ANA 209 Exam 2 Flashcards
What are the three types of muscles?
Skeletal, cardiac, smooth
What is myology?
The study of the muscular system.
What does the term muscular system refer to?
Only the skeletal muscles.
What are the types of intramuscular connective tissue?
Endomysium, Perimysium, and Epimysium, and Fascia.
What are the functions of muscle?
Movement (body parts, body contents, communication), stability (maintain posture, resist pull of gravity), heat production (necessary for enzyme function), glycemic control (absorb, store, and use glucose), and control body openings and passageways.
What are the properties of muscle?
Excitability, conductivity, contractility, extensibility, and elasticity.
What is the excitability property of muscle?
Responsiveness, react to stimuli.
What is the conductivity property of muscle?
Spread electrical impulse through muscle cell.
What is the contractility property of muscle?
Shorten when stimulated.
What is the extensibility property of muscle?
Can stretch without harm.
What is the elasticity property of muscle?
Can recoil from stretch.
What is skeletal muscle?
Consists of striated cells called muscle fibers or myofibers (both muscle cells), which give the striped appearance under the microscope and are the result of overlapping arrangement of proteins.
Alternates between light and dark bands. The muscle is attached to bone.
Produces voluntary movement by attaching bone.
Due to conscious control of muscle, it can be referred to as voluntary muscle.
What is cardiac muscle?
Found in the walls of the heart and responsible for its contractions.
Striated muscle.
Involuntary (Autorhythmic with influence from autonomic nervous system).
Short, stumpy, branches cells. Intercalated discs with gap junctions. Typically mononucleated.
Cells are called myocytes, cardiomyocytes, or cardiocytes.
What is smooth muscle?
Contractile proteins are not arranged in the same way as in other muscle types.
No striations, involuntary (autonomic fibers with varicosities).
Small, fusiform, cell with one nucleus. Dense bodies link cytoskeleton and membrane.
Cells are called myocytes and they are short and fusiform shape (tapered at ends).
Multiunit (independent control of smooth muscle cells) and unitary (several cells excited at once; widespread in viscera).
Label the nucleus, muscle fiber, endomysium, and striations in the skeletal muscle fibers.
What is the muscle fiber?
A long, slender cell with multiple nuclei just inside inside the plasma membrane (sarcolemma).
Sarcolemma, sarcoplasm (cytoplasm) and sarcoplasmic reticulum.
What is the sarcolemma in muscle fiber?
This extends inward as tunnel-like transverse (T) tubules that cross the cell and open to the surface on both sides.
What is the cytoplasm (sarcoplasm) in muscle fiber?
Occupied mainly by myofibrils, which are threadlike bundles of protein filaments. Muscle fibers have an abundance of mitochondria and smooth endoplasmic reticulum between the myofibrils.
Contains an abundance of glycogen (energy storage carbohydrate) and myoglobin (oxygen binding protein)
What is the sarcoplasmic reticulum in muscle cells?
The “latter.”
Forms an extensive branching network and has dilated terminal cisternae flanking each T tubule.
Reservoir of calcium ions and has gated channels that can release a flood of calcium into the cytosol.
Describe myofilaments.
Thick, thin, and elastic myofilaments.
Contains contractile proteins for contraction. Myosin and actin.
Contains regulatory proteins. Tropomyosin and troponin.
What are thick myofilaments?
Thick myofilaments: Myosin
Myosin heads project from bundled tails of hundred of molecules
What are thin myofilaments:
Thin filaments: Actin, tropomyosin, and troponin
- Fibrous (F) actin resembles necklace
- Globular (G) actin resembles one bead of necklace, active site is where myosin binding are on G actin
- Tropomyosin blocks active sites when muscle is relaxed
- Troponin attaches to tropomyosin, binds calcium when excited
What are elastic filaments?
Elastic filaments: Titin (connectin)
- Anchors thick myofilaments
What are striations?
Narrow stripes (light and dark) that run perpendicular to the length of the cell.
What is an A band?
Dark strip of thick myofilaments that partly overlap thin myofilaments.
H-bands, M line, I band, Z disc
What is an H-band and M-Line?
