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Anatomy and Physiology II > Chapter 17: Endocrine > Flashcards

Chapter 17: Endocrine Flashcards

1
Q

What are the 4 principal mechanisms of communication between cells?

A

1) Gap junctions
2) Neurotransmitters
3) Paracrines
4) Hormones

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2
Q

Define gap junctions

A

Allow molecules, nutrients, and electrolytes to move from cell to cell

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3
Q

Neurotransmitters are released from ________ neurons to ______ neurons

A

presynaptic; postsynaptic

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4
Q

Define paracrines

A

Secreted into tissue fluids to affect nearby cells

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5
Q

Define hormones

A

Chemical messengers that travel in the bloodstream to other tissues and organs

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6
Q

Define endocrine system and endocrinology

A

-The endocrine system is the glands, tissues, and cells that secrete hormones
-Endocrinology is the study of this system and the diagnosis and treatment of its disorders

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7
Q

What type of glands have ducts, and which don’t?

A

Exocrine glands have ducts, endocrine glands don’t

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8
Q

Describe exocrine and endocrine glands

A

1) Exocrine glands
-Have ducts to epithelial surface or mucosa
-“External secretions” with extracellular effects (food digestion)
2) Endocrine glands
-No ducts
-Contain dense, fenestrated capillary networks for easy uptake of hormones into bloodstream
-“Internal secretions” with intracellular effects such as altering target cell metabolism

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9
Q

What contains dense, fenestrated capillary networks for easy uptake of hormones into bloodstream?

A

Endocrine glands

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10
Q

What do the nervous and endocrine systems have in common?

A

Both systems serve for internal communication

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11
Q

Describe the difference in speed and persistence of response between the nervous and endocrine systems

A

Nervous: reacts quickly (ms timescale), stops quickly
Endocrine: reacts slowly (seconds or days), effect may continue for days or longer

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12
Q

Describe the difference in adaptation to long-term stimuli between the nervous and endocrine systems

A

Nervous: response declines (adapts quickly)
Endocrine: response persists (adapts slowly)

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13
Q

Describe the differences in areas of affect in the nervous and endocrine systems

A

Nervous: targeted and specific (one organ)
Endocrine: general, widespread effects (many organs)

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14
Q

Several chemicals function as both hormones and neurotransmitters; give 3 examples

A

Norepinephrine, dopamine, and antidiuretic hormone

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15
Q

Give an example of the nervous and endocrine systems having a similar effect on target cells

A

Norepinephrine and glucagon both cause glycogen hydrolysis in liver

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16
Q

Describe how the nervous and endocrine systems can regulate each other

A

Neurotransmitters can affect glands, and hormones can affect neurons

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17
Q

_________ cells share characteristics with both the nervous and endocrine systems

A

Neuroendocrine

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18
Q

What do both the nervous and endocrine systems require?

A

Both systems require receptors

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19
Q

Describe what part of the nervous system requires receptors and what part of the endocrine system requires receptors

A

1) Nervous system: Postsynaptic neuron requires receptors
2) Endocrine system: Target organs or cells must have receptors for a particular hormone; some target cells possess enzymes that convert a circulating hormone to its more active form

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20
Q

What forms the floor and walls of third ventricle of brain?

A

The hypothalamus

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21
Q

What does the hypothalamus do?

A

Regulates primitive functions: water balance, thermoregulation, sex drive, childbirth, etc.

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22
Q

The pituitary gland is suspended from __________ by a stalk called the infundibulum

A

hypothalamus

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23
Q

Describe the two parts of the pituitary gland

A

Adenohypophysis (anterior pituitary)
Neurohypophysis (posterior pituitary)

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24
Q

True or false: The anterior and posterior pituitary have independent origins and separate functions

A

True

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25
Q

Describe the adenohypophysis (anterior lobe) of the pituitary gland (what is it linked to, and what hormones regulate it?)

A

-Constitutes anterior three-quarters of pituitary
-Linked to hypothalamus by hypophyseal portal system
-Hypothalamic hormones regulate adenohypophysis cells (6 hormones): 4 releasing hormones and 2 inhibiting hormones

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26
Q

Name at least 3 examples of hypothalamic hormones

A

1) Prolactin-inhibiting hormone
2) Growth hormone-releasing hormone
3) Somatostatin
4) Gonadotropin-releasing hormone
5) Thyrotropin-releasing hormone
6) Corticotropin-releasing hormone

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27
Q

Name at least 3 examples of anterior lobe hormones

A

1) Prolactin
2) Growth hormone
3) Follicle-stimulating hormone
4) Luteinizing hormone
5) Thyroid-stimulating hormone (thyrotropin)
6) Adrenocorticotropic hormone

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28
Q

Define and describe the neurohypophysis (posterior lobe) of the pituitary gland

A

Definition: Neurohypophysis (posterior lobe) constitutes the posterior one-quarter of the pituitary
-Nerve tissue, not a true gland
-Nerve cell bodies in hypothalamus pass down the stalk as hypothalamo–hypophyseal tract and end in posterior lobe
-Hormones produced by cell bodies transported and stored in axon terminals in neurohypophysis

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29
Q

Nerve cell bodies in hypothalamus pass down the stalk as _______________ tract and end in _______ lobe of the pituitary gland

A

hypothalamo–hypophyseal; posterior

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30
Q

What two hormones are stored in the posterior pituitary?

