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Histology > Exam 1 > Flashcards

Exam 1 Flashcards

1
Q

Plasma membrane

A

Surrounds the outside of the cell Composed of a lipid bilayer and proteins Polar heads on outside, non- polar/hydrophobic tails on inside

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2
Q

What types of proteins are associated with the lipid bilayer?

A

Peripheral and integral membrane proteins

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3
Q

What are the two faces of the plasma membrane? How do you image them?

A

E-face and P-face Image via freeze fracture technique - pull layers apart, proteins go with layers

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4
Q

Which face of the plasma membrane usually has more integral proteins associated with it?

A

The P face

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5
Q

E-face

A

The layer of the plasma membrane backed by the extracellular space

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6
Q

P-face

A

The layer of the plasma membrane backed by the cytoplasm (protoplasm)

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7
Q

What are the functions of different integral membrane proteins?

A

Pumps Channels Receptors Linkers Enzymes Structural

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8
Q

What are the different methods of transport across the plasma membrane?

A

Simple Diffusion Carrier Proteins Channel Proteins

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9
Q

Simple diffusion

A

Requires no proteins Particles are small and hydrophobic enough to cross the bilayer

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10
Q

Carrier proteins

A

May be passive (no energy required, usually high to low concentration gradient) or active (energy required, usually ATP) Highly selective

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11
Q

Channel proteins

A

Ion selective and based on cell needs Regulated by membrane proteins May be voltage-gated

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12
Q

Forms of vesicular transport

A

Endocytosis (pinocytosis, phagocytosis, receptor-mediated endocytosis) Exocytosis (constitutive, regulated)

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13
Q

Pinocytosis

A

“Cell drinking” Nonspecific Small proteins and fluid aka clathrin-independent endocytosis

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14
Q

Phagocytosis

A

Only occurs with specialized cells (i.e. macrophages, neutrophils) - Engulf cell debris and bacteria Requires the rearrangement of the actin cytoskeleton Forms phagosomes aka clathrin-independent, actin-dependent endocytosis

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15
Q

Receptor-mediated endocytosis

A

Vemicrotubulessicles form when receptors on the surface bind to specific cargo molecules Formation of endocytic vesicles may involve pitting of the membrane (clathrin helps form pit) - Cell membrane invaginates, forms a vesicle, and the vesicle travels along - uncoat vesicle when cargo inside is ready to be unloaded Formation of endocytic vesicles may be clathrin dependent or independent

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16
Q

Endosomes

A

Generally the end point of vesicular important May be early endosomes or late endosomes, although they eventually may become lysosomes As they mature, they become more acidic within the lumen

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17
Q

Early endosomes

A

Sort and recycle proteins pH 6.2-6.5 (slightly acidic, close to neutral)

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18
Q

Late endosomes

A

Pre-lysosomes pH around 5.5 (more acidic) Late endosomes fuse with lysosomes for degradation of lumenal content

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19
Q

Lysosomes

A

Degrade proteins/molecules from endocytic pathways and autophagy Very acidic - pH around 4.7 Digestive organelles with tough membranes that resist digestion - Contain a diverse array of acid hydrolases that become active when the lumen reaches a pH of 5 Lysosomal membrane proteins include lysosome-associted membrane proteins, glycoproteins, and other integral membrane proteins

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20
Q

What are the four pathways that lead to intracellular digestion in lysosomes?

A

Receptor-mediated endocytosis Pinocytosis Phagocytosis Autophagy

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21
Q

Proteasomes

A

Large nonmembranous cytoplasmic or nuclear protein complexes that are capable of degrading single polypeptides and proteins

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22
Q

Lysosomal Storage disorders

A

Deficiency in one or more lysosomal enzymes, leading to accumulation of substrate in the lysosome, which cause a cell to malfunction and eventually die Tay-Sachs disease I-cell disease Niemann-Pick disease (type A) Gaucher disease - Also includes the mucopolysaccharideoses, which result in deficiency in enzymes that degrade glycosaminoglycans, leading to accumulation of partially degraded glycosaminoglycans that, over time, leads to thickening of the tissue and compromised cell and organ function

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23
Q

Tay-Sachs disease

A

Lysosomal storage disorder characterized by: - loss of vision and hearing - muscle atrophy due to loss of nervous tissue - early death (often by age 5) - deficiency is in hexoaminidase - substrate that accumulates is GM2 ganglioside in neurons

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24
Q

I-cell disease

A

Lysosomal storage disorder characterized by: - skeletal abnormalities - hepatomegaly - mental retardation due to abnormal cellular architecture - early death (often by age 8) - deficiency is in N-acetylglucosaminyl-1-phosphotransferase - this leads to lysosomal hydrolases being secreted instead of being phosphorylated in the Golgi

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25
Q

Niemann-Pick disease (type A)

A

Lysosomal storage disorder characterized by: - hepatosplenomegaly - neurodegeneration - progressive wasting due to sphingomyelin accumulation in all cells of body - early death (often by 3 years) - deficiency is in sphingomyelase - sphingomyelin accumulates

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26
Q

Gaucher disease

A

Lysosomal storage disease which affects the spleen, liver, lungs, and bone marrow due to accumulation of glucosylceramide in cells of the macrophage-monocyte system - deficiency is in Beta-glucocerebrosidase - accumulation of glucosylceramide

