Hormones Flashcards
What are hormones?
Chemical signals that are secreted into extrecellular fluids, gain entry into the circulatory system, and communicate regulatory messages within the body.
DO hormones act on all cells?
NO, JUST THEIR INTENDED TARGET CELLS
What two systems coordinate communication throughout the body?
The endocrine system - secretes hormones that coordinate slower, but longer-acting responses
The nervous system - high-speed electrical signals along specialized cells that regulate other cells, faster and shorter-acting.
What is the difference between endocrine, paracrine, and autocrine signaling?
Endocrine - secreted molecules diffuse into blood stream and trigger response at target cells elsewhere in body. HORMONES
Paracrine - molecules diffuse locally and trigger response in neighboring cells LOCAL REGULATOR
Autocrine - molecules diffuse locally and trigger response in cells that secrete them. LOCAL REGULATOR
Describe synaptic signaling as well as neuroendocrine signaling.
Synaptic signaling - NEUROTRANSMITTERS diffuse across synapses and trigger response in cells of target tissues
Neuroendocrine signaling - NEUROHORMONES diffuse into the bloodstream and trigger response in target cells elsewhere in the body
What are pheromones? Give an example of their use.
Pheromones are emical signals released into the external envirnment that have a purpose of communication with other members of the same species.
Serve many functions, like marking trails that lead to food, predator warning, attracting mates.
Asain army ants use their antennae to follow a pheromone-marked trail.
What are the 4 classes of chemical regulators?
Prostaglandins
cytokines
growth factors
nitric oxide
What are the three chemical classes of hormones? What are the two different solubility of hormones?
Chemical:
- polypeptides
- amines
- steroid hormones
Solubility:
- lipid-soluble
- water-soluble
Describe how solubility affects the location of the receptors for it on the target cell.
Lipid-soluble - these pass easily through the cell membrane, receptors usually located in cytoplasm or nucleus of cell.
Water-soluble - cannot diffuse through the plasma membrane of cell, receptors are located on cells surface.
Which chemical class of hormones are water-soluble vs lipid-soluble? What is an example of each?
Steroids - lipid soluble - cortisol
Polypeptides - water-soluble - insulin
Amines - BOTH - epinephrine (water-soluble) and thyroxine (lipid-soluble)
Do water-soluble and lipid-soluble hormones have different response pathways?
YES
Describe the response pathway of a water-soluble hormone.
The hormone is secreted via EXOCYTOSIS and travels FREELY in the bloodstream, once it reaches its target cell it binds to a receptor on the SURFACE
Describe the response pathway of a lipid-soluble hormone.
These hormones DIFFUSE accross the cell membrane and travel in the bloodstream bound to TRANSPORT PROTEINS and bind to INTRACELLULAR RECEPTORS.
In the water-soluble hormone pathway, describe what happens after the hormone binds to its receptor on the surface of the cell.
A signal transduction pathway is initiated that leads to a response in the cytoplasm that activates enzymes and causes a change in gene expression
Look at this cells response to the water-soluble Amine hormone Epinephrine
One the lipid soluble hormone binds to its receptor in the cells cytoplasm or on the cells nucleus, what happens?
The complex that is formed acts as a regulatory transcription factor that alters gene expression of specific genes.
Look at this example of the lipid-soluble steroid hormone estradiol:
Do different cells have different receptor types that respond to the same hormone, but, may trigger a different response in each? Example?
YES
Look at this picture of epinephrines different effects:
Tkae a look at a list of these endocrine clands and their hormones. Focus on the ones that you ar emore unfamiliar with.
DO IT
Look at this picture and have an understanding of the basic endocrine pathway that takes place.
Do it.
Look at this picture of a simple neuroendocrine pathway. Be able to describe this.
sensory neurons respond to stimulus by sending nerve impulse to neurosecretory cell which triggers the release of a neurohormone.
Once the neurohormone reaches its target cell it triggers a response.
Look at this example of oxytocin and its positive feedback mechanism.
Describe the actions of prothoracicotropic hormone and juvenille hormone and their effects of metamorphosis of a butterfly. First describe what a tropic hormone does.
Tropic hormones are hormones that target endocrine glands.
PTTH - is released from cells in the brain that promote the excretion of ecdysteroids from the prothoracic gland.
Ecdysteroids - induce a molt in the larava
JH - dictate the outcome of the molt, if levels are high full metamorphosis is inhibited and a new larval stage results from molte.
When JH levels fall low enough ecdysteroids will activate a molt that results in metamorphosis and result in an adult insect.
What is the function of the hypothalamus?
To receive information from the nervous system and initiate responses through the endocrine system.
What gland is attached to the hypothalamus? What are its two parts and their basic functions?
Pituitary gland:
Anterior - makes and releases hormones under regulation of the hypothalamus
Posterior - stores and secretes hormones that are made in the hypothalamus
What are the two hormones that the posterior pituitary releases? Where are these hormones made? ARe these tropic hormones, what does this mean?
The posterior pituitary is essentially an extension of the hypothalamus.
Neurosecretory hormones in the hypothalamus produce the hormone and these are stored in the posterior pituitary and then released from there.
ADH - enhances water reabsorption in the kidneys
Oxytocin - stimulates uterine contractions and milk release
These are not tropic hormones which means that their target cells are not endocrine cells.
Describe the hormone cascade pathway. What three things are involved in this response?
