Anatomy and Cell Biology 3309 Lecture Notes - Lecture 26: Pineal Gland, Bronchiole, Pancreatic Islets
22 May 2018
School
Department
Professor
Histology 3309
Pineal Gland and Endocrine Pancreas
Practice Questions: Alveoli are present in the wall of:
a) Trachea
b) Respiratory bronchioles
a. If you see a section of the bronchioles and it has no cartilage and there are alveoli
coming off the walls, that’s a respiratory bronchioles
c) Terminal bronchioles
d) Secondary bronchi
e) Primary bronchi
Practice Question: a pheochromocytoma is a rare tumor of the adrenal medulla resulting in excessive
hormone production. Which of the following symptoms would most likely be observed in the presence
of this tumor?
a) Excretion of excessive amounts of dilute urine
b) Galactorrhea (excessive milk production), amenorrhea (lack of ovulation), and loss of libido
c) Gypercalcemia, decalcification of bones and kidney stones
d) Weight gain, constipation and lethargy
e) Weight loss, anxiety, elevated HR and blood pressure, and headaches
Learning Objectives
1. describe the location and histological appearance of an Islet of Langerhans
2. name 3 cell types in the islets and their secretory products
3. list the functions of 3 Islet hormones
4. explain the location and origin of the pineal gland
5. name two cell types in the pineal gland and state their function
6. discuss the regulation of melatonin secretion.
- Imagine you are taking a section at the green line right there you would see the image on the
right
- Small intestine has an epithelial lined tube
- Then there is a large blue staining mass of tissue
- In the red box, you can see some whiter spots which will be zoomed into in the next slide
- The dark stained mass at the bottom right corner is the spleen
Endocrine Pancreas:
- Exocrine pancreas is made of secretory acini that have nuclei in the center (centroacinar cells)
o The red staining is the enzymes being secreted
find more resources at oneclass.com
find more resources at oneclass.com
- Then we have globular arrangement of cells staining light →this is the endocrine pancreas
(islets of Langerhans)
o You can see these redish channels going through (these are capillaries)
- Islets of Langerhans produce:
1. insulin →decreases blood glucose levels
2. glucagon →increases blood glucose levels
Pancreatic Vascular Components
- each islet of Langerhans receives blood through an insuloacinar portal system forming a
network of fenestrated capillaries
- exocrine pancreas have a dual blood supply
- the exocrine pancreas receives blood:
o from the islet capillaries
▪ blood that first profuses the islets of langerhans
o from an independent acinar vascular system
▪ capillary network that arises from arterioles coming in that carry blood away
- capillaries form veins that then provide capillaries surrounding the acini (portal system)
o the secretion of enzymes by acini cells is under the control of a hormone that is
produced by the islets of Langerhans
Major cell types in the islets of Langerhans
- there are fenestrated capillaries designed to receive hormones produced by these cells living in
the islet of Langerhans
- there is no particular morphological arrangement – its just a loose network of cells that are
sitting side by side and have access to the bloodstream
- there are 4 groups of cells located there, shown in the table
- somatostatin is a regulator of the activity of the alpha and beta cells
find more resources at oneclass.com
find more resources at oneclass.com
o if they get too active, somatostatin downregulates their activity
- the activity of the exocrine pancreas is under control, in part, by the islet of Langerhans
- pancreatic polypeptide is the hormone that does this
o it downregulates enzyme secretion in the exocrine pancreas
o this is where the insuloacinar portal system comes into play so the cells receive that
hormone from the islet of langerhans
Distribution of cell types in the islets of Langerhans
- these 4 cells above cant be distinguished – but we have techniques we can use to identify them
(stain with antibodies)
- if we take a section and label it with an antibody against glucagon you would see it at the
periphery of the islets →so alpha cells are located mostly at the periphery
Distribution of cell types in the islets of Langerhans
- you can do the same thing with an antibody against insulin (right image)
- beta cells are located in the center of the islets
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Practice questions: alveoli are present in the wall of: trachea, respiratory bronchioles. If you see a section of the bronchioles and it has no cartilage and there are alveoli coming off the walls, that"s a respiratory bronchioles: terminal bronchioles, secondary bronchi, primary bronchi. Practice question: a pheochromocytoma is a rare tumor of the adrenal medulla resulting in excessive hormone production. Imagine you are taking a section at the green line right there you would see the image on the right. Then there is a large blue staining mass of tissue. The dark stained mass at the bottom right corner is the spleen. In the red box, you can see some whiter spots which will be zoomed into in the next slide. Exocrine pancreas is made of secretory acini that have nuclei in the center (centroacinar cells: the red staining is the enzymes being secreted.
