Glands Flowchart

Flowchart nodes

• Glands

• Classification based on FUNCTION

• Classification  based on SHAPE (EXOCRINE)

• Classification by secretion type and morphology (EXOCRINE)

• Direction of secretion

• Apical 

• Basal

• secrete onto free epithelial surface

• EXOCRINE

• Derived from epithelial layer in embryo. Retain connection via drainage duct

• secrete contents into underlying connective tissue

• secretions pass into tissue fluid and blood vessels

• ENDOCRINE  Secretory product is a hormone

• Embryological origins of ENDOCRINE

• Epithelial But lose connection

• Neuronal - different phenotypes

• Neuronal - retain morphology

• Endocrine - under neuronal control

• Simple - with or without duct

• Compound - branching duct

• Sebaceous glands - no duct, opens direct into hair follicle

• Sweat glands - has a duct

• Majority of glands. Epithelial barrier only pierced at one point

• eg. parotid salivary glands

• Mucous

• Mixed

• Serous

• Made entirely of mucous eg. oesophageal glands. Secrete proteoglycans (mucus) and form TUBULAR secretory units. 

• Units are made up of columnar epithelial cells that are pale staining 

• The mucus store flattens the nucleus

• Eg, parotid gland. Made entirely of serous cells. Proteins secreted are mainly enzymes

• Minority- other purposes. Nutritive proteins from mammary gland. 

• Mammary gland also secretes lipid

• Serous form ALVEOLAR secretory units. PYRAMIDAL SHAPE.  Strong staining due to intracellular proteins.

• Round and unflattened nucleus

• Eg. mandibular salivary gland 

• both mucous and serous - comprised of tubular and alveolar  secretory units

• Some secretory units are mixed with some mucous tubular units capped by crescent shaped serous cells

• Serous DEMILUNES

• Not classified in same way as exocrine

• Thyroid gland

• Adrenal gland

• Produce T3 and T4 - regulate basic metabolic rate

• Small lipophilic hormones

• Immediately diffuse out of cell

• Precursor protein is thyroglobulin (TGB)

• Three or more glands in one

• Adrenal medulla 

• Adrenal cortex

• Outer layer of gland. Cells synthesise and release hormones

• centre of gland - derived from sympathetic neurons

• Their neurohormone is secreted into blood

• Secrete mainly adrenaline - under nervous control