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CELL 302 > Lecture B3, B4 > Flashcards

Lecture B3, B4 Flashcards

1
Q

Digestive system parts: _____

A

The digestive tract: Oral cavity, esophagus, stomach, small and large intestine, anus
Associated Glands: salivary glands, liver, pancreas

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2
Q

digestive system comes from which germ layer?

A

endoderm

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3
Q

endoderm forms ______

A

foregut, midgut (small intestine), hindgut (colon)

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4
Q

endodermal cells form a _____ which molds into an epithelial tube surrounded by _____. This process requires many different signaling pathways and multiple transcription factor genes encoding proteins involved in ____

A

-polarized sheet
-mesoderm
-adhesion, the cell cycle and differentiation

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5
Q

Signaling pathways that regulate differentiation of the
different areas of the digestive tract

A

-Wnt/FGF4,BMP from mesoderm (increases down the digestive tube)

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6
Q

Four main layers of small intestine

A
  1. Mucosa (mucous membrane): Epithelial lining, Lamina propria – loose connective tissue, Rich in blood vessels, Thin smooth muscle layer (muscularis mucosae)
  2. Submucosa, connective tissue, links to underlying muscle layers
  3. Muscularis: inner layer (circular), outer layer (longitudinal)
  4. Serosa: outermost layer connective tissue, blood vessels, adipose
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7
Q

Mesentery surrounds the _____ and suspends them from _____

A

-stomach, small and large intestine
-the abdominal wall

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8
Q

Movement of nutrients from the lumen of small intestine to be absorbed into the bloodstream happens across the _____. Transcellular transport requires: (2)

A

-epithelial cells
-Membrane transport proteins in the apical surface (active
transport) & the basolateral surface (facilitated diffusion)

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9
Q

the small intestine folds ____ to create _____

A

-mucosa and submucosa (epithelial lining)
-dense apical fingerlike projections called villi to increase absorptive area

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10
Q

villi are covered by _____ and contain ____

A

-columnar epithelial cells
-goblet cells and absorptive enterocytes

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11
Q

each villus is connected to _____ which contains ____

A

-the lamina propria
-the capillary network

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12
Q

enterocyte/absorptive cell has ____ to increase absorption

A

-dense microvilli (brush border) on apical surface

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13
Q

circular and longitudinal muscle layers of small intestine are responsible for ____

A

peristalsis

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14
Q

SC of intestine is marked by ____ and differentiates into ___ then into _____

A

-LGR5+
-TA cells
-enterocytes, goblet cell, tuft cell, enteroendocrine cell, paneth cell

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15
Q

SC of intestine & paneth cells are in _____ and move up the villus when differentiating

A

-crypts

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16
Q

BMP signalling increases _____

A

up the villus

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17
Q

WNT signalling increases _____

A

down the villus (in the crypt)

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18
Q

WNT signalling in villi does what? Notch? BMP? Hh?

A

-maintains ISCs, Paneth cells
-differentiation of enterocytes
-differentiation of enteroendocrine cells, keeps stem cell from dividing too much
-Sense epithelial integrity

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19
Q

Niche of ISC

A

-ECM
-Signaling molecules
-Basement membrane
-Physical factors
-Paneth cells support intestinal stem cells (ISCs) via secretion of Wnt, Notch (DLL) and EGF

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20
Q

After injury to intestine, Progenitors and also enterocytes can dedifferentiate into ______

A

-LGR5+ intestinal stem cells (ISCs) through WNT-mediated niche signals

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21
Q

absorptive intestinal surface forms from ____ signalling (2) + function

A

-Wnt5 (Highly proliferative during tube elongation -> cells grow in height just prior to villi formation)
-Hh (Villi emergence)

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22
Q

after Hh signalling, cells at tip of villus transition have ______ while cells are inter-villi region remain _____

A

-simple columnar structure (expanding apical surface)
-pseudostratified

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23
Q

selective absorption of intestine requires _____, giving the gut structure to resist sheer forces in the tube

A

TJ, AJ, Desmosomes, Hemidesmosomes

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24
Q

what we know about microvilli (3)

A

-They are dynamic – always recycling actin filaments.
-their structure and the role of actin and actin binding proteins.
-Ezrin plays an important role.

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25
Q

defects in villi formation or structure causes this disease?

