grouping muscles that accomplish similar Think, Pair, functions together for increased strength and organization. Share Activity A disadvantage of muscular compartments is that a disease or Answer injury that affects one muscle may quickly affect others in the compartment, leading to a loss of function. Think, Pair, Share Activity When lifting heavy objects, instructions often say “lift with your legs.” Considering the muscles that move the thigh, why are these instructions given? Think, Pair, Share Activity Answer These instructions are given because the largest, strongest muscles of the body are in the femoral (thigh) region. Instructions recommend lifting with the legs because lifting heavy objects would require the force generated by these muscles. Breakout Group Activity In your group, practice identifying the location of superficial appendicular muscles on other group members. Also, have the group members contract those muscles and record the movement that occurs as a result.  By the end of this chapter, you should be able to: Define terms used to describe the points of attachment of skeletal muscles. Summary Discuss how skeletal muscles are named. Identify the location, origin, insertion, and action of major skeletal muscles. The Endocrine System Internal Communication Nervous and endocrine systems facilitate long-distance communication Nervous system uses electrical signals Neurotransmitters used for communication between one cell and another Endocrine system uses hormones Chemical signaling molecules that travel in blood Reach most cells of the body Have widespread effects Functions of the Endocrine System Helps maintain homeostasis by regulating: Use of calories and nutrients Secretion of wastes Blood pressure and blood osmolarity Growth Fertility and sex drive Lactation Sleep  Chemical Signaling Hormones—chemical messengers used by endocrine system Most are released into blood Paracrine signaling—hormone affects neighboring cells Autocrine signaling—hormone affects same cell that released it Endocrine signaling—hormone travels through blood to affect cells throughout body Neurotransmitters—used by neurons and the nervous system Endocrine and Exocrine Glands Chemical secretions exit glands via exocytosis Endocrine gland secretion releases product into bloodstream or extracellular fluid Exocrine gland secretion releases product into duct that carries product to a body surface Include the pituitary, thyroid, parathyroid, adrenal, and pineal glands Mainly secrete hormones Some have non-endocrine functions Do not have a duct for secretion Secretions enter blood or interstitial fluid Hormones affect target cells Cells with receptors for that specific hormone Other Organs That Have Endocrine Function Contains cells that have endocrine functions Includes the hypothalamus, thymus, heart, kidneys, stomach, small intestine, liver, adipose tissue, ovaries, and testes  Target Cells Hormones travel through the bloodstream They can reach almost any cell in the body Hormones only affect target cells Cells with a receptor for a particular hormone Binding of hormone to receptor on target cell initiates intracellular signaling  Both nervous and endocrine systems allow control and communication of the body Comparison of Nervous They accomplish this in different ways: and Endocrine Systems Neurotransmitters versus hormones Nervous system is generally faster to make a change Endocrine system has more widespread effects Endocrine system effects generally last longer  Matching Activity: Match the characteristic to the system. 1. Nervous system A. Responses are fast 2. Endocrine system B. Uses hormones C. Responses can be widespread throughout body D. Responses are slower E. Uses neurotransmitters Hormones Types of Hormones Based on chemical structure Steroid hormones—cross cell membrane easily Lipid-based hormones Amine-based hormones—modified amino acids Water-soluble; cannot cross cell membranes Peptide and Protein hormones—made from chains of amino acids Water-soluble; cannot cross cell membranes  Steroid Hormones Produced from cholesterol molecules Lipid-soluble hormones Can pass through cell membrane Require transport proteins to travel in blood Examples include testosterone and estrogens Amine Hormones Made from individual amino acids Water-soluble hormones Cannot freely pass through the cell membrane Do not require transport proteins in blood Examples include melatonin, epinephrine, and