Chapter 45 Hormones and Endocrine System Flashcards
What are hormones?
Chemical signals that are secreted into circulatory system; and communicates regulatory messages within the body.
What is the endocrine system?
This is the system where there is ductless glands
What are exocrine glands?
Glands that have ducts
Where do hormones in the endocrine system go?
Goes to the bloodstream
What is the function of the endocrine system?
Chemical signaling by hormones
What is the nervous system?
Network of specialized cells—neurons—that transmit signals along dedicated pathways
What are the two criteria for signals being transmitted b/w animal cells?
- type of secreting cell
- route taken by the signal in reaching its target
What are the 5 types of intercellular signaling?
- endocrine signaling
- paracrine signaling
- autocrine signaling
- synaptic signaling
- neuroendocrine signaling
What is endocrine signaling?
Hormones are secreted into extracellular fluids by the endocrine cells via the bloodstream
What are the functions of the endocrine signaling? (3)
- maintains homeostasis
- mediates responses to stimuli
- regulates growth and development
What are local regulators?
Molecules that act over short distances, reaching target cells solely by diffusion
What happens during paracrine signaling?
Target cells lie near the secreting cells
What happens during autocrine signaling?
Target cells is also the secreting cell
What are synapses?
Neurons that form specialized junctions with target cells
What are neurotransmitters?
Molecules that diffuse short distances and bind to receptors on target cells
What are neurohormones?
Molecules that travel to target cells via the bloodstream during neuroendocrine signaling.
What secretes neurohormones?
Neurosecretory cells
What are prostaglandins?
Local regulators that function in reproduction, immune system, and blood clotting.
What does paracrine and autocrine signaling have a role in? (3)
- blood pressure regulation
- nervous system function
- reproduction
What are pheromones?
Chemicals that are released into the environment for communication
What are the functions of pheromones? (4)
- marking trails for food
- defining territories
- warning of predators
- attracting potential mates
What are the 3 types of local regulators?
- modified fatty acids
- polypeptides
- gases
What is nitric oxide?
Gas that functions in the body as both a local regulator and a neurotransmitter
What happens if oxygen levels in blood decrease?
Nitrix oxide activates an enzyme that results in vasodilation, increasing blood flow to tissues
What are the 3 types of hormones?
- polypeptides
- steroids
- amines
Which hormones are water-soluble? Which hormones are lipid/fat-soluble?
Water-soluble: Polypeptides and amines
Lipid/fat-soluble: Steroid and other nonpolar hormones
What is an example of water-soluble polypeptide?
Insulin
What is an example of water soluble amine?
Epinephrine
What is an example of a lipid-soluble steroid?
cortisol
What is an example of a lipid soluble amine?
Thyroxine
What is the cellular response pathway for water soluble hormones?
- secreted by exocytosis,
- travel freely in the bloodstream,
- bind to cell-surface receptors
What is the cellular response pathway for lipid-soluble hormones?
- Diffuses across cell membranes
- travel in bloodstream bound to transport proteins
- Diffuses into the membrane of target cells where they’ll bind to the receptors
What does signal transduction lead to? (3)
- Responses in the cytoskeleton
- Enzyme activation
- change in gene expression
What is does epinephrine have a role in?
In mediating the body’s response to short term stress
What does epinephrine help to trigger?
Binds to receptors on plasma membrane of liver cells
Leads to release of messenger molecules that activates enzymes that releases glucose into bloodstream
What does a response to a lipid soluble hormone usually result in?
Usually result in a change in gene expression
What is the pathway for lipid soluble hormones?
Steroid hormone binds to cytosolic receptor –> Hormone receptor complex forms that moves into nucleus
Receptor part of this complex acts as a transcriptional regulator of specific target cells
What are the different effects the same hormone can have on a target cell?
- different receptors for the hormone
- different signal transduction pathways
What is an example of the multiple effects of hormones?
Hormone epinephrine can increase blood flow to major skeletal muscles, but decrease blood flow to the digestive tract
What are some examples of endocrine glands? (4)
- thyroid gland
- parathyroid gland
- testes
- ovaries
What is an example of an exocrine gland?
Salivary gland
What happens in a simple hormone pathway? (3)
1 Hormones are released from an endocrine cell
2. Travels throughout the bloodstream
3. Interacts with the specific receptors w/in target cell to cause a physiological response
What is an example of a pathway response of a simple neuroendocrine pathway? (4)
- Suckling of an infant stimulates signals in the nervous systems
- This suckling signals reach the hypothalamus
- This triggers the release of oxytocin, from posterior pituitary gland
- Mammary glands secrete milk
What is a negative feedback loop?
Inhibits a response by reducing the initial stimulus, thus preventing excessive pathway activity
What is a positive feedback loop?
Reinforces a stimulus to produce an even greater response
What is an example of positive feedback loop?
The stimulation of oxytocin for release of breastmilk or muscle contraction during childbirth
What does the endocrine pathway have a role in for invertebrates?