Central region of “A” band that is a little lighter due to lack of thin myofilaments.
M-line is the midline of an A band (and H band) that anchors thick myofilaments together.
What is the I band and the Z disc?
I band is the light stripe of thin myofilaments only.
Z disc (also called Z line) is the midline of the I band. Also the protein that anchors thin and elastic filaments. Defines boundaries of a sarcomere.
Describe how A-band, I-band, H-band, Z-disc, and M-line work in striated muscle.
Myosin and actin are organized where they overlap and produce alternating dark A bands and light I bands that repeat at regular intervals along the length of the cell. (These bands are the striations)
The dark A bands consist of a midregion called the H-band where only thick filament occur, flanked by even darker regions where the thick and thin filament overlap.
The light A bands are bisected by a thin dark line called a Z disc. The thin filaments and elastic filaments are anchored to the Z discs. The region from one Z disc to the next is called a sarcomere. When a muscle fiber contracts, the sarcomeres become shorter and the Z discs are pulled closer together.
What is the sarcomere?
The functional unit of muscle contraction.
When a muscle fiber contracts, the sarcomeres become shorter and the Z discs are pulled closer together.
Explain blood supply in terms of muscle.
At rest, muscle receives about 1/4 of heart’s output.
During heavy exercise, muscular system receives more than 3/4 of heart’s output ( larger % of larger output).
Muscle is generally well vascularized.
Explain the nerve-muscle relationship.
Skeletal muscle contracts only when stimulated by a somatic motor neuron.
The axon (somatic motor fiber) of one neuron branches at its tip and leads to a few hundred muscle fibers, but each muscle fiber receives only one nerve fiber.
The nerve and muscle fiber meet at a complex of synapses called a neuromuscular junction. Each tip of the nerve fiber ends in a dilated bulb, the synaptic knob, nestled in a depression of the muscle fiber sarcolemma. The synaptic cleft separates the synaptic bulb from the sarcolemma.
The synaptic knob contains synaptic vesicles filled with neurotransmitter acetylcholine (ACh), which stimulates a muscle fiber to contract. The sarcolemma across from the knob has proteins that act as ACh receptors. An enzyme called acetylcholinesterase (AChE), found in the synaptic cleft and as part of the sarcolemma, breaks down ACh to terminate stimulation of the muscle fiber.
What is the synaptic cleft?
A narrow gap that separates the synaptic bulb from the sarcolemma.
What is the synaptic knob?
The synaptic knob contains synaptic vesicles filled with neurotransmitter acetylcholine (ACh), which stimulates a muscle fiber to contract. The sarcolemma across from the knob has proteins that act as ACh receptors. An enzyme called acetylcholinesterase (AChE), found in the synaptic cleft and as part of the sarcolemma, breaks down ACh to terminate stimulation of the muscle fiber.
What is a motor unit?
Consists of one motor neuron and multiple muscle fibers. Behave as a single functional unit. Fibers from one unit are dispersed in muscle, which causes a weak contraction over a wide area.
Multiple motor units in a muscle help to prevent fatigue. The muscle as a whole can sustain long-term contraction.
Where are small motor units found?
These are found in areas where we need fine motor control.
Ex: the muscles that cause subtle movements of the eyeball (only have 3-6 muscle fibers per nerve fiber)
What are the 4 phases of contraction and relaxation?
Excitation, excitation-contraction coupling, contraction and relaxation.
Describe excitation.
Acetylcholine from a motor neuron diffuses across the synaptic cleft and binds to receptors on the sarcolemma. Receptors are gated sodium/potassium channels that open as long as acetylcholine is bound to them. The flow of ions through the sodium and potassium gated channels leads to a change in voltage across the sarcolemma. This sets off a wave of electrical excitation that spreads along the sarcolemma, down the T tubules, and to the interior of the cell.
OR
- Nerve signal arrives at knob.
- Knob releases ACh, which binds to muscle’s receptors, opening ion gates and exciting muscle.
- Excitation spreads down and through muscle cell.
Describe excitation contraction coupling.
- Electrical impulse triggers calcium release from sarcoplasmic reticulum (SR)
- SR releases calcium to the cytosol
- Calcium binds to troponin, which moves tropomyosin to expose actin
Describe contraction.
