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
