Endocrinology Questions from quiz 1.

Explain the interconnection between physiology and endocrinology. In your answer define each one in your OWN words!

Physiology is the study of the interconnected functions of the body and its parts, including organ systems, organs, tissues, etc. Endocrinology would fall under a subcategory of Physiology, as it primarily involves the study of hormones, how they affect the body, and all that comes with them (that is how they are interconnected).

What type of tissue is the anterior pituitary gland composed of?

Glandular tissue.

What type of tissue it the Posterior Pituitary gland composed of?

Nervous tissue.

What are some other names of the Anterior pituitary gland?

Adenohypophysis, Pars anterior, and Pars distals.

What are some other names of the Posterior Pituitary gland?

Neurohypophysis

Define Exocrine glands.

Contains ducts, when ready, will secrete their products into these ducts, which will take said product to the lumen of organs or to the outside surface of the cell. Sweat glands or sweating are examples of the exocrine system in motion.

Define Endocrine glands.

Does not contain ducts, but instead secretes its products directly into the blood to be sent around the body

Compare and contrast Exocrine and Endocrine glands.

Exocrine glands have ducts and will carry their substance to the membrane surface, whereas endocrine glands do not have ducts and will release their hormone into the tissue fluid around them, additonally they will be picked up by blood capillaries for further transport throughout the body. The endocrine system also acts as the body's hormonal control mechanism, aka the "Wireless system", in which hormones are released to elicit certain stimuli.

Are the different endocrine glands either exocrine glands or endocrine glands, or can they be both.

As a general rule, yes, there are certain systems for the endocrine and exocrine glands. The only exception is the pancreas, which utilizes both systems.

Explain the anatomical interaction/connections of the hypothalamus with the pituitary gland.

The Hypothalamus is located slightly dorsal to the pituitary gland and is interconnected with it via the pituitary stalk. The Hypothalamus is known as the relay center because it responds to both internal and external stimuli affecting the body. The different nuclei that compose the hypothalamus will respond to stimuli and secrete different hormones to the pituitary gland, which will then secrete peripheral hormones that act to cause other stimuli, a never-ending downhill slide.

LIST and DESCRIBE the 5 types of hormones classifications. Additionally, provide an example of ONE hormone for each classification.

1. Amines: Hormones produced from a single Amino Acid or AA, biochemical modifications of a single AA. Epinephrine.

2. Polypeptides and Proteins: Hormones which are produced from long or short chains of proteins. Insulin.

3. Glycoproteins: Protein hormones with the addition of a carbohydrate. FSH.

4. Steroids: Hormones that are synthesized from cholesterol. Testosterone.

5. Eicosanoids: Hormones that are derived from arachidonic acid. PGF2a.

Which scientists coined the term "hormone"?

Bayluss and Starling are credited with coining the term Hormone.

Define Autocrine

Autocrine is defined as the production of a hormone that will act on itself. This hormone essentially binds to the same cell that produced it.

Explain the neural control mechanism of the body.

Also known as the "wire system," is the group of control mechanisms that deals with nerves and neurons. This system is extremely fast and has a short-lived response, unlike some systems, which require no genetic translation or protein synthesis to get the job done.

Explain the hormonal control system and its mechanisms.

Also known as the "wireless system", is the group of control mechanisms that deal with endocrine secretions. This system can be both fast and short-lived, or slow and long-lasting; more often than not, it is the latter, as some hormones have half-lives of several days.

Explain the Neuroendocrine system and its mechanisms.

The coordination between the nervous and endocrine control systems. These two systems work in tandem throughout the body to maintain homeostasis and keep the ball rolling.

Describe a neuroendocrine reaction.

The Neuroendocrine reaction is the result of the coordination of the different body processes via the hypothalamus. The hypothalamus releases several hormones that trigger a chain reaction of actions and responses throughout the body. The rabbit examples are the result of a neurostimulation during mating, and cats are another example of these reactions.

Describe the three cell types of the thyroid gland.

Colloid, Follicular cells, and Parafollicular cells. Colloid cells are half of the thyroid's structural and functional unit. Follicular cells are composed of a cuboidal epithelium and will arrange themselves as a single layer. They synthesize proteins, creating thyroglobulin. Thyroglobulin is released into the colloid space, causing a downstream reaction leading to the synthesis of thyroid hormones. In response to certain stimuli, follicular cells will engulf colloid cells via phagocytosis, colloid cells will then be degraded and will yield thyroid hormones. Parafollicular cells are also known as C-Cells or Clear cells. Parafollicular cells are present within the follicular wall and the extracellular space between thyroid follicles, helping to fill in the gaps. They are a very important source of calcitonin, which is essential for hormonal homeostasis.

