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
2
Q
What types of proteins are associated with the lipid bilayer?
A
Peripheral and integral membrane proteins
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
4
Q
Which face of the plasma membrane usually has more integral proteins associated with it?
A
The P face
5
Q
E-face
A
The layer of the plasma membrane backed by the extracellular space
6
Q
P-face
A
The layer of the plasma membrane backed by the cytoplasm (protoplasm)
7
Q
What are the functions of different integral membrane proteins?
A
Pumps Channels Receptors Linkers Enzymes Structural
8
Q
What are the different methods of transport across the plasma membrane?
A
Simple Diffusion Carrier Proteins Channel Proteins
9
Q
Simple diffusion
A
Requires no proteins Particles are small and hydrophobic enough to cross the bilayer
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
11
Q
Channel proteins
A
Ion selective and based on cell needs Regulated by membrane proteins May be voltage-gated
12
Q
Forms of vesicular transport
A
Endocytosis (pinocytosis, phagocytosis, receptor-mediated endocytosis) Exocytosis (constitutive, regulated)
13
Q
Pinocytosis
A
“Cell drinking” Nonspecific Small proteins and fluid aka clathrin-independent endocytosis
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
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
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
17
Q
Early endosomes
A
Sort and recycle proteins pH 6.2-6.5 (slightly acidic, close to neutral)
18
Q
Late endosomes
A
Pre-lysosomes pH around 5.5 (more acidic) Late endosomes fuse with lysosomes for degradation of lumenal content
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
20
Q
What are the four pathways that lead to intracellular digestion in lysosomes?
A
Receptor-mediated endocytosis Pinocytosis Phagocytosis Autophagy
21
Q
Proteasomes
A
Large nonmembranous cytoplasmic or nuclear protein complexes that are capable of degrading single polypeptides and proteins
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
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
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
25
Niemann-Pick disease (type 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
26
Gaucher disease
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
27
Peroxisomes
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
28
Zellweger Syndrome
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
29
[![]() ](https://s3.amazonaws.com/brainscape-prod/system/cm/154/108/001/q_image_card.jpg?1438524296)
Pinocytosis
30
[![]()](https://s3.amazonaws.com/brainscape-prod/system/cm/154/108/200/q_image_thumb.jpg?1438524477)
Phagocytosis
31
[![]()](https://s3.amazonaws.com/brainscape-prod/system/cm/154/108/202/q_image_thumb.jpg?1438524529)
Peroxisomes
32
[![]()](https://s3.amazonaws.com/brainscape-prod/system/cm/154/108/219/q_image_thumb.png?1438524559)
Formation of endocytic vesicles
33
[![]()](https://s3.amazonaws.com/brainscape-prod/system/cm/154/108/285/q_image_thumb.jpg?1438524590)
Clathrin-coated pits
34
Types of Exocytosis
Constitutive
Regulated
35
Constitutive Endocytosis
Proteins are secreted when they are made
i.e. antibodies
36
Regulated Endocytosis
Product is made and stored in vesicles
Proteins secreted when signaled
i.e. Endocrine and exocrine cells, neurons: hormones and neurotransmitters
37
Trafficking of Secreted proteins
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
38
Alpha 1 antitrypsin deficiency
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
39
Rough Endoplasmic Reticulum
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
40
Ribosomes
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
41
Smooth Endoplasmic Reticulum
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
42
[![]()](https://s3.amazonaws.com/brainscape-prod/system/cm/154/109/237/q_image_thumb.jpg?1438525294)
Smooth Endoplasmic Reticulum
43
Golgi Apparatus
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
44
Mitochondria
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
45
[![]()](https://s3.amazonaws.com/brainscape-prod/system/cm/154/109/342/q_image_thumb.png?1438525639)
Mitochondria
46
Nonliving inclusions
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
47
[![]()](https://s3.amazonaws.com/brainscape-prod/system/cm/154/109/389/q_image_thumb.png?1438525815)
Dark spots are glycogen inclusions
48
What types of particles make up the cytoskeleton?
Microtubules (involved in transportation and movement)
Actin (involved in membrane structure and motility)
Intermediate filaments (involved in mechanical strength)
49
Structure of Microtubules
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
50
Functions of Microtubules
Vesicular Transport
Movement of Cilia and Flagella
Alignment, separation of chromosomes during cell division
51
What motor proteins aid in transport along microtubules?
Kinesins (towards the plus end, out to the membrane)
Dyneins (towards the minus end, in towards the MTOC/nucleus)
52
Centrosomes
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
53
Centrioles
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
54
Kartagener's syndrome
Dysfunction of microtubules
Leads to immobilization of cilia, infertility
55
How is chemotherapy related to microtubules?