norepinephrine Peptide and Protein Hormones Chains of amino acids Water-soluble hormones Cannot freely pass through the cell membrane Do not require transport proteins in blood Examples include antidiuretic hormone and insulin Production of Hormones Steroid hormones—made on demand by modifying cholesterol molecules Cannot be stored Not soluble in blood Travel bound to transport proteins when in blood Peptide hormones—translated like other proteins Modified and stored in vesicles until release Soluble in blood Travel in a “free” state  Hormone Receptors Receptors can be intracellular or on the cell surface Lipid-soluble hormone receptors are usually intracellular (cytosol or nuclear) This is because lipid-soluble hormones can pass through cell membrane Water-soluble hormone receptors usually on surface of cell This is because these hormones are usually unable to cross cell membrane Intracellular Hormone Receptors Associated with steroid and thyroid hormones Hormone must be lipid-soluble to pass through membrane May be in cytosol or nucleus Results in increased transcription and increased protein synthesis Membrane-bound Hormone Receptors Associated with water-soluble hormones Amine and peptide hormones Hormone serves as first messenger in the pathway An intracellular second messenger relays message inside the cell Second Messenger System Hormone binds to receptor in cell membrane G protein is activated G protein activates adenylyl cyclase Adenylyl cyclase converts ATP to cyclic adenosine monophosphate (cAMP) cAMP activates protein kinases Protein kinases phosphorylate proteins Phosphorylated proteins cause change Second Messenger System Amplification allows a small amount of hormone to cause significant change Phosphodiesterase (PDE) breaks down cAMP: : Quickly stops internal cellular changes Other second messenger systems may use calcium ions as a second messenger Anatomy of a Steroid hormones are made on demand in endocrine cell Enzymes modify cholesterol during synthesis Steroid Secreted into blood and travel bound to a transport protein Hormone Reach target cells where they are released from transport protein Bind to intracellular receptors within the target cell Anatomy of a Protein hormones are made by rough ER or ribosomes in the endocrine cell Protein Secreted into blood and travel in a “free” state Do not need transport proteins Hormone Reach target cells and bind to receptors on surface of cell Initiate second messenger systems  Which enzyme breaks down cyclic AMP? Knowledge A. G protein Check B. Adenylyl cyclase C. Adenylylase Activity D. Phosphodiesterase Knowledge Which enzyme breaks down cyclic AMP? Check D. Phosphodiesterase Answer  The number of receptors a target cell has influences the strength of response Downregulation—decrease in receptor Factors number Occurs when hormone level is Affecting chronically higher Target Cell Cells become less sensitive to hormone Upregulation—increase in receptor number Response Occurs when hormone levels are chronically low Cells become more sensitive to hormone  Regulation of Hormone Secretion Most hormones regulated Oxytocin is regulated by a via negative feedback positive feedback loop loops As hormone level rises, Suckling leads to secretion will slow down oxytocin release or stop Higher levels of oxytocin will increase rate of release Think, Pair, Share Activity Describe the process of a negative feedback loop using the heating/cooling system in a home as the example. Think, Pair, Share Activity In a negative feedback loop, the response is the opposite of the stimulus. For a heating/cooling system in a home, as the temperature increases, the response of the system is to decrease the temperature via cooling. If the temperature decreases, the response of the system is to increase the temperature via heating.  