endocrine part 1

Question 1

A new hormone is discovered to be lipid-soluble but does not require a plasma protein for transport. What is the most likely reason for this anomaly?

a) The hormone has a unique charge distribution that allows it to dissolve in plasma
b) The hormone is small enough to diffuse freely without binding proteins
c) The hormone mimics water-soluble hormones by binding to membrane receptors
d) The hormone has a rapid clearance rate, making binding proteins unnecessary

Answer 1

The hormone has a unique charge distribution that allows it to dissolve in plasma
b) Even small lipid-soluble molecules usually need transport proteins unless they’re also polar, which would make them not truly “lipid-soluble” in the usual sense.

c) Refers to mechanism of action, not transport in the bloodstream.

d) Rapid clearance would make it more dependent on binding proteins to prolong its half-life, not less.

Question 2

why are endocrine and exocrine glands different?

Answer 2

endocrine glands lack a duct system

exocrine glands have a duct system (salivary gland)

*some glands have both endo and exocrine properties such as the pancreas

Question 3

explain the types of cell to cell communication

Answer 3

1. endocrine (endocrine hormone travels in the bloodstream and bind to a target cell (far cell)
2. nueroendocrine- neurosystem works with endocrine system, carried by axon, given into blood and reaches distant target cell
3. paracrine: cell produces hormone and releases hormones onto many target cells NEARBY
4. autocrine: the cell produces hormone and works on the cell that is secreted from

Question 4

how do communication in endocrine and nervous system differs?

Answer 4

endocrine: secreted into blood stream and travels long distances, slow due to long distances, and targets multiple cells, some specifity

nervous system: uses diffusion to release nuerotransmitters, acts on nearby cells, fast, and more specufuc

Question 5

Which of the following is correct about
cellular communication?
* Endocrine hormones :
a. have targets far away from the source at a
distant site
b. work on cells in the immediate surrounding
area
c. work on the same cells that produce the

Answer 5

only a is the correct staement

Question 6

If a lipid-soluble hormone suddenly loses its ability to diffuse across the plasma membrane, what is the most likely molecular alteration?
a) It has undergone excessive phosphorylation
b) It has lost its ability to bind to its intracellular receptor
c) Its polarity has increased, making it behave like a water-soluble hormone
d) It has been metabolized into an active derivative

Answer 6

Its polarity has increased, making it behave like a water-soluble hormone

Question 7

Why do water-soluble hormones require membrane receptors instead of intracellular receptors?

Answer 7

their polarity prevents them from entering and going through the lipid bilayer

Question 8

How does hormone solubility influence its mechanism of action?
a) Water-soluble hormones rely on second messengers, while lipid-soluble hormones directly alter gene expression
b) Lipid-soluble hormones are stored in vesicles, while water-soluble hormones are made on demand
c) Water-soluble hormones act slower than lipid-soluble hormones due to membrane receptor activation
d) Lipid-soluble hormones require active transport across the membrane before binding receptors

Answer 8

Water-soluble hormones rely on second messengers, while lipid-soluble hormones directly alter gene expression

Question 9

which of the following hormones are considered as water solubleÉ
a. steroids
b. monoamines
c. proteins
d. thyroid hormones
e. catecholamines

Answer 9

proteins and catecholamines are water soluble

Question 10

which of the following statments is correct?
1. steroid hormones are water soluble
2. all steroid hormones require cholesterol as the starting source
3. steroids are fast acting
4. steroid hormones are made on demand and aren’t stored

Answer 10

• steroid hormones arent stored and made on demand
• steroid hormones orginate from cholesterol

Question 11

what is the difference bewteen protein hormones and steroid hormones in the context of storage and receptors?

Answer 11

protein hormones are synthesized as a prehormone, stored in the cell as secretory vesicles and secreted as a hormone. they bind to receptors on the surface (proteins and catecholamines)

steroid hormones arent stored after synthesis, but made on demnad. bind to intracellular receptors (steroids and thyroid hormones)

Question 12

what triggers the synthesis of steroid hormones?

Answer 12

a hormones that triggers ynthesis of steroid hormones by binding to a receptor on the outside of the cell

Question 13

Why do factors like plasma protein binding and water solubility affect hormone activity?

Answer 13

factors affect biological response. water soluble proteins and lipid soluble hormones generate a different biological response

Plasma protein binding extends hormone half-life, while water solubility affects receptor interaction and clearance

Explanation:

Plasma protein binding protects hormones (e.g., steroid and thyroid hormones) from degradation, prolonging their activity.
Water solubility determines how hormones travel in the blood and interact with receptors—water-soluble hormones act quickly via membrane receptors, while lipid-soluble hormones enter cells and act via intracellular receptors.