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27
Q

Peroxisomes

A

Single membrane proteins synthesized on cytoplasmic ribosomes - Contain catalase and other peroxidases (which break down hydrogen peroxide) - Abundant in kidney and liver cells Involved in: -Beta-oxidation of fatty acids - detoxification of ethanol - synthesis of plasmalogens, which maintain membrane integrity, especially in CNS

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28
Q

Zellweger Syndrome

A

Inability to import proteins to peroxisomes, leading to accumulation of long-chain fatty acids - plasmalogen synthesis is compromised - results from a mutation in a gene incoding the integral membrane protein Pex2 - nonfunctional peroxisomes, CNS demyelination, early death

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29
Q

A

Pinocytosis

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30
Q

A

Phagocytosis

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31
Q

A

Peroxisomes

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32
Q

A

Formation of endocytic vesicles

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33
Q

A

Clathrin-coated pits

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34
Q

Types of Exocytosis

A

Constitutive

Regulated

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35
Q

Constitutive Endocytosis

A

Proteins are secreted when they are made

i.e. antibodies

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36
Q

Regulated Endocytosis

A

Product is made and stored in vesicles

Proteins secreted when signaled

i.e. Endocrine and exocrine cells, neurons: hormones and neurotransmitters

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37
Q

Trafficking of Secreted proteins

A

Proteins that are 1) secreted, 2) will become integral membrane proteins, or 3) will be membrane-bound/part of an organelle, are synthesized on the rough ER ribosomes and then trafficked to the proper location based on a signal sequence within the polypeptide chain

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38
Q

Alpha 1 antitrypsin deficiency

A

A single amino acid substitution renders the rER unable to export alpha-1 antitrypsin (A1AT)

  • this leads to decreased activity of A1AT in the blood and lungs and abnormal deposition of defective A1AT within the rER of liver hepatocytes, resolting in emphysema (COPD) and impaired liver function
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39
Q

Rough Endoplasmic Reticulum

A

Continuous with nuclear envelope

Contains Ribosomes

Involved in Synthesis of Secreted and membrane proteins

Highly developed in secretory Cells - i.e. osteoblasts and glandular cells

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40
Q

Ribosomes

A

Composed of proteins and ribosomal RNA

They may be free in the cytoplasm or membrane-bound to the rough ER

  • they play an essential role in protein synthesis
  • Stain basophilic
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41
Q

Smooth Endoplasmic Reticulum

A

No ribosomes

Tubular in appearance

Tubular in appearance

Abundant in cells that function in:

  • lipid metabolism
  • detoxification
  • steroid synthesis

In skeletal muscle, it is referred to as the sarcoplasmic reticulum (SR) and it plays a major role in Ca++ storage

In response to drugs (including ethanol), hepatocytes will greatly increase the amount of sER in the cell

Stains acidophilic

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42
Q

A

Smooth Endoplasmic Reticulum

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43
Q

Golgi Apparatus

A

Functions in post-translational modification, sorting, and packaging of proteins

  • typically found close to the nucleus
  • consists of flattened sacs of cisternae along with small vesicles and larger vacuoles
  • Modifications include addition and trimming of sugar moieties and sulfation
  • Packaged proteins may be secreted, become a part of the plasma membrane (integral membrane proteins), or be shipped to an organelle (such as a lysosome)

The cis Golgi Network is closest to the nucleus, the trans Golgi network is furthest from the nucleus

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44
Q

Mitochondria

A

The “powerhouses” of the cell

Function in generation of energy (ATP) via oxidative phosphorylation, tricarboxylic acid cycle, Beta-oxidation of fatty acids

  • Derived from prokaryotic cells - have own (circular) DNA, division and replication do not follow that of the cell cycle for the cell they are located in

2 membranes, 2 compartments

Not present in red blood cells or terminal kartinocytes

  • many in oxidative skeletal muscle fibers
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45
Q

A

Mitochondria

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46
Q

Nonliving inclusions

A

Secretory granules

Stored energy (e.g. glycogen and fat)

Pigments (e.g. hemoglobin and melanin)

Crystals (e.g. those in Sertoli and Leydig cells)

Inclusions typically contain products of metbolic activity

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47
Q

A

Dark spots are glycogen inclusions

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48
Q

What types of particles make up the cytoskeleton?

A

Microtubules (involved in transportation and movement)

Actin (involved in membrane structure and motility)

Intermediate filaments (involved in mechanical strength)

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49
Q

Structure of Microtubules

A

Gamma-tubulin ring

Alpha and beta tubulin molecules (which bind GTP/GDP)

Growing (+) and non-growing (-) ends

Dynamic instability is used to describe microtubules as they are constantly remodeling

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50
Q

Functions of Microtubules

A

Vesicular Transport

Movement of Cilia and Flagella

Alignment, separation of chromosomes during cell division

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51
Q

What motor proteins aid in transport along microtubules?

A

Kinesins (towards the plus end, out to the membrane)

Dyneins (towards the minus end, in towards the MTOC/nucleus)

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52
Q

Centrosomes

A

Function in aligning the mitotic spindle during cell division

Basal bodies, an assembly of cilia and flagella, are found at the base

-Microtubules composing the centrosomes extend from the basal bodies

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53
Q

Centrioles

A

Composed of 9 sets of microtubule triplets

Central point of MTOC (Microtubule organizing center) assumbly

Short, drum-like appearance

When 2 centrioles are paired at 90 degrees from each other, it is called a centrosome

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54
Q

Kartagener’s syndrome

A

Dysfunction of microtubules

Leads to immobilization of cilia, infertility

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55
Q

How is chemotherapy related to microtubules?

