Lesson 5 Flashcards
four primary tissues
- epithelial
- connective
- nervous
- muscular
organ
structure with discrete boundaries that is composed of two or more tissue types
epithelial tissue
sheet of closely adhering cells, one or more cells thick, with upper surface exposed to environment or internal space
where can epithelial tissue be found?
- body surfaces (skin)
- lines body cavities
- constitutes most glands (endocrine, exocrine, sweat)
epithelial tissue is vascular/avascular?
avascular, is usually nourished by underlying connective tissue
functions of epithelial tissue: protection
protect deeper tissues from injury and infection
functions of epithelial tissue: secretion
produce and release mucus, sweat, enzymes, hormones, and other substances
functions of epithelial tissue: excretion
void wastes from the tissues
functions of epithelial tissue: absorption
absorb chemicals, such as nutrients
functions of epithelial tissue: filtration
all substances leaving the body are selectively filtered by an epithelium
functions of epithelial tissue: sensation
nerve endings in epithelia detect stimuli
- neuroepithelium: specialized for specific sensory function
characteristics of epithelial tissue: cellularity
cells interconnected by cell junctions
characteristics of epithelial tissue: polarity
cells have orientation (apical/basal)
characteristics of epithelial tissue: attachment
attached to basement membrane, consists of two layers
characteristics of epithelial tissue: attachment - basal membrane
secretes clear layer (lamina lucida/basal lamina), prevents proteins and large molecule movement from connective tissue to epithelium
characteristics of epithelial tissue: attachment - underlying connective tissue
secretes dense layer (lamina densa/reticular lamina) to provide strength, filtration of materials
characteristics of epithelial tissue: avascularity
lacks blood vessels
characteristics of epithelial tissue: regeneration
continuously replacing cells by mitosis of epithelium stem cells
three surfaces of epithelial cells
- basal
- apical
- lateral
epithelial surface: basal
surface facing the basement membrane
epithelial surface: apical
surface that faces away from the basement membrane, can contain microvilli or cilia
epithelial surface: lateral
surface between the basal and apical surface, ‘side wall’
what are epithelia classified by?
the number of cell layers
simple epithelia
each cell is anchored to the basement membrane
stratified epithelia
have cells on top of others, not all contact the basement membrane
individual epithelial cells may be specialized to…(3)
- move fluid over the epithelium; protection and lubrication
- move fluids through the epithelium, controls permeability
- produce secretions that protects and/or acts as messengers
exfoliative cytology
epithelial cells or fluids produced from the epithelial lining are removed and checked for abnormal cellular changes
- pap smear
mesothelium
lines body cavities
endothelium
lines inner surfaces of the heart chambers and all blood vessels
ventral body cavity
divided by the diaphragm into the thoracic and abdominopelvic cavities
the thoracic cavity contains…
trachea, esophagus, heart, and lungs
the abdominopelvic cavity contains…
digestive, reproductive, and urinary organs
cranial cavity contains
brain
cranial cavity membranous lining
meninges
vertebral canal contains
spinal cord
vertebral canal membranous lining
meninges
the thoracic cavity contains…
the lungs and the heart
membranous lining of the lungs is called…
pleurae
membranous lining of the heart is called…
pericardium
the abdominopelvic cavity contains…..
digestive organs, spleen, kidney, urinary bladder, rectum, reproductive organs
abdominal cavity membranous lining is called…..
pericardium
pelvic cavity membranous lining is called…
peritoneum
thoracic cavity: mediastinum
located between the pleural cavities, contains the trachea, esophagus, thymus, and pericardial cavity
abdominal cavity
superior component of the abdominopelvic cavity, from the diaphragm to the top of the pelvic bones (peritoneal cavity)
pelvic cavity
inferior component that is medial to the pelvic bones (pelvic cavity)
retroperitoneal space
outside the peritoneum
what organs are in the retroperitoneal space?
pancreas, kidneys, ureters, and parts of the digestive system
three types of cellular junctions
- tight
- gap
- desmosomes/hemidesmosomes
tight junction
zipper-like, interlocking linkage between two adjacent cells by transmembrane cell-adhesion proteins
characteristics of tight junctions (3)
- encircles an epithelial cell near its apical surface
- joins epithelial cells with neighboring cells
- seals off intercellular space, making it difficult or impossible for substances to pass between
example of a tight junction
these appear in the stomach and the intestines to prevent digestive juices from seeping between epithelial cells and digesting underlying tissues
gap (communicating) junction
channel between cells formed by ring-like proteins
connexon
ring-like structure that forms gap junctions, consists of SIX transmembrane proteins arrange like segments of an orange around a water-filled channel
characteristics of a gap junction (2)
- ions, nutrients, and other small solutes pass between cells
- important in coordinating contractions of cardiac muscles
where can gap junctions be found? (5)
cardiac and smooth muscle, embryonic tissues, lens, and cornea
desmosome
patch that holds cells together, like a clothing snap
characteristics of desmosomes (3)
- keeps cells from pulling apart, are very strong and resist mechanical stress
- hook-like, J shaped proteins arise from cytoskeleton
- common in epidermis and other epithelia
hemidesmosomes
half-desmosome that anchors basal cells of an epithelium to an underlying basement membrane, prevents epithelium from peeling away from underlying tissues
gland
cell or organ that secretes substances for sure elsewhere in the body, or releases them for elimination from the body
exocrine glands
maintain their contact with surface of epithelium but way of a duct
endocrine glands
have no ducts, but do have many blood cappilaries, secrete hormones that enter the blood
unicellular glands
secretory cells found in an epithelium that is predominantly non-secretory, can be exocrine or endocrine
example of a unicellular gland
- mucus-secreting goblet cells in the trachea
- endocrine cells of the stomach
multicellular glands
secretory sheet where gland cells form epithelium that releases their product into an inner compartment
example of multicellular glands
mucin-secreting cells in the stomach, salivary glands
two types of duct shapes
- simple - unbranched
- compound - branches
secretory portions of glands (3)
- tubular
- acinar
- tubuloacinar/tubuloalveolar
tubular secretory portions
narrow secretory portion, duct and secretory portion are of uniform diameter
acinar secretory portions
secretory cells for dilated sac
- acinus or alveolus
tubuloacinar secretory portion
secretory cells are in both tubular and acinar portions
serus glands
produce thin, water secretions
examples of serus glands
perspiration, milk, tears, digestive juices
mucous glands
produce glycoprotein mucin, which absorbs water to form mucus
example of a mucus gland
goblet cells
mixed glands
contain both serous and mucous cell types and produce a mixture of the two types of secretions
example of a mixed gland
the two pairs of salivary glands in the chin
eccrine (merocrine) glands
release their Golgi products by exocytosis
apocrine secretion
lipid droplet covered by membrane and cytoplasm; buds from cell surface
holocrine secretion
cells accumulate a product and the entire cell lyses and disintegrates
