Collection of organs and cells that secrete chemical signals into the bloodstream.
What are the six categories of chemical signals in animals? what are their functions?
Autocrine signal- Act on the same cell that secrete them.
Paracrine signal- Diffuse locally and act on neighboring cells.
Endocrine signal- Hormones carried between cells by blood or other body fluids.
Neural Signal-Diffuse a short distance between neurons.
Neuroendocrine signal- Are released from neurons but are carried by blood or other body fluids and act on distant cells.
Pheromones- Are released into the environment and act on a different individual.
What are glands?
Organs that secret endocrine signals for the production of hormones.
What happens when an action potential arrives at a synapse?
It triggers the release of neurotransmitter that bind to receptors on the postsynaptic cell and induce a change in membrane potential- altering the tendency for the postsynaptic cell to fire action potentials.
How are information about the internal or external environment gathered?
Gathered at the receptor and then integrated by the neurons in the central nervous system (CNS) prior to the production of a hormonal signal. Neurons in the CNS respond by releasing neuroendocrine signals that:
Act on effector cells directly
Stimulate cells in the endocrine system, which respond by producing a hormone.
What are the 3 types of signaling pathway ?
Direct from an endocrine cell
Direct from CNS
CNS-to-endocrine-system are regulated by negative feedback or feedback inhibitors.
What a negative feedback?
Self regulating, corrective response in which a deviation in some variable triggers response aimed at returning the variable to normal.
What is a feedback inhibitors?
A type of metabolic control in which high concentration of the product of a metabolic pathway inhibit one of the enzymes early in the pathway. A way of negative feedback
What reduces the production and the secretion of hormone secretion?
What are endocrine glands?
Organs that secrete a hormone into the bloodstream.
What are the major human glands?
Ovaries or Testes.
What is the role of leptin?
Leptin helps regulate the amount of fats stored in the body.
In contrast to endocrine glands, what is the role of exocrine glands?
Exocrine glands deliver their secretion through outlets called ducts into a space other than the circulatory system.
What are the 3 major chemicals that can act as hormones in animals?
Polypeptides, which are chains of amino acids linked by peptide bonds.
Amino acids derivatives
Steroids, which are a family of lipids distinguished by a 4-ring structure.
What are the major difference between the three hormone chemicals found in animals?
The major difference is that steroids are lipid soluble, while polypeptides and most amino acids derivatives are not.
How do hormones enter the target cell?
All polypeptides and most amino acid derivatives bind to a receptor on the cell surface. Lipid-soluble hormones, in contrast, can didduse through the plasma membrane and bind to receptor inside the cell.
What are the 3 situations in which a hormone coordinate the cell activity?
Development, reproduction, and growth.
What is metamorphosis?
The process from changing from an immature, aquatic tadpole to a sexually mature, terrestrial frog, toad, or salamander (double-lives).
What is T3? What is it's role? What happens when cells respond to increase the level of T3 ?
Triiodothyronine, is responsible for most of the changes in metamorphosis. When cells respond to increase level of T3 in one of 3 ways:
By growing and forming new structures, such as legs
By dying, as structures- such as a tadpole's tail-disintegrate
Or by changing function and function.
What is testosterone?
A steroid hormone that induces early development of the male reproductive tract.
What is a Mullerian inhibitory substance?
A polypeptide hormone inhibits development of the females reproductive tract.
What is estradiol? What is estrogens?
Estradiol- stimulates the development of the female reproductive tract, growth of ovarian folliicles, and growth of breast tissues. Produced by the ovaries of female mammals.
Estrogens- promote female-like tracts. Secreted by the gonads, fat tissues, and some other organs.
What does secretin do? What is the role of cholecystokinin?
Secretin induces the pancreas to secrete an alkaline solution that neutralizes acid.
Cholecystoinin signals the pancrease to secrete digestive enzymes into the small intestine. Also causes the gallbladder to eject bile salts into the intestine.
What role does flight-to-flight response have with the production of epinephrine?
Flight-to-flight is triggered by the sympathetic nervous system. In response to fear, action potentials from your sympathetic nerves would stimulate your adrenal medulla and lead to the release of epinephrine.
What is cortisol ? What role does cortisol have on the long term after effects of an epinephrine "rush"?
Cortisol primary function is to ensure the continued availability of glucose for use by the brain during long-term stress (including the after effects of (epinephrine). Epinephrine decreases digestion and lowers the flow of blood, Cortisol increases the availability of glucose which brings the blood to homeostasis.
What are the 3 main processes of Cortisol that maintain glucose production?
Cortisol induces the synthesis of liver enzymes that make glucose from amino acds and other chemical precursors.
Cortisol makes adipose tissues and resting muscles resistant from insulin ()insulin normally stimulate adipocytes and resting muscle cells to remove glucose from the bloodstream.
Cortisol promotes the release of fatty acids which are used by the heart and muscles.
How are hormones involved in homeostasis?
