1. Exocrine gland

2. Glands Cells or aggregations of cells that synthesizes a substance
to be released, either in the blood stream or into cavities inside the body or its outer surface

3. Formation of Glands
Every gland is formed by an in growth from an epithelial surface.
This ingrowths may possess a tubular structure from the beginning, but in other instances glands may start as a solid column of cells which subsequently becomes tubulated.

4. Classification of Glands
Broadly the glands can be classified on basis of where they release their secretion
ENDOCRINE GLANDS
- via bloodstream.
EXOCRINE GLANDS
–via system of ducts.

5. Exocrine glands Examples: Sweat Sebaceous Salivary & Mammary
These glands pour their secretion onto an epithelial surface either or via ducts.
Examples:
Sweat
Sebaceous
Salivary &
Mammary

6. Exocrine Glands Classification
According to number of cells
According to structure
According to method of secretion
According to product secreted

7. According to Number of Cells
Unicellular Glands
consist of a single secretory cell.
In mammals the only example of unicellular exocrine glands are goblet cells, which occur in the epithelium of many mucous membranes. Goblet cells secrete the glycoprotein mucin , which by the uptake of water is converted into a slimy substance, mucus.
Multicellular glands
These are formed by invagination, or in-pouching, of an epithelial sheet.
The epithelium grows down from the surface into the underlying tissues to form either a simple or compound tube.
The blind end of the tube constitutes the secretory parts of the gland and may stay tubular or expand to form round bags called acini or alveoli.

8. According to Structures
Simple glands
in which the portion of duct (not the secretory portion) does not have branches
Compound glands
in which the duct portion has branches

9. According to Structures………contd
Tubular
refers to glands whose secretory portion forms tube
Acinar / alveolar
refers to glands whose secretory portion forms sac like structure
Both tubular and alveolar types can be branched or unbranched

10. According to Method of Secretion
Apocrine : A portion of cell containing secretions is released as it separates from rest of the cell. Eg; Mammary glands Merocrine/Eccrine : Secretions pass through the cell membranes of the secretory cells. Eg; Pancreatic acinar cells Holocrine : Entire secretory cells disintegrate and are released along with their contents. Eg: Sebaceous glands on skin and nose

11. According to Product Secreted
Serous glands : Secretes proteins, often enzymes
e.g : Chief cells of stomach
B)Mucus Glands : Secretes mucus
e.g: esophageal glands, pyloric glands
C)Mixed Glands : Secretes both proteins and mucous
e.g: Salivary glands
D)Sebaceous Glands : Secretes oil / lipids

12. Salivary Glands
Parotid glands
Submandibular glands
Sublingual glands

13. Parotid Gland Paired parotid glands are largest of salivary glands
lying largely below the external acoustic meatus between mandible and sternocleidomastoid muscle
it also projects forwards on the surface of masseter

14. Gross Anatomy of Parotid Gland
Size – 25g.
Shape – Inverted pyramid.
In 30% cases upper and lower poles are rounded.
Surface – Irregular, lobulated.

15. Parotid Duct Also known as Stensen’s duct.
Length of parotid duct – 5 cm.
Lumen width – 3mm, narrow at the oral orifice.

16. Nerve Supply to Parotid Gland
Parasympathetic – stimulates watery secretion.
Sympathetic – stimulates mucus rich thick secretion and also vasomotor.

17. Submandibular Gland
The paired submandibular glands (submaxillary glands) are salivary glands located beneath the floor of the mouth.
In humans, they account for 70% of the salivary volume and weigh about 15 grams.
The percentage contribution to whole saliva; ~25% Parotid, Submandibular and Sublingual ~ 67% and ~8% minor mucous glands. During stimulated secretion the parotid gland produces majority of the saliva.

18. Anatomy of Submandibular Gland
They lie superior to the digastric muscles
Each submandibular gland is divided into 2 lobes
superficial and
deep lobes,
which are separated by the mylohyoid muscle.

19. Anatomy of Submandibular Gland……..contd
The superficial portion is the smaller portion. The mylohyoid muscle runs under it.
The deep portion comprises most of the gland.
Secretions are delivered into the Wharton's ducts on the deep portion after which they hook around the posterior edge of the mylohyoid muscle and proceed on the superior surface laterally.

20. Anatomy of Submandibular Gland……contd
Lobes contain smaller lobules, which contain adenomeres, the secretory units of the gland.
Each adenomere contains one or more acini, or alveoli, which are small clusters of cells that secrete their products into a duct.
The acini of each adenomere are composed of either serous or mucous cells, with serous adenomeres predominating.

