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Exam 1 flashcards by MATI (endocrine system)

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이 집합의 용어 (65)

  • what are the main differences of the endocrine system compared with the nervous system?

    1. initiates slow responses

    2. long duration responses

    3. acts over long distances

    4. acts via hormones released into the blood

    5. acts at diffuses locations (anywhere blood reaches targets can be)

    6. signal strength coded by concentration of hormone

  • What are the major processes controlled and integrated by the endocrine system?

    1. reproduction

    2. growth and development

    3. regulation of electrolytes/water/nutrients

    4. balance of blood

    5. regulation of cellular metabolism and energy balance

    6. mobilization of body defenses

  • What are exocrine glands?

    1. Produce nonhormonal substances (e.g., sweat, saliva)

    2. Have ducts to carry secretion to a (cutaneous or mucous) membrane surface

  • What are endocrine glands?

    1. Produce hormones

    2. Ductless; hormones secreted directly into the surrounding extracellular fluid

  • what are types of endocrine glands?

    1. pituitary

    2. thyroid

    3. parathyroid

    4. adrenal

    5. pineal glands

  • The hypothalamus is what type of organ and what does that mean?

    It is a neuroendocrine organ meaning it works with both (acts a bridge) the endocrine and nervous system; it receives signals from the nervous system and responds by releasing hormones into the bloodstream

  • what are hormones?

    long-distance chemical signals of the endocrine system; travel in blood to reach target cells

  • What are paracrines?

    locally acting chemicals that affect neighboring cells (talking to a neighbor)

  • what are autocrines?

    chemicals that exert effects on same cells that secrete them (auto = its own self)

  • What are the two main classes of hormones?

    1. amino based

    2. steroids

  • Characteristics of amino based acids?

    1. Amino acid derivatives, peptides, and proteins

    2. Water soluble (except thyroxine), cannot cross plasma membrane

  • Characteristics of steroids?

    1. Synthesized from cholesterol

    2. Lipid soluble, can cross plasma membrane

    3. Includes gonadal and adrenocortical hormones

  • What is a possible third class of hormone?

    eicosanoids, are considered hormones by some scientists, but most classify them as paracrine and autocrine given their highly localized effects

  • Tissue cells with receptors for a specific hormone are called?

    Target cells

  • How do hormones alter target cells?

    1. Alter plasma membrane permeability and/or membrane potential by opening or closing ion channels

    2. Stimulate synthesis of enzymes or other protein

    3. Activate or deactivate enzyme

    4. Induce secretory activity

    5. Stimulate mitosis (cell division)

  • How do amino-acid based hormones act?

    1. Act on plasma membrane receptors

    2. Cannot cross plasma membrane to enter cell (water-soluble)

    3. Most are coupled via G proteins to second messengers

  • How do steroid hormones act?

    1. Act on intracellular receptors that directly activate genes

    2. Can diffuse across plasma membrane to enter cell (lipid-soluble)

  • What are the 2 types of second messengers used by amino acid hormones?

    1. Cyclic AMP

    2. PIP2- Calcium

  • What does the cAMP signaling mechanism look like?

    1. Hormone binds receptor

    2. Receptor activates G protein

    3. G protein activates/inhibits adenylate cyclase

    4. ATP → cAMP

    5. cAMP activates kinases that phosphorylate proteins

    6. Cascade amplifies signal

    7. Proteins activated/inactivated

    8. Phosphodiesterase degrades cAMP, ending cascade

  • what does the pip2 calcium signaling mechanism look like?

    1. G protein activates phospholipase C

    2. PLC splits PIP2 into DAG + IP3

    3. DAG activates protein kinases

    4. IP3 triggers Ca²⁺ release from storage

    5. Ca²⁺ alters enzymes/channels or binds calmodulin

    6. Ca²⁺-calmodulin activates enzymes, amplifying response

  • what could be other types of signaling mechanisms?

    1. cGMP (cyclic guanosine monophosphate) is a second messenger for some hormones

    2. Other hormones work w/o second messenger system

      1. insulin receptor is a tyrosine kinase enzyme that auto phosphorylates upon insulin binding

        1. It provides docking sites for relay proteins that trigger cell responses

  • what is a first messenger?

    an extracellular signaling molecule that binds to a cell surface receptor to initiate a cellular response

  • what is a second messenger?

    a small molecule inside a cell that relays and amplifies a signal from a hormone outside the cell with a message stuck on the outside of the cell's surface.

  • what is a G protein?

    a molecular switch inside a cell that transmits chemical signals from the outside of the cell to the inside, it sits next to a receptor in cell membrane (binds to GTP)

  • What is Adenylate cyclase?

    a cell enzyme that turns cellular energy (ATP) into a chemical messenger called cyclic AMP (cAMP) (second messenger)

  • what is phosphodiesterase?

    a type of enzyme that breaks down (degrades) specific chemical bonds inside cells

  • what is phospholipase C?

    an enzyme that breaks down (degrades) phospholipids

  • What is PIP2?

    a minor phospholipid component of cell membranes (molecular switch located on the inner surface of the cell membrane that helps transmit signals from outside the cell to the inside)

  • what is Diacylglycerol (DAG)?

    a type of fat molecule made of a glycerol (helps pass chemical signals inside the body's cells)

  • What is inositol triphosphate (IP3)?

    a water-soluble second messenger molecule that helps cells respond to outside signals like hormones

  • What calmodulin?