- Myosin breaks down ATP and extends head
- Myosin forms cross-bridge with actin
- Myosin pulls actin in power stroke, then detaches, reattaches, pulls again, etc.
Describe relaxation.
- Nerve signals stops
- SR reabsorbs calcium, troponin blockade resumes, and tension subsides
What are the two classes of muscle fibers?
Slow oxidative (SO) and fast glycolytic (FG)
What are slow oxidative muscle fibers?
Slow-twitch, red, type I fibers. Small diameter. Aerobic ATP production. Abundant in mitochondria, myoglobin, capillaries. Low levels of glycogen. Resistant to fatigue. Predominate in postural muscles, such as soleus.
What are fast glycolytic muscle fibers?
Fast twitch, white, type II fibers. Large diameter. Anaerobic ATP production. Modest quantities of mitochondria, myoglobin, and capillaries. Abundant glycogen. Fatigue quickly. Predominate in quick response muscles, such as gastrocnemius.
Explain muscle growth and atrophy.
Resistance exercise stimulates production of more myofilaments, thus more myofibrils.
Growth by hypertrophy, not hyperplasia (muscle fibers do not undergo mitosis)
Exercise also stimulates production of mitochondria, myoglobin, glycogen, and blood vessels.
Unused muscles atrophy (shrink).
Explain embryonic development of muscle.
- Arises from embryonic mesoderm. Myoblasts -> primary myotubes. Secondary and tertiary myotubes increase size of muscle.
- Week 4. Migration of mesodermal cells to somites. Form myotomes. Major axial muscles.
- Week 9. Most muscle groups present. Nerve fibers have synapsed.
- Week 10. Fibers begin contracting.
- Week 17. Mother can feel fetal muscle contractions.
What are satellite cells?
Stem cells
Describe the aging of the muscular system.
Loss of lean body mass (muscle). Fat and fibrous tissue accumulation. Fast glycolytic fibers show earliest and most severe atrophy. Reduction in muscle cell components. Reduction in motor neuron number, ACh release, and sympathetic nervous system efficiency.
What are the different diseases of the muscular system?
Myopathies: disease of muscle
- Muscular dystrophy. Hereditary (sex-linked). Defective gene for dystrophin. Skeletal muscle degeneration.
- Myasthenia gravis (MG). Autoimmune disease. Destruction of ACh receptors.
What is the endomysium?
WRAPS CELLS
Thin sleeve of loose connective tissue that surrounds each muscle fiber. Creates room for blood capillaries and nerve fibers to reach every muscle fiber.
Provides extracellular chemical environment for the muscle fiber and its associated nerve ending.
Excitation based on exchange of calcium, sodium, and potassium ions between the endomysial tissue fluid and the nerve and muscle fibers.
What is the perimysium?
WRAPS FASCICLES
Thicker connective tissue sheath that wraps muscle fibers into bundles called fascicles. Fascicles are visible to the naked eye as parallel strands (grain in a cut of meat).
Carries the larger nerves and blood vessels as well as stretch receptors called muscle spindles.
What is the epimysium?
WRAPS MUSCLE
Fibrous sheath that surrounds the entire muscle. On the outer surface, epimysium grades into fascia and its inner surface issues projections between the fascicles to form the perimysium.
What does the fascia do?
Wraps muscles groups.
Describe fascicles and muscle shapes.
- Fusiform muscles are thick in middle, tapered at ends.
- Parallel muscles uniform width, fascicles aligned.
- Triangular (convergent) muscles are broad at one end, narrow at other ends.
- Circular muscles (sphincters) form rings around body openings.
Be able to classify muscles according to fascicle orientation.
What are muscle groups and compartments?
Compartments are spaces enclosed by fasciae called intermuscular septa.
Each compartment is one or more functionally related muscles (nerves and blood vessels).
Upper limbs (anterior and posterior compartments).
Lower limbs (anterior, posterior, medial, and lateral compartments).
Describe muscular attachments.
- Indirect attachments: Tendon attach muscle to bone. Connect into periosteum then matrix.
- Aponeurosis: Broad sheet of tendon.
