Endocrinology: Hormones and Their Sources

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Questions and Answers

Which characteristic is true regarding acidophils compared to basophils?

They are PAS positive. (correct)

They have larger secretory granules than basophils.

Their structure is more complex than that of basophils.

They are less numerous than basophils.

Which statement accurately describes the structural components of the pituitary gland?

The infundibular stalk connects the pars distalis and the pars nervosa.

The pars tuberalis lies anterior to the infundibular stalk.

The pars intermedia is located between the pars tuberalis and the infundibular stalk.

The infundibulum consists of both the infundibular stalk and the surrounding pars tuberalis. (correct)

What is the significance of PAS staining in histology?

It stains polysaccharides and glycoproteins. (correct)

It identifies nucleic acids within cells.

It differentiates between cell types based on size.

It highlights the presence of proteins in tissues.

What distinguishes the cellular functions of acidophils in the pituitary gland?

They secrete hormones that primarily regulate metabolism. Signup and view all the answers

Which of the following statements about the structure of the thyroid gland is correct?

Reticular fibers form a supporting network within the gland. Signup and view all the answers

What characterizes steroid hormones among the types of hormones listed?

They include hormones such as cortisol and aldosterone. Signup and view all the answers

Which type of cells in the pituitary gland primarily secrete growth hormone?

Acidophils Signup and view all the answers

Which hormone is NOT secreted by the pancreas?

Thyroxine Signup and view all the answers

What is the significance of PAS staining in histological studies of endocrine tissue?

It helps visualize mucopolysaccharides. Signup and view all the answers

Which structures are responsible for the secretion of hormones in the adrenal cortex?

Corticosteroid-producing cells Signup and view all the answers

What role does the hypothalamus play in the endocrine system?

It controls the secretion of many endocrine glands. Signup and view all the answers

Which hormones are derived from tyrosine?

Thyroxine and triiodothyronine Signup and view all the answers

Which of the following is a dispersed endocrine cell type found in the ovaries?

Ovarian follicles Signup and view all the answers

Which structure is characteristic of steroid secreting cells?

Mitochondria with tubular cristae Signup and view all the answers

How do acidophils appear histologically in comparison to basophils?

Acidophils have eosinophilic vacuolated cytoplasm Signup and view all the answers

What is a key structural feature of the anterior lobe of the pituitary gland?

It is dark and cellular Signup and view all the answers

Which type of staining is most relevant for visualizing secretory granules in protein secreting cells?

PAS staining Signup and view all the answers

What is an incorrect characteristic of protein secreting cells?

Presence of lipid droplets Signup and view all the answers

Which component is NOT part of the general structure of endocrine glands?

Smooth muscle fibers Signup and view all the answers

Where are protein secreting cells typically located within the body?

Pituitary gland Signup and view all the answers

Which structure is indicative of the vascular support in endocrine glands?

Fenestrated blood capillaries Signup and view all the answers

Study Notes

Hormones and Sources

Testes produce testosterone.
Catecholamines are derived from tyrosine, originating from the adrenal medulla.
The placenta synthesizes estrogen and progesterone.

Steroid Hormones

Derivatives of cholesterol.
General structure of steroid-secreting cells includes:
- Electron microscopy (EM): Well-developed smooth endoplasmic reticulum and mitochondria with tubular cristae; presence of lipid droplets.
- Light microscopy (LM): Eosinophilic and vacuolated cytoplasm.

Protein and Peptide Hormones

General structure includes:
- EM: Well-developed rough endoplasmic reticulum, Golgi apparatus, and mitochondria with lamellar cristae; presence of secretory granules.
- LM: Euchromatic nucleus with a prominent nucleolus and basophilic cytoplasm.

Comparison: Steroid vs. Protein Secreting Cells

Steroid secreting cells: Acidophilic vacuolated cytoplasm, mitochondria with tubular cristae, prominent smooth endoplasmic reticulum, and present lipid droplets; found in suprarenal cortex, gonads, and placenta.
Protein secreting cells: Basophilic cytoplasm, mitochondria with lamellar cristae, well-developed rough endoplasmic reticulum, Golgi apparatus, and secretory granules; located in pituitary gland, thyroid gland, adrenal medulla, parathyroid glands, and pancreas.

Structure of Endocrine Glands

Composed of secretory cells and fenestrated (sinusoidal) blood capillaries.
Supported by a highly vascular connective tissue.

Pituitary Gland (Hypophysis Cerebri)

Anatomical location: Inside the hypophyseal fossa (sella turcica) of the sphenoid bone, connected to the brain via the infundibulum and covered by the diaphragma sellae.
Histological structure: Divided into anterior lobe (adenohypophysis) and posterior components:
- Anterior lobe: Dark and cellular.
- Posterior lobe: Pale fibrous part, includes infundibular stalk and surrounding pars tuberalis.

Acidophils in the Pituitary Gland

Larger than basophils.
Positive for periodic acid-Schiff (PAS).
Secretory granules are smaller compared to basophils.
More numerous than basophils.

Thyroid Gland Anatomy

Located in the anterior lower neck; consists of two lobes connected by an isthmus.
Stroma features:
- Double capsule: Outer pretracheal fascia and inner true connective tissue capsule.
- Fibrous septa divide the gland into lobes and lobules.
- Reticular fibers provide structural support.

Endocrine System Overview

Endocrine glands are ductless and responsible for synthesizing and secreting hormones.
Hormones are released into interstitial spaces, absorbed by fenestrated capillaries, and delivered to target organs through the bloodstream.
Interconnected with the nervous system via the hypothalamus, which regulates the secretion of several glands.

Types of Endocrine Glands

Major endocrine glands include:
- Pituitary gland, thyroid gland, parathyroid gland, suprarenal gland, pineal gland.
Dispersed endocrine cell types:
- APUD cells in organs such as pancreas (Islets of Langerhans), testis (Leydig cells), ovary (follicles, corpus luteum), and placenta.

Types of Hormones

Steroid Hormones: Produced by adrenal cortex (cortisol, androgens, aldosterone) and gonads (estrogen, progesterone).
Protein and Peptide Hormones: Include anterior and posterior pituitary hormones, parathyroid hormones, and pancreatic hormones.
Hormones derived from amino acid tyrosine: Thyroid hormones (Thyroxine and Triiodothyronine), and adrenal medullary hormones.

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Description

This quiz focuses on the various types of hormones, their sources, and cellular structures related to hormone secretion. It explores the differences between steroid and peptide hormones, alongside their morphological characteristics. Test your knowledge on the endocrine system and its crucial components.