Chapter 5: The Endocrine System Flashcards
1
Q
Based on their chemical identities, what are the three types of hormones?
A
- Peptides
- Steroids
- Amino acid derivatives
2
Q
What are peptide hormones derived from?
A
- From larger precursor polypeptides that are cleaved during posttranslational modification
- These smaller units are transported to the Golgi apparatus for further modifications that activate the hormone and direct it to the correct location in the cell
3
Q
Why must peptide hormones bind to an extracellular receptor?
A
Because they are charged and cannot pass through the plasma membrane
4
Q
Peptide hormones are considered _______ messengers.
A
first
5
Q
At each step of a signaling cascade, there is the possibility of what?
A
Amplification
6
Q
What are some common secondary messengers?
A
cAMP, inositol triphosphate (IP3), and calcium
7
Q
What are the characteristics of the effects of peptide hormones? Why?
A
Rapid and short-lived because these hormones act through transient second messenger systems
8
Q
Which hormones are quicker to turn on and off: peptide hormones or steroid hormones?
A
Peptide hormones, but their effects do not last without constant stimulation
9
Q
Do peptide hormones require carriers?
A
No since they are generally water-soluble, they can travel freely in the bloodstream
10
Q
What are steroid hormones derived from? What are they primarily produced by?
A
- Derived from cholesterol
- Produced primarily by the gonads and adrenal cortex
11
Q
Which hormones can easily cross cell membranes? Why%
A
Steroid hormones because they are derived from nonpolar molecules
12
Q
Where are the receptors for steroid hormones usually found?
A
Intracellularly (cytosol) or intranuclearly (nucleus)
13
Q
How do steroid hormones function?
A
- Steroid-receptor intracellular complex undergoes conformational changes (ex: dimerization)
- The receptor binds directly to DNA to alter gene transcription (increase or decrease) –> alterations in the amount of mRNA and protein present in a cell
14
Q
Do steroid hormones require carriers?
A
- Yes, since they are not water-soluble
- They must dissociate from their carrier to function
15
Q
What are amino acid-derivative hormones derived from?
A
One or two amino acids, usually with a few additional modifications
16
Q
How do catecholamines function? What kind of hormone are they? Give examples.
A
- Amino acid-derivative hormones (epinephrine and norepinephrine)
- Bind to G protein-coupled receptors
17
Q
How do thyroid hormones function? What kind of hormone are they?
A
- Amino acid-derivative hormones
- Bind intracellulary
18
Q
What are the characteristics of the catecholamines?
A
Extremely fast onset but are short-lived
19
Q
What are the characteristics of thyroxine and triiodothyronine?
A
Slower onset but a longer duration
20
Q
What are direct hormones? What major effects do they have? Give an example.
A
- Hormones that are secreted and then act directly on a target tissue
- Major effects in non-endocrine tissues
- Insulin released by the pancreas
21
Q
What are tropic hormones? What major effects do they have? Give an example.
A
- Hormones that require an intermediary to act
- Major effects in other endocrine tissues
- GnRH stimulates LH and FSH
22
Q
Where do tropic hormones usually originate in?
A
Brain and anterior pituitary gland
23
Q
Most peptide and amino acid-derivative hormones have names that end in what?
A
-in or -ine
24
Q
Most steroid hormones have names that end in what?
A
-one, -ol, -oid
25
What structure regulates the pituitary gland? How?
The hypothalamus through tropic hormones
26
Where is the hypothalamus located?
In the forebrain, directly above the pituitary gland and below the thalamus
27
What is negative feedback?
Occurs when a hormone (or a product) later in the pathway inhibits hormones (or enzymes) earlier in the pathway
28
What system directly connects the hypothalamus with the anterior pituitary?
Hypophyseal portal system
29
GnRH, released by the hypothalamus, causes the release of what other hormones? From where?
- FSH and LH
| - From the anterior pituitary
30
GHRH, released by the hypothalamus, causes the release of what other hormones? From where?
- Growth hormone
| - From the anterior pituitary
31
THR, released by the hypothalamus, causes the release of what other hormones? From where?
- Thyroid-stimulating hormone (TSH)
| - From the anterior pituitary
32
Corticotropin-releasing factor (CRF), released by the hypothalamus, causes the release of what other hormones? From where?
- Adrenocorticotropic hormone (ACTH)
| - From the anterior pituitary
33
As long as the hypothalamus releases ____________, no __________ will be released.
prolactin-inhibiting factor (PIF)
| prolactin
34
Prolactin-inhibiting factor is actually what?
Dopamine
35
What inhibits the hypothalamus and anterior pituitary from releasing CRF and ACTH?
ACTH causes the adrenal cortex to increase the levels of cortisol, which inhibits the secretion of CRF and ACTH in a negative feedback loop
36
What connects the hypothalamus to the posterior pituitary?