- Direct (fleshy) attachment: Close association with bone. Gap contains collagen fibers of the epimysium and continuous with the periosteum.
- Muscles of facial expression attach to collagen fibers of the dermis.
Can attach to tissues other than bone
What are intrinsic muscles?
Both origin and insertion contained within a particular region.
What are extrinsic muscles?
Acts upon a designated region but has its origin elsewhere.
Describe the coordinated groups of muscles.
Action: Effect produced by a muscle. Produce or prevent movement.
Prime mover (agonist): Produces main force of action.
Synergist: Aids prime mover. May stabilize joint.
Antagonist: Opposed prime mover. Antagonist pair act on opposite sides of joint.
Fixator prevents bone movement.
Explain muscles, bones, and levers.
Levers add speed, distance, or force of motion.
Lever -> bone
Fulcrum -> joint
Resistance (load) -> object movement
Mechanical advantage is when length of effort arm divided by length of reistance arm.
Define the classes of levers.
First class: Fulcrum in middle. Seesaw. Extending neck.
Second class: Resistance in middle. Lifting wheelbarrow. Bounding child on knee.
Third class: Effort in middle. Paddling canoe. Flexing elbow.
What is the mechanical advantage?
The MA of a lever is the ratio of its output force to its input force.
High-MA = high power, low speed
Low-MA = Low power, high speed
How are muscles named?
Size, shape, location, number of heads, orientation of fibers, and action.
What is muscle innervation?
Describes which nerve stimulates the muscle.
Spinal nerves arise from the spinal cord and innervate muscles below the neck.
Cranial nerves emerge from the brainstem and innervate muscles of the head and neck.
Describe the muscles of facial expressions.
Frontalis elevates eyebrows. Occipitalis retracts and tenses scalp. These two are connected through the fibrous galea aponeurotica into the occipitofrontalis.
Orbicularis oculi closes eyes. Orbicularis oris closes lips. Levator palpebrae superioris, and corrugator supercilii also move tissues around the eyes.
Zygomaticus major and minor raise corners of mouth for smile. Risorius expresses horror.
Muscles insert on the dermis of the skin and subtly communicated sophisticated emotions. Most muscles are innervated by cranial nerve VII (facial nerve).
Describe the expression created by the orbicularis oris.
Closes the mouth. Lips are acted on by orbicularis oris, levator labii superioris, levator anguli oris, zygomaticus major and minor, risorius, depressor anguli oris, depressor labii inferioris, and mentalis.
Describe the expression created by the frontalis.
The frontalis elevates the eyebrows and skin of the forehead; the occipitalis retracts and tenses the scalp; and the two are connected through the fibrous galea aponeurotica into what is sometimes regarded as a single muscle, the occipitofrontalis.
Describe the expression created by the depressor anguli oris.
Depresses the corner of the mouth. The lips are acted on by the orbicularis oris, levator labii superioris, levator anguli oris, zygomaticus major and minor, risorius, depressor anguli oris, depressor labii inferioris, and mentalis.
Explain the muscles of swallowing.
Genioglossus protrudes tongue or moves it to one side if used unilaterally. Hyoglossus depresses tongue. Styloglossus pulls tongue up and back. (Glossus means tongue)
Tongue is important for both functions. Composed mainly of intrinsic muscles. Extrinsic muscles connect the tongue to other structures of the head and contribute to its agility.
Explain the muscles of chewing?
4 paired muscles for chewing:
Temporalis, masseter, and medial pterygoid elevate manidble and move it sideways. Lateral pterygoid depresses mandible and moves it sideways.
Temporalis and masseter (clenching)
Medial and lateral pterygoids (side to side motion and weak elevation of mandible)
Explain the muscles of the neck.
Digastric depresses mandible. Sternohyoid depresses hyoid. Sternothyroid depresses larynx.
Muscle that move the head insert on the cranial bones. Sternocleidomastoid (prime mover in neck flexion) rotates head to side when unilaterally active, draws head forward when bilaterally active.
Three scalenes originate on the cervical vertebrae and flex the neck laterally and contribute to respiration by elevating the ribs.
Explain the muscles of the shoulder and nuchal regions.
