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Ocular Anatomy > Exam 1 (Histology) > Flashcards

Exam 1 (Histology) Flashcards

1
Q

What are the two components of H&E staining and the characteristics of each?

A

H=Hematoxylin, stains blue, basophilic

E=Eosin, stains red, acidophilic

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2
Q

What are the differences between heterochromatin/heterochromatic nucleus and euchromatin/euchromatic nucleus?

A

Heterochromatin is densely packed regions of chromatin that are transcriptionally and metabolically INACTIVE portions of the genome. A heterochromatic nucleus is identified to have a solid color blue nucleus and poorly defined nucleolus. It is most likely terminal/not actively dividing.

Euchromatin is loosely coiled chromatin that is transcriptionally and metabolically ACTIVE. In a nucleus it is lightly pigmented spots. A euchromatic nucleus is lightly dyed with a round, fully developed nucleolus.

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3
Q

What structures are made of microfilaments?

A

Tiny rods composed of actin. Microvilli, terminal web, contractile ring, muscle cells (actin filaments)

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4
Q

What is made of microtubules?

A

Hollow tubes of tubulin. Centrioles, Mitotic spindle, Cilia, Flagella (Axoneme and Basal Bodies)

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5
Q

What are characteristics of mitochondria?

A

Large, motile organelles composed of 2 unit membranes (inner membrane is folded into cristae). They are self replicating and generate ATP. They stain red and are responsible for the red staining of the cytoplasm. Cells that require a lot of energy will stain intensely pink/red.

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6
Q

What is the function of ribosomes?

A

Contains RNA from nucleolus and assemble amino acids into proteins. They stain blue. Ribosomes associated with the RER produce secretory, lysosomal and integral proteins. Free ribosomes produce proteins for their own cell’s use.

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7
Q

What is the function of the Golgi bodies?

A

Primary center for recycling, packaging, distributing membranes and segregated proteins (membrane bound). They chemically modify proteins. Package secretory proteins into secretory vesicles and hydrolytic enzymes into lysosomes.

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8
Q

What s the function of RER?

A

It is the site of protein synthesis for proteins that need to be enclosed in a membrane (secretory proteins, lysosomal proteins and integral proteins of cell membrane. Stains blue due to ribosomes.

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9
Q

What is the function of SER?

A

Contains enzymes for synthesis of lipid and cholesterol derived products. Well developed in cells that secrete lipids, lipoproteins and steroid hormones. Stain light/light pink (no ribosomes).

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10
Q

What’s the difference between apoptosis and necrosis?

A

Apoptosis is a programmed cell death that is due to internally programmed suicide coding. Necrosis is due to an outside influence and acute cell injury (ischemia, mechanical injury, toxins).

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11
Q

Which cells give red or blue color in H&E staining?

A

Red-acidophilic structures: mitochondria, secretory vesicles, lysosomes

Blue-basophilic: ribosomes, RER, secretory vesicles

*Vesicles depend on what the substance inside is

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12
Q

What is the difference between simple and stratified epithelium?

A

Simple is one cell layer thick with each cell touching the basal lamina. Stratified epithelia only has the basal cells attached to the basal lamina. The are classified by the shape of the surface cells in a x.s

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13
Q

Which simple cell is responsible for gas exchange, diffusion and filtration?

A

Simple squamous

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14
Q

Which type of collagen makes up the basal lamina?

A

Type IV collagen makes up the basal laminae forming a delicate meshwork.

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15
Q

What are the two layers of the basement membrane that can be seen in the EM?

A

Basal lamina-made of type IV collagen that is secreted by the epithelial cells
Reticular lamina- secreted by the fibroblasts of the connective tissue (primarily type III collagen fibrils)

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16
Q

What type of junction are areas of complete fusion between adjacent cell membranes?

A

Tight Junction/Zonula Occludens, basis of blood brain barrier

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17
Q

Which type of junction are used for cell-cell communication/metabolic/electrical coupling?

A

Gap junction/Communicating nexus junction (common in smooth muscle, cardiac muscle, osteocytes)

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18
Q

What’s the difference between merocrine, apocrine and holocrine secretion?

A

Merocrine/Eccrine: secretion with little or no loss of apical cytoplasm (most common)
Apocrine: secretion with loss of some apical cytoplasm (mammary/specialized sweat glands)
Holocrine: secreted when cell explodes/disintegrates (sebaceous glands)

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19
Q

What’s the difference between serous and mucous cells as seen in an EM?

A

Serous: vesicles are dark and nucleus is large, round and light
Mucous: vesicles are light (clear) and nucleus is flat and dark

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20
Q

The classification of malignant vs benign is based on what?

