Hormones Introduction

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Questions and Answers

Where are the receptors for thyroid hormone (TR) and 1α,25(OH)2-vitamin D3 (VDR) typically found?

In the endoplasmic reticulum

In the nucleus (correct)

In the mitochondria

In the cytoplasm

What is the function of the receptors for cortisol (GR) and aldosterone (MR) in the cytoplasm?

To be maintained in an inactive state (correct)

To bind to DNA

To regulate ligand binding

To activate DNA transcription

Which domain is highly conserved in nuclear receptors?

E/F domain

Ligand binding domain

DNA binding domain (correct)

N-terminal A/B domain

What is the function of the CI zinc finger in nuclear receptors?

Recognition of specific DNA sequence Signup and view all the answers

How many α-helices are arranged in three layers in the ligand-binding domains of nuclear receptors?

12 Signup and view all the answers

What is the function of AF-1 in nuclear receptors?

Activation of gene transcription Signup and view all the answers

What is the primary function of serine endoproteases in post-translational processing?

To catalyze cleavage reactions at specific sites in the precursor protein Signup and view all the answers

Where is the ligand binding pocket located in nuclear receptors?

In the ligand-binding domain Signup and view all the answers

Where do the post-translational processing reactions primarily take place?

In the rough endoplasmic reticulum and Golgi apparatus Signup and view all the answers

What is the function of corepressor molecules in nuclear receptors?

To suppress DNA transcription Signup and view all the answers

What is a characteristic of peptide and protein hormones?

They have receptors that are membrane-spanning proteins Signup and view all the answers

What is the smallest hormone?

NO Signup and view all the answers

What is a common feature of steroid hormones and vitamin D and its metabolites?

They are derived from cholesterol Signup and view all the answers

What is the function of hormone receptors in the cell membrane?

To deliver the hormone message to the interior of the cell Signup and view all the answers

How do amino acid derivatives interact with receptor proteins in the cell?

They interact with receptor proteins already associated with specific DNA regions Signup and view all the answers

What is a characteristic of hormone classes in terms of molecular structure and mechanism of action?

They are heterogeneous in molecular size, chemical properties, and pathways of synthesis Signup and view all the answers

What is the origin of the term 'hormone'?

Greek word for 'set in motion' Signup and view all the answers

What is the meaning of the term 'endocrine'?

Internal or within, and separate Signup and view all the answers

What is an example of the application of basic principles to clinical medicine?

Effective therapy for hormone imbalance Signup and view all the answers

What is required for the body to function properly?

A constant internal environment Signup and view all the answers

What is the primary function of the nervous system?

To allow rapid transmission of information Signup and view all the answers

What is the primary function of the hormonal system?

To maintain homeostasis through widespread and longer lasting regulatory actions Signup and view all the answers

How many hormones were discovered during the period 1900-1960?

25 Signup and view all the answers

What is the relationship between the nervous system and the hormonal system?

They are complementary Signup and view all the answers

What is the function of vasopressin in the kidneys?

Promote the reabsorption of water from the urine Signup and view all the answers

What are the two hormones produced by the neurons in the hypothalamus and stored in the posterior pituitary?

Vasopressin and oxytocin Signup and view all the answers

What is the primary function of cortisol in the human body?

Control carbohydrate, protein, and lipid metabolism Signup and view all the answers

What are the two layers of the adrenal gland?

The cortex and the medulla Signup and view all the answers

What is the function of aldosterone in the human body?

Regulate the body's water and electrolyte balance Signup and view all the answers

What are the two substances generated by the adrenal medulla as part of the fight-or-flight response?

Adrenaline and noradrenaline Signup and view all the answers

Which hormone stimulates the contractions of the uterus during childbirth?

Oxytocin Signup and view all the answers

What is the primary source of sex hormones in the human body?

The adrenal cortex Signup and view all the answers

What is the primary function of the hypothalamus?

To serve as the link between the nervous and endocrine systems Signup and view all the answers

What is the function of corticotropin-releasing hormone (CRH)?

To regulate carbohydrate, protein, and fat metabolism Signup and view all the answers

What is the function of gonadotropin-releasing hormone (GnRH)?

To help control sexual and reproductive functions, including pregnancy and lactation Signup and view all the answers

What is the function of thyrotropin-releasing hormone (TRH)?

To help regulate metabolic processes in all cells Signup and view all the answers

What is the function of dopamine?

To repress lactation until it is needed Signup and view all the answers

What is the function of the anterior pituitary?

To stimulate target glands to produce hormones or directly affect target organs Signup and view all the answers

What is the relationship between the hypothalamus and the pituitary gland?

Hormones from the hypothalamus get into the hypothalamic-hypophyseal portal system, thereby reaching the pituitary gland Signup and view all the answers

What is the function of somatostatin?

To have an opposite effect to that of growth hormone-releasing hormone (GHRH) Signup and view all the answers

Study Notes

Hormones and Endocrine System

The term "hormone" comes from the Greek word "hormon", meaning "to set in motion".
The term "endocrine" is derived from the Greek words "endo" (meaning internal or within) and "krinein" (meaning separate), describing the distance between the site of hormone secretion and the site of action.

Biomedical Importance

Hormones are essential for maintaining homeostasis, a constant internal environment, in the body.
The nervous system and hormonal system work together to ensure communication between different body regions.
The nervous system is responsible for rapid transmission of information, while the hormonal system is better suited for longer-lasting, widespread regulatory actions.

Hormone Structure and Classification

Hormones are classified into several categories: steroids, amino acid derivatives, polypeptides, and proteins.
Each class of hormone has a unique molecular structure and mechanism of action.
Steroid hormones, such as vitamin D and its metabolites, are derived from cholesterol.
Peptide and protein hormones have receptors that are membrane-spanning proteins.

Hormone Receptors

Nuclear receptors, such as those for thyroid hormone, vitamin D, estrogen, and cortisol, are typically found in the nucleus of target cells.
These receptors function as DNA-binding proteins, regulating gene transcription in a ligand-dependent manner.
The ligand-binding domain of nuclear receptors is less conserved than the DNA-binding domain, but shares a similar three-dimensional structure.

Hypothalamus and Its Hormones

The hypothalamus is the major link between the nervous and endocrine systems.
The hypothalamus produces several hormones, including corticotropin-releasing hormone (CRH), growth hormone-releasing hormone (GHRH), gonadotropin-releasing hormone (GnRH), thyrotropin-releasing hormone (TRH), and dopamine.

Pituitary Gland and Its Hormones

The pituitary gland is located in the brain and consists of two parts: the anterior pituitary and the posterior pituitary.
The anterior pituitary produces several important hormones, including adrenocorticotropic hormone (ACTH), gonadotropins (luteinizing hormone and follicle-stimulating hormone), thyroid-stimulating hormone (TSH), growth hormone (GH), and prolactin.
The posterior pituitary stores and releases two hormones produced by the hypothalamus: vasopressin and oxytocin.

Adrenal Glands and Their Hormones

The adrenal glands are located on top of the kidneys and consist of an outer layer (cortex) and an inner layer (medulla).
The adrenal cortex produces corticosteroids (glucocorticoids and mineralocorticoids) and small amounts of sex hormones.
The adrenal medulla produces adrenaline and noradrenaline as part of the fight-or-flight response to stress.
The primary glucocorticoid in humans is cortisol, which helps control carbohydrate, protein, and lipid metabolism.
The primary mineralocorticoid in humans is aldosterone, which helps regulate the body's water and electrolyte balance.

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Description

Learn about the biomedical importance of hormones, their origin and function in the human body, including the pancreas, thyroid, and reproductive glands.