HUB191 L25 Endocrine System 1: Introduction Flashcards

Question

Hormones?

Answer 1

Are chemicals released by endocrine cells

Answer 2

Signals that act locally on nearby cells. They don't travel far through the blood

Answer 3

Signals that act on the same cell that secreted them. The cell "talks to itself" to regulate its own activity

Answer 4

Amino acid derivatives are hormones that are made by changing (modifying) certain amino acids The body takes an amino acid (like tyrosine or tryptophan) and chemically changes it to make a hormone

Answer 5

Think of amino acids like basic ingredients (like flour or sugar). The body modifies them into different "baked goods" (different hormones) depending on what it needs

Answer 6

Peptide hormones are short chains of 3–49 amino acids, are water soluble, and act by binding to receptors on the outside of cells. Examples include ADH and oxytocin. Analogy: Peptide hormones are like small messengers that swim through your blood (like little boats) and knock on the outside doors of cells to deliver a message

Answer 7

Protein hormones are large chains of 50–200 amino acids, like growth hormone, insulin, and prolactin. If they have sugars attached, they are called glycoprotein hormones Protein hormones are like big delivery trucks made of amino acids, carrying important messages through your blood. If they have "sugar decorations" stuck onto them, they are called glycoproteins — like trucks with colourful banners added!

Answer 8

Protein and peptide hormones are first made as large inactive preprohormones on the RER, then trimmed into prohormones in the ER, packaged into vesicles in the Golgi, and finally cut into active hormones before being secreted by exocytosis Analogy: Preprohormone = rough, oversized model with extra parts. Prohormone = trimmed down model, but still not perfect. Active hormone = final, working toy ready to ship. Inactive fragments = leftover pieces you throw away.

Answer 9

Steroid hormones are lipid-soluble hormones made from cholesterol, with differences in attached chemical groups giving them diverse effects. They are carried in the bloodstream by transport proteins, allowing them to remain active longer than peptide hormones. Analogy: Imagine steroid hormones are like special delivery packages made from a fatty material. Because they are lipid-soluble, they can easily travel through fatty walls (like cell membranes) and need a truck (transport proteins) to carry them to the target areas in the body

Answer 10

The hormone itself and The particular target cells Water-soluble hormones bind to receptors on the cell membrane. Lipid-soluble hormones bind to receptors inside the cytoplasm or nucleus.

Answer 11

Free thyroid hormone crosses the cell membrane, binds to receptors in the mitochondria to boost energy production, and binds in the nucleus to change gene activity and make new proteins through gene activation Thyroid hormone, like a VIP guest, walks straight into the cell (no key needed), boosts energy in the power room (mitochondria), and updates instructions in the control room (nucleus)

Answer 12

Hormone as the "first messenger" When the hormone arrives, it binds to the receptor (integral membrane proteins) on the outside of the cell. The hormone is called the "first messenger" because it delivers the message to the receptor. Activating the G protein and making a "second messenger" The receptor changes shape when the hormone binds and activates a G protein (a helper inside the membrane). The G protein then activates enzymes, like adenylate cyclase (AC). These enzymes create second messengers inside the cell Summary: Water-soluble hormones bind to receptors on the cell surface, use a G protein to activate enzymes, and create second messengers like cAMP or calcium to carry the signal inside and cause changes

Answer 13

Think of the hormone like someone ringing a doorbell. They don’t come inside, but when they ring it (bind the receptor), it alerts people inside (the G protein and second messengers) to start doing stuff!

Answer 14

Part of the GPCR sticks outside the cell to catch signals (like hormones), and part sticks inside to talk to the inside of the cell. G-proteins are helper proteins inside the cell, attached to the GPCR. They can bind special energy molecules called GTP (active form) or GDP (inactive form). A hormone binds to the outside part of the GPCR. (Like pressing a doorbell!). This activates the G-protein inside the cell. The G-protein then splits into parts, and these parts can do two things: Activate an enzyme (like adenylate cyclase), which then makes a second messenger (like cAMP) inside the cell. Open ion channels, like calcium (Ca²⁺) channels, letting Ca²⁺ flow into the cell. These second messengers (like cAMP or Ca²⁺) then turn other enzymes on or off inside the cell Summary: GPCRs are special receptors that, when a hormone binds, activate G-proteins inside the cell to either create second messengers like cAMP or control ion channels like Ca²⁺, leading to changes inside the cell.

Answer 15

Think of GPCRs like a doorbell system: The hormone presses the button outside (binds the receptor), This wakes up people inside (activates the G-protein), They send a text or open a door (make second messengers or open ion channels) Which makes the house do things (switch enzymes on/off)

Answer 16

At rest, the G-protein inside the cell is inactive and holds GDP. When a hormone binds to the G-protein coupled receptor (GPCR) on the cell surface, the receptor changes shape and causes the G-protein to release GDP and bind GTP instead. This switch to GTP activates the G-protein. The activated G-protein then splits apart, and its α subunit (carrying GTP) travels inside the membrane

Answer 17

Think of the G-protein like a delivery driver: At first, they are sitting in the office (with an old job ticket — GDP). A new call (hormone) comes in, and they swap the old ticket for a new delivery ticket (GTP). They rush off to deliver the package (activate enzymes or ion channels). Once they finish the delivery, they throw away the ticket and come back to the office (reset to GDP and inactive).

Answer 18

Can bind to an ion channel, calcium acts as a second messenger, calcium binds to Calmodulin, activating Enzymes producing Intracellular Effects. Can bind to adenylate cyclase on the inner membrane, adenylate cyclase with ATP becomes lots of cAMP (cyclic adenosine monophosphate), activating protein Kinase A which attaches phosphates groups to enzymes producing Intracellular Effects.

Answer 19

Phosphodiesterase breaks down cAMP (cyclic adenosine monophosphate), converting it into 5AMP terminating the process Activated G-protein hydrolyses GTP back to GDP so everything goes back to resting state, Alpha subunit goes back rejoins G-protein terminating the process.

HUB191 L25 Endocrine System 1: Introduction Flashcards

(44 cards)