Histology summary
L1 Epithelia/glands
Epithelia = covering tissue, skin or inside of gut
Basement membrane = basal lamina = separates epithelia from underlaying tissue
- Lamina lucida
- Lamina densa
- Rectular lamina
Epithelia functions:
- Covering/protecting, transport (skin)
- Absorption (intestine)
- Secretion (glands)
Transport:
- Paracellular = next to cells
- Transcellular = via cells
Simple = single layer
- Squamous = wider than tall
- Cuboidal = as tall as wide = isodiametric (kidney)
- Columnar = taller than wide, can have cilia
Pseudo-stratified = looks stratified but all cells connected to basal membrane, against pathogens
Stratified = multiple layers
- Squamous
- Keratinised
- Non-keratinised
- Cuboidal
- Columnar
- Transitional = dome shaped, in urinal tract
Keratinised: not in aqueous environment (only terrestrial animals)
cells move up because the ones below divide -> make more keratin granules -> get keratinised
Transitional: look like mushrooms, hover over multiple cells. Protect against poisonous urine
Macrophages in epithelium -> endocytosis:
- Phagocytosis = “eating”, solid particle
- Pinocytosis = “drinking”, fluid
- Receptor-mediated = hormone regulated
Layers of epidermis:
- Stratum disjunctum = half loose pieces on top
- Stratum corneum = fully keratinized, top layer
- Stratum lucidum = not always there, only thick skin. Lost nuclei/organelles
- Stratum granulosum = cells fill up with keratin granules
- Stratum spinosum = thickest layer, spindle shaped cells due to desmosomes
- Stratum basale = bottom layer, connected to basal membrane, one cell layer
Underneath: dermis = connective tissue, with hair follicles and glands
, Glands
- Exocrine = secretion to outside world, via duct
- Endocrine = secretion to blood
Unicellular, ex. goblet cells
Multicellular
Merocrine = protein
o Serous = protein secretion
o Mucus = glycoprotein secretion
Apocrine = fatty in watery solution (milk)
Holocrine = fatty
Tubular acinar alveolar
Basic product -> pink dyed
Acidic product -> dark dyed
Sweat gland:
- Eccrine: for cooling down, is exocrine
- “apocrine”: for signalling, out via hair follicle, merocrine (still exocrine)
Salt glands
Salivary glands
- Parotid: serous secretion
- Submandibular: seromucous secretion
- Sublingual: seromucous secretion
- Lots of small ones: mucous secretion
Sebaceous glands: hair grease, holocrine secretion
Pancreas:
Endo- (=islets of langerhans) + exocrine (main structure) -> heterocrine
Main structure secretes bicarbonate
Islets of langerhans secrete insulin (b), glucagon (a), and more
Thyroid gland:
Follicle cells = thyrocytes
- Exocrine cells: secrete thyroglobulin
- Absorbing cells: absorb colloid
- Endocrine cells
C-cells: neurocrest cells migrate to thyroid + become C-cell, produce calcitonium
No thyroid hormone -> no feedback -> no inhibition -> more thyroid production -> big gland (thick neck)
Parathyroid glands: produce PTH (parathyroid hormone)
Parenchyma = cells responsible for organs main function
Stoma = supporting cells, usually connective tissue
L1 Epithelia/glands
Epithelia = covering tissue, skin or inside of gut
Basement membrane = basal lamina = separates epithelia from underlaying tissue
- Lamina lucida
- Lamina densa
- Rectular lamina
Epithelia functions:
- Covering/protecting, transport (skin)
- Absorption (intestine)
- Secretion (glands)
Transport:
- Paracellular = next to cells
- Transcellular = via cells
Simple = single layer
- Squamous = wider than tall
- Cuboidal = as tall as wide = isodiametric (kidney)
- Columnar = taller than wide, can have cilia
Pseudo-stratified = looks stratified but all cells connected to basal membrane, against pathogens
Stratified = multiple layers
- Squamous
- Keratinised
- Non-keratinised
- Cuboidal
- Columnar
- Transitional = dome shaped, in urinal tract
Keratinised: not in aqueous environment (only terrestrial animals)
cells move up because the ones below divide -> make more keratin granules -> get keratinised
Transitional: look like mushrooms, hover over multiple cells. Protect against poisonous urine
Macrophages in epithelium -> endocytosis:
- Phagocytosis = “eating”, solid particle
- Pinocytosis = “drinking”, fluid
- Receptor-mediated = hormone regulated
Layers of epidermis:
- Stratum disjunctum = half loose pieces on top
- Stratum corneum = fully keratinized, top layer
- Stratum lucidum = not always there, only thick skin. Lost nuclei/organelles
- Stratum granulosum = cells fill up with keratin granules
- Stratum spinosum = thickest layer, spindle shaped cells due to desmosomes
- Stratum basale = bottom layer, connected to basal membrane, one cell layer
Underneath: dermis = connective tissue, with hair follicles and glands
, Glands
- Exocrine = secretion to outside world, via duct
- Endocrine = secretion to blood
Unicellular, ex. goblet cells
Multicellular
Merocrine = protein
o Serous = protein secretion
o Mucus = glycoprotein secretion
Apocrine = fatty in watery solution (milk)
Holocrine = fatty
Tubular acinar alveolar
Basic product -> pink dyed
Acidic product -> dark dyed
Sweat gland:
- Eccrine: for cooling down, is exocrine
- “apocrine”: for signalling, out via hair follicle, merocrine (still exocrine)
Salt glands
Salivary glands
- Parotid: serous secretion
- Submandibular: seromucous secretion
- Sublingual: seromucous secretion
- Lots of small ones: mucous secretion
Sebaceous glands: hair grease, holocrine secretion
Pancreas:
Endo- (=islets of langerhans) + exocrine (main structure) -> heterocrine
Main structure secretes bicarbonate
Islets of langerhans secrete insulin (b), glucagon (a), and more
Thyroid gland:
Follicle cells = thyrocytes
- Exocrine cells: secrete thyroglobulin
- Absorbing cells: absorb colloid
- Endocrine cells
C-cells: neurocrest cells migrate to thyroid + become C-cell, produce calcitonium
No thyroid hormone -> no feedback -> no inhibition -> more thyroid production -> big gland (thick neck)
Parathyroid glands: produce PTH (parathyroid hormone)
Parenchyma = cells responsible for organs main function
Stoma = supporting cells, usually connective tissue
