Chapter 42- Endocrine System Flashcards
What is a hormone? Where is it secreted into and how does it travel to different types of the body?
Regulatory chemical that is secreted into extracellular fluid and carried by the blood
What are the 2 basic hormone characteristics?
- Must be sufficiently complex to convey regulatory information to their target cells
- Must be adequately stable to resist destruction before
reaching their target cells
What are the 5 mechanisms for signaling? describe each
1) classical endocrine - systemic
2) paracrine regulators - allow cells of organ to regulate eachother and do not travel in blood
3) autocrine regulators - self
4) neurohormone - released from neruons and travel in blood
5) pheromones - chemicals released into the environment to communicate among individuals of a single species, Not involved in normal metabolic regulation within an animal
What is the difference between neurotransmitters and neurohormones?
neurotransmitters act locally typically in the synapse while neurohormones are carried by blood. However, both can travel in the blood and act as a hormone.
What is norepinephrine? Is it a neurotransmitters or neurohormones?
It’s a neurotransmitter that coordinates the activity of heart, liver, and blood vessels during stress
What is antidiuretic hormone? Is it a neurotransmitters or neurohormones?
It’s a neurohormone secreted by neurons of the brain
What are the 4 classes of signaling molecules?
amine, steroid, peptide, and fatty acid
What signaling mechanisms do amine hormones use?
classical and neuroendocrine
What are most amine hormones based on?
tyrosine
What are amine hormones?
Most are hydrophilic molecules, which diffuse readily into the ECF and bind to receptors at the cell surface
What is thryoxine?
hydrophobic amine hormone secreted by the thyroid gland – it passes through the plasma membrane and binds to a receptor inside the target cell
What signaling mechanisms do peptide hormones use?
classical and neuroendocrine, may also act in paracrine and autocrine signaling
What is the structure of peptide hormones? Examples
Made of amino acid chains (3 to >200 amino acids), Some have carbohydrate groups attached. They are released into the blood or ECF. ex) growth factors
What signaling mechanisms do steriod hormones use?
classical
What are all hydrophobic molecules derived from?
cholesterol
What is the structure of steroid hormones? examples?
Combine with hydrophilic carrier proteins to form water soluble complexes that can diffuse through the ECF and
enter the bloodstream.
On contacting a cell, the hormone is released from its carrier protein, passes through the plasma membrane of the target cell, and binds to internal receptors in the nucleus or cytoplasm
ex) aldosterone, cortisol,
and the sex hormones
What signaling mechanisms do fatty acid hormones use?
paracrine and autocrine
What are prostaglandins? (3 functions)
1) local regulator fatty acid hormone, which can Increase contractions of smooth muscle cells, particularly in the uterus.
2) Induce contraction or relaxation of smooth
muscle cells in blood vessels and air passages in
the lungs.
3) Intensify pain and inflammation in injured cells
What are the two functional classes of hormones?
lipophilic fat soluble and hydrophilic water soluble
What are lipophilic fat soluble hormones? (4)
nonpolar, steroid and thyroid hormones, travel on transport proteins in blood, bind to intracellular receptors, long active period
What are hydrophilic water soluble hormones? (4)
all other hormones, freely soluble in blood, bind to extracellular receptors, act over a brief time period
What is amplicfication?
each activated protein activates a larger number of
proteins for the next step in the pathway, small amounts of hormone can created a large effect
What does structures do the endocrine system include? 9 main glands?
all organs and tissues that secrete hormones
thyroid gland, parathyroid glands, adrenal medulla, adrenal cortex, gonads, pancreas, pineal gland, pituitary, hypothalamus
What is the pituitary gland also known as? location? structure?
aka hypophysis, hangs by a stalk from the hypothalamus, made of anterior pituitary (adeno-hypophysis) and posterior pituitary (neuro-hypophysis)
Describe the pituitary gland origin?
diagram on 18
What is the appearance of the anterior pituitary?
glandular
What is the appearance of the posterior pituitary? key 2 facts?
fibrous, different embryonic origins, different hormones
What are the 7 essential hormones that the anterior pituitary produces? what type of hormones are they?
1) Thyroid Stimulating Hormome (TSH)
2) Adrenocorticotropic hormone (ACTH)
3) Melanocyte-stimulating hormone (MSH)
4) Growth hormone (GH)
5) Prolactin (PRL)
6) Follicle Stimulating Hormone (FSH)
7) Luetinizing Hormone (LH)
most are tropic hormones or tropins
What are tropic hormones or tropins?
Act on other endocrine glands
What are 4 non-tropic hormones? functions?
1) Melanocyte-stimulating hormone (MSH) - Stimulates melanin production in melanocytes, little production in adults
2) Growth hormone (GH) - stimulates cell division, protein synthesis, and bone growth in children and adolescents, thereby causing body growth. GH also stimulates protein synthesis and cell division in adults
3) Prolactin (PRL) - milk synthesis post-parteum
4) Endorphins - peptide hormones produced by the hypothalamus and pituitary that help control pain
What two hormones are produced by the posterior pituitary? function?
