Histology Exam 2 Other Lectures

85 flashcards · Other · by Jared Blackwell

1. What are the components of the CNS and PNS?

   CNS: Gray matter and White matter PNS: Ganglia and Nerves

2. Does nervous tissue have a lot of extracellular matrix?

   No, nervous tissue has very little nervous tissue and density cellular. Primary function is to transmit electrical impulses.

3. How does CNS & PNS develop? What does the neural tube and neural crest give rise to?

   Develop from ectoderm during neurulation. -Neural tube gives rise to CNS, the folds elevate & pinch off neural tube. Neural crest gives rise to PNS. Neural crest loosens and turns mesenchymal.

4. What are the two cell types that neural tube and neural crest differentiate into?

   They differentiate into Neuron the functional cell and Glial Cell the supporting cell. Creates microenvironment for neuron.

5. What is the difference in appearance in Neurons and Glial Cells?

   Neurons are bigger with more euchromatic nuclei, (darker stain). Neurons also have basophilic cytoplasm while glial cells have poor staining cytoplasm.

6. For neurons what do these mean? a) "-lemma" b) "-plasm" c) "-perikaryon" d "-Nissl"

   a) "lemma" means plasma membrane b) "plasm" cytoplasm c) "perikaryon" is cell body d) "Nissl" refers to ribosomes.

7. What is yellow, blue, purple?

   Yellow: Mitochondria- cells require ATP. Nissl substance has: Blue: Free Ribosomes Purple: Rough ER

8. What type of proteins do free ribosomes and rER make?

   rER are membrane-bound ribosomes that produce proteins that are exported from the cell to be used elsewhere like secretory and membrane proteins. Free ribosomes produce proteins that are used inside the cell itself, soluble proteins.

9. What stain do neurofilamets stain and describe them?

   Neurofilaments = Stain black with Silver stain. They are a type of intermediate filament for neurons with abdudant cell body and provide structural support.

10. What is the function of Microtubules in Neurons?

    Microbtubules aid in vesicular transport. Secretory vesicles contain neurotransmitters.

11. What is labeled as DS and what are its function?

    DS = Dendritic Spines, bumps on dendrites. DS is where signal is passed from neuron to neuron. They increase SA and have action filaments that aid learning aka neural plasticity.

12. Describe an Axon (nerve fiber). What is the labeled yellow box and star?

    -Generally one axon per neuron. -They are longer, constant diameter, and less branching than dendrite. -Contain mitochondria, microtubules, and neurofilaments, but no ribosomes. Yellow box: is the weakly staining axon hillock. Star: the initial segment of axon, nerve impulses aka action potentials begin.

13. What are the yellow, blue, and purple arrows pointing to and their functions?

    Yellow: Mitochondria, powers fast transport. Blue: Microtubules, for bidirectional transport of organelles, vesicles, & molecules. Purple: Neurofilaments, maintain diameter of axon, support.

14. What are the red arrows pointing to and what type of stain is this?

    This is a trichrome stain pointing at an axon.

15. Describe myelination of axon

    Myelin is lipid-based and provides electrical insulation. Because lipid, poor staining under LM. Formed by two types of glial cells that are specific to CNS or PNS.

16. How is the myelin sheath formed?

    Glial cell wraps around axon. The glial cell's cytoplasm and nucleus get pushed to periphery. Cytoplasm and nucleus surrond myelin sheath.

17. What is labeled star and white bar? Function?

    The star (gap) is the node of Ranvier. Action potentials "jump" from node to node via saltatory conduction. The bar is the internodal segment. Each glial cell only wraps around one portion of axon. Thick myelin = fast AP conduction.

18. Describe an unmyelinated axon.

    In the PNS, axons with small diameters don't have multiple wrapping of myelin sheath. Instead, unmelinated axons in PNS have a simple fold of glial cell.

19. What are yellow and blue lines pointing to?

    This is an unmyelinated axon in PNS. Yellow is the axon. Blue is PNS glial cell. The glial cell can envelop several axons.

20. What are the types of axon synapses you can have?

21. What is the swollen end and distal branches of an axon called?

    The distal branches are terminal arborization -Arborization = Greek for end of tree. Swollen end of axon branch is the terminal bouton. When the terminal bouton makes contact with another neuron or cell its a synapse.

