Week 2 Flashcards
Indirect vs Direct Hernia
Indirect: Congenital vs adult, through inguinal canal and transversalis fascia, lateral to inferior epigastric artery
Direct: Not through inguinal canal, medial to inferior epigastric artery
Neural crest derivatives
DRG, sympathetic trunk, collateral ganglia, adrenal medulla cells, parasympathetic ganglia, melanocytes
Describe how a muscle is organized into cells and fasicles and how they relate to endomysium, perimysium and epimysium
Fibrils–>Fibers(cells)–>Fasicles–> Muscle
Endomysium- thin connective tissue layer surrounding fibers
Perimysium- surrounds fasicles and forms the larger septa within muscles
Epimysium- connective tissue surrounding the whole muscle
Describe the internal organization of a muscle cell (skeletal)
Thin myofilaments- actin, tropomyosin, troponin complex
Thick myofilaments- myosin (tail consisting of 2 heads with actin/ATP binding site+ 2 tails with heavy chains)
Sarcomere- from Z line to Z line, unit of contraction
Nuclei are peripheral
Describe the internal organization of a muscle cell (skeletal) cont.
Mitochondria- between myofibrils
Sarcoplasmic reticulum- smooth ER and reservoir of calcium
T-tubule- adjacent to SR, bring depolarization into interior of the cell
Triad- 2 terminal cisterna of SR + t-tubule
Z line
A band
H band
Marks the boundaries of sarcomere, attached to thin and thick filaments
Length of the thick filament in the middle of the sarcomere, contant length through contraction
Center with only myosin no actin
M line
I band
Overlap and interconnection of thick filaments
Consists of thin filaments. Z band bisects the I band
I+H band shorten during contraction
Histological Basis of DMD and myasthenia gravis
DMD- loss of dystrophin, loss of connection of muscle cells to connective tissue
MG- autoimmune disease where antibodies block the Ach receptor sites on the sarcolemma
Contraction Cycle
Nerve impulse arrives, t tubules carry depolarization to A and I band junction, L-type channel change conformation so open SR Ca channels to release calcium into sarcoplasm, calcium binds to troponin c, changes conformation of troponin I, allows myosin to bind with actin, ATP binding causes release, ATP hydrolysis causes head bending and new site attachment, P release causes head to tightly bind to actin
Muscle Innervation
Terminal axon enters sarcolemma of muscle cell at synaptic cleft defined as a motor end plate, sacrolemma of synaptic cleft has numerous folds
Motor unit- number of muscle fibers supplied by 1 neuron
More motor units great force of contraction
imaging modalities
x-ray radiographs, ultrasound, computerized tomography, magnetic resonance imaging, nuclear medicine, positron emission tomography
5 x-ray densities (from black to white)
air, fat, soft tissue or water, calcium or bone, metal or contrast
ALARA
minimize exposure to ionizing radiation
Identify organs of the lymphatic system
lymph vessels, lymph nodes and nodules, thymus, spleen, bone marrow, tonsils
Functions of the lymphatic system
Drain excess fluids from body tissues, re-circulate proteins from blood capillaries, absorb emuslified fat via lacteals in intestinal villi, B and T cells
Differences between lymphatic circulation and cardiovascular circulation
Lymphatic vessels begin blindly with no connection to blood capillaries, endothelial cells have no basal lamina and the cells have gaps between them
B vs. T lymphocytes
T cells undergo initial differenitaitonin the thymus and are involved in cell=mediated response to foreign invasion
B cells undergo initial differentiation in the bone marrow and travel to peripheral sites (plasma or memory cells)
Primary Lymphoid Tissue
Secondary Lymphoid Tissue
Thymus and bone marrow
Lymph Nodes, Mucosa associated lymphatic tissue, Spleen
Lymphatic component of Lymph nodes
Blood Vascular Component
Cortical afferent lymphatics, subcapsular sinus, trabecular sinus, medullary sinus, hilus and efferent lymphatics