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
56
Assembly of Actin
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)
57
Functions of actin filaments
Cell shape/structure
Microvilli
Anchorage and movement
Extension of cell processes
Locomotion
58
Phalloidin
Compound found in some poisonous mushrooms
Prevents depolymerization by binding to F-Actin
59
Cytochalasin B and D
Prevents polymerization
Inhibits lymphocyte migration, phagocytosis, cell division
60
Intermediate filaments
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
61
Keratins
A class of intermediate filaments found in all epithelial cells
62
Vimentins
A class of intermediate filaments found in fibroblasts and neurons
63
Neurofilaments
A class of intermediate filaments found in neurons
64
Lamins
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
65
Alcoholic Liver cirrhosis
Accumulation of keratins (intermediate filaments)
Formation of Mallory bodies (intracellular lesions)
66
Alzheimer's disease
Involves accumulation of neurofilaments, which form neurofibrillary tangles
67
[![]()](https://s3.amazonaws.com/brainscape-prod/system/cm/154/124/811/q_image_thumb.png?1438543578)
Alcoholic liver cirrhosis
Arrows are pointing at Mallory bodies
68
[![]()](https://s3.amazonaws.com/brainscape-prod/system/cm/154/124/819/q_image_thumb.png?1438543638)
Neurofibrillary tangles in Alzheimer's disease
69
The Nucleus
A membrane-limited compartment that contains the genome (genetic information) in eukaryotic cells
Contains - nuclear envelope, nuclear lamina, chromatin (heterochromatin and euchromatin), nucleolus
70
The nuclear envelope
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
71
Nuclear lamina
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
72
What are some diseases related to impaired nuclear lamina architecture?
Progeria (lamin A/C)
Emery-Dreifuss muscular dystrophy (EDMD; lamins, lamin receptors, emerin)
73
Heterochromatin
More condensed chromatin that stains darker
Not transcriptionally active
74
Euchromatin
Lighter staining chromatin, less condensed
Transcriptionally active
75
Nuclear pore complex
Allows for transport into and out of the nucleus
During mitosis, the nuclear envelope disappears
76
Nucleolus
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
77
Progeria
Premature aging, typically live to mid to late teens
Disruption in lamins (intermediate filaments in nuclear lamina) including Lamin A/C
78
[![]()](https://s3.amazonaws.com/brainscape-prod/system/cm/154/125/244/q_image_thumb.jpg?1438544296)
Nuclear lamina
79
[![]()](https://s3.amazonaws.com/brainscape-prod/system/cm/154/125/302/q_image_thumb.jpg?1438544337)
The nuclear envelope
Indents in the membranes indicate nuclear pores
80
Chromatin
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
81
Chromosomes
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
82
Telomerase
Enzyme which repeatedly adds nucleotide sequences to the telomere end
Role in oncogenesis (formation of malignant cells)
83
Barr Body
In individuals with two X chromosomes, one X chromosome is repressed and stays tightly condensed
This is often found adjacent to the nuclear envelope
84
Nucleostemin
A protein regulates the cell cycle and influences cell differentiation
May play a role in malignancy
85
Types of cell renewal
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
86
Phases of the cell cycle
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
87
88
Mitotic Catastrophe
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)
89
A malfunction at which cell cycle checkpoint may result in malignant transformation?
G1 restriction checkpoint
90
What checkpoints exist in G1?
G1 DNA Damage checkpoint
G1 restriction checkpoint (right before it moves into S phase)
91
What cell cycle checkpoints exist in S phase?
S DNA damage checkpoint
92
What cell cycle checkpoints exist in G2 phase?
Unreplicated DNA checkpoint
G2 DNA damage checkpoint
93
What cell cycle regulatory checkpoints exist in M phase?
Spindle-assembly checkpoint
Chromosome-segregation checkpoint
94
Cell Cycle Regulation is accomplished by which proteins?
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
95
Which cyclin-CDK complex is active during the M phase checkpoints?
Cyclin E-Cdk1
96
Which cyclin-Cdk complex is active during G2 phase checkpoints?
Cyclin A-Cdk1
97
Which cyclin-Cdk complex is active during the G1 restriction checkpoint?
Cyclin E-Cdk2
98
Mitosis
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
Meiosis
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
What are types of cell death?
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
Apoptotic bodies
Condensation of nuclear material
102
[![]()](https://s3.amazonaws.com/brainscape-prod/system/cm/154/125/997/q_image_thumb.jpg?1438545663)
Arrowheads are condensed nuclear material
Arrows are pointing to apoptotic bodies
103
What are the four basic types of tissue?