A

Celiac disease

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26
Q

Microvilli are made of _____

A
  • bundles of actin filaments
    -Actin binding accessory proteins like Myosin delivers components
    -Actin filaments insert into Terminal web or intermediate
    filaments
    -Formin and other proteins cap F-actin at the top
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27
Q

Microvilli formation during enterocyte differentiation

A

-Microvilli initially appear as small membrane buds on apical surface
-Protrusions self organize into distinct clusters mediated by adhesion between distal tips
-Distal Tip adhesion promotes packing of bundles together to form an organized structure
-actin filament cores attach to actin binding bundling proteins (fimbrin, villin, espin) and are cross linked to apical membrane by Ezrin

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28
Q

enterocytes absorb _____

A

lipids, proteins, sugar components

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29
Q

lipid absorption by enterocytes

A

-Hydrolyzed lipid components enter the cell by passive diffusion
-lipids accumulate in SER then fatty acids are resynthesized as triglycerides
-TGs are processed through the RER and
Golgi and covered in a thin protein layer to form chylomicrons (larger lipid droplet) near the nucleus
-These are exocytosed from the lateral membrane

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30
Q

sugar absorption by enterocytes

A

-Secrete disaccharidases into the glycocalyx (ECM)
-Hydrolyses disaccharides into monosaccharides
-monosaccharides are actively transported across microvilli and deposited in the underlying capillaries (sodium dependent)

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31
Q

protein absorption by enterocytes

A

-Secrete peptidases into the glycocalyx (ECM)
-Hydrolyses dipeptides into monopeptides
-monopeptides are actively transported across microvilli and deposited in the underlying capillaries

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32
Q

Goblet cells are essentially _____

A

a single cell gland (merocrine)

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33
Q

Goblet cells descr.

A

-Secretory vesicles filled with mucin/mucin2 (glycoproteins)
-interspersed amongst enterocytes
-nuclei and organelle in bottom part of the cell

34
Q

mucus produced by goblet cells acts to protect and lubricate the ____

A
  • lining of the intestine
35
Q

Enteroendocrine Cells have varying numbers along _____

A

-length of small intestine

36
Q

enteroendocrine cells secrete _____

A

-various peptide hormones that coordinate food ingestion and nutrient ingestion

37
Q

Enteroendocrine Cells descr.

A

-Constricted apical surface with microvilli that contact the intestinal lumens
-Can also have open top in contact with lumen
-has chemoreceptors which determine levels of nutrients and regulate release of peptide factors/enzymes, signal to nerves, smooth muscle

38
Q

paneth cells function

A

-Release lysozyme, Phospholipase A, Defensins that Bind and break down walls of microorganisms and
bacteria
-part of Innate Immunity
-regulate microenvironment of small intestine

39
Q

paneth cells descr.

A

-Exocrine cells
-eosinophilic secretory granules in apical cytoplasm

40
Q

Tuft cells descr.

A

-act as sentinels to alert the innate immune system of the presence of parasites, initiating a T helper cell immune response against them

41
Q

Functions of Kidney

A

-regulate balance of water and electrolytes
-excretion metabolic wastes/bioactive substances to bladder through uteters
-secretion of renin (protease the regulates blood pressure)
-secretion of erythropoietin (glycoprotein GF) to increase RBC production
-conversion of vitamin D to active form
-gluconeogenesis during starvation

42
Q

kidney development comes from 4 key progenitor cell types: ________

A

-nephron progenitors, ureteric progenitors, endothelial progenitors and stromal progenitors

43
Q

kidney development steps

A
  1. In response to signals from ureter epithelium the
    mesenchyme forms a cap around the ureteric tip
  2. Signals from the mesenchyme cause the ureter tip cells to undergo branching morphogenesis to form the collecting ducts and ureter
  3. Under WNT signaling, cap mesenchyme aggregate and
    condense then undergoes a mesenchymal to epidermal
    transition to form nephron progenitors (renal vesicle)
44
Q

Each kidney contains ____ functioning units called ____ which originate in ____

A

-1 to 4 million
-nephrons
-the cortex

45
Q

Each nephron contains a ____ and a long simple epithelia _____

A
  • corpuscle
    -renal tubule with 3 parts
46
Q

The renal corpuscle surrounds a tuft of _____

A

-glomerular capillaries

47
Q

Renal tubule parts

A
  • proximal convoluted tubule which enters the medulla
  • loop of henle which contains thin descending and thick ascending limb
  • distal convoluted tubule in cortex with connecting tubules and collecting ducts that empty into the calyx
48
Q

PCT features? location? major function?

A

-simple cuboidal epithelium, lots of mitochondria, tall microvilli, basal membrane invaginations
-cortex
-reabsorption of nutrients, water, proteins & secrection of H+, NH4+

49
Q

Thin limb of loop of henle features? location? major function?

A

-simple squamous epithelium, few mitochondria
-medulla
-passive reabsorption of Na+ Cl-

50
Q

Thick limb of loop of henle features? location? major function?