Regulation of Hormone Secretion Other factors influence hormone release: A. Chemical levels within blood (humoral) B. Endocrine system—tropic hormones control release of other hormones (hormonal) C. Nervous system stimulation (neural) Endocrine Control by the Hypothalamus and Pituitary Gland The Hypothalamus and the Pituitary Hypothalamus: Part of diencephalon of the brain Regulates secretion of hormones from pituitary gland Connected to posterior pituitary gland by infundibulum Connected to anterior pituitary by hypothalamic-hypophyseal portal system  The Anterior and Posterior Pituitary Anterior pituitary Blood from hypothalamus travels through the is composed of hypophyseal portal vein to the anterior pituitary glandular tissue Posterior pituitary Axons from hypothalamus project through infundibulum contains nervous Hormones stored and released into blood at tissue the posterior pituitary  Posterior Pituitary Stores and Oxytocin and antidiuretic hormone (ADH) releases two Hormones are produced in hypothalamus and transported to posterior pituitary hormones Release regulated by positive feedback loop Responsible for milk ejection reflex Oxytocin Promotes uterine contractions Contributes to social bonding behavior  Discussion Activity List reasons synthetic forms of oxytocin may be used during labor and delivery. Discussion Activity Answer Synthetic forms of oxytocin are used during labor and delivery to promote uterine contractions and help delivery proceed.  Antidiuretic Hormone Released in response Conserves body fluids to high blood by increasing water Can also cause osmolarity reabsorption by kidney constriction of blood The solute concentration of Urine becomes darker vessels blood Release inhibited by Leads to overall drugs like alcohol increase in blood Higher amounts of urine pressure produced  Diabetes Insipidus (DI) Results from chronic Without ADH, kidneys underproduction of do not reabsorb anti-diuretic hormone adequate amounts of (ADH) water DI leads to excessive thirst and increased Ionic imbalances can water consumption occur in severe cases of Osmotic imbalance persists, DI however, due to lack of ADH  Where are the hormones secreted by the posterior pituitary produced? Knowledge A. Thalamus Check B. Posterior pituitary Activity C. Hypothalamus D. Epithalamus E. Anterior pituitary Knowledge Where are the hormones Check secreted by the posterior Activity pituitary produced? C. Hypothalamus Answer Anterior Pituitary Produces six hormones Secretion is regulated by tropic hormones from hypothalamus Tropic hormones travel from hypothalamus to anterior pituitary in hypothalamic- hypophyseal portal system  Anterior Pituitary Hormones Growth hormone—anabolic hormone that promotes protein synthesis and tissue building Thyroid-stimulating hormone—causes release of thyroid hormones from thyroid gland Adrenocorticotropic hormone—stimulates release of cortisol from adrenal cortex Follicle-stimulating hormone—promotes gamete production Luteinizing hormone—promotes release of sex hormones and initiates ovulation Prolactin—promotes milk production Growth Hormone Release regulated by GHRH and GHIH from hypothalamus Causes production of insulin-like growth factors (IGFs) in target tissues Causes growth via: Increased protein synthesis Increased lipolysis Increased blood glucose levels  Growth Hormone Disorders In general, growth hormone promotes growth of epiphyseal Leads to elongation of bones plate during childhood Decreased stature due to decreased secretion of GH during Pituitary dwarfism childhood Substantially increased height due to excessive GH secretion Gigantism during childhood Excessive GH secretion during adulthood Acromegaly Causes increased cartilage growth leading to larger hands, feet & ears. May cause cardiovascular complications due to diabetogenic effect  Think, Pair, Share Activity What are some potential consequences of decreased secretion of GH?  Think, Pair, Share Activity Answer Consequences of decreased secretion of GH depend on the timing. If decreased secretion of GH occurs during childhood, it may lead to dwarfism. Decreased secretion of GH during adulthood may lead to slow healing of the body.  The Major Hormones of the Body  The Thyroid Gland Located anterior to trachea and inferior to larynx Two lateral lobes connected by isthmus Histology: Thyroid follicles—spherical units of thyroid Internal cavity filled with colloid Synthesis and Release of Thyroid Hormones Thyroid hormone (TH) made by follicular cells Stimulated by TSH from anterior pituitary gland Intermediaries are combined to form T3 (triiodothyronine) and T4 (tetraiodothyronine) T4 commonly known as thyroxine  Regulation of Thyroid Hormone Synthesis Negative feedback regulates TH secretion Low levels of TH stimulate TRH release from hypothalamus TRH stimulates release of TSH from anterior pituitary TSH stimulates release of TH from thyroid gland Functions of Thyroid Hormones Increase basal metabolic rate (BMR): Cause every cell to increase production of ATP Promote protein