A
  1. Fidelity to precursor cells (do they look like parent cells or are they anaplastic?)
  2. What is the rate of growth and location of growth?
  3. Are they able to invade other tissues/metastasize?
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21
Q

What are the major types of fibers found in CT?

A

Collagen fibers- type I, large fibers easily seen in H&E as acidophilic bundles, very strong/flexible
Reticular Fibers- Delicate, thin fibers made of type 3 collagen, not visible in H&E (only silver stain), form delicate framework for cells
Elastic fibers-thin, branching fibers made of elastin, not visible in H&E unless in large amounts, must use special stain, important in stretch and recoil

22
Q

What is the function of the fibroblast cell?

A

It is the principle cell of the CT and it secretes and maintains the extracellular matrix including all fibers and the ground substance. It is motile and it can reproduce.

23
Q

What are the function of adipose cells?

A

Store neutral fat

24
Q

What is the function of macrophages?

A

Derived from monocytes (in the blood), they perform phagocytosis of invaders, remove cellular debris, and are critical in immune function (present antigens to lymphocytes)

25
Q

What is a feature of plasma cells and their function?

A

Plasma cells are derived from B-lymphocytes and have an eccentric nucleus with an unusual pattern of heterochromatin that makes it appear like a soccer ball. It secretes circulating antibodies (immunoglobulins)

26
Q

What determines loose vs dense CT?

A

It is dependent on the number of fibers NOT the number of cells

27
Q

What is the difference between dense irregular and dense regular?

A

Dense irregular is typically haphazardly arranged collagen fibers that can resist stress from multiple directions. Dense regular tissue is large bundles of collagen that are parallel and extend in the direction of tension

28
Q

Where are elastic fibers found and how can they been seen on a slide?

A

They are present in vocal cords, the tissue between adjacent vertebrae, the lamina of muscular arteries and in elastic arteries such as the aorta. A special stain needs to be used to see them

29
Q

Where is reticular tissue located and how can it be seen?

A

It makes up the stroma of lymphatic and hemopoietic tissues. A silver stain must be used to see the tissues

30
Q

What are the 6 features of bone?

A
  1. It is calcified support tissue that acts as a reservoir for minerals (Ca, K, others)
  2. Extracellular matrix contains type I collagen fibers, ground substance and minerals (has organic and inorganic phases, organic phase makes up 67% of the bone)
  3. Matrix contains osteocytes trapped in lacunae, cells are interconnected via canaliculi
  4. Bone is highly vascular containing many many blood vessels and lymphatic vessels
  5. Bone matrix is constantly being remodeled (matrix is constantly destroyed and produced)
  6. There are two classifications of bone that is based on the presence of osteons (spongy bone and compact bone)
31
Q

What are the four kinds of bone cells and their features?

A

-Osteoprogenitor cell: differentiates into osteoblasts then osteocytes, they can undergo mitosis, hiding in periosteum
-Osteoblast: primary producer of bone matrix, it is a basophilic cell w round euchromatic nucleus, lined up in one-cell thick rows on surface of bones, secretes organic components of bone matrix and matrix vesicles that initiate bone mineralization
-Osteocyte: osteoblast that has become trapped in a lacunae, thin cell processes called canaliculi, communicate via gap junctions, maintain the bone matrix, cannot undergo mitosis
Osteoclasts: large, multinucleated cell w acidophilic cytoplasm, derived from monocytes, secretes acid, collagenases and other lytic enzymes that break down bone matrix

32
Q

What is a Haversian system?

A

AKA osteons, 4-20 lamellae of matrix/osteocytes surrounding central canal (Haversian canal) where the blood vessel lies. Chains of 10-20 osteocytes linked by canaliculi can be supplied w oxygen and nutrients via the BV. The HS runs longitudinally

33
Q

What are the four features of compact bone?

A
  1. Have Haversian systems
  2. Have Volkmann’s canals: transverse canals that bring BV to and from periosteum, Haversian canals and marrow cavities
  3. Have interstitial lamellae: remnants of partially reabsorbed osteons
  4. Circumferential lamellae: the first few lamellae of bone nearest the periosteum/marrow cavity (there is outer and inner circumferential lamellae)
34
Q

What is intramembranous ossification and which bones are formed by this process?

A

There is no prior cartilage tissue (which is present in endochondral ossification), this process form flat bones of skull and face and clavicle

35
Q

What is endochondral ossification?