Which make up the thyroid follicle?

Colloid and Follicular cells make up the Thyroid follicle.

List and describe the FOUR steps of hormones binding to membrane receptors involved in membrane receptor hormone action.

1a. Hormone -Receptor binding, diffuses from the blood and binds to the receptor.

2a. Adenylate cyclase becomes active, and ATP is converted to cAMP. cAMP acts as a second messenger, triggering downstream events and propagating the signal by turning on the Kinases.

3a. Protein Kinase becomes active, via the second messenger, it donates phosphorous molecules that will become enzymes, resulting in turning substrates into products.

4a. Synthesis of new products, these products are either kept in the cell or secreted to cause other downstream reactions.

What classes of hormones can bind to a membrane receptor via hormone action?

Lipid-soluble hormones can bind specifically in the way we described, to membrane receptor types; Water-soluble membranes rely heavily on the process.

Explain the lock and key mechanism of hormones and their receptors

Because hormone action has to be activated by the presence of specific receptors on the target tissue, the process has to work similarly to a lock and key mechanism. Every lock has a very specific key which has to be used in order to unlock the door, lock box, or safe, etc. Similarly, every hormone action (door) must have a very specific receptor complex (key) in order to be activated.

Explain the importance of receptors in the process of hormones directing/regulating cellular processes

Hormones have to regulate the mechanisms of hormone action by binding to specific receptors on the target cell/tissue. They also have to get their message into the cell, and lastly, they must stimulate signal transduction (this carries the signal inside the target cell to elicit the desired response).

What type of test subjects did Berthold use in his experiment?

Roosters.

What did Berthold remove?

Testes.

Explain/describe the methods of each of Berthold's experiments: control subjects, negative control subjects, and the different experiment subjects.

In his control group (1), he did not perform any surgery. As they matured, the comb and wattles were of normal size; they had an interest in hens, a normal crow, aggressive behavior, and were described as having larger testes than some other subjects. In group 2, he removed both testes from the subjects. As they matured, their comb and wattles were small, they had no interest in hens, their crow was weak, and they were less aggressive. Group 3 had one testis ablated and replaced in the abdominal cavity; once they matured, they exhibited the same behavior as group 1 subjects. Group 4 had both testes ablated and replaced in the abdominal cavity. Once they matured, they exhibited the same behavior as group 1 subjects.

List and describe the FOUR steps of hormones binding to intracellular receptors (Intracellular/Nuclear Receptor Hormone Action).

1a. Steroid Transport: Because steroids are not water soluble, they cannot be transported freely throughout the blood and must instead attach to molecules that are water soluble, allowing them to be transported.

2a. Movement: When the steroid hormone and the protein carrier complex come into contact with the cell membrane, the steroid will dissociate and diffuse through the lipid bilayer of the cell membrane. Once inside the cell, the steroid can bind to a receptor.

3a. Binding: Lock and key mechanism previously mentioned, the steroid is the key and must bind to the correct lock (receptor). The steroid-nuclear receptor complex is referred to as a "transcription factor" because it initiates DNA transcription into mRNA.

4a. Synthesis of mRNA and Protein: Newly created mRNA will exit the nucleus and bind to ribosomes, where it will direct the creation of specific proteins, which will enhance reproductive processes.

What class of hormones can bind via Intracellular/Nuclear Receptor Hormone Action.

Steroid Hormones.

What are the THREE major roles of thyroid hormones?

Growth and Development, Thermogenesis and Oxygen Consumption, and Permissive Actions. Thyroid hormones are required for and support the actions/production of GH, which is essential for growth and development. Thyroid hormones stimulate mitochondrial oxygen consumption and ATP production (the body's fuel); they also stimulate oxygen consumption in every cell of the body. Permissive actions include bodily actions such as reproduction and milk production.

What pathway is responsible for prostaglandin hormone production from arachidonic acid?

Cyclooxygenase Pathway

What pathway is responsible for leukotriene production from arachidonic acid?

Lipoxygenase Pathway

What are the main functions of Prostaglandin hormones?

