IAS19-21,23,29-30,39 Flashcards
The embryonic origin of epithelium? Examples of epithelium for each?
Ectoderm: skin epithelium
Mesoderm: endothelium of blood vessels, lymphatics, mesothelium (pericardium, peritoneum, pleura), urogenital system (genital ducts, urinary ducts and tubules)
endoderm: GI tract lining, lining of lower respiratory system
Features of epithelial tissues?
1) lie on basement membrane
2) avascular
3) junctional complexes present to form 1 continuous layer
4) presence of cytokeratin for attaching to junctional complexes
5) little or no intracellular matrix
Examples of simple squamous epithelium?
Endothelium of blood vessels, mesothelium, respiratory epithelium
Example of stratified squamous epithelium (keratinized and non-keratinized)
Keratinized: skin epithelium
non-keratinized: esophagus lining, vaginal lining, buccal cavity lining
Example of stratified cuboidal epithelium?
Rare and uncommon type of epithelium: duct of sweat gland
Example of simple cuboidal epithelium?
Lining of most ducts, eg pancreatic gland, thyroid gland
Example of simple columnar epithelium?
Absorptive lining of small intestine, oviduct (ciliated)
Example of stratified columnar epithelium?
Lining of large excretory ducts, anus
Example of pseudostratified columnar epithelium?
Lining of trachea, bronchi, epididymis
Example of transitional epithelium?
Urinary bladder lining
Functions of microvilli and their mechanism for their function?
For absorption of nutrients from intestinal lumen
mechanism of absorption: microvilli have actin core connected to terminal web, when terminal web contracts microvilli can absorb foodstuff
Functions of cilia and mechanism of action?
Coordinated unidirectional movement
What are junctional complexes composed of?
Tight junction, Adhering junction, desmosome/hemidesmosome
Which components of junctional complex are belt like structures and their function?
Tight junction, adhering junctions
functions:
tight junction for sealing, prevent fluid leakage between epithelial cells (vacuum seal)
adhering junction for adhesion between cells (aa glue)
desmosomes: connected to cytokeratin fibers, anchor the cells together to prevent damage when stretched/when tearing forces applied(anchor)
Functions of gap junctions?
communication, coordinated muscle contraction
Serous meaning?
watery protein-based secretions, basophilic
Mucinous meaning?
thick mucin-based secretions, pale stain
Merocrine vs apocrine vs holocrine?
Merocrine: exocytosis
apocrine: loss apical (decapitation secretion)
holocrine: lysis of entire secreting unit
Locations where mucous membranes are located?
body cavity connecting to outside (eg respiratory, GI, GU tract)
in the epithelium and connective tissue (lamina propria + muscularis mucosae)
Locations where serous membrane are located?
Lining of peritoneal, pleural and pericardial cavities
in the mesothelium and connective tissues
Connective tissue origins?
From the mesoderm: undifferentiated mesenchymal cells (resident cells) AND hematopoietic stem cells (transient cells)
What cells derives from mesenchyme?
Chicken wing -
fibroblasts (the meat)
osteoblasts (bone)
Chondroblast (cartilage)
adipocyte (fat)
What cells derive from blood?
RBC
Megakaryocyte (platelet)
basophil, eosinophil, neutrophil, lymphocyte
monocyte
mast cell
Features of connective tissue?
1) NO cellular junctions
2) DOES NOT rest on basement membrane
3) Rich blood supply
4) No cytokeratin
5) abundant ECM
Types of connective tissue?
Embryonic connective tissue: mesenchyme, mucous connective tissue (eg umbilical cord)
mesenchyme differentiates into:
1)connective tissue proper (lamina propria, dermis of skin, tendon, ligament)
2) specialized connective tissue (bones and cartilage, adipose tissue)
3) hematopoeitic tissues (may not be from mesenchyme)
Composition of connective tissue?
Extracellular matrix, cellular component
Extracellular matrix components?
Fibrous components, ground substances
fibrous components: collagen 3, collagen 1 (MOST ABUNDANT), elastic fibers (elastin, fibrillin)
ground substances:
proteoglycan: core protein + GAG - component of hyaluronic acid
glycoprotein
Types of cartilage? Their appearance/morphology?
Hyaline - glassy, less cells
fibrocartilage - regular fibers
elastic cartilage - bundles of irregularly arranged elastic fibers
Loose connective tissue examples?
Lamina propria, mesentery
Dense connective tissue types and examples?
Dense irregular: dermis of skin
dense regular: tendons, ligaments, aponeurosis
Functions/morphology of cellular components of connective tissues?