synthesis Increase effectiveness of epinephrine and norepinephrine Increase body temperature: Heat given off due to ATP production Required for adequate growth and development of skeletal and nervous tissue in childhood  Thyroid Disorders Goiter = enlarged thyroid Caused by accumulation of colloid Hypothyroidism = insufficient production of thyroid hormones May lead to weight gain and cold intolerance Hyperthyroidism = excessive production of thyroid hormones May lead to weight loss and increased body temperature Calcitonin Secreted by parafollicular cells Secreted in response to elevated blood calcium levels Decreases blood calcium levels Inhibits osteoclast activity and stimulates osteoblast activity Decreases calcium absorption by the intestine Increases calcium loss in urine Calcium Regulation 01 02 03 Calcium plays a role in Levels are regulated by Calcitonin from thyroid many biological hormones and parathyroid processes hormone (PTH) from the parathyroid glands work antagonistically to regulate calcium levels  Parathyroid Glands Located on posterior of thyroid gland Chief cells secrete parathyroid hormone (PTH) Secreted in response to low calcium levels Increases blood calcium levels Stimulates osteoclasts that breakdown bone matrix releasing calcium Inhibits osteoblasts Stimulates calcitriol production to increase absorption of dietary calcium  Parathyroid Disorders Hyperparathyroidism = excessive secretion of PTH leads to excessive bone resorption Leads to increased blood levels of calcium resulting in: Decreased bone density, leading to increased fractures Reduced responsiveness of nervous system Increased calcium deposits in tissues and organs Hypoparathyroidism = insufficient production or secretion of PTH Leads to low blood levels of calcium, causing muscle twitching, cramping, convulsions, or paralysis Breakout Group Activity Role-play the process of calcium homeostasis. Assign group members to play the roles of calcitonin and parathyroid hormone and describe the changes that they cause to regulate blood calcium levels. Breakout Group Activity Answer As blood calcium levels increase, calcitonin is released and decreases blood calcium levels. As blood calcium levels decrease, parathyroid hormone is released and increases blood calcium levels.  The Adrenal Glands Triangular glands on top of each kidney Covered by capsule Divided into adrenal cortex (superficially) and medulla (deeper) Adrenal cortex has three zones: Zona glomerulosa Zona fasciculata Zona reticularis Hormones of the Most superficial region of adrenal cortex Zona Glomerulosa Secretes mineralocorticoids – PISO WHERE SODIUM GOES, WATER FOLLOWS, OFR EVERY MINERALOCORTICOIDS SODIUM TO BE ABSORBED, POTASSIUM IS ELIMINATED Main mineralocorticoid is aldosterone: Increases sodium and water reabsorption by kidney: Increases blood pressure Involved in renin-angiotensin-aldosterone system (RAAS) Hormones of the Most superficial region of adrenal cortex Zona Glomerulosa Secretes mineralocorticoids – PISO WHERE SODIUM GOES, WATER FOLLOWS, OFR EVERY MINERALOCORTICOIDS SODIUM TO BE ABSORBED, POTASSIUM IS ELIMINATED Main mineralocorticoid is aldosterone: Increases sodium and water reabsorption by kidney: Increases blood pressure Involved in renin-angiotensin-aldosterone system (RAAS)  Intermediate region of adrenal cortex Secretes glucocorticoids Hormones of the Zona Fasciculata Main glucocorticoid is cortisol Released in response to stress Release stimulated by ACTH GLUCOCORTICOIDS Suppresses immune system Stimulates breakdown of stored nutrients for energy Glycogenolysis Lipolysis Gluconeogenesis  Deepest region of adrenal cortex Hormones of Secretes androgens: These are male sex the Zona hormones Reticularis Main androgen secreted is dehydroepiandrosterone (DHEA) SEX Supplements testosterone in males HORMONES Promotes libido in females  The Adrenal Medulla Releases epinephrine and norepinephrine; collectively called catecholamines Produced by chromaffin cells Considered hormones when released into the blood Considered neurotransmitters at locations where they are released into a synapse Release results in fight-or-flight responses of the sympathetic nervous system  Adrenal Gland Disorders Cushing’s disease = hypersecretion of cortisol Results in hyperglycemia and lipid deposits around face and neck Symptoms: Moon-shaped face, buffalo hump on back of neck, rapid weight gains, and hair loss Complications: Increases risk of type 2 diabetes and decreases immunity Addison’s disease = hyposecretion of cortisol Results in hypoglycemia and low blood levels of sodium (hyponatremia) Symptoms: May result in general weakness, weight loss, nausea, vomiting, sweating and craving salty foods Matching Activity: Match the zone of the adrenal gland to the function of the hormone it releases. 