Prostaglandin Hormones: There are many different types, but the 4 main types are PGI2, PGE2, PGF2a, and TXA2. Prostaglandin Hormones are produced by most tissues (autocrine, paracrine, and endocrine actions). PGI2 results in antiplatelet aggregation and vasodilation. PGE2 results in smooth muscle relaxation and vasodilation. PGF2a results in smooth muscle contraction, vasoconstriction, and luteal regression. TXA2, also known as Thromboxane, results in platelet aggregation and vasoconstriction. As a general rule PG's will degrade very quickly in the lungs, up to 80% in one pass.

What are the main functions of Leukotriene hormones?

Their primary function includes the control of inflammation, bronchoconstriction, Vasoconstriction, and Capillary Permeability.

What is so special about the posterior pituitary gland?

Acts as a storage mechanism for hormones and then secretes said hormones, composed of neural tissue/neurons. In contrast to the anterior, which synthesizes said hormones and then releases them to the body.

What hormones are secreted from the posterior pituitary gland?

ADH and Oxytocin synapse at the posterior pituitary for storage and are then released when needed.

FULLY describe the three steps of thyroid hormone biosynthesis.

The main function of the thyroid is to accumulate iodine, which can bind to AA tyrosine, allowing it to create Thyroid hormone. Buosynthesis occurs in three stages: Trapping of iodine from the blood plasma/circulation of the animal, Iodination of Tyrosine (can be different structures), and Proteolysis of Thyroglobulin (breaking down the thyroglobulin protein). Iodine can be obtained from the diet, and TSH allows it to be transported to and trapped in the thyroid. Iodination of tyrosine can result in mono (MIT) or diiodotyrosine (DIT), 2 DIT molecules create Thyroxin (T4), the most abundant in the body)), 1 DIT + 1 MIT creates Triiodothyronine (T3). These molecules tend to stay in the thyroid until isolated by a lysosome and transported out of the thyroid and into the bloodstream. Proteolysis of Thyroglobulin only occurs when the Thyroid hormone is needed.

Which cells of the parathyroid are responsible for producing parathyroid hormone?

Chief cells are responsible for the production of Parathyroid Hormones (PTH).

What is the scientifically detailed definition of a hormone?

Hormones are chemical messengers that are secreted by cells of endocrine glands and tissues. These messengers help to regulate the activity of other cells in the body and work together to help maintain homeostasis and to provide drive to the individual.

What is the 'grandma terms' definition of a hormone?

Hormones are chemical messengers that are produced by glands and secreted into the body to control the actions of a target tissue or cell down the line (in order to get the ball rolling, hormones push it downhill, causing several different reactions to occur even after reaching the target site).

List the 4 biological processes that hormones regulate/control.

Hormones control/regulate several different biological processes, including but not limited too: Physiological and metabolic regulation and cell division, function, and differentiation

Explain autocrine/paracrine mechanism of action of PGF2alpha.

Autocrine/paracrine mechanism results in local secretions leading to uterine contractions. The uterus produces PGF2a and then acts on itself in an autocrine manner to produce said contractions.

Explain the endocrine mechanism of action of PGF2alpha.

Endocrine mechanism: The uterus produces PGF2a, which is then released into the uterine vein. It is then picked up by the ovarian artey through the counter current exchance and delivered back to the artery where it causes the corpus luteum to lysis (Luteal regression).

(1) What types of cells are present in the anterior pituitary gland, provide their NAMES (hint there are 5 types).

(2) Which hypothalamic releasing hormone do the cell bind/respond to

(3) As a result of the hypothalamic hormones binding to the receptors on the anterior pituitary cells types what hormones do they produce!

1. Cortictroph responds to Corticotropin-releasing hormone, and as a result, secretes ACTH (Adrenocoritcotropic hormone).

2. Thyrotroph responds to Thyrotropin-releasing hormone, and as a result, secretes TSH (Thyroid Stimulating hormone).

3. Gonadotropin responds to Follitropin or Lutropin releasing hormones, and as a result, secretes FSH (Follicle-stimulating hormone) or LH (Luteinizing hormone).

4. Lactotroph (mammotroph) responds to Prolactin-releasing hormone, and as a result, secretes PRL (Prolactin).

5. Somatotroph responds to Growth hormone-releasing hormone, and as a result, secretes GH (Growth Hormone).

What is special about TSH, LH, and FSH?

They can all be grouped into a subfamily known as glycoprotein hormones. They have a similar alpha subunit but differ in their beta subunit, which confers biological activity.