Fibroblast: Synthesize fibrous components and ground substance (ECM)
Fibroblast (active) > fibrocyte (quiescent)
Macrophage: For ingestion of particles and digestion by lysosomal enzymes, For immune defense (antigen presentation, secrete growth factors & cytokines)
Phagocytic, from monocyte
Mononuclear phagocyte system
Kupffer cells in liver, microglial cells in CNS, Langerhans cells in skin, osteoclasts in bone
Mast cell: Cell surface receptors for IgE, Granule (heparin, histamine) release triggered by antigen binding to IgE
Plasma cell: From B cell, for synthesis of antibody, Eccentrically placed nucleus (clock-face), basophilic cytoplasm
Leukocyte: Migrate from blood during inflammation
Neutrophil, eosinophil, basophil, lymphocyte
Adipose cell
Unilocular (white) vs multilocular (brown)
White: main energy source
Brown: numerous mitochondria, important in first few months postnatal
Properties of type 1 skeletal muscle? (in terms of:
1)color and/or oxidative property
2) twitch and fatigue
2)myoglobin/mitochondria/blood capillary content,
3) contraction time and respiration type,
4) ATP enzyme velocity and ATP production mechanism
1) red meat, slow oxidative
2) slow twitch, fatigue resistant
3) high amount of myoglobin, mitochondria, blood capillaries (so appears red?)
4) long and slow contraction, aerobic respiration
5) lower ATP enzyme velocity, ATP produced by oxidative phosphorylation
Properties of type 2a skeletal muscle? (in terms of:
1) oxidative property
2) twitch and fatigue
3)myoglobin/mitochondria/blood capillary content,
4) contraction time and respiration type,
5) ATP enzyme velocity and ATP production mechanism
1) fast oxidative glycolytic
2) fast twitch, fatigue resistant
3) intermediate between type 1 and 2b
4) intermediate contraction time (faster than type 1 but slower than type 2b), can be both aerobic/anaerobic respiration
5) intermediate ATP enzyme velocity, both oxidative phosphorylation and glycolysis used for ATP production
Properties of type 2b skeletal muscle? (in terms of:
1) oxidative property, color
2) twitch and fatigue
3)myoglobin/mitochondria/blood capillary content,
4) contraction time and respiration type,
5) ATP enzyme velocity and ATP production mechanism
1） fast glycolytic, white meat
2) fast twitch, fatigue prone
3) lowest amount of myoglobin, mitochondria, blood capillaries compared to t1 and t2a
4) fast contraction time, anaerobic respiration
5) fast ATP enzyme velocity, exclusively by glycolysis
which 2 muscle types are striated and their distribution
cardiac (walls of heart, vena cava, pulmonary vein)
skeletal (attached to skeleton or visceral tissue)
smooth muscle distribution
walls of blood vessels, glands, organs, viscera
cellular unit of skeletal muscle?
1 muscle fiber - formed of multiple myogenic cells fused together
How are the calcium releasing units arranged in skeletal and cardiac muscle
c+t+c in skeletal, triad at AI junction
c+t dyad in cardiac, at Z line
Functions and morphology of intercalated discs of cardiac muscle?
Adhering junction - transverse, the z line for muscle attachment
desmosome - transverse and lateral, protect gap junction from stretch and tear
gap junction - lateral, for transmission of electrical synapse and synchronized muscle contraction
Which muscle type has NO t tubule
smooth muscle
nucleus position of the types of muscle cells?
skeletal: peripheral
cardiac, smooth: central
Muscle response to increased demand?
Skeletal, cardiac: hypertrophy ONLY
smooth: hypertrophy and HYPERPLASIA
CNS components of white and gray matter? and functions of white and gray matter?
gray: for synapses - neuron cell body, glial cells, unmyelinated neuropil, capillaries
white body - for signal transmission (like wires): glial cells, myelinated axons
PNS components?
Ganglion - cell bodies, nerves: bundles of myelinated/unmyelinated axons and glial cells
Examples of pseudounipolar and bipolar neurons?
Pseudo: dorsal root ganglion cell
bipolar: retina, olfactory cells
Initial region of axon function?
Initiate action potential
CNS neuroglia? Functions?
Astrocytes (white matter: fibrous, grey matter: proteoplasmic), ependymal cells, microglia, oligodendrocyte
astrocyte: maintain blood brain barrier, injury response, physical and metabolic support for neurons, buffer electrolyte and neurotransmitter
ependymal cells: composes part of choroid plexus to produce CSF
oligodendrocyte: accelerate transmission of action potential, electrical insulation and protection
microglia: immune surveillance, antigen presentation, phagocytic, remove debris in injury
PNS neuroglia?
Schwann cells (axons), perineuronal satellite cells (ganglion)
PNS injury and regeneration?
1) lots of toxic debris
2) debris removed very quickly
3) wallerian degeneration
4) schwann cells form myelin sheath to reach original target
5) axon grows back to function normally
CNS injury and regeneration?
1) lots of toxic debris
2) microglia cannot move to remove debris quickly because of BBB
3) astrocytes rush to rescue and forms glial scar
4) regeneration route completely cut off by glial scar
5) debris still present, releases inhibitors to prevent regeneration
Skin layers? the appendages?
Epidermis, dermis, subcutaneous layer
appendages: hair, nails, adnexal structures (pilosebaceous units, eccrine, apocrine glands)
Epidermis layers from bottom to surface? how long does it take for cells to proliferate up to surface? What cells make up epidermis?
Stratified basale, stratified spinosum, stratified granulosum, stratified corneum, 30 days, keratinocytes
Function of dermo-epithelial junction?