A

-simple cuboidal epithelium, no microvilli, many mito.
-medulla
-active reabsorption of various electrolytes

51
Q

DCT features? location? major function?

A

-simple cuboidal epithelium, basal membrane invaginations, short microvilli
-cortex
-reabsorption of various electrolytes

52
Q

cells of collecting system + function

A

-principal cells (most abundant) : regulated secretion of K+
-intercalated cells: reabsorption of K+, regulation of acid-base balance
-transitional cell: between those cell rype

53
Q

glomerular podocyte descr.

A

-polarized cells with large central body from which primary processes project into foot processes

54
Q

CNT descr.

A

Less extensive basolateral invaginations, fewer
mitochondria

55
Q

interstitial fibroblast descr.

A

In cortex and medulla, long processes, produce proteins
(extensive ER)

56
Q

Distal Convoluted tubule (DCT) divided into _____. Cells have extensive ______

A

-early (DCT1) and late (DCT2)
-basolateral membrane invaginations and high numbers of mitochondria

57
Q

Connecting tubule (CNT) is just downstream of ___. Cells have less extensive ______

A

-DCT
-basolateral membrane invaginations and fewer mitochondria

58
Q

In chronic kidney disease, ____ of CCD are lost , marked by an increase in ___ signalling that converts _____

A

-intercalated cells
-NOTCH
-intercalated cells into principal cells

59
Q

The interconversion of intercalated cells and principal cells via a transitional cell type is regulated by _____

A

NOTCH signalling

60
Q

Transcellular transport (def.)

A

highly regulated transport through cell; both apical and basal membrane
-either passive down a conc gradient or active against conc gradient and needs ATP & transport proteins in membrene

61
Q

Paracellular transport (def.)

A

-transport across epithelium between cells
-passive down a conc gradient by diffusion or convection
-not tightly regulated
-unselectibe (based on size and charge of molecule)
-rate limiting barrier is tight junction

62
Q

combination of different claudins proteins in TJ are essential in _____

A

-structure and function of renal tubules

63
Q

glomerular capsule contains ____

A

capillaries and podocyte cells

64
Q

blood enters the glomerulus via ____ arterioles

A

afferent

65
Q

blood leaves the glomerulus via ____ arterioles

A

efferent

66
Q

layer of the capsule is made of podocytes which cover each capillary forming _____

A

slits between interdigitated processes called pedicles

67
Q

filtrate is produced in renal corpuscle when _____

A

blood plasma is forced through filtration slits formed by pedicles under pressure

68
Q

The glomerular filtration barrier has 3 parts: ______

A

-The fenestrated capillary endothelium
-The Glomerular basement membrane (GBM)
-The filtration “slit diaphragms”between pedicels.

69
Q

glomerular filtration barrier is formed by the fusion of ______

A

-basal lamina of a podocyte and a capillary endothelial
cell (GBM)

70
Q

capillaries in glomerulus are ____

A

fenestrated

71
Q

The _____ of podocytes contains the pedicels (foot processes that bind the GBM)

A

-basal domain

72
Q

Endothelial slit fenestrations are _____ wide

A

-60 to 80 nm

73
Q

GBM (300-360 nm) is the ECM containing macromolecules such as _____. Formed by fusion both the ____. Functions to separate the _____

A

-Laminin , collagens, fibronectin
-podocyte and capillary basal laminae
-blood from the capsule space

74
Q

Filtration slits between the interdigitating pedicles are _____ wide which allows for filtration of the blood and retention of ______

A

-25 to 30 nm
-plasma proteins

75
Q

podocyte proteins that contribute to slit structure include ______

A

nephrin, Neph1, podocin, ZO1, CD adaptor protein a, Fat and Pcadherin

76
Q

Slit diaphragm formation requires ____

A

junction proteins

77
Q

slit diaphragm complex links to ____

A

intracellular actin cytoskeleton which allows for remodeling of podocyte structure and function

78
Q

____ forms the structural framework of podocytes

A

actin cytoskeleton

79
Q

podocytes sits on GBM through ____

A

intergrins

80
Q

______ are podocyte progenitors

A

-Parietal epithelial cells (PECs)

81
Q

Parietal epithelial cells express stem cell markers _____ + and transcription factors ____

A

-CD24, CD133
-Oct4 and BmI-1

82
Q

PEC are located where? & do what?

A

-located at urinary pole (renal tubule) which leads to PCT- -divide and produce progenitors that migrate slowly around the capsule and eventually replace lost or damaged podocytes

CELL 302 (18 decks)

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