Epithelium (either covering or glandular)
Muscle
Nervous Tissue
Connective Tissue (i.e. adipose)
104
What are the characteristics of Epithelium?
Epithelial Cells are:
Organized
Cohesive
Shape is important to function
Avascular
Contain cytokeratins
105
What layers make up the basement membrane?
Basal lamina - Lamina densa, Lamina lucida (rara)
- contains IV collagen, Laminin, Heparin sulfate
Reticular Lamina - connective tissue, reticular fibers
106
What are the functions of the basement membrane?
Compartmentalizing things
Supporting tissues
Selectively pereable barrier
Helps determine the direction in which an epithelial cell may move
107
Apical surface
The side of the cell adjacent to the lumen
i.e. skin (open to outside), blood vessel (hollow portino in center)
108
Basal surface
The surface of the cell adjacent to the basement membrane
109
What are the functions of epithelium?
1. Protection
2. Absorption
3. Secretion
4. Transport
5. Contractility (myoepithelium)
6. Sensaton (neuroepithelium)
110
What are the types of intracellular junctions?
1. Adhering junctions: zonula adherens, desmosome, hemidesmosome
2. Impermeable Junctions: zonula occuldens
3. Communicating junctions: gap junctions
111
Zonula Occludens
aka tight junctions
Form a belt around the cell
Fusion of adjacent cell membranes
Function: prevents movement of materials between cells
112
Zonula Adherens
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
Desmosome
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
Hemidesmosomes
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
Gap junctions
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
Types of covering epithelium
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
Microvilli
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
Goblet cells
Single-celled gland
Produce mucin
Rough ER seen towards bototm of cell, golgi apparatus
Accumulate mucin (glycoproteins) and granules onto surface
119
Cilia
Made of microtubules: 9+2 arrangement
- 9 doublets form circle, two singles in center
Motile
120
Flagella
Same 9+2 pattern of microtubules
121
Steriocilia
Nonmotile cilia
Found in inner ear (mechanoreception)
122
What are the two types of stratified squamous epithelium?
Keratinized
Nonkeratinized
123
Where is keratinized stratified squamous epithelium found?
Skin
Roof of your mouth
Identifiable by way more layers of keratinized cells on top, look for melanocytes, etc. underneath it
124
Where is non keratinized stratified squamous epithelium found?
The mouth (except for roof)
Vagina
Nose
Anus
Generally moist surfaces (except for roof of mouth, which is keratinized)
125
Stratified cuboidal epithelium
Not very common
Found in ducts, glands, sebacious flands
Usually about 2 layers of cells
126
Stratified columnar epithelium
Not very common
Found in large ducts (i.e. duct system of male reproductive tract)
127
Transitional epithelium
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
Serous Glands
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
Exocrine Glands
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
Endocrine Glands
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
[![]()](https://s3.amazonaws.com/brainscape-prod/system/cm/154/211/446/q_image_thumb.png?1438637846)
Serous Glands
132
[![]()](https://s3.amazonaws.com/brainscape-prod/system/cm/154/211/531/q_image_thumb.png?1438637935)
Desmosome (macular adherens)
133
[![]()](https://s3.amazonaws.com/brainscape-prod/system/cm/154/211/761/q_image_thumb.jpg?1438638015)
Hemidesmosomes
134
[![]()](https://s3.amazonaws.com/brainscape-prod/system/cm/154/211/791/q_image_thumb.png?1438638142)
Simple squamous
135
[![]()](https://s3.amazonaws.com/brainscape-prod/system/cm/154/211/941/q_image_thumb.png?1438638199)
Simple squamous
136
[![]()](https://s3.amazonaws.com/brainscape-prod/system/cm/154/212/127/q_image_thumb.png?1438638250)
Simple Cuboidal
137
[![]()](https://s3.amazonaws.com/brainscape-prod/system/cm/154/212/173/q_image_thumb.png?1438638307)
Simple columnar
138
[![]()](https://s3.amazonaws.com/brainscape-prod/system/cm/154/212/207/q_image_thumb.png?1438638381)
Pseudostratified Epithelium
139
[![]()](https://s3.amazonaws.com/brainscape-prod/system/cm/154/212/290/q_image_thumb.png?1438638455)
Stratified Squamous Epithelium
140
[![]()](https://s3.amazonaws.com/brainscape-prod/system/cm/154/212/303/q_image_thumb.png?1438638528)
Transitional Epithelium
141
Mucous glands
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
[![]()](https://s3.amazonaws.com/brainscape-prod/system/cm/154/212/400/q_image_thumb.png?1438638747)
Mucous glands
143
Mixed glands
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
[![]()](https://s3.amazonaws.com/brainscape-prod/system/cm/154/218/278/q_image_thumb.jpg?1438645360)
Mixed glands
145
Merocrine Secretion
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
Holocrine Gland
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
Apocrine Secretion
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
[![]()](https://s3.amazonaws.com/brainscape-prod/system/cm/154/218/994/q_image_thumb.jpg?1438646575)
Sebaceous cyst, aka boils
149
Myoepithelial Cells
Good if need to expel something from a duct or tube
Contract and push the fluid through
150
Diffuse Neuroendocrine system
APUD: Amine Precursor uridine something or other
Secrete peptide hormones
Identify by dark staining areas in silver stain (argentophilic)
151
[![]()](https://s3.amazonaws.com/brainscape-prod/system/cm/154/220/282/q_image_thumb.png?1438647240)
Diffuse Neuroendocrine system
152
Steroid-secreting cells
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
What are some cancers derived from epithelium? Why are they so common?