Trapezius extends neck.
Explain the muscles of respiration.
Diaphragm is the prime mover of inspiration.
Explain the muscles of the anterior abdominal wall.
Rectus abdominis flexes waist. Transverse abdominal compresses abdominal contents.
Explain the muscles of the thoracic and abdominal regions.
The fibrous rectus sheath, inguinal ligament, linea alba, and linea semilunaris mark some of the boundaries and insertions of these abdominal muscles.
Explain the muscles of the back.
The back has numerous complex muscles that extend, rotate, and laterally flex the vertebral column and aid in breathing.
Two groups -> Superficial and deep
Superficial group: Erector spinae extends the spine and is the main postural muscle. Divided into iliocostalis, longissimus, and spinalis.
Deep group: Include semispinalis, which extends and rotates the vertebral column. Deep multifidus connects vertebrae to each other from the cervical to the lumbar region.
Explain the muscles of the vertebral column.
Multifidus stabilizes adjacent vertebrae. Quadratus lumborum aids respiration by stabilizing the diaphragm and rib 12.
Some major back muscles (for the vertebral column) include the erector spinae (which is subdivided into the iliocostalis, longissimus, and spinalis muscle columns); the semispinalis thoracis; the quadratus lumborum; and the multifidus.
Explain the muscles of the pelvic floor.
Layers of muscle that extend between the coccyx, pubis, and ischial tuberosities from the floor of the pelvic cavity.
Perineum, superfiicial perineal muscles, deep layer muscles, and pelvic diaphragm.
Define superficial perineal muscles of the pelvic floor.
Superficial perineal muscles (bulbospongiosus and ischiocavernosus) assist in erection of the clitoris and penis, ejaculation, and voiding urine.
Middle compartment (urogenital triangle) consisting of urogenital diaphragm: composed of fibrous membrane and the minor deep transverse perineal muscle and the external urethral sphincter.
Anal triangle: middle compartment has one muscle, external anal sphincter.
What is the pelvic diaphragm?
Deepest compartment of the pelvic floor is the pelvic diaphragm. Consists of two muscles, the levator ani and coccygeus.
Explain the actions of some thoracic muscles on the scapula.
Levator scapulae elevates shoulder.
Muscles that act on the pectoral girdle originate on the axial skeleton and insert on the scapula and clavicle. Scapula is loosely connected to the rib cage. Some muscles act to stabilize it while others act to rotate it to perform movement at the shoulder joint.
What is the anterior group in terms of muscles acting on the scapula.
The pectoralis minor attaches to the coracoid process of the scapula.
The serratus anterior attaches to the anterior aspect of the medical border of the scapula. Responsible for rotating the scapula so that the glenoid fossa is oriented cranially (helps raise arm above the head)
Both act to protract the scapula.
What is the posterior group related to the muscles acting on the scapula?
The trapezius attaches to the spine of the scapula.
The rhomboids attach to the medial border of the scapula. Major and minor.
The levator scapulae attaches to the superior aspect of the medial border of the scapula and elevates it.
The rhomboids and trapezius retract and elevate the scapula. Trapezius can also depress the scapula.
Explain the muscles acting on the arm.
Pectoralis major and latissimus dorsi are major muscles originating on the check and back but both insert on the arm and are prime movers of the shoulder joint.
Pectoralis major flexes, adducts, and medially rotates humerus.
Latissimus dorsi extends, adducts, and medially rotates humerus.
Teres major extends and medially rotates humerus.
Deltoid can flex, extend, medially rotate, or abduct arm depending on which fibers are active.
Name the pectoral muscles of the cadaver.
Name the brachial muscles of the cadaver.
Explain the rotator cuff muscles in relation to the scapula.
Rotator cuff composed of tendons of 4 muscles: Supraspinatus, infraspinatus, teres minor and subscapularis.
The tendons insert on the proximal end of the humerus and form a sleeve around it, providing for stability for the mobile joint.
What are the muscles acting on the forearm.
Brachialis, Bicep brachii, Brachioradialis, Tricep brachii, supinator, pronator teres and pronator quadratus.
Pronator teres and pronator quadratus pronate forearm. Supinator and biceps brachii supinate forearm
What are the muscles acting on the wrist and hand?
