Endocrinology overview Quiz

Endocrinology Overview

• This unit is called AGEP Endocrinology with unit code VETS10018.
• Dr Nobue Itasaki is teaching this unit.

Learning Outcomes

• Students should describe hormones and their classifications in the body.
• Students should identify the location and different parts of the pituitary gland.
• Students should understand the main hormones and their target organs from the anterior pituitary.
• Students should understand the main hormones and their target organs from the posterior pituitary.
• Students should compare and contrast the structures and functions of the anterior and posterior pituitary.
• Students should understand the structure and function of the pineal gland, thyroid gland, parathyroid gland, adrenal gland, and pancreas.

Overview of Lecture

• The lecture will recap the endocrine system from a previous lecture on basic tissues.
• The lecture will cover an overview of each main endocrine gland.
• Pituitary gland - Covered in the current lecture.
• Pineal gland - Covered in the current lecture.
• Thyroid gland - Next day's lecture.
• Parathyroid gland - Next day's lecture.
• Adrenal gland - Next lecture.
• Pancreas - Next lecture.

What is Endocrine?

• Endocrine glands release hormones directly into the bloodstream for systemic circulation.
• Endocrine vs Exocrine: Endocrine hormones released into the bloodstream; Exocrine secretions released into ducts.

The Main Organs of the Endocrine System

• Pituitary gland: Located in the brain, produces several hormones directly influencing other endocrine organs.
• Parathyroid glands: Usually four glands near the thyroid; secrete parathyroid hormone, regulating calcium metabolism.
• Thyroid gland: Located over the trachea; produces hormones for metabolism and growth. T4, T3, calcitonin.
• Adrenal glands: Paired glands near the kidneys; cortex makes mineralocorticoids, glucocorticoids & sex steroids; medulla makes adrenaline & noradrenaline.
• Kidney: Produces renin, erythropoietin,etc..
• Ovary: Produces estrogen and progesterone.
• Testis: Produces estrogen and testosterone.
• Pancreas: Produces insulin and glucagon. Secretes digestive enzymes via exocrine function.

Endocrine System

• Endocrine glands secrete hormones into blood, lymph, or tissue fluid to target organs to regulate functions.
• Things that regulate hormone secretion include nerve stimulation, other hormones, and levels of chemicals in the blood; these are also controlled by feedback loops.
• The endocrine system is involved in homeostasis, reproduction, growth, and adaptation to stress & infection, as well as behaviour.

Endocrine Organs

• There are three types of endocrine organs:

1. Primary endocrine organs (like pituitary, pineal, thyroid, parathyroid, and adrenal glands).
2. Organs with combined endocrine and other functions (like pancreas, testes, ovaries, and placenta).
3. Organs with endocrine components but a different primary function (like brain, kidneys, liver, thymus, heart, and gastrointestinal tract).

Learning Outcomes (repeat)

• Understand hormones and their classifications.
• Understand pituitary location and division.
• Understand anterior pituitary hormones and target organs.
• Understand posterior pituitary hormones and target organs.
• Contrast the structure and functions of the anterior and posterior pituitary.
• Understand the pineal, thyroid, parathyroid, adrenal, and pancreas.

Pituitary Gland (Hypophysis)

• The pituitary gland is the master gland in the endocrine system due to its control of other endocrine glands.
• It is attached to the brain below the hypothalamus.
• The pituitary gland and the hypothalamus work together to control the endocrine and nervous systems.
• The hypothalamus controls the release of hormones from the pituitary gland based on hormones, sensory information, and the emotional state.

The Hypophysis (Anterior Lobe)

• The anterior lobe, Adenohypophysis, develops from the roof of the mouth.
• It secretes hormones such as FSH, LH, ACTH, TSH, prolactin, and STH (GH).
• The secretion of these hormones is controlled by neurohormones from the hypothalamus. These neurohormones (e.g. GnRH for FSH and LH) are secreted into the bloodstream.