A sensory receptor that monitors conditions relative to a set point
An integrator that processes information from the sensor
Effector cells that return conditions to the set point.
What is triglyceride? What roles does triglyceride take in energy reserving?
Triglyceride is an effective storage molecule because large ATP can be generated when its three fatty-acid subunits are oxidized. The energy is used as lipid triglyceride which is used during decreased food availability.
Why is glucocorticoid important in regulating blood glucose after a long-term stress response?
It makes amino acids available for glucose synthesis by promoting proteins in muscles.
It impair wound healing and suppress immune and inflammatory responses.
What does adipocytes do?
Removes glucose from the bloodstream.
What is the role of antidiuretic hormone (ADH)?
Increases the absorbency of water from the urine back into the body.
What is the role of aldosterone?
Aldosterone increases the re-absorbency of sodium ions in the distal tubules.
What does Erythropoitein (EPO) do?
It is a homeostatic system for blood oxygen levels which stimulates the production of red blood cells.
What is the basic connection CNS and the endocrine system?
The link between the hypothalamus and pituitary is the basis of the connection between the CNS and the endocrine system.
What is ACTH? What is CRH?
ACTH is adrenocoricotropic hormone that rises the level of cortisol in the blood.
Corticotropin-releasing hormone stimulates the cells in the anterior potuitary to secrete ACTH into the bloodstream.
How is Cortisol or glucocorticoid, ACTH, and CRH an example of feedback inhibitors?
When humans are injected with cortisol, ACTH levels drop. Cortisol inhibits release of CRH from hypothalamus. If glucocorticoid level become too high, ACTH levels fall. If glucocorticoid levels become to low then ACTH levels rise and increase the production of glucocorticoid.
What is neurosecretory cells and what is it's role in hormone release?
The neurosecretory cells release hormones under the control of the brain regions responsible for integrating information about external or internal environment. Also, hypothalamic neuron synthesis and hormone release.
What is posterior pituitary?
The part of the gland that contains the ends of hypothalamic neurosecretory cells and from which oxytocin and antidiuretic hormone are secreted.
What is anterior pituitary?
Part of the pituitary gland containing endocrine cells that produce and release a variety of peptide hormone in response to other hormone from the hypothalamus.
How do posterior pituitary work?
Neurosecretory cells from the hypothalamus produce the hormone ADH and oxytocin, which are then stored in the posterior pituitary. ADH and oxytocin are released into the bloodstream.
How does anterior pituitary work?
Neurosecretory cells from the hypothalamus secrete stimulatory or inhibitory neuroendocrine signals into blood vessels, which then carry the signal to the anterior pituitary . The anterior pituitary alters the secretion of hormones that enter the bloodstream and acr on target tissues or glands.
What are the role of catecholamines?
It functions as neurotransmitters and as well as hormones. Some neurotransmitters initiate changes in gene expression in neurons which lead to gene activation and changes in behavior of the synapse. Many hormones exert their effects by activating particular genes in target cells.
Why can steroid hormones pass through a cells membrane and not peptide and polypeptide hormones?
Steroid are lipid soluble and small lipid molecule that pass enters the cell with no difficulty. Peptides and polypeptides are non-lipid soluble and are large size and electrical charge makes it difficult for them to enter the cell.
What part of the cell do the 3 different chemical type of hormones act upon?
Steroid act inside the cell while peptide and polypeptide act on the cells surface.
How do target cells recieve the signal carried by estradiol?
When does signal transduction occur?
Signal transduction occurs when a chemical message at the cell surface triggers a response inside the cell. Cell-surface receptors "read" hormonal messages and initiate an appropriate response.
What is phosphorylase?
An enzyme that catalyzes a reaction that cleaves glucose molecules off glycogen.
How does epinephrine increase glucose levels in the blood?
An enzyme called phosphorylase catalyzes a reaction that cleaves glucose molecules off glycogen. Phophyorylase exists in active and inactive form; the enzyme switches when it is phosphorylated or dephosphorylated by another enzyme.
What is the molecule that activates phosphorylase?
A molecule called cyclic adenosine monophosphate, or cyclic AMP (cAMP).
What is a second messenger?
A nonprotein signaling molecule that increases in concentration inside a cell in response to a received signal- a molecule that binds at the surface.
What produces cAMP? What activates Adenylyl cyclase?
cAMP is produced from ATP in a reaction that is catalyzed by the enzyme adenylyl cyclase. Adenylyl cyclase is activated by a G protein which is activated when epinephrine binds to its receptor.
What triggerssignal transduction cascade?
Epinephrine binds to its receptor, which then stimulates the G protein and activating adenylyl cyclase. Adenylyl cyclase produces cAMP by ATP. cAMP then binds to an enzyme called cAMP-dependent protein kinase A. cAMP-dependent kinase responds by phosphorylation of the phosphorylase kinase, which then activates phosphorylase (reducing ATP0. Then producing glucose molecules from glycogen.
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