1. Zona glomerulosa A. Promotes glycogenolysis 2. Zona reticularis B. Promotes sexual libido in women 3. Zona fasciculata C. Increases water reabsorption by kidney Matching Activity: Match the zone of the adrenal gland to the function of the hormone it releases. 1. Zona glomerulosa - C 2. Zona reticularis - B 3. Zona fasciculata - A  The Pancreas Located within abdomen posterior to stomach Both endocrine and exocrine gland Exocrine function is to secrete digestive enzymes Endocrine cells in pancreatic islets: Alpha cells—secrete glucagon Beta cells—secrete insulin  Regulation of Blood Glucose Insulin lowers blood glucose by: Stimulating uptake by cells Glycogenesis Lipogenesis Glucagon increases blood glucose by: Glycogenolysis Gluconeogenesis Lipolysis  Insulin Mechanism of Action Insulin stimulates glucose uptake in cells Primary target cells include skeletal muscle cells and adipocytes Binding of insulin leads to increased number of glucose transporters (GLUT) in membrane of target cells  Discussion Activity Diabetes mellitus occurs when fasting blood glucose levels are elevated. One lifestyle change that helps improve glucose levels is increased exercise. How does an increase in muscle activity and mass lead to improved blood glucose levels? (Hint: think about the target tissues of insulin). Discussion Activity Answer Insulin increases uptake of glucose by skeletal muscle cells. Exercise causes growth of skeletal muscle cells. An increase in the size of skeletal muscle requires more glucose, leading to upregulation of insulin receptors. This helps remove additional glucose from the blood and improves blood glucose levels. The Thymus Located within mediastinum, superior to heart Site of T lymphocyte maturation within the immune system More active during childhood and decreases in size with age Secretes thymosin Aids in development and differentiation of T lymphocytes  The Heart Secretes atrial natriuretic peptide (ANP) Decreases blood pressure in response to increased blood volume or increased blood pressure Increases sodium and water loss by the kidneys (via urine), to decrease blood volume and blood pressure The Gastrointestinal Tract Endocrine cells located in walls of stomach and small intestine Hormones aid in digestion Gastrin stimulates release of hydrochloric acid by stomach Other hormones aid in regulation of glucose metabolism  The Kidneys Produce renin that is involved in the renin-angiotensin-aldosterone system (RAAS); regulation of blood pressure Secretes calcitriol that aids in regulation of calcium homeostasis Produces erythropoietin (EPO) Stimulates production of red blood cells Adipose Tissue Hormones are collectively called adipokines Involved in metabolism and nutrient storage Secretes the hormone leptin Binds to neurons within brain to cause feeling of satiety after a meal Helps reduce appetite Secretes the hormone adiponectin Reduces cellular insulin resistance  The Skin Involved in production of vitamin D Absorbs UV radiation to convert cholesterol into inactive vitamin D Can be converted into active vitamin D by liver and kidneys Active vitamin D is involved in absorption of dietary calcium and immune functions The Liver Secretes insulin-like growth factor (IGF) in response to GH Produces angiotensinogen Precursor to angiotensin, a hormone involved in increasing blood pressure Secretes thrombopoietin, a hormone that stimulates platelet production Secretes hepcidins that regulate iron levels 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 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  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 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 male reproductive system Required for sperm cell production 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 Human Chorionic Gonadotropin Summary At the end of this chapter, you should be able to: Compare and contrast endocrine and exocrine glands. Identify the gross location of endocrine glands. Discuss the cells that produce hormones. Discuss the functions of hormones. end