21. Anatomy of Submandibular Gland……contd
Submandibular Glands
Superficial or
Deep
Lobes
Lobules
Adenomeres
Acini
Alveoli
Serous/ Mucous cells

22. Functions of Submandibular Gland
The mucous cells are the most active and therefore the major product of the submandibular glands is saliva.
In particular, the serous cells produce salivary amylase, which aids in the breakdown of starches in the mouth.
Mucous cells secrete mucin which aids in the lubrication of the food bolus as it travels through the esophagus.
The submandibular gland's highly active acini account for approximately 70% of salivary volume. The parotid and sublingual glands account for the remaining 30%.

23. Sublingual gland
is a mixed secretion- producing gland (seromucous secretion with prevalence of the Mucous component)
is located in the tissue under the tongue.

24. Anatomy of Sublingual gland
They lie anterior to the submandibular gland inferior to the tongue, as well as beneath the mucous membrane of the floor of the mouth.
They are drained by 8-20 excretory ducts called the ducts of Rivinus. The largest of all, the sublingual duct (of Bartholin) joins the submandibular duct to drain through the sublingual caruncle.  

25. Pancreas
The pancreas, named for the Greek words pan (all) and kreas (flesh),
is a 12-15–cm long J-shaped (like a hockey stick), soft, lobulated, retroperitoneal organ.
It lies transversely, although a bit obliquely, on the posterior abdominal wall behind the stomach, across the lumbar (L1-2) spine

26. Pancreas……..contd
The pancreas is a gland organ in the digestive and endocrine system of vertebrates.
It is both an endocrine gland producing several important hormones, including insulin, glucagon, and somatostatin,
as well as an exocrine gland, secreting pancreatic juice containing digestive enzymes that pass to the small intestine. These enzymes help in the further breakdown of the carbohydrates, protein, and fat in the chyme.

27. Pancreas

28. Anatomy of Pancreas The pancreas has three main sections:
Head: area of pancreas to right of the superior mesenteric vein.
Pancreatic neck: area of pancreas between the superior mesenteric vein, the superior mesenteric artery and the hepatic artery.
Tail: area of pancreas anterior to the left kidney and near the hilum of spleen.
The most common site is the head of the pancreas. The pancreas is in direct contact with the stomach, duodenum, spleen, and major vessels of the abdomen.

29. Microscopic Anatomy
The pancreas is a composite gland containing both exocrine and endocrine components. Acini, formed of zymogenic cells around a central lumen, are arranged in lobules. Each lobule has its own ductule, and many ductules join to form intralobular ducts, which then form interlobular ducts that drain into branches of the main pancreatic duct.
Under stimulation of secretin and cholecystokinin (CCK), the zymogenic cells secrete a variety of enzymes — trypsin (digests proteins), lipase (digests fats), amylase (digests carbohydrates), and many others. Ductular cells produce bicarbonate, which makes the pancreatic fluid (juice) alkaline.
Pancreatic islets (clusters) of Langerhans are scattered throughout the gland containing beta cells (about 75% of islets; these secrete insulin), alpha cells (about 20% of islets; these secrete glucagon), delta cells (these secrete somatostatin), and several other hormone-secreting cells. Islets constitute only about 2% of the pancreatic parenchyma.

30. Pancreas Function
The pancreas is a dual-function gland, having features of both endocrine and exocrine glands.
Endocrine
The part of the pancreas with endocrine function is made up of approximately a million cell clusters called islets of Langerhans. There are four main cell types in the islets. : α cells secrete glucagon, β cells secrete insulin, δ cells secrete somatostatin, and PP cells secrete pancreatic polypeptide.

31. Pancreas Function Exocrine
The exocrine pancreas produces digestive enzymes and an alkaline fluid (referred to as pancreatic juice), and secretes them into the small intestine through a system of exocrine ducts in response to the small intestine hormones secretin and cholecystokinin. Digestive enzymes include trypsin, chymotrypsin, pancreatic lipase, and pancreatic amylase, and are produced and secreted by acinar cells of the exocrine pancreas. Specific cells that line the pancreatic ducts, called centroacinar cells, secrete a bicarbonate- and salt-rich solution into the small intestine.

32. Sebaceous Glands Lipid producing structures Unilobular or Multilobular
Associated with hair follicles.
Holocrine gland

33. Location of Sebaceous Glands

34. Anatomy of Sebaceous Glands
Consists of one or more lobules leading into common excretory duct.
Glands are composed of sebocytes and keratinocytes lining the sebaceous gland.
As cells mature before disintegration, lipid droplets completely fill the cytoplasm and compress the centrally located nucleus.
Disintegrate into amorphous mass of lipids and cellular debris – Sebum.

