Histology of the Endocrine System

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Questions and Answers

What are the secretions produced by endocrine cells called?

Neurotransmitters

Hormones (correct)

Enzymes

Proteins

Which gland is referred to as the hypophysis cerebri?

Thyroid gland

Pineal gland

Pituitary gland (correct)

Adrenal gland

What structure suspends the hypophysis cerebri from the third ventricle of the brain?

Nervous tissue

Infundibulum (correct)

Pineal stalk

Sphenoid canal

How is the activity of the hypophysis cerebri influenced?

By the hypothalamus and the pineal body Signup and view all the answers

Which part of the hypophysis cerebri is known as the pars anterior?

Anterior part Signup and view all the answers

What type of cells are present in the pars posterior of the hypophysis cerebri?

Nerve fibers Signup and view all the answers

Which of the following is NOT a characteristic of endocrine glands?

They typically have ducts to transport hormones. Signup and view all the answers

Where is the hypophysis cerebri located?

In the upper surface of the sphenoid bone Signup and view all the answers

What is the primary function of C-cells in the body?

Secrete thyro-calcitonin to lower calcium levels Signup and view all the answers

What characterizes chief cells in the parathyroid glands?

Have vesicular nuclei and clear cytoplasm Signup and view all the answers

Which hormone is secreted by chief cells?

Parathyroid hormone Signup and view all the answers

What is the effect of thyro-calcitonin on bone resorption?

Suppresses bone resorption by osteoclasts Signup and view all the answers

What is the primary hormone produced by the pineal gland?

Melatonin Signup and view all the answers

How many parathyroid glands are typically present in humans?

Four Signup and view all the answers

What role does the pineal gland play in relation to circadian rhythms?

It acts as a biological clock. Signup and view all the answers

What distinguishes oxyphil cells from chief cells?

Oxyphil cells have larger, more prominent nuclei Signup and view all the answers

What is the primary role of parathyroid hormone in the body?

Increase serum calcium levels by stimulating osteoclastic activity Signup and view all the answers

What structure covers the thyroid gland?

Fibrous capsule Signup and view all the answers

Where are the suprarenal glands located?

Near the upper poles of the kidneys Signup and view all the answers

Which of the following hormones is considered more active in the thyroid gland?

Triiodothyronine (T3) Signup and view all the answers

What is found in the cavity of thyroid follicles?

Colloid Signup and view all the answers

What happens to follicular cells when they are inactive?

They become flat (squamous). Signup and view all the answers

What composition is essential for the synthesis of thyroid hormones?

Iodine Signup and view all the answers

What type of connective tissue surrounds the thyroid follicles?

Loose connective tissue Signup and view all the answers

What hormone stimulates the secretion of oestrogens by the ovaries?

Follicle-stimulating hormone (FSH) Signup and view all the answers

What is the primary function of luteinizing hormone (LH) in males?

Stimulates testosterone production Signup and view all the answers

Which anterior pituitary hormone is associated with the maturation of the corpus luteum?

Luteinizing hormone (LH) Signup and view all the answers

What type of cells primarily compose the pars tuberalis?

Undifferentiated cells Signup and view all the answers

Which hormone is primarily produced in the supraoptic nucleus?

Vasopressin (ADH) Signup and view all the answers

What is the function of oxytocin in the body?

Controls contraction of smooth muscle of the uterus Signup and view all the answers

What is a notable feature of the pineal gland as per its histological sections?

Presence of calcium salt masses Signup and view all the answers

Which cells produce melanocyte stimulating hormone (MSH)?

Cells in the pars intermedia Signup and view all the answers

What are the two parts of the Neurohypophysis?

Pars posterior and infundibular stalk Signup and view all the answers

Which region is known as the median eminence?

Floor of the third ventricle near the infundibulum Signup and view all the answers

Which hormone do somatotrophs produce?

Growth hormone Signup and view all the answers

What type of cells produces mammotropic hormone?

Mammotrophs Signup and view all the answers

Which cells are classified as acidophil cells?

Mammotrophs and somatotrophs Signup and view all the answers

What hormone do gonadotrophs produce in females?

Follicle stimulating hormone Signup and view all the answers

Which cells are responsible for producing TSH?

Thyrotrophs Signup and view all the answers

What is the function of corticotrophs?

Stimulate secretion of adrenal cortex hormones Signup and view all the answers

Study Notes

Overview of Endocrine System

Endocrine tissue consists of hormone-producing cells that release secretions directly into the bloodstream.
Hormones affect target cells with specific receptors, influencing various bodily functions.
Endocrine organs work alongside the autonomic nervous system for metabolic regulation.
Primary endocrine glands: hypophysis cerebri (pituitary), pineal gland, thyroid, parathyroid glands, and suprarenal glands.
Other organs with endocrine functions include the pancreas, testes, ovaries, kidneys, thymus, and placenta.

Hypophysis Cerebri (Pituitary Gland)

Suspended from the third ventricle by the infundibulum, located within the sphenoid bone.
Divided into anterior (pars anterior), intermediate (pars intermedia), and posterior (pars posterior) parts.
Adenohypophysis (pars anterior and intermedia): contains secretory cells that produce various hormones.
Neurohypophysis (pars posterior): contains nerve fibers and releases hormones like vasopressin (ADH) and oxytocin.

Cell Types in Pars Anterior

Chromophil Cells:
- Acidophils: Secrete growth hormone (somatotropin) and prolactin.
- Basophils:
  - Corticotrophs produce ACTH, stimulating adrenal cortex.
  - Thyrotrophs produce TSH, stimulating thyroid activity.
  - Gonadotrophs produce FSH and LH, regulating reproduction in males and females.

Pelvic and Tubular Structure

Pars Tuberalis: Contains undifferentiated and some acidophil/basophil cells.
Pars Intermedia: Contains colloid-filled vesicles and cells that produce melanocyte stimulating hormone (MSH).

Pineal Gland (Epiphysis Cerebri)

Small structure located near the third ventricle, earlier considered vestigial but now recognized as functional.
Composed of cells, blood capillaries, and nerve fibers; contains calcium salt masses known as corpora arenacea (brain sand).
Main hormone produced is melatonin, regulated by light exposure, influencing circadian rhythms.

Thyroid Gland

Encapsulated and divided into lobules by septa; consists of follicles lined by follicular cells filled with colloid.
Follicular Cells: Shape changes with activity; cuboidal during average activity, squamous when inactive, columnar when active.
Produces two key hormones:
- Triiodothyronine (T3): Active form, regulates metabolism.
- Thyroxine (T4): Less active, requires iodine.
C-Cells (Parafollicular Cells): Produce calcitonin, reducing serum calcium levels.

Parathyroid Glands

Typically four glands located adjacent to the thyroid, each surrounded by a connective tissue capsule.
Composed mainly of two cell types:
- Chief Cells: Produce parathyroid hormone (PTH), increasing serum calcium levels by stimulating bone resorption and renal calcium reabsorption.
- Oxyphil Cells: Larger cells with acidophilic granules, function less clearly defined.

Suprarenal Glands (Adrenal Glands)

Positioned near the upper poles of the kidneys; crucial for stress response and metabolic functions.
Consist of an outer cortex producing steroids and a medulla producing catecholamines (epinephrine and norepinephrine).

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Description

Explore the histology of various endocrine glands including the pituitary, pineal, thyroid, parathyroid, and adrenal glands. This quiz delves into the structure and function of endocrine tissues and their role in hormone secretion and regulation. Perfect for students studying histology or endocrinology.