Have a role in the molting of their larva
What happens in the molting of the larva for invertebrates?
- Neurosecretory cells in the larval brain produces PTTH
- Produced in the prothoracic gland, PTTH directs the release of the ecdysteroid
- Ecdysteroid triggers the formation of the molt and metamorphosis
What does the hypothalamus do? (2)
- receives information from the nervous system
- initiates responses through the endocrine system
What is the pituitary gland composed of?
Composed of the posterior pituitary and anterior pituitary gland; attached to hypothalamus
What does the posterior pituitary gland do?
Stores and secretes hormones that are made in the hypothalamus
What does the anterior pituitary gland do?
Makes and releases hormones under regulation of the hypothalamus
- also inhibits hormones secreted by the hypothalamus
How do the posterior pituitary hormones travel?
Via neurons
How do the anterior pituitary hormones travel?
Via the capillaries
What are tropic hormones?
Anterior pituitary hormones in hormone cascade pathways
What makes up a hormone cascade pathway? (3)
- hormones from hypothalamus
- hormones from anterior pituitary gland
- target endocrine gland
What is endemic goiter (hypothyroidism)?
Enlargement of thyroid gland due to iodine deficiency
What are symptoms of hypothyroidism? (3)
Weight gain, lethargy, cold intolerance
What are symptoms of hyperthyroidism? (5)
High temperature, sweating, weight loss, irritability, and high blood pressure
What is an example of hyperthyroidism?
Graves’ disease
What does the parathyroid hormone do?
Increases the level of calcium in the blood
- Releases calcium from bone and reabsorption of calcium in the kidneys
What does calcitonin do?
Decreases the level of calcium in the blood
-Stimulates calcium deposition in bones and secretion by kidneys
What are catecholamines?
Epinephrine (adrenaline) and norepinephrine (noradrenaline)
The adrenal medulla has to do with sympathetic or parasympathetic?
Sympathetic –> flight or fight
What are the 3 functions of epinephrine and norepinephrine?
- trigger release of glucose and fatty acids into blood
- increase oxygen delivery to body cells
- direct blood toward heart, brain, and skeletal muscles; direct blood away from skin, digestive system, and kidneys
What are the two types of corticosteroids that humans produce?
- glucocorticoids
- mineralocorticoids
What are glucocorticoids?
Corticosteroids that influence glucose metabolism and the immune system
- example: cortisol
What are mineralcorticods?
Corticosteroids that affect salt and water balance.
- example: Aldosterone
What does the testes mainly secrete? What does it do?
- Androgens and testosterone
- stimulate development and maintenance of the male reproductive system
What hormones are secreted by the ovaries?
Estrogen (estradiol) and progesterone (progestins)
What controls the synthesis of the sex hormones?
Follicle stimulating hormone (FSH)
Luteinizing hormone (LH)
What is the function of estrogen?
responsible for maintenance of the female reproductive system and the development of female secondary sex characteristics
What is the function of progesterone?
primarily involved in preparing and maintaining the uterus for pregnancy
What is diethylstilbestrol (DES)?
A synthetic estrogen that’s an endocrine disruptor that interrupts the normal function of a hormone pathway of estrogen
What does the pineal gland do?
Secretes melatonin
What are some functions of the melanocyte-stimulating hormone (MSH)? (2)
- Regulates skin color in amphibians, fish, and reptiles
- Plays a role in hunger and metabolism along with coloration in mammals
What hormones are in the hypothalamus/posterior pituitary gland? (2)
- oxytocin: stimulates contraction of muscles during childbirth
- Vasopressin/ADH: retention of water for kidneys
What hormones are secreted from the anterior pituitary gland? (6)
- Follicle-stimulating hormone (FSH) & Luteinizing hormone (LH): stimulates ovaries and testes
- Thyroid Stimulating Hormone (TSH): Stimulates thyroid gland
- Adrenocorticotropic hormone (ACTH): stimulates adrenal cortex
- Prolactin: Stimulates mammary gland cells
- Growth Hormone (GH): Stimulates growth and metabolic functions
What does hormones does the thyroid gland release? (2)
- thyroxine hormone (T3 and T4): stimulates and maintains metabolic processes
- Calcitonin: lowers blood calcium levels
What hormones are in the adrenal medulla? (2)
Epinephrine and norepinephrine
What hormones are in the adrenal cortex? (2)
- Glucocorticoids
- Mineralocorticoids
What hormones are in the pancreas? (2)
- insulin: lowers blood glucose levels
- Glucagon: Raises blood glucose levels
What are the steps of the thyroid regulation? (4)
- If thyroid hormone level drops in blood, hypothalamus secretes thyrotropin-releasing hormone (TRH).
- TRH stimulates for the anterior pituitary gland to secrete thyroid-stimulating hormone (TSH)
- TSH stimulates the release of the thyroid hormone by the thyroid gland.
- Thyroid hormone increases thyroid levels which represses TRH and TSH