Anterior compartment muscles flex the wrist (carpus), fingers (digits), and thumb (pollex). Muscles are generally wrist flexors.
Posterior compartment muscles extend the wrist, fingers, and thumb. Muscles act to extend the wrist.
Fasciae divide the forearm muscles into anterior and posterior compartments.
Describe the intrinsic muscles of the hand.
Three groups of muscles enable precise movement of the hands.
- Thenar muscles at the base of the thumb include the abductor pollicis brevis, adductor pollicis, flexor pollicis brevis, and opponens pollicis.
- Hypothenar muscles associated with the little finger are comprised of the abductor digiti minimi, flexor digiti minimi brevis, and opponens digiti minimi.
- Midpalmar muscles consist of the interosseous muscles (between the metacarpal bones) and the lumbricals.
What is carpal tunnel syndrome?
Compression of the median nerve in this relatively narrow space results in pain and wasting of thenar muscles. Pressure causes tingling and muscular weakness in the palm and lateral side of the hand and pain that may radiate to the arm and shoulder.
Common in those who do competitive wrist motions.
What are the muscles acting on the hip and thigh?
Iliopsoas (iliacus and psoas major), medial compartments of the thigh, gluteus maximus, gluteus medius, and gluteus minimus.
Describe the anterior muscles of the thigh.
Quadriceps femoris extends the knee and consists of 4 muscles in the anterior compartment:
- Rectus femoris: Only head that crosses two joints; in addition to extending the knee, it flexes the thigh
- Vastus lateralis
- Vastus medialis
- Vastus intermedius
Describe the posterior compartment of the thigh.
Hamstrings occupy the posterior compartment flex the knee and extend the thigh. 3 muscles.
- biceps femoris
- semimembranosus
- semitendinosus
Describe the anterior muscles acting on the foot.
Front of the leg has little musculature.
Tibialis anterior dorsiflexes and inverts the ankle. Extensor digitorum longus and extensor hallucis longus lift up the toes.
Describe the posterior muscles acting on the foot.
Gastrocnemius and soleus muscles form the bulge in the calf and converge on the calcaneal (Achilles) tendon. They plantar flex the foot.
Lateral compartment contains fibularis (peroneus) longus and fibularis (peroneus) brevis. They evert the foot and assist with plantar flexion.
Describe the intrinsic muscles of the foot.
Provide arch support and aid in locomotion.
Ventral (inferior) muscles help flex the toes.
Hallucis muscles (abductor hallucis, adductor hallucis, flexor hallucis brevis) act on the big toe.
Centrally, and arranged in layers from superficial to deep, are muscles that act to flex and adduct the toes (flexor digitorum brevis, quadratus plantae, lumbricals, and interosseous muscles).
Muscles on the lateral side of the foot are associated with the little toe (abductor digiti minimi and flexor digiti minimi brevis).
What are the components of blood?
55% plasma, 45% formed elements (cells and cell fragments; include erythrocytes, platelets, and five kinds of leukocytes)
What is the most abundant plasma solute (by weight)?
Proteins (3)
Albumin (60%) (most abundant and acts to transport solutes, buffer pH, and contributes to viscosity and osmolarity)
Globulins (36%) (play roles in transport, clotting, and immunity)
Fibrinogen (4%)(precursor of fibrin, a clotting protein)
General properties of blood.
Explains the form and function of electrolytes.
Red bloods cells (RBC) carries O2 and CO2.
Discoid cells with a sunken center and no organelles (no nucleus or mitochondria). Have a cytoskeleton of spectrin and actin that reinforces the plasma membrane.
Carries millions of hemoglobin molecules.
Molecules on cell membrane determine the blood type.
Explain hemoglobin in depth.
Iron-containing gas-transport protein. (transports nearly all of the O2 and some of the CO2 in the blood)
Found in RBC. Cytoplasm of RBCs consists mainly of hemoglobin molecules (about 280 million molecules per cell).
4 globins with a heme group. (four amino acid chains, two alpha chains and two beta chains)
Ferrous ions in center bind oxygen.