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
Characteristics of skeletal muscle
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
[![]()](https://s3.amazonaws.com/brainscape-prod/system/cm/154/294/442/q_image_thumb.png?1438720953)
Longitudinal view of Skeletal Muscle
156
Characteristics of Cardiac Muscle
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
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Characteristics of Smooth Muscle
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
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How is skeletal muscle formed?
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
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What is skeletal muscle composed of?
Thin (actin) filaments and thick (myosin) filaments
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What are thin filaments composed of?
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
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What are thick filaments made of?
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
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What is the line in the middle of the sarcomere called?
M line
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What is the area consisting only of thick filaments called?
H Zone
H zone contracts when sarcomere contracts
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What is the area spanning the entire thick filament called?
A band
Stays the same length during contraction
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What is the area consisting of only thin filaments called?
I band
This shortens during muscle contractions
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What is an entire contractile unit of muscle called?
Sarcomere
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True or false: the zone of overlap does not change size
False - the zone of overlap consists of the area where the thick and thin filaments overlap, and it gets longer during contraction
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Sarcoplasmic Reticulum
Endoplasmic reticulum in muscle cell
Good for collecting, storing, and releasing calcium
Wraps around the muscle filament
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T-tubules
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
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Red Fibers
Slow Contractors
Longevity
More myoglobin
Aka Type I or slow oxidative fibers
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White Muscle Fibers
Aka type IIb fibers or fast glycolytic fibers
Fast contractors
Short amount of time
Fast-twitch, fatigue prone
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Intermediate muscle fibers
Aka Type IIa fibers or Fast oxidative glycolytic fibers
Fast-twitch, fatigue-resistant motor units
Sort of a combination of fast and slow
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Motor End Plate
Interaction between synapse and muscle cell itself
Neurotransmitter for skeletal muscle = acetylcholine (cleared by acetylcholinesterase)
Terminal bouton
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Tendons
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
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Motor Unit
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
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What is the purpose of gap junctions found in cardiac muscle cells?
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
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In what manner do muscle cells contract?
Rotational, wringing contraction
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How does smooth muscle contract?
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
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Morphology of Connective Tissue
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
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Primary function of connective tissue
"Space-filling" role - fills gaps between the epithelium, muscle and other tissues (loose connective tissue)
Supportive role - mechanical function - bone, cartilage, dense supporting tissue
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What are components of the extracellular matrix?
Fibers: collagen, reticular, elastic
Ground substance: glycoproteins (mostly fibronectin, laminin); Glycosaminoglycans - chondroitin sulfate, keratane sulfate, dermatan sulfate, heparin sulfate, hyaluronic acid; proteoglycans
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[![]()](https://s3.amazonaws.com/brainscape-prod/system/cm/154/479/323/q_image_thumb.png?1438905971)
Hyaluronic acid with proteoglycans sitting on surface and glycosaminoglycan side chains (looks like pin feathers)
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Characteristics of Collagen Fibers
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
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Characteristics of Type I Collagen
Found in bone, skin, tendon, ligament
Formation: mainly fibroblasts, osteoblasts
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Where is Type II collagen found?
Hyaline cartilage
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Where is Type III collagen found?
Reticular fibers
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Where is Type IV collagen found?
Basement membrane
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[![]()](https://s3.amazonaws.com/brainscape-prod/system/cm/154/479/589/q_image_thumb.jpg?1438906358)
Type I Collagen Fibers
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Reticular Fibers
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
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[![]()](https://s3.amazonaws.com/brainscape-prod/system/cm/154/479/653/q_image_thumb.jpg?1438906527)
Reticular or Type III Collagen Fibers
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Elastic Fibers
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
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What are elastic fibers composed of?