Neurons in the hypothalamus send their axons down the pituitary stalk directly into the posterior pituitary
37
What is the mnemonic to remember the products of the anterior pituitary?
F: FSH (tropic)
L: LH (tropic)
A: ACTH (tropic)
T: TSH (tropic
P: Prolactin (direct)
E: Endorphins (direct)
G: Growth hormone (direct)
38
What does nipple stimulation cause?
Activation of the hypothalamus
39
Activation of the hypothalamus by nipple stimulation leads to two effects. What are they?
1) Oxytocin is released from the posterior pituitary; contraction of the smooth muscle of the breast and ejection of milk through the nipple
2) Hypothalamus stops releasing dopamine onto the anterior pituitary
40
Where does bone growth originate?
In epiphyseal plates
41
What does an excess of growth hormone released in childhood cause? What does a deficit cause?
- Excess: gigantism
| - Deficit: dwarfism
42
What is acromegaly?
An excess of growth hormone in adults, which results in an increase in the size of small bones (hands, feet, head)
43
What is the function of follicle-stimulating hormone? What type of hormone is it? What is the source?
- Anterior pituitary
- Peptide
- Stimulates follicle maturation in females; spermatogenesis in males
44
What is the function of luteinizing hormone (LH)? What type of hormone is it? What is the source?
- Anterior pituitary
- Peptide
- Stimulates ovulation in females; testosterone synthesis in males
45
What is the function of adrenocorticotropic hormone (ACTH)? What type of hormone is it? What is the source?
- Anterior pituitary
- Peptide
- Stimulates the adrenal cortex to synthesize and secrete glucocorticoids
46
What is the function of thyroid-stimulating hormone? What type of hormone is it? What is the source?
- Anterior pituitary
- Peptide
- Stimulates the thyroid to produce thyroid hormones
47
What is the function of prolactin? What type of hormone is it? What is the source?
- Anterior pituitary
- Peptide
- Stimulates milk production and secretion
48
What is the function of endorphins? What type of hormone is it? What is the source?
- Anterior pituitary
- Peptide
- Decreases sensation of pain; can promote euphoria
49
What is the function of growth hormone? What type of hormone is it? What is the source?
- Anterior pituitary
- Peptide
- Stimulates bone and muscle growth; raises blood glucose levels
50
What is the function of antidiuretic hormone (ADH; vasopressin)? What type of hormone is it? What is the source?
- Hypothalamus (released by posterior pituitary)
- Peptide
- Stimulates water reabsorption in kidneys by increasing permeability of collecting duct
51
What is the function of oxytocin? What type of hormone is it? What is the source?
- Hypothalamus (released by posterior pituitary)
- Peptide
- Stimulates uterine contractions during labor and milk secretion during lactation; may promote bonding behavior
52
What is the function of triiodothyronine (T3) and thyroxine (T4)? What type of hormone is it? What is the source?
- Thyroid (follicular cells)
- Amino acid-derivative
- Stimulate metabolic activity
53
What is the function of calcitonin? What type of hormone is it? What is the source?
- Thyroid (parafollicular or C cells)
- Peptide
- Decreases blood calcium concentrations
54
What is the function of parathyroid hormone (PTH)? What type of hormone is it? What is the source?
- Parathyroids
- Peptide
- Increases blood calcium concentrations
55
What is the function of glucocorticoids (cortisol and cortisone)? What type of hormone is it? What is the source?
- Adrenal cortex
- Steroid
- Increase blood glucose concentrations; decrease protein synthesis; anti-inflammatory
56
What is the function of mineralocorticoids (aldosterone)? What type of hormone is it? What is the source?
- Adrenal cortex
- Steroid
- Increase water reabsorption in the kidneys by increasing sodium reabsorption; promote potassium and hydrogen ion excretion
57
What is the function of epinephrine and norepinephrine? What type of hormone is it? What is the source?
- Adrenal medulla
- Amino acid-derivative
- Increase blood glucose concentrations and heart rate; dilate bronchi; alter blood flow patterns
58
What is the function of glucagon? What type of hormone is it? What is the source?
- Pancreas (a-cells)
- Peptide
- Stimulates glycogen breakdown; increases blood glucose concentration
59
What is the function of insulin? What type of hormone is it? What is the source?
- Pancreas (B-cells)
- Peptide
- Lowers blood glucose concentrations and increases anabolic processes
60
What is the function of somatostatin? What type of hormone is it? What is the source?
- Pancreas (delta-cells)
- Peptide
- Suppresses secretion of glucagon and insulin
61
What is the function of testosterone? What type of hormone is it? What is the source?
- Testicals (and adrenal cortex)
- Steroid
- Develops and maintains male reproductive system and male secondary sex characteristics
62
What is the function of estrogen? What type of hormone is it? What is the source?
- Ovary (and placenta)
- Steroid
- Develops and maintains female reproductive system and female secondary sex characteristics
63
What is the function of progesterone? What type of hormone is it? What is the source?