A

Many chemotherapy treatments prevnt microtubules from working properly, thus preventing cell division

i. e. taxol prevents depolymerization, which is necessary during mitosis for choromsome to separate (cell gets stuck in metaphase)
- Vinblastine and vincristine inhibit the formation of the mitotic spindle in cell division

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56
Q

Assembly of Actin

A

Spontaneously assemble, dissassemble

Requires energy (ATP)

Actin binding proteins help stabilize actin filaments as they form, help to send them in the proper direction

Flexible (thinner than microtubules)

Directionality - plus end (where actin is added on) and minus end (where actin depolymerizes)

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57
Q

Functions of actin filaments

A

Cell shape/structure

Microvilli

Anchorage and movement

Extension of cell processes

Locomotion

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58
Q

Phalloidin

A

Compound found in some poisonous mushrooms

Prevents depolymerization by binding to F-Actin

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59
Q

Cytochalasin B and D

A

Prevents polymerization

Inhibits lymphocyte migration, phagocytosis, cell division

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60
Q

Intermediate filaments

A

Differe from microtubules and actin in that it has no monomers that polymerize or depolymerize

  • Static structure (does not form and reform)

Plays a structural role in Cell-cell and cell-matrix junctions

Classes of Intermediate filaments: Keratins, Vimentins, Neurofilaments, Lamins

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61
Q

Keratins

A

A class of intermediate filaments found in all epithelial cells

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62
Q

Vimentins

A

A class of intermediate filaments found in fibroblasts and neurons

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63
Q

Neurofilaments

A

A class of intermediate filaments found in neurons

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64
Q

Lamins

A

A class of intermediate filaments found in most differentiated cells and all nucleated cells

  • this is the class of intermediate filament found in the nucleus, not the cytoplasm
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65
Q

Alcoholic Liver cirrhosis

A

Accumulation of keratins (intermediate filaments)

Formation of Mallory bodies (intracellular lesions)

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66
Q

Alzheimer’s disease

A

Involves accumulation of neurofilaments, which form neurofibrillary tangles

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67
Q

A

Alcoholic liver cirrhosis

Arrows are pointing at Mallory bodies

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68
Q

A

Neurofibrillary tangles in Alzheimer’s disease

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69
Q

The Nucleus

A

A membrane-limited compartment that contains the genome (genetic information) in eukaryotic cells

Contains - nuclear envelope, nuclear lamina, chromatin (heterochromatin and euchromatin), nucleolus

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70
Q

The nuclear envelope

A

Two bilayer membranes with a perinuclear space in between

Perinuclear space is continuous with the endoplasmic reticulum

During cell division the nuclear envelope breaks up

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71
Q

Nuclear lamina

A

Scaffolding for the chromosomes and the nuclear pores in the nucleus

Cross-hatch look to it - made of intermediate filaments

A type of cytoskeleton that helps keep chromatin organized so it’s not floating around in the nucleus

Exists right underneath the nuclear envelope

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72
Q

What are some diseases related to impaired nuclear lamina architecture?

A

Progeria (lamin A/C)

Emery-Dreifuss muscular dystrophy (EDMD; lamins, lamin receptors, emerin)

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73
Q

Heterochromatin

A

More condensed chromatin that stains darker

Not transcriptionally active

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74
Q

Euchromatin

A

Lighter staining chromatin, less condensed

Transcriptionally active

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75
Q

Nuclear pore complex

A

Allows for transport into and out of the nucleus

During mitosis, the nuclear envelope disappears

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76
Q

Nucleolus

A

Structure inside nucleus that functions in rRNA synthesis, ribosome assembly

More prominent in cells that are active in protein synthesis

Functions in regulation of the cell cycle - Nuclepstemin-p53 binding protein

Target of viruses - alter cell cycle to control viral replication

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77
Q

Progeria

A

Premature aging, typically live to mid to late teens

Disruption in lamins (intermediate filaments in nuclear lamina) including Lamin A/C

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78
Q

A

Nuclear lamina

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79
Q

A

The nuclear envelope

Indents in the membranes indicate nuclear pores

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80
Q

Chromatin

A

A combination of DNA and structural proteins packaged to fit into the nucleus

Heterochromatin is tightly packed

Euchromatin is less packed and transcriptionally active

What chromosomes are made of

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81
Q

Chromosomes

A

Composed of condensed chromatin

Consists of 2 chromatids connected by a centromere

Visible during metaphase, mitosis only (interphase, chromatin is generally not condensed)

Two ends are telomeres, which shorten with each cell division

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82
Q

Telomerase

A

Enzyme which repeatedly adds nucleotide sequences to the telomere end

Role in oncogenesis (formation of malignant cells)

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83
Q

Barr Body

A

In individuals with two X chromosomes, one X chromosome is repressed and stays tightly condensed

This is often found adjacent to the nuclear envelope

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84
Q

Nucleostemin

A

A protein regulates the cell cycle and influences cell differentiation

May play a role in malignancy

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85
Q

Types of cell renewal

A

Static: no longer divide (CNS, cardiac muscle)

