Chapter 16 - Endocrine

The hypophyseal portal system:

- Carries neurosecretions to the anterior lobe of the pituitary - Is a blood connection between the hypothalamus to the AP - has two capillary plexuses connected by short veins - Carries ADH and OXT

membrane receptors are used by which type of hormones?

- Catecholamines - Peptide hormones - Eicosanoids

What hormones are produced by the pars distalis of the adenohypophysis?

- Corticotropin (stimulates release of steroid hormones from cortex) - FSH - TSH - somatotropin

Melanocyte-stimulating hormone (MSH) is secreted by the human pars intermedia

- During fetal development - During pregnancy - In some disease processes - In very young children

Secretory cells of the adenohypophysis release

- FSH - GH - TSH - ACTH

The pituitary hormone that promotes ovarian secretion of progesterone and testicular secretion of testosterone is

LH

Destruction of the supraoptic nucleus of the hypothalamus would have result in what?

Loss of ADH secretion

The hormone produced by the pars intermedia of the adenohypophysis during early childhood is

MSH

What are androgens?

Male steroid sex hormone

What is calcitrol?

Medicine to treat low calcium

Thyroid hormones are structural derivatives of the amino acid

Tyrosine

If the hypophyseal portal system is destroyed, the hypothalamus would no longer be able to control the secretion of what hormones

TSH, ACTH and PRL

Cells that respond to a hormone are called ______ cells

Target

Thyroixne and calcitonin are secreted by the

Thyroid gland

The hormone that plays a pivotal role in setting the metabolic rate and thus impacting body temperature is

Thyroxine

Hormones known as "catecholamines" are

Derivatives of the amino acid tyrosine

The pituitary hormone that promotes egg development in ovaries and sperm development in testes is

FSH

Excess secretion of growth hormone during early development will cause

Gigantism

If the adenyl cyclase activity of liver cells were missing, what hormone could no longer stimulate release of glucose

Glucagon

Which of the following hormones may lead to acromegaly is hypersecreted after closure of the epiphyseal plates

Growth hormone

What are somatotropins?

Growth hormone - a steroid

All target cells:

Have hormone receptors

What are tropic hormones?

Have other endocrine glands as their target. Most secreted from the AP - "turn on" other glands"

Peptide hormones are:

composed of amino acids

________ are chemical messengers that are released by cells and transported in the bloodstream to alter the activities of specific cells in other tissues

Hormones

The most complex endocrine responses involve the

Hypothalamus

Mental and physical sluggishness and low body temperature may be signs of

Hypothyroidism

The primary function of ADH is to

decrease the amount of water lost at the kidneys

The thyroid gland is composed of many ______ that produce and store thyroid hormone

follicles

Where does the chemical reaction between thyroglobulin and iodine take place?

In the lumen of the thyroid follicle

What hormones are water soluble and therefore binds to extracellular receptors?

Insulin and EPI

What element is necessary for the production of thyroid hormone?

Iodine

All of the following are true of the nervous system EXCEPT that it does not: - respond rapidly to stimuli - Function independently of the endocrine system - Respond specifically to stimuli - Respond with motor output - Communicate by the release of neurotransmitters

- Function independently of the endocrine system

Inadequate iodine in the diet may lead to

- Hypothyroidism - High blood levels of TSH - Cretinism - Myxedema (severe hypothyroidism)

What are known effects of thyroid hormone on peripheral tissues?

- Increased O2 consumption - Increased HR - Increased body temp - Increased sensitivity to autonomic stimulation

What are the actions of TSH?

- Increases cAMP concentration within thyroid follicle cells - Stimulates iodide trapping by thyroid follicle cells - stimulates pinocytosis of colloid by thyroid follicle cells - Stimulates T3 and T4 secretion

What organs contain target cells for oxytocin?

- Mammary glands - Ductus deferens - Prostate - Uterus

Hormone release may be controlled by which of the following factors?

- Nervous stimuli - Blood level of glucose - Blood level of a hormone - Blood level of an ion like calcium

Hormones can operate on what level(s) of organization?

- Organ - Tissue - Cellular - Organismic

The anterior lobe of the pituitary can be divided into three parts. What are they?

- Pars distalis - Pars intermedia - Pars tuberalis

What is calcitonin?

- Produced in the thyroid (C-cells) - regulates calcium homeostasis

What does Growth hormone do?

- Promotes amino acid uptake by cells - Promotes muscle growth - Promotes bone growth - Spares glucose

What does oxytocin do?

- Promotes uterine contractions - Triggers prostate gland contraction - Is responsible for milk expression from the mammary glands - Is produced by the hypothalamus

Delta cells

- Secrete GH-IH - target is alpha and beta cells - inhibits the release of glucagon and insulin/slows absorption in the kidneys

Alpha cells

- Secrete glucagon - target is the liver - increase blood glucose by increasing rate of glycogen breakdown

Beta cells

- Secrete insulin - target is every cell - decrease blood glucose by telling cells to take up glucose

Hormones can be divided into different groups based on their chemistry. These categories include:

- Steroids - AA derivatives - Eicosanoids - Peptides

Why is it that steroid hormones use receptors inside of target cells, whereas protein, peptide and amino acid hormones do not?

