Microanatomy Flashcards
Where would you find stratified squamous epithelium?
Epidermis, esophagus , outer layer of mouth and vagina
Where would you find simple squamous epithelium?
Blood vessels and alveoli, minimal barrier for exchange of nutrients, wastes, gases
Where would you find simple cuboidal epithelium?
Kidney tubules. Secretion and absorption.
Where would you find stratified cuboidal?
Mammary glands. Sweat ducts. Rare
Where would you find simple columnar epithelium?
Digestive organs. Has goblet cells.
Where would you find stratified columnar epithelium?
Rare. Epididymis, mammary glands
Where do you find pseudo stratified epithelium?
Also called respiratory epithelium. Trachea. Has goblet and cilia.
Where do you find transitional epithelium?
Urinary system. Ureter, bladder.
What are the ECM components of connective tissue?
- ground substance: made of proteoglycans and glycoproteins, gel like. provides nutrient supply and mechanical support
- fibers: collagen, elastic, reticular. provides strength and resistance
How are collagen fibers formed?
procollagen->tropocollagen->fibril->fibers->fiberbundles
What are the components of elastic fibers? Function? Location?
- made of elastin and fibrillin
- strength and elasticity
- found in dermis, mesenteries, lungs, elastic cartilage, large blood vessels
What are reticular fibers composed of? Function?
- Type III collagen
- form part of basement membrane
- support and strength in many soft tissues such as around fat and smooth muscle cells, liver, lymph nodes, spleen.
Where is loose connective tissues (LCT) found?
- around vessels and nerves, under epithelia, spaces between other tissues, subcutaneous layer of skin
- e.g. lamina propria and mesentery
Where can regular Dense connective tissue (r DCT) be found?
tendons and ligaments
Where can irregular dense connective tissue (irDCT) be found?
- dermis of skin, organ capsules, heart valves, perichondrium, periosteum
- where pulling forces are exerted in various directions
What is the ECM of rDCT made mainly of?
Type I collagen fiber bundles
What is the ECM of adipose tissue made of?
reticular fibers and small amt of ground substance
What is the main ECM component of LCT?
ground substance
Where is hyaline cartilage found?
fetal skelton, articular ends of long bones, nose, larunx, trachea, bronchi, ribs (costal cartilage)
What are the functions of hyaline cartilage?
protection, anchoring, growth, regeneration. Flexibility and support at joints, reduces friction, absorbs shocks
What are components of hyaline cartilage?
- Chondroblast–>chondrocytes
- chondrocytes in isogenous groups
- ECM made of type II collagen fibrils
- sulphated GAGs make ECM basophilic
- surrounded and nourished by perichondrium
- Avascular
What is perichondrium composed of?
irDCT. Has chondrogenic progenitors
Where is elastic cartilage found?
Ear, auditory canal, auditory tube, epiglottis
What is elastic cartilage composed of?
-many chondrocytes,
-ECM has branching elastic fibers
-
What is the Function of elastic cartilage?
mainly flexibility
How do elastic and hyaline cartilage grow?
By appositional as well as interstitial growth
Where is fibrocartilage found?
capsules and ligaments of joints, IV disks, pubic symphysis, insertions of some tendons and ligaments. Found in places where stress is placed.
What is fibrocartilage composed of?
- No perichondrium
- fibroblasts and collagen fibers alongside chondrocytes
- columnar isogenous groups of chondrocytes
- ECM of type I collagen
What is the function of fibrocartilage?
strongest of three types of cartilage. For stength and rigidity
What are the cells of bone?
osteoblasts, osteocytes, osteoclasts, osteogenic cells
What are osteoclasts?
- large multinucleated cells from monocytes
- invovled in bone resorption-osteolysis
- foamy, acidophilic cytoplasm
What are the functions of Neutrophils?
phagocytosis and destruction of bacteria
What are the functions of Eosinophils?
destroy larger parasites and modulate allergic inflammatory responses
What are the functions of basophil?
release histamine and heparin when activated
What are the functions of monocyte?
mature into tissue macrophages
What are the functions of lymphocytes?