Adhesion - pemphigoid blister results as epidermis loses adhesion
cellular migration (for wound healing)
cellular signalling between epithelium and dermis
The most abundant type of collagen in connective tissue?
The types of collagen in epidermis to connective tissue?
Collagen 1
epithelium: 7
basal lamina: 4
reticular lamina: 3
connective tissue: 3,1
2 layers of basement membrane?
Basal lamina, reticular lamina
Functions of subcutis?
Calorie reserve
heat insulation
cushion effect
Origin of pilosebaceous unit?
Epidermal downgrowth
Pilosebaceous unit composition?
hair follicle, arrector pili muscle, sebaceous gland
4 types of pilosebaceous unit? locations?
TVAS:
terminal (scalp and beard area)
vellus: majority of body
Apopilosebaceous: axilla, groin
sebaceous: face, back, chest
Hair follicle comparison between scalp and forehead?
scalp: terminal hair follicle, larger follicle, extends to subcutis, smaller sebaceous gland
forehead: vellus hair follicle, smaller follicle size, larger sebaceous gland
Causes of androgenetic alopecia?
Proportion of hair shifts from terminal to vellus
Hair cycle processes and how long each takes for scalp hair? What % of hair in each phase?
how long is the hair cycle for eyebrow?
anagen (active growing phase) - 3 years, 90%
catagen (transition to quiescence) -3 weeks, ~1%
telogen (resting) - 3 months, ~10%
4 months
Telogen effluvium causes and consequences?
Physical, psychological stress, 70% hair follicles enter telogen prematurely
Sebaceous gland vs eccrine sweat gland vs apocrine sweat gland - locations, opening, secretions?
glabrous skin vs hair-bearing skin (locations, what it contains)
Locations:
sebaceous: only in hair-bearing skin
apocrine: axilla, genitalia, mammary areas
eccrine: most of the body
secretions:
sebaceous: oily,
apocrine: lipid-rich production
eccrine: active sweating during thermoregulation
openings:
sebaceous: open into spaces around hair root
apocrine: open into axillary and other hair follicles
eccrine: open into skin surface
glabrous skin: palms and soles only, have encapsulated sensory organs BUT no hair follicles and sebaceous glands
Hair-bearing skin: most of the body, NO encapsulated sensory organs, have hair follicles and sebaceous glands
Embryonic origin of skin?
ectoderm: epithelium, nervous system
mesoderm: dermis, skin appendages
Skin functions?
1) barrier through stratified corneum (cornified cell envelope with glutamyl-lysyl isodipeptide bonds, fatty acids prevents inward and outward passage of water)
2) UV absorption - by stratum corenum, epithelial keratinocytes, melanin (melanin produced by melanocytes, then transferred as melanosomes to keratinocytes (hair production))
3) Thermoregulation (shivering/sweating/circulation alteration)
4) immune response (innate + adaptive) - innate: dermal dendritic cells, macrophages doing phagocytosis, antimicrobial peptides, alarmins
adaptive immunity: antigen-presenting cells trigger Th1, Th2 response
5)Sensation (eg Meissner’s corpuscles/Merkels’s receptors)
6) Vitamin D synthesis
7) homeostasis (regeneration of skin appendages/proliferation etc)
Skin stem cell location?
- Bulge area of follicles
– Basal area of the inter-follicular epidermis
– Base of sebaceous glands
Perspiration types?
How is active sweating controlled (in terms of nervous innervation)?
Insensible (passive water evaporation from skin surface)
Active sweating from eccrine sweat glands
Sympathetic innervation, cholinergic, stimulated by pilocarpine and inhibited by atropine
Arrange Erysipelas, cellulitis and necrotizing faciitis in terms of how deep the level or redness is?
Erysipelas (epidermis/upper dermis) > cellulitis (dermis) > necrotic faciitis (deep fascia)
Cell cycle steps?
G1 phase, S phase, G2 phase, M phase
Sequence of CDKs and cyclins? The complex’s functions?
CDK: 4/6, 2, 2, 1
cyclins: DEAB
CDK4/6, cyclin D: move cell from G0 to G1 and prepare it to move from G1 to S
CDK2, cyclin E: prepares cell for DNA replication
CDK2, cyclin A: Activate DNA replication inside nucleus for S-phase
CDK1, cyclin B: Promote mitotic spindle assembly, reorganizes cytoplasm to prep for mitosis
Know that:
Retinoblastoma as eye cancer in children
RB inactivating mutations
Inhibitor effect on E2F > phosphorylated to kickstart replication
CDK4/6i in use to treat breast cancer (with hormonal therapy)
CIP/KIP and INK4 proteins remember p16, p21, which p21 is regulated by p53
Mechanism and function of p53 and p21?
DNA damage > p53 protein p53 phosphorylated and activated
p53 binds to regulatory region of p21, activates p21 transcription > p21 translation
p21 inactivates G1/S-CDK-cyclin complex and S-CDK/cyclin complex
Function: leads to cell cycle arrest
If anything serious leads to DNA repair and then apoptosis
