Endocrine system and homeostasis

Question 1

What is a hormone?

Answer 1

A chemical messenger secreted by endocrine glands that acts on distant target tissues via the bloodstream.

Question 2

Name the three main classes of hormones.

Answer 2

Polypeptides, amino acid derivatives, and steroids.

Question 3

Which hormones are lipid-soluble?

Answer 3

Steroid hormones like cortisol and testosterone.

Question 4

How do lipid-soluble hormones act on a cell?

Answer 4

They enter the cell and bind intracellular receptors to alter gene transcription.

Question 5

What is a second messenger?

Answer 5

A molecule inside cells that transmits signals from receptors to target molecules (e.g., cAMP).

Question 6

Why do only certain cells respond to a hormone?

Answer 6

Only cells with the appropriate receptor can respond.

Question 7

Can one hormone affect multiple cell types?

Answer 7

Yes, if those cells have the appropriate receptors.

Question 8

What determines hormone effect specificity?

Answer 8

The type of receptor and downstream signaling in the target cell.

Question 9

What gland links the nervous and endocrine systems?

Answer 9

The hypothalamus.

Question 10

Which gland is called the “master gland”?

Answer 10

The pituitary gland.

Question 11

What hormone regulates growth during development?

Answer 11

Growth hormone (GH).

Question 12

What are the functions of the thyroid hormones?

Answer 12

Regulate metabolism, temperature, and development.

Question 13

What hormone controls water

Answer 13

balance?
Antidiuretic hormone (ADH).

Question 14

What hormones regulate sexual development?

Answer 14

Estrogen, testosterone, LH, and FSH.

Question 15

What is the function of oxytocin?

Answer 15

Triggers uterine contractions and milk release; promotes bonding

Question 16

What hormones does the adrenal gland secrete?

Answer 16

Cortisol, aldosterone, epinephrine, and norepinephrine.

Question 17

What does melatonin do?

Answer 17

Regulates sleep-wake cycles and circadian rhythms.

Question 18

What is the HPA axis?

Answer 18

The hypothalamic-pituitary-adrenal axis, coordinating stress and metabolic responses.

Question 19

What hormones does the posterior pituitary release?

Answer 19

ADH and oxytocin.

Question 20

What does ACTH do?

Answer 20

Stimulates cortisol release from the adrenal cortex.

Question 21

How is the pituitary controlled?

Answer 21

By releasing hormones from the hypothalamus.

Question 22

What feedback loop governs cortisol?

Answer 22

Negative feedback from cortisol to the hypothalamus and pituitary.

Question 23

What is the role of the anterior pituitary?

Answer 23

Secretes hormones regulating other endocrine glands.

Question 24

What happens under chronic stress?

Answer 24

Persistent HPA activation, increased cortisol, suppressed immune function.

Question 25

What hormone is linked to “fight or flight”?

Answer 25

Epinephrine.

Question 26

Which hormone modulates water retention?

Answer 26

ADH.

Question 27

How does the brain influence hormone release?

Answer 27

Via sensory input and hypothalamic control.

Question 28

What is an endocrine disruptor?

Answer 28

A chemical that interferes with normal hormone signaling.

Question 29

How do disruptors act?

Answer 29

As hormone mimics (agonists) or blockers (antagonists).

Question 30

Why are small doses of disruptors dangerous?

Answer 30

They act at low concentrations and persist in tissues.

Question 31

What are health impacts of endocrine disruptors?

Answer 31

Fertility issues, developmental problems, hormone-related cancers.

Question 32

What organs are vulnerable to disruption?

Answer 32

All endocrine glands (e.g., thyroid, gonads).

Question 33

What is bioaccumulation?

Answer 33

The buildup of toxins in organisms over time.

Question 34

What is an example of wildlife affected by DDT?

Answer 34

Birds laying thin-shelled eggs.

Question 35

How do disruptors affect the placenta?

Answer 35

They can alter hormonal signaling to the fetus.

Question 36

What is epigenetic disruption?

Answer 36

Long-term changes in gene expression without altering DNA sequence.

Question 37

What is homeostasis?

Answer 37

The regulation of internal conditions to maintain stability.

Question 38

Which systems regulate homeostasis?

Answer 38

The nervous and endocrine systems.

Question 39

What hormone regulates blood sugar?

Answer 39

Insulin and glucagon.

Question 40

What regulates blood calcium?

Answer 40

Calcitonin and parathyroid hormone (PTH).

Question 41

Give an example of positive feedback.

Answer 41

Oxytocin release during labor.

Question 42

Give an example of negative feedback.

Answer 42

Cortisol inhibits ACTH and CRH.

Question 43

What is the role of ADH?

Answer 43

Regulates water balance in kidneys.

Question 44

How does temperature affect homeostasis?

Answer 44

Organisms use behavioral and physiological mechanisms to maintain body temperature.

Question 45

What are ectotherms?

Answer 45

Organisms that rely on external heat sources.

Question 46

What are endotherms?

Answer 46

Organisms that produce metabolic heat.

Question 47

What is brown fat used for?

Answer 47

Non-shivering thermogenesis in mammals.

Question 48

What structure regulates body temperature?

Answer 48

The hypothalamus.

Question 49

What is vasodilation?

Answer 49

Expansion of blood vessels to release heat.

Question 50

What is shivering?

Answer 50

Muscle contractions that generate heat.

Question 51

What adaptations reduce heat loss in cold climates?

Answer 51

Shorter extremities (Allen’s rule), thick fur or fat layers.

Question 52

What is hibernation?

Answer 52

Controlled lowering of body temperature and metabolism.

Question 53

How do bees regulate hive temperature?

Answer 53

By vibrating wings and bodies to generate heat collectively.

Question 54

What is the main trade-off for endotherms?

Answer 54

High energy demand to maintain constant body temperature.