Hormones and Homeostasis Quiz

Question 1

Similarities between Peptide and Steroid Hormones

Answer 1

-Act on target cells/ organs
-Travel through the bloodstream
-Effective at very low concentrations
-Effects last longer than neurotransmitters

Question 2

Examples of Peptide Hormones

Answer 2

Insulin, ADH, Glucagon, FSH, LH, Prolactin, Oxytocin, Growth hormones, Leptin

Question 3

Peptide Hormones Overview

Answer 3

-Made from amino acids (proteins/ water soluble/ polar)
-Do NOT enter target cells (cannot pass through plasma membrane), so bind to receptors on plasma membrane surface (of target cells)
-Binding of hormones to receptors activates a cascade of reactions, carried out by secondary messengers in the cytoplasm of the cell (such as cAMP), which activates or inhibits enzymes/ changes cell’s physiology (such as protein kinase, in the cell).
-Requires use of ATP

Question 4

Examples of Steroid Hormones

Answer 4

Estrogen, Testosterone, Progesterone

Question 5

Steroid Hormones Overview

Answer 5

-Made from cholesterol (lipid soluble/ nonpolar)
-Pass through plasma membrane (phospholipid bilayer) of target cells (steroids are small, hydrophobic molecules)
-Bind to receptor protein(s) in cytoplasm of target cell, forming a receptor-hormone complex - note that these receptor proteins are often gene regulatory proteins
-Receptor-hormone complex moves into nucleus (through nuclear membrane) and regulates gene expression/ act directly on DNA/ binds to DNA (directly promotes or inhibits transcription of specific genes - which controls protein production in a cell – drastically altering the biochemistry of the cell/ tissue etc.)
-Does not require use of ATP

Question 6

The hypothalamus controls…

Answer 6

hormonal secretions by the anterior and posterior pituitary

Question 7

What are the anterior pituitary hormones?

Answer 7

TSH (Thyroid Stimulating Hormone), FSH (Follicle Stimulating Hormone), LH (Luteinizing Hormone), Prolactin, and Growth Hormones

Question 8

TSH (thyroid-stimulating hormone)

Answer 8

Targets cells of the thyroid to make and secrete thyroxin (increases metabolic rate/ energy use/ heat production)

Question 9

FSH (follicle-stimulating hormone)

Answer 9

Targets cells of gonads. In males causes meiosis I to produce secondary spermatocytes. In females it causes primary oocyte to mature and complete meiosis I to produce one secondary oocyte and one polar body.

Question 10

LH (luteinizing hormone)

Answer 10

Targets cells of the gonads In males it causes Leydig cells to make and secrete testosterone (for sperm production). In females, it causes ovulation of an oocyte.

Question 11

Prolactin

Answer 11

Targets cells of the mammary glands for lactation (growth and produce milk; inhibited by progesterone so no milk prior to birth)

Question 12

Growth Hormones

Answer 12

Targets cells throughout the body; stimulates mitosis

Question 13

What are the posterior pituitary hormones?

Answer 13

ADH (Antidiuretic hormone) and Oxytocin

Question 14

ADH (Antidiuretic hormone)

Answer 14

Targets cells of the kidney, increasing the amount of water that is reabsorbed into the blood

Question 15

Oxytocin

Answer 15

Produced in neurosecretory cells in hypothalamus but stored in/ secreted from posterior pituitary; Targets cells of the uterine muscles and mammary glands, causing contractions (for birth) and milk secretion (note that nursing then causes oxytocin to be released to allow milk to be secreted too)

Question 16

Hypothalamus

Answer 16

Body temperature is monitored and controlled by a “biological thermostat” in your brain called the hypothalamus (36 -38°C)

Question 17

HYPOthermia

Answer 17

-Body temp is too LOW (metabolic reactions cannot occur – death below 32°C)
-Thermoreceptors in skin send signals to hypothalamus
-Hypothalamus releases chemical signals that trigger:
* Vasoconstriction (arterioles get smaller, blood is diverted to deep tissues/ organs, less heat loss)
* Shivering of skeletal muscle (generates heat)
* “Goosebumps” – raises hair follicles on skin (traps heat/ insulates against heat loss)

Question 18

HYPERthermia

Answer 18

-Body temp is too HIGH (tissues/ enzymes damaged, above 40°C is deadly)
-Thermoreceptors in skin send signals to hypothalamus
-Hypothalamus releases chemical signals that trigger:
* Vasodilation (arterioles get bigger, fill with blood, transfer heat to skin and out of body)
* Increased sweat gland activity (evaporative cooling)