Stimulus reaches the hypothalamus
Hypothalamus send hormone to the anterioir pituitary via its portal circulation
Anterior pituitary responds by releasing a tropic hormone (doesnt only secrete tropic hormones)
IN OTHER WORDS
Signals to the brain stimulate the hypothalamus to secrete a hormone that stimulates or inhibits release of an anterior pituitary hormone. This hormone, in turn, acts on another endocrine organ, stimulating the secretion of yet another hormone.
- Hypothalamus
- Anterior pituitary
- target endocrine gland
Hormone triggers endocrine target tissue to secrete its hormone to trigger effect somewhere in body.
What are the Tropic, nontropic, and hybrid hormones that the anterior pituitary releases?
Tropic:
- FSH and LH
- TSH
- ACTH
Nontropic:
- Prolactin
- MSH (melanocyte-stimulating hormone)
Both:
- Growth hormone
What controls the production of hormones by the anterior pituitary? What is an example of this?
releasing and inhibiting hormones from the hypothalamus
Prolactin-releasing hormone from the hypothalamus stimulates the release of prolactin from the anterior pituitary
Look at this picture of the first three steps thyroid regulation pathway and be able to verbalize steps 1-3 what is going on.
DO IT.
Verbalize steps 4-6 of the thyroid regulation pathway. Refer to the picture if needed.
Do it.
What is required for the production of T3 and T4?
Iodine
The number in the name refers to how many iodine are attached
What might you encounter s/s wise with hyperthyroidism and hypothyroidism?
Hypothyroidism - weight gain, lethargy, cold intolerance
Hyperthyroidism - high body temp, diaphoresis, weight loss, HTN
What is graves disease?
This is an autoimmune disorder that results in antibodies binding to and activating TH receptors, which results in sustained TH production.
How does low iodine effect the production of TH?
Low iodine may result in overproduction of TSH, due to the lack of negative feedback by TH, this can in turn cause the thyroid gland to swell resulting in a goiter.
What is the function of growth hormone? What does this trigger the release of?
Promotes growth via stimulating the release of insulin-like growth factors from the liver.
IGFs stimulate the growth of bone and cartilage.
What are some effects of hyposecretion and hypersecretion of growth hormone? S/S? Treatment?
Hyposecretion:
- retards long-bone growth
- may lead to pituitary dwarfism
- treated with recombinant HGH
Hypersecretion:
- Excessive bone growth
- May lead to gigantism
- Causes acromegaly
Where are the parathyroid glands located?
These are a set of four small structures hidden on the posterior surface of the thyroid gland.
CALCIUM REGULATION CARD:
What hormone is secreted by the parathyroid gland and what is its action?
What hormone released from the thyroid has the opposite effect?
Parathyroid hormone (PTH) - reacts to a decrease in calcium levels, acting on kidneys and bone to increase calcium levels, also activates vitamin D (promotes calcium uptake in intestines).
Calcitonin FROM THYROID - Responds to an increase in calcium levels, inhibits bone breakdown and increases calcium excretion from kidneys. Calcitonin TONES DOWN calcium levels in blood.
What are the two divisions of the adrenal glands?
The adrenal cortex and the adrenal medulla.
What type of hormones does the adrenal medulla secrete? What are some examples?
Catecholmines in response to SHORT-TERM stress.
Example: epinephrine and norepinephrine, both involved in the fight-or-flight response.
What type of hormones does the adrenal cortex secrete? What are the subcategories and some examples?
Corticosteroids in response to stimuli from the HYPOTHALAMUS (corticotropin-releasing hormone) and ANTERIOR PITUITARY (ACTH), in response to LONG-TERM stress.
Corticosteroids:
- Glucocorticoids (cortisol) - increase glucose synthesis and metabolism and anti-inflammatory effects
- Mineralocorticoids (aldosterone) - involved in mineral homeostasis and metabolism
Describe the hormone cascade pathway involved in the release of sex hormones. What are the three sex hormones discussed? Are all 3 present in males and females?
GnRH (gonadotropin-releasing hormone) is released from hypothalamus to the anterior pituitary
anterioir pituitary releases FSH and LH
FSH and LH control the synthesis of sex hormones at the respective glands in males and females
- Androgens - prmote male reproductive structure development and secondary sexual characteristics
- Estrogens - promote development of female reproductive stuctures and secondary sexual characteristics
- Progestins - prepare and maintain tissues of uterus to support an embryo
THESE ARE FOUND IN BOTH MALE AND FEMALES, JUST IN VARYING QUANTITIES
An embryo has bipotential gonads that can become either the male or female reproductive structures, what dictates this? Example of XY or XX embryo?
The sex hormones
XY - becomes testes, secretes testosterone which promotes formation of sperm-carrying ducts, and AMH promotes the degeneration of the female ducts.
XX - Lack of release of testosterone and AMH promotes degeneration of male structures and the formation of female ducts.
Where is the pineal gland located? What does it release and what is its effect? What controls its release and in turn our “biological clock”.
The pineal gland is located near the center of the brain and releases melatonin.
Melatonin - affects skin pigmentation (production of melanin) and primarily effects the biological rhythms associated with reproduction and activity levels.
The Suprachiasmatic nucleus is a group of neurons in the hypothalamus that controls the release of melatonin, this is ultimately the “biological clock” of our body. Light sensitive neurons in our retina help in the control by the SCN.