Question 14

How do hormones ensure a specific response in their target cells?

a) Hormones circulate freely in the blood and act on all cells they encounter
b) Hormones bind selectively to receptors that specifically recognize them, triggering intracellular signaling or gene expression changes
c) Hormones enter all cells and directly alter their function without requiring receptors
d) Hormones require enzymatic activation before they can bind to any receptor

Answer 14

Hormones bind selectively to receptors that specifically recognize them, triggering intracellular signaling or gene expression changes

Question 15

what is the classification of hormones based on?

Answer 15

1. receptor location (surface or inside the cell)
   this determines the hormones solubility type
2. activation of mechanisms
   (eg surface receptors activate gproteins and catalytic responses)

Question 16

How does signal amplification occur in hormone action?

a) A single hormone molecule activates multiple intracellular molecules, leading to a cascade effect that magnifies the response
b) Hormones increase in concentration over time to ensure a stronger cellular response
c) Hormones bind permanently to their receptors, continuously activating signaling pathways
d) Signal amplification occurs only with lipid-soluble hormones because they directly influence gene transcription

Answer 16

Amplification occurs through second messengers: A single hormone binding event can trigger the production of many second messengers (e.g., cAMP, calcium), which then activate multiple enzymes and proteins inside the cell.
Enzyme activation cascades: One activated enzyme can activate many downstream molecules, greatly amplifying the signal even with a small amount of hormone.
Example: A small amount of epinephrine can trigger a large metabolic response due to second messenger activation.

a

Question 17

What is a hormone?
Which of the following best defines a hormone?
A) A molecule that functions as a neurotransmitter within the nervous system
B) A chemical messenger secreted by a gland that exerts its effect only on nearby cells
C) A signaling molecule released into the bloodstream that regulates physiological functions
D) A protein that catalyzes biochemical reactions in endocrine tissues

Answer 17

A signaling molecule released into the bloodstream that regulates physiological functions

: Hormones are chemical messengers secreted into the bloodstream to regulate physiological processes. Choice A refers to neurotransmitters, while B describes paracrine signaling. D describes enzymes rather than hormones.

Question 18

Hormones can influence body functions in various ways. Which of the following is not a function of hormones?
A) Regulating metabolic processes
B) Directly catalyzing chemical reactions
C) Controlling growth and development
D) Modulating reproductive processes

Answer 18

Directly catalyzing chemical reactions

Rationale: Hormones act as messengers rather than catalysts. Enzymes catalyze biochemical reactions, whereas hormones regulate cellular processes by binding to receptors and initiating signaling pathways.

Question 19

Hormones are commonly classified based on their structure. Which of the following correctly represents a structural classification of hormones?
A) Peptide, steroid, and amine hormones
B) Endocrine, paracrine, and autocrine hormones
C) Lipophilic, hydrophilic, and amphipathic hormones
D) Primary, secondary, and tertiary hormones

Answer 19

Peptide, steroid, and amine hormones

Rationale: Hormones are classified based on their chemical structure into peptide, steroid, and amine hormones. B describes modes of hormone action, while C and D are not common classifications.

Question 20

Which of the following statements about peptide and steroid hormones is true?
A) Peptide hormones bind intracellular receptors, while steroid hormones bind cell surface receptors
B) Steroid hormones act faster than peptide hormones because they directly activate second messengers
C) Peptide hormones are synthesized and stored in vesicles, whereas steroid hormones are synthesized on demand
D) Both peptide and steroid hormones travel freely in the bloodstream

Answer 20

Peptide hormones are synthesized and stored in vesicles, whereas steroid hormones are synthesized on demand

Peptide hormones are stored in vesicles and released upon stimulation, while steroid hormones are synthesized as needed because they are lipid-soluble and cannot be stored in vesicles. A is incorrect because peptide hormones bind cell surface receptors, and steroid hormones bind intracellular receptors. B is incorrect because peptide hormones act faster due to second messengers. D is incorrect because steroid hormones require carrier proteins for transport in the blood.

Question 21

How do hormones act on cells?
Which of the following mechanisms is used by steroid hormones to exert their effects?
A) Binding to membrane receptors to trigger second messenger cascades
B) Directly activating intracellular receptors to regulate gene expression
C) Using vesicle-mediated endocytosis to enter cells
D) Binding ion channels to alter membrane potential

Answer 21

B) Directly activating intracellular receptors to regulate gene expression

Rationale: Steroid hormones are lipophilic and diffuse through the membrane to bind intracellular receptors, leading to gene expression changes. Peptide hormones, not steroid hormones, use second messengers (A). C and D do not describe the action of steroid hormones.