Question 19

Role of Thyroxin

Answer 19

-Thyroxin is a hormone secreted by the thyroid gland of the endocrine system in response to signals initially derived from the hypothalamus
-Role = regulation of the body’s basal metabolic rate (the amount of energy a body uses AT REST)
-Thyroxin acts on almost all cells in the body, and causes an increase in the body’s metabolic rate/ increases body’s rate of energy release and use
-Causes an increase in carbohydrate and lipid metabolism (more oxidation of glucose and fatty acids)
-Causes increased oxygen consumption and the hydrolysis of ATP; thereby causing an increase in the body’s temperature
-In a regular person, if the body’s temperature drops, a release in thyroxin will stimulate heat production causing the body’s temperature to rise

Question 20

What are the causes of thyroxin deficiency?

Answer 20

-Thyroxin contains iodine
-Prolonged deficiency to iodine in the diet prevents the production of thyroxin (iodine is an essential nutrient)

Question 21

What are the consequences of thyroxin deficiency?

Answer 21

-Iodine deficiency causes the thyroid gland to become enlarged (trying to compensate for iodine deficiency), resulting in a disease known as goitre
-If there is an insufficient (low) amount of thyroxin in the body (due to diet or deficiency in soils that food is grown in), hypothyroidism can occur
* Some of the symptoms are weight gain, loss of energy, feeling cold all the time, forgetfulness and depression, stunted growth, stunted mental development
If there is an excess amount of thyroxin in the body, hyperthyroidism can occur
* Some of the symptoms include excessive sweating/ hunger, hyperactivity, mood swings, rapid heart rate, difficulty sleeping, weight loss, muscle weakness/ tremors

Question 22

What is melatonin?

Answer 22

Produced in pineal gland of brain in response to changes in light.

Question 23

Function of Melatonin

Answer 23

-Controls/regulates 24-hr circadian rhythm/ biological clock (the body’s physiological responses to the 24-hour day-night cycle of activity).
Production/ amount of melatonin secreted is controlled by amount of light detected by the retina.
-Higher production/secretion in the dark vs little to no production in daytime (production is suppressed by bright light - mostly blue wavelengths).
-Amount of melatonin produced is proportional to night time duration as well (longer nights = more melatonin)
-Amount of melatonin secreted and timing of melatonin secretion becomes entrained in the body over prolonged periods of time
-Melatonin affects sleep-wake cycles and
seasonal reproduction
-Promotes sleep in diurnal animals (like us)
-Promotes activity in nocturnal animals
-As we age, melatonin levels naturally decrease

Question 24

What is jet-lag?

Answer 24

a physiological condition resulting from a change to the body’s normal circadian rhythm

Question 25

Causes of jet-lag

Answer 25

-The body’s inability to rapidly adjust to a new time zone (following extended air travel through multiple time zones)
-The pineal gland continues to secrete melatonin according to the “old” time zone schedule

Question 26

Consequences of jet-lag

Answer 26

-Sleep disturbance and fatigue - symptoms include headaches, lethargy, irritability, and reduced cognitive function

Question 27

Treatments of jet-lag

Answer 27

-Taking melatonin supplements (artificially increasing melatonin levels in the body) around the sleep time of the new time zone can help to alleviate symptoms of jet lag and help the body adjust to the new time zone faster

Question 28

Hormonal and Nervous Communication Similarities

Answer 28

-Both use chemicals that bind to receptors
-Both used for COMMUNICATION between cells in the body
-Both cause a response in target cells
-Both can stimulate or inhibit processes in target cells
-Both can cause changes over long distances
-Both use feedback mechanisms to maintain homeostasis
-Both under (overall) control of brain/ CNS

Question 29

Hormonal and Nervous Communication Differences

Answer 29

-Chemical (messenger) / Electrical (nerve impulse)
Messenger (hormones) transported in blood / Signal transported by neurons
Slower / Faster
-Carried throughout body / -Carried to single/ specific cell/ muscle fibre
-Wide range of organs/ tissues affected / Only muscles/ glands receive signals
-Long-term/ persistent response (usually) / Short-term/ short-lived response

Question 30

Anterior Pituitary Overview

Answer 30

produces “releasing factors,” released into portal blood vessels by neurosecretory cells, cause endocrine cells in anterior pituitary to release hormones into blood

Question 31

Posterior Pituitary Overview

Answer 31

Hypothalamus neurosecretory cells extend down into posterior pituitary and release hormones into blood (hormones produced by hypothalamus)

Question 32

What are the overall functions of the pituitary? (MARGE

Answer 32

Metabolism
Adult development
Reproduction
Growth
Equilibrium/
homeostasis (ADH and water balance)