    1. a small, specialized protein found in all eukaryotic cells (cells with a nucleus).

    2. It acts as a calcium sensor and messenger. Because it cannot function without calcium (binds to it)

    3. Calmodulin acts like an on/off switch for other proteins in the body

  • what are the 3 types of endocrine stimuli?

    1. humoral

    2. neural

    3. hormonal

  • what is a humoral stimulus?

    Changing blood levels of ions and nutrients directly stimulate release of hormones

  • what is an example of humoral stimulus?

    1. a drop in blood calcium levels stimulates the parathyroid gland to secrete Parathyroid Hormone (PTH)

    2. PTH causes calcium causes calcium to rise and stimulus ends

  • What is a neural stimulus?

    Nerve fibers cause hormone release

  • what is an example of a neural stimulus?

    1. stressors activate neurons in hypothalamus

    2. signals down spinal cord

    3. to preganglionic fibers

    4. stimulate adrenal medulla to secrete catecholamines such as norepinephrine and epinephrine (happens when there's trauma to the body) (fight or flight from sympathetic system)

  • what is a hormonal stimulus?

    Hormones stimulate other endocrine organs to release their hormones

  • what is an example of a hormonal stimulus?

    1. Hypothalamic hormones stimulate the anterior pituitary gland to releases hormones

    2. anterior pituitary hormones cause release of hormones of other endocrine organs such as adrenal cortex, thyroid gland and gonads

    3. these target organs inhibit hormonal release from anterior pituitary and hypothalamus

  • Degree of target cell activation depends on what 3 factors?

    1. Blood levels of hormone

    2. Relative number of target cell receptors

    3. Affinity (strength) of binding between hormone and receptor

  • what is up-regulation?

    1. target cells add receptors in response to persistently low levels

      1. Allows target cell to become more sensitive to less hormone

  • what is down-regulation?

    1. cells remove receptors in response to persistently high levels

      1. Desensitizes the target cells to prevent them from being over stimulated

  • what is a half-life?

    1. time required for level of hormone in blood to decrease by half

    Note: Varies from a fraction of a minute to a week, depending on hormone

  • what is permissiveness?

    one hormone cannot exert its effects without another hormone being present

  • what is synergism?

    more than one hormone produces same effects at target cell and combined effects are amplified

  • what is an example of synergism?

    glucagon and epinephrine both cause liver to release glucose

  • what is antagonism?

    one or more hormones oppose(s) action of another hormone

  • what is an example of antagonism?

    glucagon raises blood glucose while insulin lowers it

  • Hypothalamus is connected to pituitary gland (hypophysis) via a stalk called?

    Infundibulum

  • what are the 2 major lobes of the pituitary gland?

    1. posterior pituitary (neurohypophysis)

    2. anterior pituitary (adenohypophysis)

  • the posterior pituitary gland made of neurla tissue secretes 2 of what type of hormone?

    neurohormones

  • what are the 2 neurohormones are secreted by the posterior pituitary?

    1. oxytocin

    2. ADH

  • what is ADH?

    Antidiuretic Hormone

  • the anterior pituitary mad of glandular tissue derived from an out pocketing of oral mucosa secretes how many hormones?

    6 (GH, TSH, ACTH, FSH, LH, PRL)

  • what is GH?

    Growth Hormone

  • what is TSH?

    Thyroid Stimulating Hormone

  • what is ACTH?

    Adrenal Corticotropic Hormone

  • what is FSH?

    Follicle Stimulating Hormone

  • what is LH?

    Luteinizing Hormone

  • What is PRL?

    Prolactin

  • Axons connecting hypothalamus to posterior pituitary form what?

    hypothalamic-hypophyseal tract

  • this tract arises from what neuron cell bodies?

    paraventricular and supraoptic nuclei of hypothalamus and runs through the infundibulum

  • the anterior pituitary is vascularly connected to hypothalamus via a hypophyseal portal system, which consists of what 3 structures?

    1. Primary capillary plexus

    2. Hypophyseal portal veins

    3. Secondary capillary plexus

  • how does the hypophyseal portal system (special blood vessels) play a role in the secretion of hormones?

    1. the releasing and inhibiting hormones from hypothalamus travel through hypophyseal portal system to anterior pituitary to regulate secretion of its 6 hormones

    2. in other words, the hypophyseal portal system controls the release of anterior pituitary hormones

  • Posterior pituitary consists of axon terminals of neurons whose cell bodies form hypothalamic nuclei, what are these nuclei and what hormone do they secrete?

    1. Paraventricular nuclei mostly produce oxytocin

    2. Supraoptic nuclei mostly produce antidiuretic hormone (ADH)

  • These 2 hormones are made of what?

    small peptides (nine amino acids each)