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Endocrine system (1)
Bio 3 Lecture 11
| Question | Answer |
|---|---|
| What's the second control system of our body? The first? | The endocrine system, first is the nervous system |
| Does the endocrine system act slowly or fastly? | Slowly |
| In general, how does the endocrine system works? | It uses chemical messages called hormones. |
| Where are hormones produced? | They're produced in organs called glands and carried in the blood |
| What distributes neurotransmitters? Give an example of a neurotransmitter | It's distributed by the blood and act as neuro-hormones. Ex: norepinephrine |
| What are neuro-hormones? What are they carried by? | Neurohormones are hormones associated with the nervous system rather than the endocrine system. They're carried by blood. |
| Recall how a message is transmitted from the axon to the postsynaptic cell (aka synaptic transmission) | Axon secrete chemical messengers called neurotransmitters into the synaptic cleft. The chemicals diffuse at a short distance of the postsynaptic membrane where they bind to their receptor proteins and stimulate the postsynaptic cell. |
| In message transmition from the axon to the postsynaptic cell, we can conclude that a (short/long) distance is needed for transmission | Short, because the chemicals diffuse from the synaptic cleft to the postsynaptic membrane, which are at short distance from eachother. |
| What is a hormorne and how are they different from synaptic transmission? | A hormone is a regulatory chemical that is secreted into extracellular fluid and carried by the blood, it can therefore act at a distance from its source (synaptic transmission is done at a short distance) |
| Does the blood carry hormones in every cell of the body? | Yes, but it only targets cells witht he appropriate receptor for the given hormone |
| The highly specific interaction between hormones and their receptors enable hormones to active at a ... concentration. | Hormones can activate at very small concentration bc of the high specific interaction |
| We have neurotransmitters and hormones which act as chemical messengers, how do we call the other chemicals released that act within an organ on nearby cells as local regulators? | Paracrine regulators |
| What are paracrine regulators? How are they different from endocrine hormones? | Chemicals released that act within an organ on nearby cells as local regulators. They don't travel by blood to reach their target. |
| What are endocrine and exocrine glands? | Endocrine glands secrete hormones into the blood. Exocrine glands secrete their product (like saliva and milk) into a duct for transport to the outside. |
| There's different types of chemical messengers, what are they? | The function of organs are influenced by: neural, paracrine and endocrine regulators (which are all chemical messengers) |
| Chemical hormones can be divided into 2 sybtypes, what are they? | Subdivided according to chemical structure and polarity |
| What is included into the chemical structure subtype? | 1) Proteins 2) Amino acids and derivatives 3) Steroids |
| What is included into the polarity subtype? | 1) Lipophilic (fat-soluble, non-polar) 2) Hydrophilic (water-soluble, polar) |
| [Polarity subtype] What do lipophilic and hydroplilic bind to? | Lipophilic binds to intracellular receptors and hydrophilic binds to extracellular receptors |
| Explain the process of transport of hormones through the blood | 1) Hormones are secreted into extracellular fluid and diffuse out into the bloodstream 2)Hormones are distributed by blood to all cells. They diffuse from blood to extracellular fluid 3) Target cells with receptor are activated by hormones |
| What happen to unused desactivated hormones? | They are removed by the liver and kidney (excreted by bile or urine) |
| Does stimulation occur in nontarget cells? | No bc they lack the receptors needed for stimulation to occur |
| Which type of hormone is desactivated more rapidly? Why? | Hydrophilic hormones are desactivated more rapidly than lipophilic hormones bc hydrophilic are active a brief period of time vs. lipophilic are active over prolonged periods of time |
| Hormones can be separated into sterioids and nonsteroids, what category contains the most hormones? | Nonsteroids |
| What is included into nonsteroid hormones? | Proteins, glycoproteins, peptides and amino acid derivatives |
| Where and how does lipophilic hormones circulate? | Circulate in the blood attached to a transport protein |
| [Lipophilic] When does the lipophilic hormone detach from the carrier? | When it reached the target cell |
| [Lipophilic] They pass through the cell membrane and bind to what? | After passing through the cell membrane, tjey bind to intracellular receptor (either in cytoplasm or nucleus) |
| [Lipophilic] What forms once the lipophilic hormone passes through the cell membrane and binds to the receptor? | A hormone-receptor complex is formed to regulate gene expression |
| Explain the mechanism of lipophilic hormone action. | 1)Hormone passes through PM 2)Inside the target cell, the hormone binds to a receptor protein in the cytoplasm/nucleus 3)Hormone-receptor complex binds to hormone response response element on DNA, regulating gene transcription 4)Protein synthesis |
| What is cellular response? | The change in protein synthesis after the hormone-receptor complex binds to the hormone response element on DNA. |