Stable: divide as necessary (smooth muscle and endothelial cells)

Slow renewing: fibroblasts, epithelial cells of the eye lens

Fast renewing: blood cells, epithelial cells

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86
Q

Phases of the cell cycle

A

M-phase: mitosis

Interphase:

  • G1 - Gap 1 (proteins needed for DNA synthesis)
  • S (DNA synthesis)

G2 - Gap 2 (growth and reorganization, accumulation of energy for division)

G0 phase

GTD - terminal differentiation

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87
Q
A
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88
Q

Mitotic Catastrophe

A

Malfunction of any of the DNA damage checkpoints of the spindle assembly checkpoint in early mitosis

Failure to arrest the cell cycle before or at mitosis results in abberrant chromosome segregation (i.e. aneuploidy, tumor cell development)

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89
Q

A malfunction at which cell cycle checkpoint may result in malignant transformation?

A

G1 restriction checkpoint

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90
Q

What checkpoints exist in G1?

A

G1 DNA Damage checkpoint

G1 restriction checkpoint (right before it moves into S phase)

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91
Q

What cell cycle checkpoints exist in S phase?

A

S DNA damage checkpoint

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92
Q

What cell cycle checkpoints exist in G2 phase?

A

Unreplicated DNA checkpoint

G2 DNA damage checkpoint

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93
Q

What cell cycle regulatory checkpoints exist in M phase?

A

Spindle-assembly checkpoint

Chromosome-segregation checkpoint

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94
Q

Cell Cycle Regulation is accomplished by which proteins?

A

Two protein complexes

Cyclin

Cyclikn-dependent kinase

These are checkpoint regulators

Different complexes act at different stages of the cell cycle

Some cancer treatments may target cyclin and/or cyclin dependent inase that is affected in cancerous growth

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95
Q

Which cyclin-CDK complex is active during the M phase checkpoints?

A

Cyclin E-Cdk1

96
Q

Which cyclin-Cdk complex is active during G2 phase checkpoints?

A

Cyclin A-Cdk1

97
Q

Which cyclin-Cdk complex is active during the G1 restriction checkpoint?

A

Cyclin E-Cdk2

98
Q

Mitosis

A

Cell division that results in 2 daughter cells with the same chromosome number (n) and DNA content (d)

Cell goes from 4d before division (after DNA replication during S phase) to 2d after division

99
Q

Meiosis

A

A specialized form of cell division used to create gametes

A reduction division down to 1n (Meiosis I is reductional)

Males: 4 spermatids

Females: one oocyte and 3 polar bodies

100
Q

What are types of cell death?

A

Necrosis - accidental cell death, usually as a result of mechanical or chemical injury, results in cell lysis and swelling

Apoptosis - programmed cell death, debris is removed by phagocytosis, process is 20x faster than mitosis

101
Q

Apoptotic bodies

A

Condensation of nuclear material

102
Q

A

Arrowheads are condensed nuclear material

Arrows are pointing to apoptotic bodies

103
Q

What are the four basic types of tissue?

A

Epithelium (either covering or glandular)

Muscle

Nervous Tissue

Connective Tissue (i.e. adipose)

104
Q

What are the characteristics of Epithelium?

A

Epithelial Cells are:

Organized

Cohesive

Shape is important to function

Avascular

Contain cytokeratins

105
Q

What layers make up the basement membrane?

A

Basal lamina - Lamina densa, Lamina lucida (rara)

  • contains IV collagen, Laminin, Heparin sulfate

Reticular Lamina - connective tissue, reticular fibers

106
Q

What are the functions of the basement membrane?

A

Compartmentalizing things

Supporting tissues

Selectively pereable barrier

Helps determine the direction in which an epithelial cell may move

107
Q

Apical surface

A

The side of the cell adjacent to the lumen

i.e. skin (open to outside), blood vessel (hollow portino in center)

108
Q

Basal surface

A

The surface of the cell adjacent to the basement membrane

109
Q

What are the functions of epithelium?

A
  1. Protection
  2. Absorption
  3. Secretion
  4. Transport
  5. Contractility (myoepithelium)
  6. Sensaton (neuroepithelium)
110
Q

What are the types of intracellular junctions?

  1. Adhering junctions: zonula adherens, desmosome, hemidesmosome
  2. Impermeable Junctions: zonula occuldens
  3. Communicating junctions: gap junctions
A
111
Q

Zonula Occludens

A

aka tight junctions

Form a belt around the cell

Fusion of adjacent cell membranes

Function: prevents movement of materials between cells

112
Q

Zonula Adherens

A

Actin filaments insert into plaques

  • Cell Adhesion Molecules (CAMs)

Function: contribute to adhesion

Belt-like structure going all the way around the cell - belt of fibers made of actin network, helps anchor inside cell

113
Q

Desmosome

A

Macular Adherens (macula = spot or patch)

Attachment plaque

Big - can be seen with a light microscope

Intermediate cytokeratin filaments - thick fibers anchor to internal structure (also cytokeratin filaments)

Cadherin family (of cell adhesion molecules)

Function: tight adhesion between cells

Membranes of cells interweave with one another - looks kind of like a zipper, makes it harder to pull apart

114
Q

Hemidesmosomes

A

Junction between cell and basement membrane

Form tight adhesion with basement membrane

  • Prevent cell from being pulled away from basement membrane
  • Intermediate filaments (cytokeratin)

Integrins family

Function: tight adhesion to basal lamina

115
Q

Gap junctions

A

Formed from connexins - subunits of connexins come together and forma a pore in the membrane

Generate a central pore

Depending on type of connexin subunits - allow ions, molecules to pass from cell to cell

  • Not unique to epithelium

Function: communication - passing information

116
Q

Types of covering epithelium

A

Simple squamous (found in lumen of blood vessels, alveoli for gas exchange)

Simple cuboidal (found in kidney tubules - proximal, distal, etc.)