1) Anti-diuretic Hormone (ADH) - stimulates kidney cells to
absorb more water from urine, thereby increasing
the volume of the blood
2) Oxytocin - stimulates the ejection of
milk from the mammary glands of a nursing mother, Males have it as well
What are goiters caused by?
lack of iodine in the diet
What are the 3 hormones secreted by the thyroid gland? function?
1) thyroxine (T4) - precursor converted in liver to T3
2) triiodothyronine (T3) - More active form Thyroid
hormones bind to nuclear receptors
3) Calcitonin - Peptide hormone, Stimulates the
uptake of calcium (Ca2+) into bones– lowering blood Ca2+ levels. Appears less important in the day-to-day
regulation of Ca2+ levels in adult humans
What are the parathyroid glands? Hormone and function?
◦ 4 small glands attached to the thyroid
◦ Produce parathyroid hormone (PTH) - stimulates osteoclasts to release Ca2+ into blood, stimulates kidneys to reabsorb Ca2+ from urine, Vitamin D activated by a PTH controlled enzyme, stimulates the intestinal
absorption of Ca2+
Structure of Adrenal Glands?
1) medulla (inner portion)
2) cortex (outer portion)
What is the function of the medulla?
Stimulated via the sympathetic nervous system
Secretes the catecholamines: epinephrine and
norepinephrine
What is the function of the cortex?
stimulated by ACTH and secretes corticosteroids (glucocorticoids and aldosterone (mineralocorticoid))
What are glucocorticoids?
long-term stress response which effects lipid and carbohydrate metabolism, immune system, and damage repair.
What are catecholamine hormones?
short-term stress response which effects cardiovascular
system, carbohydrate and lipid metabolism, central
nervous system.
What is the structure of the pancreas?
◦ Connected to the duodenum of the small intestine by the pancreatic duct
◦ Islets of Langerhans are scattered clusters of cells throughout the pancreas that produce hormones
based on blood glucose levels
What two functions does the pancreas have?
exocrine and endocrine
What is insulin secreted by? function?
◦ Secreted by beta (β) cells of the islets
◦ Stimulates cellular uptake of blood glucose and its storage as glycogen in the liver and muscle cells, or as fat in fat cells
What is glucagon secreted by? function?
◦ Secreted by alpha (α) cells of the islets
◦ Promotes the hydrolysis of glycogen in the liver and fat in adipose tissue
What is diabetes mellitus?
cannot take up glucose from blood
What is type 1 diabetes?
◦ Individuals lack insulin-secreting β cells
◦ Treated by daily injections of insulin
insulin-dependent
What is type 2 diabetes?
more common, low number of insulin receptors, treated by diet and exercise
noninsulin-dependent
Structure and function of pineal gland?
◦ Located in the roof of the third ventricle of the brain
◦ Secretes hormone melatonin
What is the role of melatonin?
◦ Synchronizes various body processes to a circadian rhythm
◦ Secretion of melatonin activated in the dark
What are the gonads? function?
Ovaries and testes in vertebrates. Produce sex steroids that regulate reproductive development
What are the female hormones?
estrogen and progesterone
What are the male hormones?
androgens, testosterone and its derivatives
In annelids (worms), arthropods, and mollusks, endocrine cells and glands produce hormones that regulate?
reproduction, water balance, heart rate, and sugar levels
What are the 3 major hormones that regulate molting and metamorphosis in insects?
Prothoracicotropic hormone (PTTH), Ecdysone, Juvenile hormone (JH)
What does Prothoracicotropic hormone (PTTH) do?
a peptide hormone secreted by neurosecretory neurons
stimulates the prothoracic glands to release ecdysone.
What does Ecdysone do?
a steroid hormone secreted by prothoracic glands
promotes growth of a new exoskeleton under the old one and stimulates the release of other hormones that lead to the molt.
Locatoion and structure of Juvenile hormone (JH)?
a terpenoid secreted by the corpora allata, a pair of glands just behind the brain
What happens when JH is high? low?
If JH is high, the molt produces a larger larva – if it is low, the molt leads to pupation and the emergence of the adult
What happens after the adult emerges from the pupa?
JH levels rise again and help trigger full mature sexual behavior.
How does molting in crustaceans work? hormones involved?
◦ Before growth reaches the stage at which the exoskeleton is shed, moltinhibiting hormone (MIH), a peptide neurohormone secreted by a gland in
the eye stalks, inhibits ecdysone secretion
◦ As body size increases to the point requiring a molt, MIH secretion is inhibited, ecdysone secretion increases, and the molt is initiated
What type of neurons release neurohormones?
neurosecretory
