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Questions and Answers
What is the characteristic of holocrine secretion?
What is the characteristic of holocrine secretion?
Which type of secretion is characteristic of the pancreas and parotid gland?
Which type of secretion is characteristic of the pancreas and parotid gland?
What is the function of neuro-epithelial cells?
What is the function of neuro-epithelial cells?
Which type of secretion is characteristic of sebaceous glands?
Which type of secretion is characteristic of sebaceous glands?
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What is the function of olfactory epithelium?
What is the function of olfactory epithelium?
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What is the characteristic of merocrine secretion?
What is the characteristic of merocrine secretion?
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Which type of secretion is characteristic of salivary glands?
Which type of secretion is characteristic of salivary glands?
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What is the function of taste buds?
What is the function of taste buds?
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What is the characteristic of ceruminous glands?
What is the characteristic of ceruminous glands?
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What is the function of lactating mammary glands?
What is the function of lactating mammary glands?
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Study Notes
Tissues of the Body
- A tissue is a group of cells with similar morphological characteristics specialized to perform specific functions.
- There are 4 basic tissues in the body: epithelial, connective, muscular, and nervous tissue.
Epithelial Tissue
- Forms continuous sheets of cells that line internal cavities and cover external surfaces (skin) of the body.
- General characteristics:
- Cells are tightly joined together.
- Cell boundaries are ill-defined.
- Cells rest on a basement membrane.
- Originate from the three germ layers: ectoderm, mesoderm, and endoderm.
- Avascular but highly innervated.
- Cells can regenerate.
- Can modify to form other types (glandular epithelium, neuro-epithelium, and myo-epithelium).
Classification of Epithelium
- Surface Epithelium:
- Simple Epithelium:
- One layer of cells.
- Types: squamous, cuboidal, columnar, and pseudo-stratified columnar.
- Stratified Epithelium:
- More than one layer of cells.
- Types: stratified squamous (keratinized and non-keratinized), transitional, and stratified columnar.
- Simple Epithelium:
Simple Epithelium
- Simple Squamous Epithelium:
- Lines blood vessels.
- Lines upper respiratory tract (nasal cavity, trachea, and bronchi).
- Simple Columnar Epithelium:
- Non-ciliated: lines the gastrointestinal tract (GIT).
- Ciliated: lines the fallopian tube.
- Simple Cubical Epithelium:
- Lines the gastrointestinal tract (GIT).
- Found in thyroid follicles and fallopian tube.
Stratified Epithelium
- Mainly protective function.
- Types:
- Stratified Squamous Epithelium:
- Non-keratinized: esophagus.
- Keratinized: skin.
- Stratified Columnar Epithelium:
- Urinary passages (urinary bladder and ureters).
- Stratified Squamous Epithelium:
Glandular Epithelium
- Classified according to:
- Presence or absence of ducts:
- Endocrine glands (no ducts): pituitary gland, thyroid gland.
- Exocrine glands (with ducts): salivary gland.
- Number of cells:
- Multicellular glands: salivary glands.
- Unicellular glands: goblet cells.
- Presence or absence of ducts:
- Modes of secretion:
- Merocrine secretion: exocytosis of secretory products without loss of cell membrane (e.g., pancreatic acinar cells).
- Apocrine secretion: release of secretory products with loss of apical cytoplasm and cell membrane (e.g., lactating mammary glands).
- Holocrine secretion: destruction of secretory cells with secretion (e.g., sebum from sebaceous glands).
- Nature of secretion:
- Serous (watery) secretion: containing enzymes (e.g., pancreas and parotid gland).
- Mucous secretion (e.g., goblet cells).
- Mixed (muco-serous) secretion (e.g., salivary glands).
- Waxy secretion (e.g., ceruminous glands in the external ear).
- Creamy secretion (e.g., sebum from sebaceous glands).
Neuro-Epithelium
- Epithelial cells modified and specialized to receive sensory stimuli.
- Epithelial cells act as sensory receptors for special senses (e.g., olfactory epithelium for olfaction sensation and taste buds for taste sensation).
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Description
Learn about the 4 basic tissues in the human body, including epithelial, connective, muscular, and nervous tissue. Understand their morphological characteristics and functions.