Question 22

When a hormone binds to its receptor, what is the immediate consequence?
A) The hormone is enzymatically degraded to prevent overstimulation
B) A signal transduction pathway is initiated, leading to a cellular response
C) The receptor is internalized, preventing further hormone binding
D) The hormone-receptor complex directly generates ATP for cellular processes

Answer 22

A signal transduction pathway is initiated, leading to a cellular response

Rationale: Hormone binding activates intracellular signaling pathways, leading to changes in cellular function. A is incorrect because hormones are not immediately degraded. C can happen but is not the first step. D is incorrect because ATP production is not a direct function of hormone binding.

Question 23

Which statement best describes signal transduction in endocrinology?
A) The conversion of a hormonal signal into a cellular response via receptor activation
B) The movement of hormones through the bloodstream to distant targets
C) The direct diffusion of steroid hormones into the cytoplasm without receptor interaction
D) The use of ion channels to propagate an electrical signal from hormone binding

Answer 23

The conversion of a hormonal signal into a cellular response via receptor activation

Rationale: Signal transduction involves converting an extracellular signal (hormone binding) into intracellular actions. B refers to hormone transport. C is incorrect because steroid hormones do interact with receptors. D is incorrect because hormones do not typically generate electrical signals.

Question 24

Which of the following is not a common second messenger in endocrine signaling?
A) Cyclic AMP (cAMP)
B) Calcium ions (Ca²⁺)
C) Tyrosine kinase
D) Inositol triphosphate (IP₃)

Answer 24

Tyrosine kinase

Rationale: Second messengers relay signals within the cell, amplifying the response. cAMP, Ca²⁺, and IP₃ are well-known second messengers. Tyrosine kinase is an enzyme, not a second messenger.

Question 25

Which statement correctly distinguishes between peptide and steroid hormone action? A) Peptide hormones use intracellular receptors, while steroid hormones use surface receptors B) Peptide hormones act via second messengers, while steroid hormones regulate gene expression C) Both peptide and steroid hormones enter the nucleus to directly activate transcription D) Steroid hormones use G-protein-coupled receptors to mediate their effects

Answer 25

Peptide hormones bind to cell surface receptors and trigger second messenger pathways, whereas steroid hormones diffuse into cells and bind intracellular receptors, influencing gene transcription. A is incorrect because it reverses the roles. C is incorrect because peptide hormones do not enter the nucleus. D is incorrect because steroid hormones do not use GPCRs. Peptide hormones act via second messengers, while steroid hormones regulate gene expression

Question 26

Which of the following does not play a role in controlling hormone levels? A) Negative feedback mechanisms B) Positive feedback loops C) Random hormone degradation by cellular enzymes D) Tropic hormones that regulate endocrine glands

Answer 26

Random hormone degradation by cellular enzymes Rationale: Hormone levels are regulated by feedback loops and tropic hormones, not random degradation. Enzyme-mediated breakdown occurs but is a controlled process, not random.

Question 27

Which statement about feedback control of hormones is correct? A) Negative feedback increases hormone secretion in response to rising levels of the hormone B) Positive feedback systems amplify responses until a specific physiological event occurs C) Both negative and positive feedback loops reduce hormone secretion D) Feedback control only applies to peptide hormones, not steroid hormones

Answer 27

Positive feedback systems amplify responses until a specific physiological event occurs Rationale: Positive feedback enhances hormone secretion until a physiological goal is met (e.g., oxytocin in childbirth), while negative feedback maintains homeostasis. A is incorrect because negative feedback reduces secretion when levels are high. C is incorrect because positive feedback amplifies responses. D is incorrect because both peptide and steroid hormones are regulated by feedback.

Question 28

which of the following statements correctly describes the role of autophosphorylation in catalytic receptors? A) Autophosphorylation occurs in all cell surface receptors, allowing them to directly enter the nucleus and regulate gene transcription. B) Growth factor receptors and insulin receptors undergo autophosphorylation, which activates intracellular signaling cascades. C) Tyrosine kinase recruitment occurs after ligand binding, but autophosphorylation is unnecessary for signal transduction. D) Phosphorylation only serves to deactivate receptor activity, ensuring a controlled cellular response.

Answer 28

Growth factor receptors and insulin receptors undergo autophosphorylation, which activates intracellular signaling cascades. KNOW that GH and Insulin are catalytic receptors Rationale: Autophosphorylation is a key feature of certain catalytic receptors, such as growth factor receptors and insulin receptors. It leads to the activation of intracellular signaling pathways. A is incorrect because not all cell surface receptors undergo autophosphorylation, and they do not directly enter the nucleus. C is incorrect because autophosphorylation is essential for receptor activation and further signal transduction. D is incorrect because phosphorylation can activate as well as deactivate receptors, depending on the pathway.

Question 29

after a hormone binds to an insulin or GH catalytic receptor, the tyrosine kinase portion is recruited? what causes this?