Each heme can bind one oxygen molecule; each hemoglobin molecule can transport four oxygen molecules. About 5% of carbon dioxide molecules in the blood are transported on the globin components of hemoglobin molecules.
Show the erythrocyte life cycle.
The transformation from a pluripotent stem cell to a mature red blood cell takes from 3 to 5 days. Approximately 2.5 million red blood cells are produced every second! The cells live for an average of 120 days. They typically get trapped and die in the small capillaries of the spleen, which breaks them up and destroys them.
Explain blood types.
Several genetically determined blood groups with multiple types.
ABO group (with blood types A, B, AB, and O) and Rh most common.
Difference in type is due to glycoproteins and glycolipids on the cell surface, molecules that act as antigens.
Blood plasma contains antibodies that react against incompatible antigens on foreign red blood cells.
Interaction between the antibodies and antigens determines the compatibility of donor and recipient blood in transfusions.
Know appearance and stats of Neutrophils.
Know appearance and stats of Eosinophils.
Know appearance and stats of Basophils.
Know appearance and stats of Monocytes.
Know appearance and stats of Lymphocytes.
Explain the leukocyte life cycle.
Leukopoiesis: Production of WBCs (begins with the pluripotent stem cells in the bone marrow which differentiate into distinct kinds of colony-forming units. Three cell lines lead to mature white blood cells: 1) myeloblasts give rise to neutrophils, eosinophils, and basophils, 2) monoblasts give rise to monocytes, and 3) lymphoblasts become lymphocytes)
Granulocytes and monocytes stay in red marrow until needed.
B lympocytes and natural killer cells mature in bone marrow.
T lymphoctyes mature in thymus.
(Lymphocytes originate in bone marrow, then migrate somewhere else)
Leukocyte life span ranges: some live only days, others live for decades.
What is thrombopoiesis?
Platelets are produced through this process.
Some hematopoietic stem cells become megakaryoblasts (cells that replicate DNA several times without dividing) .
Megakaryocytes sprout proplatelet tendrils in red marrow.
Many proplatelets are broken into platelets (as they travel through the blood stream) within lung capillaries.
Know the image of a blood clot.
Explain sickle cell disease.
Hereditary hemoglobin defect.
The RBCs become elongated, stiffened, and pointed.
They congregate in the small blood vessels and block the circulation
What are the two main divisions of the cardiovascular system?
Pulmonary circuit and the systemic circuit.
Where is the heart located? What about size and shape?
In the thoracic cavity in the mediastinum, between the lungs and deep to the sternum. Slightly tilted toward the left. The broad superior portion is the base, whereas the inferior point is the apex, resting just above the diaphragm. The adult heart weighs about 300 g and measures about 9 cm wide at the base (broad superior end), 13 cm from base to apex (the bluntly pointed inferior end), and 6 cm from anterior to posterior.
Size of fist. Base is superior. Apex points inferiorly, to the left.
Label the surface anatomy of the heart.
What is the pericardium?
Double-walled sac that encloses the heart.
The outer layer, the pericardial sac (parietal pericardium), is itself composed of two layers, a superficial fibrous layer and a deeper serous layer. The tough, durable fibrous layer is made out of dense irregular connective tissue.
Epicardium (visceral pericardium) covers the surface of the heart. Pericardial fluid, found between the visceral and parietal layers, lubricates the membranes and allows the heart to beat without friction
Pericardial cavity (space between walls)
What are the three layers of heart wall?
Epicardium, myocardium, and endocardium.
Explain the anterior view of the internal anatomy of the heart.
The two upper chambers of the heart are the right and left atria, and serve to receive blood from the venae cavae and pulmonary veins, respectively.
The two lower chambers are the right and left ventricles, which eject blood into the pulmonary trunk and aorta, respectively.
The atrioventricular and interventricular sulci on the heart surface mark the boundaries of these chambers.
The ventricles are much more muscular than the atria, and the left ventricle is more muscular than the right, since it must pump blood throughout the body whereas the right ventricle pumps it only to the lungs and back.
The chambers are internally separated by an interatrial septum between the atria and interventricular septum between the ventricles.
Explain the valves.
Valves ensure a one-way flow of blood through the heart.