Elastin (central core)
Fibrillin microfibrils around the core embedded into elastin
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[![]()](https://s3.amazonaws.com/brainscape-prod/system/cm/154/479/770/q_image_thumb.jpg?1438906724)
Larger fibers: probably collagen
Thin fibers: Elastic fibers
Resorcin-fuchsin stain
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Marfan's syndrome
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
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Ehlers-Danlos syndrome
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
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Osteogenesis imperfecta
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
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What are the types of connective tissue?
Embryonic connective tissue
Connective tissue proper
Specialized connective tissue
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What are the types of the embryonic connective tissue?
Mesenchyme
Mucous connective tissue
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What are the types of connective tissue proper?
Dense connective tissue
Loose connective tissue
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What are the types of specialized connective tissue?
Adipose tissue, blood, bone, cartilage, hemopoietic tissue, lymphatic tissue
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Charateristics of embryonic connective tissue
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
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Mesenchyme
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
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Mucous connective tissue
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"
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Mesenchyme
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[![]()](https://s3.amazonaws.com/brainscape-prod/system/cm/154/480/339/q_image_thumb.jpg?1438908228)
Mucous connective tissue, aka "Wharton's jelly"
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General Characteristics of Dense Connective Tissue
Few fibroblasts
Little ground substance
Large amount of collagen fibers between them
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Dense regular connective tissue
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")
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[![]()](https://s3.amazonaws.com/brainscape-prod/system/cm/154/480/369/q_image_thumb.png?1438908400)
Dense regular connective tissue
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Characteristics of Dense irregular connective tissue
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
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[![]()](https://s3.amazonaws.com/brainscape-prod/system/cm/154/480/907/q_image_thumb.jpg?1438909158)
Dense Irregular connective tissue
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Fibroblasts
Star-shaped cells with elongated disc-like nucleus
Synthesize fibers and ground substance
Developed rER (basophilic cytoplasm) - protein synthesis
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Myofibroblasts
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
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[![]()](https://s3.amazonaws.com/brainscape-prod/system/cm/154/480/965/q_image_thumb.png?1438909380)
Fibroblast
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Characteristics of Loose connective tissue
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
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[![]() ](https://s3.amazonaws.com/brainscape-prod/system/cm/154/481/014/q_image_card.jpg?1438909507)
Loose connective tissue
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Resident cell population in loose connective tissue
Fibroblasts and myofibroblasts
Adipose Cells
Macrophages
Mast Cells
Mesenchymal cells
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Transient cell population in loose connective tissue
Migrate from other tissues to specific stimuli
Lymphocytes
Plasma cells
Neutrophils
Eosinophils
Basophils
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Adipose Tissue
Differentiates from mesenchymal cells
Two types
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White adipocytes
Single fat drop filling the cytoplasm
Ring-shaped cytoplasm and flat peripheral nucleus
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Brown adipose tissue
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
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[![]()](https://s3.amazonaws.com/brainscape-prod/system/cm/154/625/311/q_image_thumb.jpg?1439084985)
Brown adipose tissue
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[![]()](https://s3.amazonaws.com/brainscape-prod/system/cm/154/625/400/q_image_thumb.png?1439085048)
White adipose tissue
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Macrophages
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
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[![]()](https://s3.amazonaws.com/brainscape-prod/system/cm/154/625/771/q_image_thumb.png?1439085577)
Macrophage
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Mast cells
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
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Content of granules released by mastocytes
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
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Mast Cell
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Mesenchymal cells
Star or spindle-shaped cells
Pleuripotential - capable to form various cell types
In adult, they are located usually around the vessels
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[![]()](https://s3.amazonaws.com/brainscape-prod/system/cm/154/625/962/q_image_thumb.png?1439086139)
Mesenchymal cells
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Lymphocytes
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)
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Plasma Cells
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
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[![]()](https://s3.amazonaws.com/brainscape-prod/system/cm/154/626/025/q_image_thumb.png?1439086443)
The cells with dotted spots are plasma cells
The dark, basophilic cells that have barely any cytoplasm are lymphocytes
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Neutrophils
Capable of migration
Granules - small, purple, barely visible in the light microscope
Nucleus is multilobed (thus also called polymorphs)
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Eosinophils
Named after the large, esonophilic granules in the cytoplasm
Typically bilobed nucleus
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Basophils
Large, basophilic granules in the cytoplasm
Nucleus obscured by the granules
Closely related to mast cells of connective tissue - only nucleus isn't visible
