Lecture Quiz 2 Flashcards
Tissue
a group of cells that are assembled to perform a common function
What are the four basic tissues in the body?
Epithelium
-lines body cavities/surfaces and forms glands
Connective Tissue
-supporting tissue (bone)
Muscle Tissue
-Contracts to produce movement
Nervous Tissue
-integrates and coordinates body activities
Epithelium
-definition
a purely cellular, avascular layer/layers of cells covering all free surfaces (both inside and out) of the body
- form glands of the body
- typically one surface is free facing air or fluid
- other surface is attached nearly always to connective tissue
General Characteristics of epithelium
- Highly cellular-little intercellular space or substance
- No direct blood supply
- Regeneration capacity- wound healing
- cells frequently exhibits polarity with respect to orientation of cell and organelles
- Apical Surface
- Basal Surface
- Lateral Surface
Apical Surface
- definition
- surface specializations
- function
free surface-faces are or fluid
Surface Specializations
- cilia, microvilli, stereo cilia
- clathrin coated vesicles
- glycocalyx
Function:
-absorption, recognition
Basal surface
- definition
- surface specializations
- function
attached surface
-usually to connective tissue
Surface specializations:
- hemidesmosomes
- membrane folds
Function:
attachment, transport, absorption
Lateral Surface
- definition
- surface specializations
- function
often attached to other epithelial cells
Surface specializatoins
- junctional complexes
- gap junctions
- cell adhesion molecules (CAMs)
Function:
-attachment, communication
Types of Epithelium
1) Lining or membranous epithelium
2) Glandular Epithelium
Lining/Membranous Epithelium
covers the surface of the body and lines organs
ex: digestion, respiratory, and urogenital tracts
- lines blood vessels, the heart and body cavitiies
Glandular Epithelium
Forms glands(exocrine and endocrine) -specialized for secretion
Functions of epithelia
- Protection-skin
- Secretion- glands
- Excretion-Kidneys
- Absorption- lining the small intestine
- Filtration- renal corpuscle of the kidney
- Lubrication
- Reproduction
- Transport
- Sensory Perception
Histogenesis
epithelium is derived from all 3 germ layers
Basement membrane
Basal lamina + reticular lamina
Basal Lamina
produced by epithelia
2 parts:
-lamina lucida
-lamina densida
Glycosaminoglycans (GAGs)
Collagen type IV (doesnt form fibrils)
Laminin-glycoprotein, connects basal lamina to epithelial cells
Reticular Lamina
produced by connective tissue
Collagen III fibrils, AKA reticular Collagen Glycosaminoglycans GAGs) Function -support-physical, functional -Selective filtration
Simple Squamous forms?
Bowmans capsule in kidney
-lines alveoli of lungs
Mesothelium forms?
lines surface of body cavities
Peritoneal, pleural, pericardial cavities
Endothelium forms?
lines blood vessels and lymphatic vessels
Stratified Squamous
-2 types
1) Cornified (AKA keratinized)
- contains filaggrin-cross linking protein-cross links keratin intermediate filaments
2) Non-cornified (AKA Nonkeratinized)
- keratin intermediate filaments present but not cross linked
** All epithelia possess keratin intermediate filament but not all is CROSS LINKED
Exocrine Epithelial
-def
products are secreted into ducts
Endocrine
-defintion
ductless
- produce hormones that are secreted into the blood stream
- wrapped in capillaries
Mode of secretory product release
-different types?
Merocrine
Aprocrine
Holocrine
Cytogenous
Merocrine
Merocrine
-secretory granules fuse with cell membrane and contents only are released (serous or mucus)
Ex: pancreas or sweat glands
Aprocrine
Secretion is released with plasma membrane eveloping the particle
-part of the cytoplasm leaves the cell
Holocrine
Whole cell dies and is secreted
Cytogenous
whole living cell is released
Epithelia cells
cells with epithelial characteristics but LACK A FREE SURFACE
Ex: Leydig cells