Simple columnar (generally have microvilli)

Pseudostratified columnar (ciliated, respiratory epithelium)

117
Q

Microvilli

A

Apical finger-like extensions to increase surface area

Cytoplasmic membrane pushes out, extends fingerlike projections, looks fuzzy through light microscope

Core of actin

Glycocalyx - protein secreted, surrounds microvilli

Together, microvilli and glycocalyx make brush border

118
Q

Goblet cells

A

Single-celled gland

Produce mucin

Rough ER seen towards bototm of cell, golgi apparatus

Accumulate mucin (glycoproteins) and granules onto surface

119
Q

Cilia

A

Made of microtubules: 9+2 arrangement

  • 9 doublets form circle, two singles in center

Motile

120
Q

Flagella

A

Same 9+2 pattern of microtubules

121
Q

Steriocilia

A

Nonmotile cilia

Found in inner ear (mechanoreception)

122
Q

What are the two types of stratified squamous epithelium?

A

Keratinized

Nonkeratinized

123
Q

Where is keratinized stratified squamous epithelium found?

A

Skin

Roof of your mouth

Identifiable by way more layers of keratinized cells on top, look for melanocytes, etc. underneath it

124
Q

Where is non keratinized stratified squamous epithelium found?

A

The mouth (except for roof)

Vagina

Nose

Anus

Generally moist surfaces (except for roof of mouth, which is keratinized)

125
Q

Stratified cuboidal epithelium

A

Not very common

Found in ducts, glands, sebacious flands

Usually about 2 layers of cells

126
Q

Stratified columnar epithelium

A

Not very common

Found in large ducts (i.e. duct system of male reproductive tract)

127
Q

Transitional epithelium

A

aka Urinary epithelium

  • Really only found in the bladder

Found in a little bit of ureters, urethra right next to bladder

Have kind of a rounded top (aa balloon or umbrella cells)

When bladder is empty, cell layers are thick (lots of them)

When bladder is full, transitional epithelia stretches thin

128
Q

Serous Glands

A

Secretion is watery and rich in enzymes

Cells form spherical structures (i.e. alveolus/acinus)

Found in parotid glands, empties into mouth and moistens food

Enzymes are proteins

Stain - rough ER stains darkly in periphery, stain is relatively dark for secretions

129
Q

Exocrine Glands

A

Secrete their products onto a surface directly or though epithelial ducts or tubes that are connected to a surface.

Ducts may convey the secretion in an unaltered form or may modify the secretion by concentrating it or adding or reabsorbing constituent substances

130
Q

Endocrine Glands

A

Lack a duct system

Secrete products directly into the connective tissue, from which they enter the bloodstream to reach their target cells

The products of endocrine glands are called hormones

131
Q

A

Serous Glands

132
Q

A

Desmosome (macular adherens)

133
Q

A

Hemidesmosomes

134
Q

A

Simple squamous

135
Q

A

Simple squamous

136
Q

A

Simple Cuboidal

137
Q

A

Simple columnar

138
Q

A

Pseudostratified Epithelium

139
Q

A

Stratified Squamous Epithelium

140
Q

A

Transitional Epithelium

141
Q

Mucous glands

A

Secretion is mucous, viscous, thick (a glycoprotein)

Nuclei show up against the edge (like with goblet cells)

Extensions are full of mucin

Found in sublingual and submandibular glands below mouth - actually mixed glands

Cells form tubules

142
Q

A

Mucous glands

143
Q

Mixed glands

A

Consists of both mucus and serous cells

Serous demilune: Serous cells form a cap over the mucus tubule

Submandibular and sublingual glands are in this category

144
Q

A

Mixed glands

145
Q

Merocrine Secretion

A

Most common type of exocrine gland

No loss of cytoplasm

Secretory product is delivered in membrane-bounded vesicles to the apical surface of the cell

Here vesicles fuse with the plasma membrane and extrude their contents by exocytosis

This is the most common mechanism of secretion and is found for example in pancreatic acinar cells

146
Q

Holocrine Gland

A

Secretory Product accumulates within the maturing cell, which simultaneously undergoes programmed cell death

Both secretory products and cell debris are discharged into the lumen of the gland

This mechanism is found in sebaceous glands of the skin and the tarsal glands of the eyelid

147
Q

Apocrine Secretion

A

Secretory product is released in the apical portion of the cell, surrounded by a thin layer of cytoplasm within an envelope of plasma membrane

  • this mechanism of secretion is found in the lactating mammary gland, also apocrine glands of skin
148
Q

A

Sebaceous cyst, aka boils

149
Q

Myoepithelial Cells

A

Good if need to expel something from a duct or tube

Contract and push the fluid through

150
Q

Diffuse Neuroendocrine system

A

APUD: Amine Precursor uridine something or other

Secrete peptide hormones

Identify by dark staining areas in silver stain (argentophilic)

151
Q

A

Diffuse Neuroendocrine system

152
Q

Steroid-secreting cells

A

Endocrine

Lots and lots of smooth ER
Lots of Lipid droplets

Steroids are made from cholesterol, which is made from lipids

Cholesterol forms backbone of steroid hormones

Smooth ER used for lipid synthesis and modification

153
Q

What are some cancers derived from epithelium? Why are they so common?