22. List the three components of a synpase.

    1.Presynaptic terminal bouton, has secretory vesicles. 2. Synaptic cleft. NeuroTs are exocytosed here. 3. Postsynaptic cell membrane. Contains receptors for NeuroT. Yellow = secretory vesicles. Orange = Presynaptic membrane. Blue = receptor for NeuroT on postsynaptic side. Purple = The postsynaptic density. Synapse is where an AP from one neuron transfers that AP to another neuron or cell.

23. What does botulism do?

    Botulism stops the release of NeuroT (ACh). This inhibits the transfer of AP to effector cell, resulting in paralysis.

24. Describe the morphological types of neurons.

    Multipolar neuron one axon, two or more dendrites, most common. Bipolar neuron only in sight, smell, and balance. One axon and one dendrite. Pseudounipolar (unipolar) neuron signel short process comes from cell body and splits. Found in spinal and most cranial ganglia.

25. What are the morpholgical types of motor, sensory, and integrative neurons?

    Motor: Multipolar Sensory: Pseudounipolar (unipolar) and Bipolar Integrative: Multipolar

26. A: Nucleus B: Axon hillock. C: Initial segment of axon. D: Axon E: Node of Ranvier

27. Describe neuropil

    "Fibrous" - dendrites & non-myelinated axons of neurons + processes of glial cells. Neuropil is found in gray matter of CNS and allows neuron-neuron synapse.

28. What are the 6 types of glial cell?

    CNS: Oligodendrocyte, Astrocyte, Ependymal cell, Microglia. PNS: Schwann cell and Satellite cell.

29. Describe an Oligodendrocyte

    Make myelin sheath in CNS. Cytoplasm wraps around axon to form internodal segments. Abundant golgi with poor staining cytoplasm. Golgi makes unit membranes. Make of majority of glial cells in white matter CNS. Can myelinate up up to 50 parts of different axons. Myelination is completed around 25-30 years of age.

30. Astrocyte ("star cell") Most common glial cell found found in CNS. Many radiating processes extend out. Glial fibrillary acid protein (GFAP) are intermediate filaments for astrocytes that support large processes. These processes have broad end feet that contribute to BBB. They cover synapses to maintain microenvironment. They aid in nutrient, ion, and waste diffusion around neurons.

31. Ependymal cells. Cuboidal or columnar epithelial-like cells. NO basal lamina. Cilia in ventricles (choroid plexus) secrete and circulate CSF. The ventrical system (brain) and central canal (spinal cord) is lined with ependymal cells.

32. Microglia are small, short, and irregular. They migrate through neuropil for host defense. Distributed evenly in gray & white matter. Become activated and go from start shape to typical phagocyte. NOT derived from neural tube or crest. Instead, from bone marrow. Clinical correlation: MS is from autoimmune damage of myelin sheath. Microglia phagocytose myelin faster than myelin can be repaired.

33. Describe Schwann cell (neurolemmocyte) Only in PNS. Derive from neural crest cells. Similar to oligodendrocytes because they tightly warp axon (create myelin). NOT similar to oligodendrocytes because Schwann cells only associate with single portion of axon. Also can envelop axon (unmelinated).

34. Describe satellite cells.

    Only in PNS ganglia. Derived from neural crest cells (like Schwann). Completely cover ganglionic neuron cell body. Ganglion is a group PNS neurons i.e. spinal & autonomic ganglia. Nerve = bundle of axons + glia & connective tissue. Support neuron via insulation, nourishment, and maintain mircoenvironment. Nucleus only visible under LM.

35. What does gray matter equal? White matter?

    Gray matter = neurons, neuropil, & CNS glia. White matter = myelinated axons & CNS glia.

36. Describe spinal ganglia.

    Spinal ganglia have: -pseudounipolar neurons -Sensory function -Many satellite cells -NO synpase

37. Describe autonomic ganglia.

    -Multipolar neuron -Visceral motor -Fewer satellite cells -Synapse

38. What is the blue box and black box?

    Blue box is spinal ganglia, many satellite cells, no synapse. Black box is autonomic ganglia, fewer satellite cells, Synpase.

39. Nerve organization.

    Each axon is eveloped by Schwann cells. Blue circle= Endoneurium, thin layer of loose CT. Dark Yellow= Perineurium, covers each fascicle. Special CT cells form tight junctions for perineurium. Fascicle contains the axons with Schwann cells & endoneurium. The fascicle has blood-nerve barrier that regulates diffusion into fascicle. Outer light yellow = Epineurium, Dense irregular CT that covers and binds groups of fascicles.