Answer 29

cytokine receptors

Question 30

why is protein phosphorylating important in cell signalling?

Answer 30

because BOTH protein kinase and protein phosphatase are involved in cell signalling, which can activate or inactivate a protein

Question 31

why do hormones with intracellular receptors act as transcription factors in the nucleus?

Answer 31

act as tf bc these hormones are lipophillic and can diffuse through the plasma membrane and directly interact with DNA and regulating gene expression (this is a slow process)

Question 32

Which of the following is correct (C) or not correct (NC)? Statement 1: Steroid hormones are water soluble Statement 2: All steroid hormones require cholesterol as the starting source Statement 3: Are fast acting

Answer 32

statement 2 is only correct

Question 33

how is upregulation and downregulation different? and how does it happen?

Answer 33

upregulation: is an increase in receptors for a shormone - happen when a hormone is on a low level all the time - why? this makes the cell more sensitive to the hormone and allowing for more cellular activity. down regulation: a decrease in receptors for a hormone - happens when there is too much hormon, this is done to reduce the constant stimulation *recall that hormones have a dose-response relationship (the more, the more sensitive the response from target cells are)

Question 34

why does the ability of a cell responding to a hormone depend on the number of receptors present for that hormone

Answer 34

hormone action follows a dose-response relationship more receptos=greater sensitivity fewer receptors = decreased response

Question 35

Which of the following best describes the permissive action of hormones?

Answer 35

one hormone (hormone A) needs to be present for the full action of another hormone (hormone b) to occur hormone a may upregulate the receptors for hormone B in a target cell (kinda like the power of friendship kinda thing)

Question 36

what is an example of a hormone amplifying the effects of another?

Answer 36

epinephrine and thyroid hormone by itself the thyroid hormone has little to no effect on fatty acid release, with the help of epinephrine, a cell response is amplified, causing large amounts of fatty acids to be released

Question 37

what is a trophic hormone? give an example

Answer 37

when a hormone controls the secretion of another hormone

Question 38

what is the difference between hyposecretion and hypersecretion?

Answer 38

hyposecretion= too little hormone released hypersecretion = too much hormone secreted

Question 39

what is the differences in the endocrine disorders, hyporesponseiveness and hyper responsiveness?

Answer 39

hyporesponsiveness is when the target cells have a reduced response (LARON DWARFISM), defective celll signalling, defective enzyme function in target cells hyperresponsiveness means increased response in target cells

Question 40

Which of the following best describes the negative feedback regulation of parathyroid hormone (PTH) secretion in response to blood calcium levels? A) Low blood Ca²⁺ stimulates PTH release, which increases blood Ca²⁺, leading to further PTH secretion. B) High blood Ca²⁺ directly stimulates the parathyroid gland to release PTH, which further increases Ca²⁺ levels. C) Low blood Ca²⁺ stimulates PTH release, which increases blood Ca²⁺; once Ca²⁺ levels are restored, PTH secretion decreases. D) PTH secretion occurs independently of blood Ca²⁺ levels and follows a circadian rhythm instead.

Answer 40

Low blood Ca²⁺ stimulates PTH release, which increases blood Ca²⁺; once Ca²⁺ levels are restored, PTH secretion decreases. Rationale: Negative feedback means that once blood Ca²⁺ rises to normal levels, PTH secretion decreases, preventing excess Ca²⁺. A is incorrect because continued PTH secretion despite increased Ca²⁺ would create a positive feedback loop. B is incorrect because high Ca²⁺ inhibits PTH, not stimulates it. D is incorrect because PTH secretion is not controlled by circadian rhythms but by Ca²⁺ levels.

Question 41

Which of the following best explains why oxytocin secretion during childbirth is an example of positive feedback? A) Oxytocin release stimulates uterine contractions, which increase cervical stretch, further stimulating oxytocin release until childbirth is complete. B) Oxytocin secretion increases as labor progresses, but once contractions start, its release is inhibited to prevent excessive contractions. C) Oxytocin binds to receptors in the brain, signaling the pituitary to stop further release, ensuring controlled uterine contractions. D) Oxytocin levels remain constant throughout labor, and contractions are regulated independently by the nervous system.

Answer 41

Oxytocin release stimulates uterine contractions, which increase cervical stretch, further stimulating oxytocin release until childbirth is complete. Rationale: Positive feedback amplifies a process until a specific event (childbirth) terminates the loop. A correctly describes this cycle: contractions → cervical stretch → more oxytocin → stronger contractions, repeating until birth. B is incorrect because oxytocin secretion is not inhibited during contractions—it is amplified. C is incorrect because oxytocin is not shut off mid-labor by the brain; rather, birth itself stops the cycle. D is incorrect because oxytocin levels increase dynamically, and contractions are influenced by hormone signaling, not just the nervous system.