A

Prostate cancer

colorectal cancer

skin cancer

breast cancer

All of the big cancers are epithelial derivatives

Epithelial cells are constantly turning over, shedding cells

Every time they divide, there’s another chance for there to be a mistake.

154
Q

Characteristics of skeletal muscle

A

Multiple nuclei located towards the outside of the fiber (smashed up against cell membrane)

Striated

Voluntary - controlled by somatic nervous system

Does not grow and divide once it’s done developing

Looks like a nice, long tube

155
Q

A

Longitudinal view of Skeletal Muscle

156
Q

Characteristics of Cardiac Muscle

A

Multinucleated (although not as many as in skeletal muscle)

  • nuclei are fairly prominent, right in the center

Striated

Intercalated Disks - as two cardiac cells come together, they interlock

Involuntary - sympathetic, autonomic, parasympathetic, hormonal control

Does not grow and divide once developed

Branching Pattern

157
Q

Characteristics of Smooth Muscle

A

One nucleus per cell - located prominently right in the center

Not striated

Involuntary - controlled by hormones and autonomics

Found in: digestive tract, vasculature, blood vessels

Uterus - muscle has to grow and divide, which is hormone-driven

Cigar (tapered) or spindle-shaped cells

158
Q

How is skeletal muscle formed?

A

Myoblasts (muscle progenitor cells) come together and fuse and form myotubules - still have divisions between cells

  • then, membranes disappear and the cells fuse

End up with mature muscle cells

159
Q

What is skeletal muscle composed of?

A

Thin (actin) filaments and thick (myosin) filaments

160
Q

What are thin filaments composed of?

A

Actin - monomers (G actin) come together to form a filament (F actin)

  • Tropomyosin, which wraps around and lays in the groove
  • Troponin, which consists of 3 subunits (Troponin T, C, and I)

T = Binds to tropomyosin, which is attached to actin

C = Ability to bind calcium, conformational change in structure when bound to calcium

I = Inhibitor, sits over the binding site of myosin, when Calcium bond to Troponin C, it moves away from binding sites

161
Q

What are thick filaments made of?

A

Myosin - a molecular motor protein consisting of a light and heavy chain

Light chain - tail portion

Heavy chain - heads sticking out

Looks like two golf clubs intertwined

Use ATP to move myosin head, head groups walk back and forth

162
Q

What is the line in the middle of the sarcomere called?

A

M line

163
Q

What is the area consisting only of thick filaments called?

A

H Zone

H zone contracts when sarcomere contracts

164
Q

What is the area spanning the entire thick filament called?

A

A band

Stays the same length during contraction

165
Q

What is the area consisting of only thin filaments called?

A

I band

This shortens during muscle contractions

166
Q

What is an entire contractile unit of muscle called?

A

Sarcomere

167
Q

True or false: the zone of overlap does not change size

A

False - the zone of overlap consists of the area where the thick and thin filaments overlap, and it gets longer during contraction

168
Q

Sarcoplasmic Reticulum

A

Endoplasmic reticulum in muscle cell

Good for collecting, storing, and releasing calcium

Wraps around the muscle filament

169
Q
A
170
Q

T-tubules

A

These run throughout the muscle bundles and Sarcoplasmic reticulum

Involved in Calcium release (voltage gated)

Sandwiched between two sarcoplasmic reticula - called a triad

Triads are unique to skeletal muscle, while diads are found in cardiac muscle

171
Q

Red Fibers

A

Slow Contractors

Longevity

More myoglobin

Aka Type I or slow oxidative fibers

172
Q

White Muscle Fibers

A

Aka type IIb fibers or fast glycolytic fibers

Fast contractors

Short amount of time

Fast-twitch, fatigue prone

173
Q

Intermediate muscle fibers

A

Aka Type IIa fibers or Fast oxidative glycolytic fibers

Fast-twitch, fatigue-resistant motor units

Sort of a combination of fast and slow

174
Q

Motor End Plate

A

Interaction between synapse and muscle cell itself

Neurotransmitter for skeletal muscle = acetylcholine (cleared by acetylcholinesterase)

Terminal bouton

175
Q

Tendons

A

Connect skeletal muscles to bone

Dense regular connective tissue

Have junction where it can hool onto muscle and bones

Interlock tendon with skeletal muscle as best as possible to give more strength

176
Q

Motor Unit

A

All of the muscles connected to one axon is called a motor unit

When a muscle contracts, it’s all or none, so strength of contraction is based on how many motor units are recruited

A few muscles contract = weak contraction

Ration is not the same in the whole body

Fine motor skills - ratio of axon:muscle cells is higher (fewer cells per axon)

Low back - probably many muscle cells to one axon

177
Q

What is the purpose of gap junctions found in cardiac muscle cells?