35. Physiology of Sebaceous Glands

36. Functions of Sebaceous Glands
Coats hair shaft and lubricates the epidermis and thus control moisture loss from the body
Protects skin from bacterial and fungal infections
Scent production
Thermoregulation : Hot & Cold conditions
Allows vitamin – E to function in the body
Acne (An inflammatory disease of the sebaceous glands and hair follicles of the skin that is marked by the eruption of pimples or pustules, especially on the face.) production

37. Sweat Glands 2 types – Eccrine Sweat Glands Apocrine Sweat Glands
Simple coiled glands that regulate body temperature
Apocrine Sweat Glands
Name derived from way of secretion - pinching off parts of their cytoplasm into the lumen.

38. Eccrine Sweat Glands No association with hair follicle.
A well acclimatized person can perspire as much as 10 L / day.

39. Anatomy of Eccrine Glands
Gland consists of a secretory coil in lower dermis and subcutaneous tissues.
Drains into the long thin duct with apical portion opening to the skin surface.
There are 3 types of secretory cells:
Larger clear cells (main secretory cells)
Small darker cells (Resembles to mucus secreting cells)
Myoepithelial cells

40. Composition of Eccrine Gland

41. Apocrine Sweat Glands
Name derived from way of secretion - pinching off parts of their cytoplasm into the lumen.
Large lumen glands associated with hair follicles.
A well acclimatized person can perspire as much as 10 L /day.

42. Anatomy of Apocrine Glands
Apocrine glands are short tubular glands, composed of –
Intra epidermal duct
Intra dermal duct
Secretory portion
Ductal portion leads to a pilosebaceous follicle entering the infundibulum above the sebaceous gland opening.
Occasionally opens directly into the skin.

43. Physiology of Apocrine Glands
Secrete an oily fluid & milky colored odorless substance (pH = 5.0 – 6.5)
Characteristic odor is due to bacterial decomposition
Stimulated by sympathetic nerve fibers- Adrenergic

44. Modified Apocrine Glands
External Auditory Meatus
(Ceruminus Glands)
Eyelids
(Moll’s Gland)
Areolar
(Montgomery tubercles)
Breast
(Mammary glands)

45. Eccrine vs. Apocrine Features Apocrine Eccrine Morphology Location
Short thick duct, opens into the upper part of follicular canal
Secretory coil with wide lumen (200 µm in diameter)
Long thin duct, opens to skin surface.
Secretory coil with narrow lumen
Location
Axillae (underarm),
Nipples,
Labia &
Glans penis
Modified Apocrine Glands
Occasionally on the face, scalp, abdomen usually small and non-functional.
Entire body surface (3,000/sq.in.) except
External ear canal
Lips
Clitoris &
Labia minora
High density on soles and palms

46. Begin to function at puberty and are affected by hormones
Eccrine vs. Apocrine
Features
Apocrine
Eccrine
Onset of Action
Begin to function at puberty and are affected by hormones
After birth
Secretion
Thick & odorous
Thin & watery
Function
Possible pheromone function
Role as odoriferous sexual attractants
Secretory & Excretory organ
Keeps the skin moist
Thermoregulation (sweating)
Maintains electrolyte balance
Excretes some systemically administered drugs such as
Griseofalvin
Ketoconazole
Chemotherapy agents
Excretion of urea
Antibacterial action

47. Mammary Glands
Anatomically related to apocrine sweat glands (modified).
Development is controlled by sex hormones and pituitary hormones
Size & Shape variable
Produce milk
In male and immature female, breast are rudimentary (early stage)
After puberty, female breast are fully developed

48. External Structure of Mammary Glands
Areola:
pigmented circular area of the skin around the base of the nipple.
irreversibly darkened after first pregnancy.
outer margin contains modified sebaceous gland
these glands enlarged during pregnancy and lactation (tubercles of montgomery)
Nipples:
conical or cylindrical projection below the centre of the breast.
usually present at the fourth intercostal space.
pierced by lactiferous ducts.

49. Location of Mammary Glands
Breast are present bilaterally in pectoral region.
Extent:
Vertically-2nd to 6th ribs
horizontally- from lateral border of sternum
To mid-axillary line along fourth rib.

50. Anatomy of Mammary Glands
The glands within the breasts are classified as compound tubuloalveolar glands
Make 15 to 20 lobes radiating out from the nipple
Each lobe is drained by its own lactiferous duct leading directly to the nipple, where it opens onto its surface.
Before reaching the nipple, each of the ducts is dilated to form a lactiferous sinus for milk storage and then narrows before passing through the nipple
Lobules

51. Anatomy of Mammary Glands….contd
Each lactiferous duct drains a segmental segments of smaller duct.
Segmental duct divides into small terminal duct
Terminal duct gives rise to numerous sectretory pouches (alveoli) like cluster of grapes.
breast parenchyma drain by lactiferous duct is known as lobules.
Lobules

52. Ceruminus Glands
Modified sweat glands found in the external auditory canal
Produce cerumen or ear wax
Helps in trapping foreign particles from reaching the eardrum