Valves open and close in response to changes in pressure gradients. When the ventricles are relaxed, pressure is low and the AV valves are open; blood flows from the atria to the ventricles. When the ventricles begin to contract, pressure rises and blood pushes against the AV valves and the cusps come together, preventing backflow of blood to the atria. Ventricular pressure also forces the semilunar valves open; when arterial pressure rises during ventricular contraction the valves close, preventing blood from flowing back into the ventricles.
Labels flows of the heart valves.
How does blood flow through chambers?
Blood returns to the right atrium from body tissues via the superior vena cava (which drains the head, neck, upper limbs and thoracic cavity) and the inferior vena cava (which drains the abdominal cavity and lower limbs).
The blood passes through the right AV valve to the right ventricle, then surges through the pulmonary valve to the pulmonary trunk, which branches to pulmonary arteries that carry the blood to the lungs.
Gas exchange occurs in the lungs.
Freshly oxygenated blood flows to the left atrium through four pulmonary veins. The blood goes through the left AV valve to the strong left ventricle, which gives it a mighty push through the aortic valve to the ascending aorta and thence to all tissues of the body.
Explain the blood supply to cardiac muscle?
Coronary circulation : Coronary circulation begins with the right and left coronary arteries, the first branches of the aorta. Blockage can cause myocardial infarction – death of heart tissue.
Left coronary artery gives off the anterior interventricular branch that runs along the anterior interventricular sulcus. It supplies both ventricles and the anterior interventricular septum. The circumflex branch (left marginal branch)
Right coronary artery (RCA): Right marginal branch. supplies the right atrium and gives off two branches. Posterior interventricular branch.
Interruption of blood supply to any part of the myocardium leads to necrosis within minutes. A myocardial infarction is sudden death of tissue that has been deprived of blood flow.
Label principle of coronary blood vessels.
Explain the conduction system.
1) Sinoatrial (SA) node fires
2) Excitation spread through atrial myocardium
3) Atrioventricular (AV) nodes fire
4) Excitation spread down AV bundle
5) Subendocardial conducting network distributes excitation through ventricular myocardium
If the SA node fails to fire other autorhythmic centers can take over (usually the AV node) but they usually fire at a pace that is too slow to sustain life.
Explain the cardiac muscle.
Cardiocytes (striated) are joined at ends by intercalated discs.
Interdigitating folds (Resemble egg cartons). Mechanical junctions
(Fascia adherens, Desmosomes).
Electrical junctions (Gap junctions).
Explain the cardiac cycle.
One complete cycle of contraction and relaxation.
Electrical events measured by electrocardiogram (ECG).
Systole – contraction of a chamber.
Diastole – relaxation of a chamber.
Electrical excitation produces systole, contraction that expels blood. Relaxation of a chamber is called diastole, the filling period. Electrical excitation is coupled with the mechanical events of the heart.
At the beginning of the cardiac cycle, all chambers are in diastole. The SA node fires, an electrical event that appears as the P wave on an electrocardiogram (ECG). Contraction of the atria immediately follows. The AV node fires shortly after the SA node. The electrical stimulation passes through the ventricles and is seen as the QRS wave on the ECG. Ventricular contraction ejects the blood into the pulmonary trunk and aorta. The ventricles then repolarize, an event marked by the T wave on an ECG. At this point, all chambers are once again in diastole and the ventricles refill with blood. The entire cycle repeats itself at intervals of about 0.8 seconds.
Explain the development of the heart.
Earliest organs to function in embryo.
By 22 to 23 days, the heart is already beating. In week 3, a region of mesoderm at the end of the embryo develops into endocardial heart tubes. As the embryo grows, the tubes are pushed together and form a single heart tube. The surrounding mesoderm forms myocardium. As the heart tube elongates it segments into five dilated spaces that will develop into chambers and some of the great vessels. As growth continues, the heart loops into an S-shape. By day 28 the looping is complete and the primordial atria and ventricles have assumed their mature positions.
In the next phase, interatrial and interventricular septa form and the chambers become defined. . The ascending aorta and pulmonary trunk develop as a septum forms between them. Abnormalities in the development of the septa account for many cardiac birth defects.
