Chapter 45: Hormones and the endocrine system Flashcards
What are hormones?
Chemical signals that affect only target cells
How are the endocrine and nervous systems different?
Endocrine: releases slow acting hormones which last for a long time, hormone travels through blood
Nervous: uses electrical signals to get quick messages through body, very quick but dissipates fast
What are the five different types of secreted signaling molecules?
Hormones: Chemical signal to cause reaction, broad term
Local regulators: Only reach neighboring cells and itself
Neurotransmitters: Electric signal used by nervous system
Neurohormones: Neuron secreted hormones
Pheromones: Release outside of the animal’s to signal something to other animals of the same species
What is the difference between an endocrine gland and an exocrine gland?
Endocrine: Releases hormones into blood
Exocrine: Uses ducts to release something onto a body surface, like sweat
What is a local regulator?
A hormone that only acts on neighboring cells and itself, does not reach bloodstream
What are the two different classes of local regulators and how do they differ?
Autocrine: Only acts on itself
Paracrine: Only acts on neighboring cells
What is the difference between a neurotransmitter and a neurohormone? Give an example of each.
Neurotransmitter: Created by a neuron and acts at a short distance through synapses, example is serotonin
Neurohormone: Created by neurosecretory cells, secreted at the neuron but diffuses into the bloodstream, example is oxytocin
What are pheromones? How might they be used?
Pheromones are hormones released out into the environment, signal something to members of the same species, such as where to find food or that the organism is ready to mate
What are the three major classes of molecules that function as hormones? Which are water soluble and which are lipid-soluble?
Polypeptides, amines, steroid hormones.
Steroid hormones are lipid soluble
Polypeptides and amines are water soluble
What is the correlation between the solubility of a hormone and the location of its receptors?
Water soluble hormones have receptors at the surface of the cell, and lipid soluble can have at the surface of the cell, but most often it is inside the cell
In addition to receptor location, water-soluble and lipid-soluble hormones also exhibit additional differences in their response pathways. What are these differences?
Water soluble: Cannot pass through cell membrane, does not need transport protein to go through blood, are secreted through exocytosis
Lipid soluble: Can pass through cell membrane with ease, needs transport proteins to travel through blood
What is a signal transduction pathway?
The series of steps that take place after a hormone attaches to a receptor
Receptor, transductor, then response
What is a G protein coupled receptor? Provide an example of a hormone that uses a G protein coupled receptor in its signal transduction pathway.
A type of surface cell receptor that reacts to hormones and begins some kind of reaction within the cell, epinephrine AKA adrenaline
If someone said to you that a particular hormone utilizes a G protein coupled receptor in its transduction pathway, would they be talking about a water- or lipid-soluble hormone?
Water-lipid
In what locations might the receptor for a lipid-soluble hormone be located?
On the cell surface or inside the cell
What is the typical cellular response initiated by a lipid-soluble hormone?
Some kind of genetical modification
What is a transport protein and why do lipid-soluble hormones require them?
A protein which can bring a molecule through the bloodstream with it, because they are not soluble in water (which is what most of blood is)
Why can the same hormone have different effects on different body tissues?
Because different cells in different areas will have different reactions to it. It is not the hormone that determines the reaction, it is the signaling pathway that determines the reaction
In the “Fight or Flight Response”, the release of epinephrine from the adrenal medulla causes skeletal muscle blood vessels to dilate while simultaneously constricting blood vessels of the intestine. Explain how this is possible.
This is possible because the different receptors in these different parts of the bodies have two completely separate reactions pre-planned for this kind of hormone
Liver cells and the blood vessels of skeletal muscle cells have identical surface receptors for epinephrine, yet the response of these two cell types is dramatically different. Explain how this is possible
Because the signaling pathways for these two hormones is completely different past the receptors causing two different reactions
List the three types of local regulators discussed in class and explain their function.
Cytokines: Draw in cells to an area where antigens are found
Nitric oxide: Causes smooth muscle cells to relax to vasodilate
Prostaglandins: Help intensify pain feeling, promote fever and inflammation, protect the lining of the stomach, and regulate platelet aggregation
Hormonal pathways generally operate on the principle of _________________, in which the response to the stimulus leads to a reduction in the stimulus
Negative feedback loops
Some homeostatic control systems rely on sets of simple hormone pathways with coordinated activities. One common arrangement is a pair of pathways, each counter- acting the other. Give an example. What is the advantage of this arrangement?
One example is insulin and glucagon, insulin causes the buildup of glycogen and glucagon causes the breakdown of glycogen. This is helpful because then the body can react to whatever may happen
Explain the action of insulin and glucagon on blood glucose levels.
Insulin: Causes the buildup of glycogen lowering blood glucose levels
Glucagon: Causes the breakdown of glycogen raising blood glucose levels
In response to low blood glucose levels, which hormone (insulin or glucagon) would be released?
Glucagon
What is diabetes mellitus? How is it caused?
It is a deficiency where the body does not produce or does not respond to insulin as well as it should, caused by either an autoimmune disease which kills the beta cells which produce insulin, or by your receptor cells not responding as much to insulin
How does type I diabetes differ from type II?
Type I: Autoimmune disease, genetic cause, body no longer produces insulin
Type II: Body has been exposed to too much insulin due to unhealthy habits, so it no longer responds as well to insulin
In the caterpillar, molting and metamorphosis are under the control of the same hormone. What is the hormone? How are these separate developmental pathways controlled by the
same hormone?
Ecdysteroid, the caterpillar has the juvenile hormone present alongside this hormone then it will molt, if it is not present then the caterpillar will undergo metamorphosis
Which part of the vertebrate brain receives information from the nervous system and initiates responses through the endocrine system?
The hypothalamus
How do the anterior and posterior pituitary differ with respect to the production and release of hormones?
Anterior: Produces and secretes its own hormones
Posterior: Stores and secretes hormones produced by the hypothalamus
Which hormones are released by the posterior pituitary? On which tissues do they act?
Oxytocin: Acts on the uterus, milk production
ADH: Acts on the kidney, water reabsorption
What does oxytocin do?
Stimulates contraction of uterus and milk production
What type of feedback system is involved in milk release by oxytocin?
Positive feedback loop
What hormones are produced by the anterior pituitary? On which tissues do they act?
Growth hormone, especially bones
Prolactin, milk production
FSH, sperm and ova production
LH, stimulates ovaries and testes
TSH, stimulates thyroid gland
ACTH, stimulates adrenal cortex
Diagram the hormone cascade pathway for the release of thyroid hormone. What type of feedback system is employed here? Which hormones are inhibited by rising thyroid hormone levels in the blood?
Stimuli of cold is received by the hypothalamus, which releasees TRH, TRH communicates with the anterior pituitary to release TSH, TSH interacts with the thyroid to release thyroid hormone, which raises metabolism to increase temperature. Negative feedback loop. TSH, which stops being produced with higher levels of thyroid hormones.