| In more details, how does lipophilic hormones affect the regulation of gene expression? | Hormone receptor binds to a specific DNA sequences in genome (called hormone receptor elements HRE). The binding has a direct effect on the level of transcription. |
| Where and how does hydrophilic hormones circulate? | They circulate in the blood WITHOUT a transport carrier. |
| Why can't hydrophilic hormone pass through the membrane of the target cells? | They're too large or polar, so they cant cross (like peptide, protein and glycoprotein hormone) |
| What does the hydrophilic hormone bind to? | To the extracellular receptors |
| [Hydrophilic] What do receptors activate and what does it alter? | Receptors activate the kinase enzymes that alter cellular activity. |
| Hydrophilic hormones work by producing something, what is it? | Work by producing second messengers (cAMP, c is for cyclic) |
| Can lipophilic hormone directly affect gene expression? | Yes |
| In resume, how fast or slow do hydrophilic and lipophilic hormones work? | Hydrophilic work rapidly, it's a matter of minutes/hours. Lipophilic takes more time, aka days to weeks |
| What are the main endocrine glands? | There's the pituitary gland, thyroid gland, parathyroid gland, adrenal glands, pineal gland, testes for males and ovaries for females, hypothalamus, |
| Where is the pituitary gland located? | It hangs by a stalk from the hypothalamus |
| The pituirary gland consist of 2 parts, what are they and what is their appearance? | 1) Anterior pituitary gland that appears glandular 2) Posterior pituitary gland that appears fibrous |
| Locate the parts of the pituirary gland | See slide 17 |
| How is the posterior pituitary gland connected to the hypothalamus? | Connected by tract of axons |
| What does the posterior pituitary gland store and releases? How are they produced? | It stores and releases 2 hormones (ADH and oxytocin) which are produced by neurons in the hypothalamus |
| [Posterior pituitary gland] What does oxytocin do? Functions | In mammals, it stimulates milk ejection reflex and uterine contraction during labor. It regulates reproductive behavior. |
| [Posterior pituitary gland] Explain for example how oxytocin works in uterine contractions (process) | 1) Head of fetus pushes against cervix 2) Nerve impulses from cervix transmitted to brain 3) Brain stimulates pituitary gland to secrete oxytocin 4) Oxytocin carried in bloodstream to uterus 5) Oxytocin stimulates uterine contractions |
| [Posterior pituitary gland] What does ADH (Antidiuretic hormone) do? | It stimulates water reabsorption by the kidney and thus inhibits urine production |
| See the negative feedback mechanisms on class notes | -_- ? |
| What are the hypothalamus and anterior pituitary gland partially controlled by? | By the hormones whose secretion they stimulate (with negative feedback inhibition) |
| Draw the negative feeback mechanism of the thyroid gland hormones | |
| What would happen if ADH was missing? | ADH takes care of water reabsorption by the kidney and thus inhibits urine production, SO if there was no ADH, the kidneys wouldn't reabsord as much water and excessive quantities of urine would be produced. |
| What kind of hormones are ADH and oxytocin? | Neurohormones |
| The anterior pituitary gland produced 6 essential hormones, what are they collectively called? | The tropic hormones |
| What are the 6 essential hormones produced by the anterior pituitary gland? | ACTH, GH, PRL, TSH, LH and FSH |
| [Anterior pituitary gland] What does GH (growth hormone) stimulates? | Growth of muscles and connective tissue. Also growth of bones but indirectly |
| [Anterior pituitary gland] What causes gigantism? | It's caused by an excessive secretion of growth hormone (GH) during childhood only. |
| [Anterior pituitary gland] What causes pituitary dwarfism? | It's caused by a deficiency in GH secretion during childhood. |
| [Anterior pituitary gland] Can GH cause an increase of height in adults? | No, because the human cartilage plates transform into bones at puberty |
| [Anterior pituitary gland] What does an excessive GH secretion cause in adults? | Causes acromegaly (aka bone and soft tissues demoformities) |
| [Anterior pituitary gland] In general, what is ACTH for? Aka what does it target? | Stimulates the adrenal cortex to produce corticosteroid hormones (and cortisol). Regulates glucose homeostatis and important in response to stress |
| [Anterior pituitary gland] In general, what is PRL for? Aka what does it target? | Mainly stimulates mammary glands to produce milk in mammals, but also regulates iron regulation and water transport. |
| [Anterior pituitary gland] In general, what is TSH for? Aka what does it target? | Stimulates thyroid gland to produce thyroxine hormone, which in turn regulates development and metabolism |
| [Anterior pituitary gland] In general, what is LH for? Aka what does it target? | Stimulates production of estrogen and progesterone by ovaries and is needed for ovulation. In males, stimulates testes to produce testosterone, which is needed for sperm production |
| [Anterior pituitary gland] In general, what is FSH for? Aka what does it target? | Required for development of ovarian follicles in females. In males, required for development of sperm. |
Created by:
Malayka
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