A

These help cells communicate to each other

Important so that cardiac muscle contracts at one point

Autonomic system can slow or speed the heartreat but heart has an intrinsic ability to beat on its own

Contractions of heart start at SA node

178
Q

In what manner do muscle cells contract?

A

Rotational, wringing contraction

179
Q

How does smooth muscle contract?

A

No banded patterns or linear aligment of contractile proteins

Bands of contractile proteins run from edge to edge and attach to the membrane

Dense body - criss-cross, attach to one another

Balls the muscle up instead of just shortening it

Contractile unit contains thin filaments, thick filaments, tropomyosin, calmodulin (not troponin)

Dense bodies form a Z line

180
Q

Morphology of Connective Tissue

A

Loose aggregation of cells with large intervening spaces filled with extracellular matrix produced by cells

  • most of the cells are migrants from the vascular system

Classified based on the types of cells and nature of the extracellular matrix

Location - usually found under the epithelial tissues as a supporting tissue

181
Q

Primary function of connective tissue

A

“Space-filling” role - fills gaps between the epithelium, muscle and other tissues (loose connective tissue)

Supportive role - mechanical function - bone, cartilage, dense supporting tissue

182
Q

What are components of the extracellular matrix?

A

Fibers: collagen, reticular, elastic

Ground substance: glycoproteins (mostly fibronectin, laminin); Glycosaminoglycans - chondroitin sulfate, keratane sulfate, dermatan sulfate, heparin sulfate, hyaluronic acid; proteoglycans

183
Q

A

Hyaluronic acid with proteoglycans sitting on surface and glycosaminoglycan side chains (looks like pin feathers)

184
Q

Characteristics of Collagen Fibers

A

Stean with eosin - red-pink

Composed of bundles of collagen fibrils

Fibrils composed of tropocollagen molecules that are arranged with a gap between them and a lag between the rows forming a period banding of the fibril

  • tropocollagen molecules are composed of 3 glycoprotein alpha chains (left handed triple helix)

The combinations of different types of alpha chains can determine 28 different collagen types; 90% of collagen falls into 4 types

185
Q

Characteristics of Type I Collagen

A

Found in bone, skin, tendon, ligament

Formation: mainly fibroblasts, osteoblasts

186
Q

Where is Type II collagen found?

A

Hyaline cartilage

187
Q

Where is Type III collagen found?

A

Reticular fibers

188
Q

Where is Type IV collagen found?

A

Basement membrane

189
Q

A

Type I Collagen Fibers

190
Q

Reticular Fibers

A

Composed of Type III collagen fibrils

Thin fibers forming mesh-like network

Supporting structure for adipocytes, muscle cells, small blood vessels, hemopoietic and lymphatic tissues

Staining: Eosin (red); PAS (red); Silver salts (black - argyrophilic fibers)

Formation: by fibroblasts (mostly), also smooth muscle cells and Scwann cells

191
Q

A

Reticular or Type III Collagen Fibers

192
Q

Elastic Fibers

A

Thin fibers forming branching network

Location: elastic cartilage, elastic arteries, and the elastic ligaments (i.e. ligamentum flavum)

Staining: eosin (red); orcein (brown); resorcin-fuchsin (bluish-gray)

Produced mostly by fibroblasts and smooth muscle cells

193
Q

What are elastic fibers composed of?

A

Elastin (central core)

Fibrillin microfibrils around the core embedded into elastin

194
Q

A

Larger fibers: probably collagen

Thin fibers: Elastic fibers

Resorcin-fuchsin stain

195
Q

Marfan’s syndrome

A

Autosomal dominant disorder

  • mutation of the fibrillin gene on chromosome 15

Fibrillin-1 is an extracellular matrix protein and it is important for maintaining the elastic fibers

May present with Chest deformity, long appendages, arachnodactyly, aortic dissection

196
Q

Ehlers-Danlos syndrome

A

Mutations affecting the genes of collagen polypeptide chains

Many subtypes

Symptoms: hyperflexibility of the joints, hyperextensibility of the skin, vascular and organ rupture in the most serious cases of EDS

197
Q

Osteogenesis imperfecta

A

Genetic mutations of the genes that assemble type I collagen

Fragile bones (“glass bone disease”)

Several forms according to the damaged genes

Most severe form (type II) involves abnormally small and fragile rib cage

198
Q

What are the types of connective tissue?

A

Embryonic connective tissue

Connective tissue proper

Specialized connective tissue

199
Q

What are the types of the embryonic connective tissue?

A

Mesenchyme

Mucous connective tissue

200
Q

What are the types of connective tissue proper?

A

Dense connective tissue

Loose connective tissue

201
Q

What are the types of specialized connective tissue?