Afferent arteriole, efferent venule
MALT (Mucosa-associated lymphatic tissue)
Unencapsulated lymphoid tissue (Peyer’s patches), lamina propria lymphocytes, plasma cells and macrophages, the mucosal intra-epithelial lymphocytes, the mesenteric lymph nodes
How do lymphatic vessels differ from blood vessels
Lymph vessles don’t have blood cells, extremely thin wall of mostly endothelium and CT, lymphatic vessles have valves to prevent backflow
Spleen (White pulp)
Periarteriolar Lymphoid sheath (T cell) Germinal Center (B cell)
Spleen (Red pulp)
Sinus and Cords
Development of Coelom
Function
Pleural and peritoneal cavities are separated by diaphagm; pleural and pericardial cavities separated by pleuropericardial folds
Function of Coelom:allows internal organs to shift around and move independently of body wall
Contents of the mediastinum
pericardium, great vessels, trachea, esophagus, vagus/phrenic/sympathetic trunk nerves
Middle mediastinum: pericardial sac and great vessels
Axons that are myelinated
somatomotor, presynaptic sympathetic, and both processes of general sensory neurons (pseudounipolar)
Cell process morphology
Unipolar Pseudounipolar (general and visceral sensory neurons) Multipolar (somatomotor, autonomic, and interneurons)
Supporting cells PNS
Schwann cells
Satellite cells
Surrounds axons in both unmyelinated and myelinated nerves (1 schwann cell surrounds many axons if unmyelinated)
Equivalent cells surrounding cell bodies
Supporting Cells CNS
Oligodendrocytes
Astrocytes
Microglia
CNS equivalent of schwann cells
A scaffolding in brain tissue, derivative from neural crest
Phagocytic cells
Sheath of Schwann (neurilemma)
Myelin
Schmidt-Lanterman Cleft
Myelin basic protein
Protein O
Cytoplasm and organelles that are squeezed to the periphery
Schwann cell membrane
Narrow bands of continuity of cyoplasm from the axon to the exterior of the sheath
Contribute to compacting the myelin layer creating intracellular major dense lines
Extracellular intraperiod lines
Epineurium
Endoneurium
Perineurium
Connective tissue sheath enveloping the entire nerve
Delicate connective tissue surround each individual neuron and its Schwann cell neurilemma
Surrounds groups of neurons, but it is not the nerve equivalent of perimycium. Contains collagen, tight junctions, and contractile filaments. Create nerve-blood barrier
Compare and contrast malformations, deformations, and disruptions
ORGAN
Malformation during embryonic period- poor formation of tissue, abnormal developmental process (incomplete, redundant, aberrant morphogenesis) ex. cleft lip, polydactyly, spina bifida
REGIONAL
Deformation during fetal period- normal tissue formation but acted upon by abnormal forces ex. mandibular asymmetry, micgrognathia
Disruptions- normal tissue formation that then breaks down ex. encephalocele due to amniotic tear
Common causes of malformation
single gene defects, chromosome abnormalities, multifactorial traits, maternal influences, unknown
Sequences
1 single anomaly leads to another anomaly. Ex. Potter’s sequence (failure of kidneys to form leads to clubbed feet)
Pleuropericardial folds
Separate pleural cavities from pericardial cavity which form fibrous layer of pericardium
Phrenic vs. Vagus
Innervation: Diaphragm versus Thoracic and abdominal viscera
Origin: Cervical 3,4,5 versus Cranial 10
Location: Adherent to pericardium versus run alongside gut tube
Factors in teratogenicity
Dose- determined by route of administeration, distribution, maternal metabolism effiency of transplacental transfer
Developmental stage- before implantation (no embryo), between 2-8 weeks (development of organs), after (affects the growth or function of organ)
Timing- critical period (when development is disrupted and may result in major congenital anomalies)
Maternal and fetal genotype- epoxide hydrolase activity and hydantoin
Torch agents
toxoplasmosis, o (syphillis), rubella, cytomegalovirus, herpes