40. Name labeled structures.

    Blue: Endoneurium Red: axon Yellow: Epineurium Orange: Perineurium

41. Name structures.

    Red arrow: axon Blue: Endoneurium Yellow: Epineurium Orange: Perineurium

42. 1. 2. 3. 4.

43. Skeletal, cardiac, smooth muscle.

44. Name structures.

    Epimysium --> Perimysium --> Endomysium.

45. Name the bands. What is a Sarcomere?

    A band is dark. I band is light, Thin filaments. Z disc are the dark lines inside I band. Sarcomere is Z disc to Z disc. It is the smallest contractile unit.

46. What is the Sliding Filament Theory? Titan, Actinin, and Dystrophin?

    Z discs come close together as myofilaments slide past eachother. Myofilaments do NOT change length. Titan connects thick filaments to Z disc. (A band to Z disc). Actinin anchors actin to Z disc. Dystrophin links actin to ECM. Clinical Correlation: Muscular dystrophies are a family of genetic disorders associated with a deficiency of the accessory protein dystrophin, which anchors myofilaments to the ECM. Results in muscle degeneration and fibrosis.

47. What is this?

    Triad - 2 terminal cisternae + 1 T-tubule. T-tubule is middle, darker line. Located at junction of A & I bands. Top right line is Sarcoplasmic reticulum. Ca2+ storage, contains terminal cisternae and SR tubulues. T-tubules invaginate sarcolemma and bring depolarization to site of Ca2+ storage - ST.

48. Explain skeletal muscle fiber motor innervation.

    1.Nerve impulse release ACh, initiates muscle impulse. 2. Muscle impulse sperads down t-tubules, Ca2+ are released from terminal cisternae.

49. What is the function of muscle spindles and Golgi tendon organs?

    Muscle spindles and Golgi tendon organs monitor changes in length and tension. Participate in stretch reflex.

50. Muscle spindle.

51. Cardiac muscle. Single centrally-located nucleus. (20% may be binucleate). Second picture is smooth muscle.

52. Fascia adherens similar to adherens junctions. Connect to actin filaments (thin filaments) to transmit contraction. Squiggly lines with dark area around. Desmosomes connect intermediate filaments to cytoskeleton. Gap junctions spread electrical stimulation.

53. Smooth muscle. Single nucleus, no striations, innervated by ANS, linked to many gap junctions. NO sarcomers but have actin & myosin.

54. Caveolae. Helps smooth muscle facilitate Ca2+ transport.

55. M line A band I band Z disc Yellow arrow: Myofilament. Bundle of myofibers (fascicle) --> Myofiber (muscle fiber) --> Myofibril (rows of myofilaments) --> Myofilament.

56. Platelet with granulomere the dark staining core. Granulomere contains granules for coagulation, vasoconstriction, platelet aggregation and adhesion, vessel repair. Hyalomere is outer light stainging rim of platelet. Hyalomere has microtubules to maintain shape. Open canclicular system invagination of plasma membrane to increase SA for secretion.

57. Giemsa, Wright's stain similar to H&E for peripheral blood stain. Label.

    Erythrocytes (RBC). Leukocyte (WBC). Platelets.

58. 1. 2. 3. 4. 5.

    Lymphocyte Basophil Neutrophil Monocyte Eosinophil

59. Neutrophil. Phagocyte bacteria. Also recruit WBC and induce fever. Lighter cytoplasm than eosinphil. Orange: Azurophilic granules (lysosome). Darker electron density. Blue in LM Yellow: Specific granules. Light density, contain antibacterial agents. Pink in LM. Blue: Mulilobed nucleus.

60. Eosinophil. Kill parasites. Also may mediate inflammation and allergic rxns. Yellow: Specific granules. Electron-dense crysatalloid body. MBP released by exocytosis, toxic effects on parasites. Blue: Bi-lobed nucleus.

61. Basophil. Least numerous blood cell. Initiate inflammation, similar to mast cells - allergies. Yellow: Specific granules Heparin (anticoagulant) Histamine (increase blood flow) Leukotriene (constricts airways) Blue: Bi/tri-lobed nucleus.

62. Mast cell and basophil.

63. Lymphocyte aka WBC. Thin rim of light blue cytoplasm. B, T, and NK cell. Only WBC to return to blood after being in CT or lymphatic organ.