B cells become plasma cells and T cells assist in immune reactions.
What are the relative abundances of formed elements in blood?
Erythrocytes, Thrombocytes, Neutrophils, Lymphocytes, Monocytes, Eosinophils, Basophils
Never let monkeys eat bananas
What molecules are involved in cell cell and cell matrix adhesion?
- Cadherins: cell cell-adherens junctions and desmosomes, Ca depend
- Immunoglobulin superfamily: mediate homophilic or heterophilic adhesion, weaker than cadherins.
- Selectins: cell-surface, low affinity allows “rolling”, bind lectins, Ca depend
- MHC: key players in immunity
What are the embryonic origins of the 4 different types of tissues?
-Epithelium: may arise from any 3 germ layers
•Ectoderm: epidermis, sweat glands, lens of eye,
•Mesoderm: endothelium, kidney tubules
•Endoderm: lining of gut, bladder, trachea
-Connective tissue: mesoderm
-Contractile tissue: mesoderm
-Nervous tissue:
•Ectoderm: CNS
•Neural crest: PNS
Where can osteogenic (osteoprogenitor) cells be found in bone?
Periosteum and endosteum
What are some disease of bones?
Rickets-Vit D deficiency, bone poorly calcified
Paget’s disease-more rapid osteoid production than mineralization
Osteoporosis-more bone resorption and less bone formation
What is the basic cellular unit of skeletal muscle?
Myofiber.
What is the structure of a muscle?
myofibrils (made of sacromeres)–>Each myofiber surrounded by basal lamina and endomysium–>group of fibers is a fascicle (surrounded by perimysium)–>many fascicles is a single muscle (surrounded by epimysium
What are the components of a sacromere?
A band: dark, overlapping actin and myosin
I band: light, actin from 2 adjacent sacromeres
Z discs-actin anchored to, within I band
M line-myosin connected to.
Which bands in muscle shorten during contraction?
I bands shorten, A bands do not
What proteins are required in a sacromere?
a-actinin, myomesin, titin, nebulin
What is a triad in muscle?
3 flattened sacs outside each myofibril at A/I junction.
-1 T tubule and 2 terminal cisterna of SER
What do t-tubules do?
they convey action potentials at neuromuscular junction. triggers release of Ca from adjacent terminal cisternae of SER into sarcoplasm. Initiates binding of myosin to actin.
Describe structure of cardiac muscle?
Single nucleus at center of cell. Often branch. myocytes joined together by intercalated discs.
What are perkinje fibers?
Modified myocytes. Larger, fewer myofibrils, lots of glycogen. Specialized conduction cells. Can sequester Ca rapidly.
Where can smooth muscle be found?
along GI tract, respiratory tract, urogenital track, blood vessel walls.
How to the three types of muscles grow?
Skeletal: hypertrophy only
cardiac: hypertrophy only
smooth: hypertrophy and hyperplasia
Where does the each type of muscle obtain Ca2+ for contraction?
skeletal: intracellular, SER
cardiac: extracellular, through t tubules
smooth: intra and extracellular. SER and Caveoli
What tissues are derived from the neural tube?
Brain and spinal cord (CNS)
What tissues are derived from the neural crest? (Ectomesenchymal)
melanocytes in skin, adrenal medulla chromaffin cells, neuronal and schwann cells of PNS, portions of connective tissue, etc.
Which direction is slow and which is fast axonal transport?
Slow: anterograde only.
Fast: bi directional. moves membrane limited organelles towards synapse via kinesin by saltatory (jerky) motion. requires ATP. Fast retrograde via dynein.
regrograde: potential pathway for toxins and viruses
What is a mast cell?
It releases heparin and histamine. Mediate inflammatory and allergic responses.
Where would you find type II collagen?
cartilage, vitreous of the eye
What do canaliculi contain?
The cytoplasmic processes of osteocytes. Gap junctions between the processes of neighboring cells. Extracelular fluid and as periosteocytic space and Ca reservoir.
What is in a Haversian canal?
blood vessels and nerves