- Steroids can cross the cell membrane because they are lipids and the membrane is lipid

Hormonal actions on cells include those that affect:

- Synthesis of enzymes - Quantities of enzymes - Gating of ion channels - Activities of enzymes

An activated G protein can trigger:

- The activation of adenyl cyclase - A fall in cAMP levels - The release of calcium ions form intracellular stores - The opening of calcium ion channels in the membrane

What are some hormones of the amino acid derivates?

- Thyroid hormone - Melatonin - NE - EPI

F cells

-Secrete PP (pancreatic polypeptide) - target is gallbladder - inhibits gallbladder contraction

The two loves of the pituitary gland together produce how many hormones?

9 AP: TSH ACTH FSH LH GH PRL MSH PP: OXT and ADH

The link between a first messenger and a second messenger in a cell that responds to peptide hormones is usually

A G protein

After brain surgery, a patient receiving postoperative care in an intensive care unit began to pass large volumes of very dilute urine. The ICU nurse administered a medicine that mimics what hormone?

ADH

Changes in blood osmotic pressure would most affect the secretion of

ADH

The pituitary hormone that causes the kidney to reduce water loss is

ADH

The posterior pituitary gland secretes what?

ADH

Neurons of the supraoptic and paraventricular nuclei of the hypothalamus manufacture what

ADH and oxytocin

When adenyl cyclase is activated,

ATP is consumed and cAMP is formed

Which of the following is TRUE of paracrine communication? - It is used for the regulation of cell and organ activities - The cells make local hormones, made by cells that affect the surrounding cells - Paracrine factors are rather similar to hormones - Many cells produce paracrine factors

All are correct

A hormone might: - Interfere with NE at a neuronal synapse - Block the production of a cell membrane - Inactivate glucose so it cannot be used - Depolarize a skeletal muscle cell - Alter a membrane channel by changing its shape, thereby affecting what can go through it

Alter a membrane channel by changing its shape, thereby affecting what can go through it

Calcium ions serve as messengers, often in combination with the intracellular protein:

Calmodulin

The intracellular protein _______ binds calcium ion. This complex can then activate enzymes

Calmodulin

Which of the following substances activates protein kinases and thus acts as a second messenger?

Cyclic AMP

After a steroid hormone binds to its receptor to form an active complex,

gene transcription is initiated

Hormones produced by the anterior lobe of the pituitary gland that regulate the male and female reproductive organs are collectively called

gonadotropins

The main action of ADH is

increase water conservation by kidneys

The two lobes of the thyroid gland are connected by the

isthmus

The condition known as hirsutism can result from too

much androgen production

The posterior lobe of the pituitary is also known as the

neurohypophysis

The hormone that may be slowly administered by IV drip to accelerate labor and delivery is

oxytocin

The hypothalamus control secretion in the adenohypophysis by

secreting releasing and inhibiting factors into a tiny portal system

The action of thyroid hormone on a target cell involves all the following steps

- Activation of a specific gene - Activation of a G protein - Binding to a cytoplasmic receptor protein - Transport into the target cell

Steroid hormones:

- Are derived from cholesterol - Bind to receptors within the cell - Are lipids - Are produced by reproductive glands

The pituitary hormone that controls the release of glucocorticoids from the suprarenal cortex is

ACTH

Steroid hormones:

Bind to receptors in the nucleus of their target cells

A simple endocrine reflex involves ________ hormone(s)

One

What cells are the target cells for the hormone that causes a decrease in blood-calcium concentration?

Osteoblasts

Increased levels of the hormone ________ will lead to increased levels of calcium ion in the blood

PTH

Before the discovery of these glands, thyroid surgery often led to a rapid drop in blood calcium levels, which triggered muscle contractions and cardiac arrhythmias. What glands are these and which hormone is lacking?

Parathyroid glands; parathyroid hormone

A kinase is an enzyme that performs

Phosphorylation

Term used to describe excess production of urine is

Polyuria

The pituitary hormone that stimulates milk production by the mammary glands is

Prolactin

PRL is to _______ as ADH is to _______

Prolactin, vasopressin

Endocrine cells:

Release their secretions directly into body fluids such as blood

When a catecholamine or peptide hormone binds to receptors on the surface of a cell, the:

Second messenger appears in the cytoplasm

What is calmodulin?

Secondary messenger that binds calcium

TSH plays a key role in the ________ of thyroid hormones.

Synthesis and release

The pituitary hormone that triggers the release of thyroid hormone from the thyroid gland is

TSH

What are osteoclasts?

a large multinucleate bone cell that absorbs bone tissue during growth and healing

The anterior lobe of the pituitary is also know as the

adenohypophysis

Increased activity of phosphodiesterase in a target cell would decrease its level of

cAMP

A hormone that can lower blood levels of calcium ion is

calcitonin

The C cells of the thyroid gland produce?

calcitonin

Receptors for _______, peptide hormones and eicosanoids are found in the cell membranes of target cells

catecholamines

The control of calcitonin excretion is an example of direct ________ regulation.

endocrine

Liver cells respond to growth hormone by releasing hormones called

somatomedins (stimulate tissue growth)

The pituitary hormone that stimulates cell growth and replication by accelerating protein synthesis is

somatotropin