64. Monocyte. Precursor to macrophages, circulate and differentiate. Kidney bean nucleus. Largest circulating leukocyte. Precursor cells of mononuclear phagocyte system Microglia - CNS Langerhans - Skin Osteoclast - Bone

65. What are connective tissue proper and specialized CT?

    Specialized CT = bone, blood, cartilage. CT proper: Dense, loose, reticular tissue.

66. Chondrocytes are cartilage cells. Produce and maintain components of ECM. L: cells are found in lacuane.

67. Isogenous group: recent mitotic activity of a chondrocyte forms a cluster of cells. After mitosis, cells secrete ECM and pushed apart. Cartilage matrix and chondrocytes. Interstitial growth - growth from within (many black arrows.) *Isogenous groups not present in bone *Bone does not have interstitial growth

68. Cartilage ECM GAGs, proteoglycans, type II collagen. Avascular, need diffusion from surrounding CT.

69. Perichondrium. NOT in fibrocartilage or articular cartilage. Dense irregular CT. Outer fibrous layer and inner cellular layer (source of stem cells). Perichondrium allows appositional growth - new cells added to edge of tissue.

70. Hyaline Cartilage, resists compression. Articular cartilage is hyaline cartilage of joints. ECM is "glassy," stains pink to blue. Perichondrium present except articular.

71. Elastic Cartilage provides elastic support, bend & return to shape. Has all general features of hyaline. However, also elastic fibers in ECM. Elastic fibers will stain dark/black with Orcein stain.

72. Fibrocartilage resits tension and compression. Combination of hyaline and dense CT. NO perichondrium. Type I and II collagen. Identify: Chondrocytes in a row and Type I collagen.

73. Circumferential bone lamellae Vascular canal Osteons Osteon - basic unit of bone, rings of lamellar bone around central canal. Haversian canal

74. Yellow: Canaliculi for communication with central canal. Green: Central canal has blood vessels & nerves, diffusion through canaliculi. Purple: Perforating canal perpendicular to central canal. Connects central canal with other vessels. Blue: Lacunae (for osteocytes)

75. Yellow: Canaliculi for communication with central canal. Connect adjacent lacunae. -In canaliculi, osteocyte processes form gap junctions to communicate. Blue: Lacunae (osteocyte resides here)

76. Muscle, Periosteum, Bone, Sharpey's fibers. Periosteum is CT covers external bone. Perorating (Sharpey's) fibers are type I collagen from periosteum embedded in bone.

77. Endosteum Monolayer of cells on internal surface on bone. Osteoprogenitor (stem) cells, osteoblasts, bone lining cells.

78. Osteoblast single layer of cuboid cells on surface. Form bone. -Extensive rER, golgi, euchromatin. Osteoblast secrete Osteoid, mineralized bone, osteocalcin (calcium-binding protein) to bind ECM components together Sythensize ECM, rER, Golgi, euchromatin OsteoBlast = B = Build Bone

79. Mineralized bone Osteoid Osteoblasts Osteoblast secrete Osteoid, mineralized bone, osteocalcin (calcium-binding protein) to bind ECM components together

80. Osteoblast Mineralized bone Osteoid Osteocyte Osteocytes are osteoblasts that are became embedded in ECM. -Maintain bone, bone remodeling. Found in lacunae. -Low rER and Golgi. Communication via gap junctions.

81. Osteoclast. Phagocytic, found on bone surface. Found in resorption cavities (Howship's lacunae) Large, multinucleated cells. -Calcitonin secreted by thyroid inhbits resorption by osteoclasts. -PTH binds osteoblasts and secrete RANKL. RANKL stimulates osteoclasts. breakdown bone increase Ca2+. Resorb bone, breakdown ECM. OsteoClast = C = "Cleave" bone.

82. Osteoclast border Ruffled border folded plasma membrane. -Proton pumps lower pH, dissolve minerals. -Lysosomal enzymes are secreted to breakdown collagen. Clear Zone site of adhesion to bone.

83. Mesenchyme Osteoblast Osteoid (light area) Mineralized matrix (pink area) Osteocytes

85. Epiphyseal Growth Plate Zones: 1.Resting zone - hyaline cartilage. 2. Proliferative zone - mitosis, stacked columns 3. Hypertrophic cartilage zone - chondrocytes enlarge. 4. Calcified zone - cartilage ECM calcifies, chondrocytes die. 5. Ossifcation zone - vascularization, calcified cartiagle replaced with acidophilic bone.