The Hypophysis (Posterior Lobe)

• The posterior lobe, Neurohypophysis, is an extension of the hypothalamus.
• It stores hormones like oxytocin and vasopressin (antidiuretic hormone), synthesised in the hypothalamus.
• The release of these hormones into the bloodstream is triggered by impulses from the hypothalamus.

Adenohypophysis Hormones

• List six anterior pituitary hormones: Growth hormone (GH), Follicle-stimulating hormone (FSH), Luteinizing hormone (LH), Adrenocorticotropic hormone (ACTH), Thyroid-stimulating hormone (TSH), Prolactin.

Major Hypothalamic Hormones Affecting Anterior Pituitary

• Explains the hypothalamic hormones that regulate the release of anterior pituitary hormones (e.g., CRH for ACTH; TRH for TSH).

Anterior Pituitary Hormones & Their Effects

• Describes the actions of anterior pituitary hormones and their target organs, including specific hormones(TSH, LH,FSH).
• Details the feedback loops involving these hormones.

Hypothalamus, Pituitary, Target Organ Axis

• The hypothalamus regulates the pituitary gland by sending signals via hormones.
• The pituitary gland releases hormones which affect target organs.
• Feedback from the target organs regulates the hypothalamus and pituitary gland.

Neurohypophysis (Posterior Pituitary)

• Describes the posterior pituitary as a storage location for oxytocin and vasopressin, produced in the hypothalamus.
• Action potentials initiate the release of these hormones into the bloodstream.

Origin and Hypothalamic Regulation of the Pituitary Glands

• Anterior pituitary originates from the mouth epithelium.
• Posterior pituitary arises from the hypothalamus.
• Hypothalamus regulates anterior pituitary through specialised blood vessels (portal system).
• Hypothalamus regulates posterior pituitary via nerve impulses.

Pineal Gland

• The pineal gland is attached to the dorsal wall of the third ventricle.
• It produces melatonin at night..
• Melatonin regulates seasonal hormonal fluctuations and sleep patterns.

Thyroid Gland

• Thyroid gland lies behind the trachea and larynx.
• Size and structure vary in different species.
• The thyroid follicles contain thyroglobulin.
• Thyroid produces the hormones thyroxine (T4) and triiodothyronine (T3).
• Calcitonin is also produced by the thyroid gland.

Thyroid Hormone Regulation

• TRH (thyrotropin-releasing hormone) from the hypothalamus stimulates TSH (thyroid-stimulating hormone) release from the anterior pituitary.
• TSH then stimulates thyroid hormone production (T3 and T4).
• Too much T3 and T4 inhibit TRH and TSH release.

Parathyroid Glands

• Usually four parathyroid glands, located near the thyroid.
• Parathyroid hormone (PTH) regulates calcium metabolism.
• PTH increases blood calcium by affecting the gut, bones, and kidneys.
• The production of PTH is regulated by calcium levels in the blood.

Adrenal Glands

• Paired glands situated craniomedially to the kidneys.
• The adrenal cortex produces mineralocorticoids, glucocorticoids, and sex steroids.
• The adrenal medulla produces epinephrine (adrenaline) and norepinephrine.
• The cortex is yellow/striated and the medulla is darker.

Pancreas

• The pancreas has both exocrine (digestive enzymes) and endocrine (insulin, glucagon, and somatostatin) functions.
• The endocrine portion is called the Islets of Langerhans.
• The pancreas generally sits between the stomach and the duodenum in most animals.

Hormone Classification

• Hormones are classified based on their chemical structure and solubility.
• Lipid-soluble hormones (e.g., steroids) can diffuse through cell membranes; Water-soluble hormones must bind to receptors on the cell surface..

Test your knowledge on the functions of endocrine and exocrine glands, particularly focusing on the pancreas. This quiz explores hormone signaling, gland structures, and their roles in the human body. Get ready to enhance your understanding of these essential biological systems.