A

Hyaline cartilage “template” is formed. Primary ossification center occurs at the diaphysis where the BV pushes thru the center. The chondrocytes hypertrophy and the matrix calcifies. The process of chondrocyte division, hypertrophy, osteoblast deposition and osteoclast resorption continues in both directions until it is restricted to the ends (epiphysis). Secondary ossification centers are at these points. Growth in length discontinues after chondrocytes in the epiphyseal plate are destroyed. Bones can increase in with throughout life via the periosteum

36
Q

What are the common features of all 3 muscle types?

A
  • Consist of long, cylindrical cells/fibers
  • Specialized to shorten/contract
  • Acidophilic cytoplasm w oval/cigar shaped euchromatic nucleus
  • Large amounts of contractile filaments
  • Anchored to CT via basal lamina
  • Capable of enlarging/shrinking
  • Requires a large vascular supply
37
Q

What is a sarcomere?

A

Repeating units of contractile filaments that make up a muscle fiber

38
Q

What is the A band, the I band, the H zone, the M line and the Z line? Which band(s) change size during contraction?

A

A band- area of myosin (dark band)
I band- free actin (light band)
H zone- free myosin, zone between the actin filaments
Z line: where the actin filaments are anchored, marks the beginning and end of a sarcomere
M line- middle of sarcomere
H and I change sizes during contraction

39
Q

What is a triad? Where is it located?

A

It consists of one t-tubule and 2 terminal cisternae. It is located at the A/I band junctions. The excitation signal travels via the t-tubule and the Ca is released via the terminal cisternae. They are found in skeletal muscle only.

40
Q

What is the motor end plate? Where is it found? What are other names for it?

A

It is the junction of the axon terminal of the neuron, a small synaptic space and the membrane of the muscle cell. It is found in skeletal muscles only where excitation is controlled by the spinal cord/brain stem. It is also known as a Neuromuscular Junction/Synapse or Myoneural Junction

41
Q

What are characteristics of skeletal muscle?

A

Multinucleated peripherally, striated and large unbranched fibers

42
Q

What are characteristics of cardiac muscle?

A

Small, branched cells with striations. In a x.s they are smaller and more variably sized. They have an oval, central euchromatic nucleus. Adjacent fibers are connected via intercalated discs.

43
Q

What is a diad? Where is it located?

A

Contains one terminal cisternae and a T tubule. It is less developed than it is in skeletal muscle. It is located in heart muscle only

44
Q

What are the components of intercalated discs?

A
  • Fascia adherens (type of intermediate junction/Zonula adherens) anchor the actin filaments of the last sarcomere to the sarcolemma.
  • Desmosomes (macula adherens) strongly attach adjacent cells together to keep them from pulling apart
  • These two adhering junctions allow for transmittance of the force of contraction from cell-cell
  • Gap/Communicating junction allow diffusion of ions and electrical excitation b/t cell (allows for in sync rhythmic contractions
45
Q

What is the type of control over cardiac muscle? How does it work?

A

Cardiac muscle is controlled autogenically. This means they exhibit a spontaneous rhythmic contraction that can only be modified by the ANS, endocrine system or the specialized muscle fibers. There is no NMJ like skeletal muscle

46
Q

What is the name of the fibers that are unique to cardiac muscle? What do they do?

A

Purkinje fibers are specialized cardiac muscle cells that are located near the endocardium of the heart. They are much larger tan typical cardiac muscle cells and contain an abundance of glycogen. They play a key role in coordination the pattern of contraction in the heart by quickly conducting/spreading excitation waves to cardiac muscle fibers via gap junctions.

47
Q

What are characteristics of smooth muscle?

A

It is small, spindle shaped and layered with no striations. There is a single central nucleus. Each fiber secretes a basal lamina and a network of reticular fibers.

48
Q

What is the appearance of a smooth muscle cell in an electron microscope?

A
  • Myofilaments are present but not organized into myofibrils and sarcomere. The filaments interconnect and are anchored to dense bodies that are anchored to the sarcolemma
  • There is no specialized membrane system but there are small invaginations called caveolae in the sarcolemma. There are pinocytotic vesicles also found in the cytoplasm
49
Q

What is the means of innervation of the smooth muscle? What controls it? Are there NMJ present?

A

There are no NMJ and the muscle contracts spontaneously. The ANS and endocrine hormones can modify the rate of contraction. They are often linked by gap junctions allowing muscle to contract in synctium (peristaltic movements in the colon) or as a single sheet. It is sensitive to touch. Contraction looks like a net cast over a blob and the net contracts

50
Q

What stage of mitosis are cells suspended in for the purpose of karyotyping?

A

Metaphase

Ocular Anatomy (3 decks)

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