A

Adipose tissue, blood, bone, cartilage, hemopoietic tissue, lymphatic tissue

202
Q

Charateristics of embryonic connective tissue

A

Few star or spindle-shaped cells forming a network (gap junctions bind them together)

Extracellular space is filled wtih huge amounts of viscous ground substance with few reticular fibers

203
Q

Mesenchyme

A

Type of embryonic connective tissue

Primitive pleuripotent connective tissue - capable of turning into other tissue cells

Cells are pleuripotent mesenchymal cells

More cell rich with ground substance in between

204
Q

Mucous connective tissue

A

Type of embryonic connective tissue present in the umbilical cord

Cells: fibroblasts and few mesenchymal cells

More space between the cells

Less reticular fibers in the gelatin-like ground substance

Gross anatomical appearance is jelly-like - “Wharton’s Jelly”

205
Q
A

Mesenchyme

206
Q

A

Mucous connective tissue, aka “Wharton’s jelly”

207
Q

General Characteristics of Dense Connective Tissue

A

Few fibroblasts

Little ground substance

Large amount of collagen fibers between them

208
Q

Dense regular connective tissue

A

Fibers are arranged in parallel array

Present in tendons, aponeuroses, and ligaments

Some ligaments (ligamentum flavum) contain a large amount of elastic fibers instead of collagen (“elastic connective tissue”)

209
Q

A

Dense regular connective tissue

210
Q

Characteristics of Dense irregular connective tissue

A

Fibers are arranged in bundles running in every direction

  • Present in the submucosa of hollow organs, connecting the mucous membrane to the underlying muscle layer

Cells are fibroblasts

211
Q

A

Dense Irregular connective tissue

212
Q

Fibroblasts

A

Star-shaped cells with elongated disc-like nucleus

Synthesize fibers and ground substance

Developed rER (basophilic cytoplasm) - protein synthesis

213
Q

Myofibroblasts

A

Similar to the fibroblast but contain contractile elements (actin-myosin)

Lack basal lamina - differ from smooth muscle cells

Located in the loose connective tissue

Involved in regulating the shape and emptying of the glands and wound contraction and closure

214
Q

A

Fibroblast

215
Q

Characteristics of Loose connective tissue

A

Loosely arranged cells and fibers

Found mostly beneath the epithelia (layer is called lamina propria mucosae)

Contains blood cells (migrated from local blood vessels)

In inflammation it can undergo significant swelling

216
Q

A

Loose connective tissue

217
Q

Resident cell population in loose connective tissue

A

Fibroblasts and myofibroblasts

Adipose Cells

Macrophages

Mast Cells

Mesenchymal cells

218
Q

Transient cell population in loose connective tissue

A

Migrate from other tissues to specific stimuli

Lymphocytes

Plasma cells

Neutrophils

Eosinophils

Basophils

219
Q

Adipose Tissue

A

Differentiates from mesenchymal cells

Two types

220
Q

White adipocytes

A

Single fat drop filling the cytoplasm

Ring-shaped cytoplasm and flat peripheral nucleus

221
Q

Brown adipose tissue

A

Several fat droplets in the cytoplasm

Brown pigment

Numberous mitochondria

Characteristic for newborns - rapid energy release

Brown because of vessels - very vascularized

Nucleus isn’t flattened against the edge

222
Q

A

Brown adipose tissue

223
Q

A

White adipose tissue

224
Q

Macrophages

A

aka histiocytes

Phagocytic cells derived from blood monocytes - garbage collectors of the tissue

  • irregular shape

Rounded nucleus; large golgi and ER

Ingested material in the cytoplasm

Antigen-presenting cells using MHC II molecules to present antigens for CD4 lymphocytes

May form Langhans cells (foreign body giant cells) by fusion

225
Q

A

Macrophage

226
Q

Mast cells

A

Large rounded cell with spherical nucleus

Basophil granules

Located next to small vessels in the connective tissue, capsule of organs

Resembles basophils

Toluidine blue stains the granules metachromatically

Responsible for anaphylactic (oversensitive) reactions: antibodies can bind to the mast cells and release the content of the granules

227
Q

Content of granules released by mastocytes

A

Heparan sulphate, heparin - blocks coagulation, responsible for the basophilia

Histamine, SRS-A - vasodilation, edema

Eosinophil chemotactic factor (ECF) and neutrophil chemotactic factor (NCF) - cell attraction

228
Q
A

Mast Cell

229
Q

Mesenchymal cells

A

Star or spindle-shaped cells

Pleuripotential - capable to form various cell types

In adult, they are located usually around the vessels

230
Q

A

Mesenchymal cells

231
Q

Lymphocytes

A

Intensely staining, slightly indented spherical nucleus

Cytoplasm is a thin, pale basophilic ring

Small lymphocytes vs. large lymphocytes

Classification - T lymphocytes (differentiateing in the thymus) - 60-80%

B lymphocytes (differentiateing in the bone marrow) - 20-30%

NK (natural killer) cells - 5-10% (bone marrow)

232
Q

Plasma Cells

A

Derived from the B cells

Antibody producing cells (only one specific antibody)

10-30 days life span

Heterochromatin in the nucleus has the pattern of cartwheel of clock face

233
Q

A

The cells with dotted spots are plasma cells

The dark, basophilic cells that have barely any cytoplasm are lymphocytes

234
Q

Neutrophils

A

Capable of migration

Granules - small, purple, barely visible in the light microscope

Nucleus is multilobed (thus also called polymorphs)

235
Q

Eosinophils

A

Named after the large, esonophilic granules in the cytoplasm

Typically bilobed nucleus

236
Q

Basophils

A

Large, basophilic granules in the cytoplasm

Nucleus obscured by the granules

Closely related to mast cells of connective tissue - only nucleus isn’t visible

Histology (3 decks)

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