- Ovary (and placenta)
- Steroid
- Promotes maintenance of the endometrium
64
What is the function of melatonin? What type of hormone is it? What is the source?
- Pineal gland
- Peptide
- Involved in circadian rhythms
65
What is the function of erythropoietin? What type of hormone is it? What is the source?
- Kidney
- Peptide
- Stimulates bone marrow to produce erythrocytes
66
What is the function of atrial natriuretic peptide (ANP)? What type of hormone is it? What is the source?
- Heart (atria)
- Peptide
- Promotes salt and water excretion
67
What is the function of thymosin? What type of hormone is it? What is the source?
- Thymus
- Peptide
- Stimulates T-cell development
68
When is ADH secreted? (2)
- In response to low blood volume (sensed by baroreceptors)
| - In response to increased blood osmolarity (sensed by osmoreceptors)
69
Which hormone has a positive feedback loop?
Oxytocin; its release promotes uterine contraction, which promotes more oxytocin release
70
What synthesizes ADH and oxytocin?
The hypothalamus; the posterior pituitary just releases them
71
What are the two major functions of the thyroid gland?
1) Setting basal metabolic rate
| 2) Calcium homeostasis
72
The iodination of tyrosine occurs in which cells of the thyroid?
Follicular cells
73
How are thyroid hormones capable of resetting the basal metabolic rate of the body?
By making energy production more or less efficient, and altering the utilization of glucose and fatty acids
74
What characterizes hypothyroidism?
Lethargy, decreased body temperature, slowed respiratory and heart rate, cold intolerance, and weight gain
75
What characterizes hyperthyroidism?
Heightened activity level, increased body temperature, increased respiratory and heart rate, heat intolerance, and weight loss
76
Which cells in the thyroid produce calcitonin?
C-cells (parafollicular cells)
77
What are the three ways in which calcitonin decreases plasma calcium?
1) Increased calcium excretion from the kidneys
2) Decreased calcium absorption from the gut
3) Increased storage of calcium in the bone
78
What are the three ways in which PTH increases plasma calcium?
1) Decreased excretion of calcium by the kidneys
2) Increased absorption of calcium in the gut (via vitamin D)
3) Increased bone resorption
79
How does parathyroid hormone affect phosphorus homeostasis?
It promotes its excretion in urine
80
What promotes the release of glucocorticoids from the adrenal cortex?
CRF from the hypothalamus promotes release of ACTH from the anterior pituitary, which promotes release of glucocorticoids from the adrenal cortex
81
What is the most noteworthy mineralocorticoid? What is its function?
- Aldosterone
- Increases sodium reabsorption in the distal convoluted tubule and collecting duct of the nephron
- Increases blood volume and blood pressure
82
Decreased blood pressure causes the _______________ cells of the kidney to secrete what?
- juxtaglomerular
| - rennin
83
What is the function of rennin?
Cleaves an inactive plasma protein, angiotensinogen, to its active form, angiotensin I
84
What is the function of angiotensin-converting enzyme? Where is it located?
Converts angiotensin I to angiotensin II in the lungs
85
What is the function of angiotensin II?
Stimulates the adrenal cortex to secrete aldosterone, which increases blood pressure
86
What are the 3 S"s of corticosteroids?
- Salt (mineralocorticoids)
- Sugar (glucocorticoids)
- Sex (cortical sex hormone)
87
Which organ has its hormones focused on the fight-or-flight response? Name its main hormones.
- Adrenal medulla
| - Epinephrine and norepinephrine
88
Islets of Langerhans contain three types of cells, what are they? In which organ are they contained?
- Alpha, beta, delta
| - Pancreas
89
Which hormones are capable of increasing plasma glucose?
- Glucagon
- Growth hormone
- Glucocorticoids
- Epinephrine
90
Diabetes mellitus is characterized by ____glycemia
hyper
91
Why is somatostatin produced by the hypothalamus?
It functions to decrease growth hormone secretion in addition to its effects on insulin and glucagon
92
Erythropoietin is secreted in response to what?
Low oxygen levels in the blood
93
Atrial natriuretic peptide is secreted in response to what?
When the cells in the atria are stretched from excess blood volume, which lowers blood volume and pressure
94
What is the target organ of FSH and LH? Which hormones are released by the target organ?
- Gonads (testes or ovaries)
| - Testosterone or estrogen and progesterone
95
What is the target organ of ACTH? Which hormones are released by the target organ?
- Adrenal cortex
| - Glucocorticoids (cortisol and cortisone)
96
What is the target organ of prolactin?
Breast tissue
97
What is the target organ of growth hormone?
Bone and muscle
98
Which three hormones are primarily involved in water homeostasis?
- Antidiuretic hormone (ADH): hypothalamus (released by posterior pituitary); increases blood volume
- Aldosterone: adrenal cortex; increases blood volume
- Atrial natriuretic peptide (ANP): heart; decreases blood volume