A

Oxytocin and antidiuretic hormone (ADH)

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31
Q

How many hormones are produced by the hypothalamus, and what do they do (two groups)?

A

1) Eight hormones produced in hypothalamus
2) Six regulate the anterior pituitary, two are released into capillaries in the posterior pituitary

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32
Q

Describe the hypothalamic hormones that regulate the anterior pituitary

A

-Six releasing and inhibiting hormones stimulate or inhibit the anterior pituitary
-TRH, CRH, GnRH, and GHRH are releasing hormones that promote anterior pituitary secretion of TSH, PRL, ACTH, FSH, LH, and GH
-PIH inhibits secretion of prolactin, and somatostatin inhibits secretion growth hormone and thyroid-stimulating hormone by the anterior pituitary

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33
Q

Name 4 hypothalamic releasing hormones that promote anterior pituitary secretion of TSH, PRL, ACTH, FSH, LH, and GH

A

TRH, CRH, GnRH, and GHRH

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34
Q

List the 6 hypothalamic hormones that regulate the anterior pituitary

A

1) TRH
2) CRH
3) GnRH
4) GHRH
5) PIH inhibits secretion of prolactin
6) Somatostatin

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35
Q

What gland produces PIH, what organ does it target, and what does it do?

A

-Produced by hypothalamus
-Targets anterior pituitary
-It inhibits secretion of prolactin

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36
Q

What does somatostatin do?

A

Inhibits the secretion of growth hormone and thyroid-stimulating hormone by the anterior pituitary

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37
Q

List the 6 hormones made by the anterior pituitary

A

1) Follicle-stimulating hormone (FSH)
2) Luteinizing hormone (LH)
3) Thyroid-stimulating hormone (TSH)
4) Adrenocorticotropic hormone (ACTH)
5) Prolactin (PRL)
6) Growth hormone (GH)

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38
Q

What are the two gonadotropin hormones that target gonads produced by the anterior pituitary?

A

1) Follicle-stimulating hormone (FSH)
2) Luteinizing hormone (LH)

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39
Q

What 3 things does follicle-stimulating hormone (FSH) do?

A

1) Stimulates secretion of ovarian sex hormones
2) Development of ovarian follicles
3) Sperm production

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40
Q

What 3 things does luteinizing hormone (LH) do?

A

1) Stimulates ovulation
2) Stimulates corpus luteum to secrete progesterone
3) Stimulates testes to secrete testosterone

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41
Q

What does thyroid-stimulating hormone (TSH) do?

A

Stimulates secretion of thyroid hormone

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42
Q

What does adrenocorticotropic hormone (ACTH) do?

A

Stimulates adrenal cortex to secrete glucocorticoids

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43
Q

What does prolactin (PRL) do?

A

After birth, stimulates mammary glands to synthesize milk

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44
Q

What does growth hormone (GH) do?

A

Stimulates mitosis and cellular differentiation

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45
Q

Name and describe the two main hypersecretion of growth hormone (GH) disorders

A

1) Acromegaly: Thickening of bones and soft tissues in adults, especially hands, feet, and face
2) Gigantism: In childhood or adolescence before growth plates close

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46
Q

Name and describe the disorder that is characterized by the hyposecretion of growth hormone

A

Pituitary dwarfism: rarely a problem since GH now made by genetically engineered bacteria

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47
Q

What two hormones are produced in hypothalamus and transported to the posterior lobe of pituitary?

A

1) ADH (antidiuretic hormone)
2) Oxytocin (OT)

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48
Q

Describe what two things ADH (antidiuretic hormone) does, and name the disorder associated with its hyposecretion

A

1) It increases water retention, thus reducing urine volume, and preventing dehydration
2) It is also called vasopressin because it can cause vasoconstriction
-Hyposecretion: Diabetes insipidus (chronic polyuria)

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49
Q

What 5 things does oxytocin (OT) do?

A

1) Stimulates labor contractions during childbirth
2) Stimulates flow of milk during lactation
3) May promote emotional bonding between lactating mother and infant
4) Surge of this hormone released during sexual arousal and orgasm
5) Promotes feelings of sexual satisfaction and emotional bonding between partners

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50
Q

True or false: The rates of pituitary secretion are consistent

A

False; rates of secretion are not constant

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51
Q

Describe how stress affects ACTH

A

It triggers the release of ACTH

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52
Q

Describe how pregnancy affects prolactin

A

It triggers prolactin secretion

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53
Q

Describe how osmoreceptors affect ADH

A

If they detect an increase in osmolarity they trigger release of ADH

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54
Q

Describe how infant suckling affects oxytocin

A

It triggers the release of oxytocin

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55
Q

Give 4 examples of hypothalamic and cerebral control

A

1) Stress: Triggers release of ACTH
2) Pregnancy: Triggers prolactin secretion
3) Osmoreceptors: If they detect an increase in osmolarity they trigger release of ADH
4) Infant suckling: Triggers release of oxytocin

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56
Q

Define negative feedback in the context of pituitary secretion

A

Increased target organ hormone levels inhibit the release of hypothalamic and/or pituitary hormones

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57
Q

Give an example of negative feedback in pituitary secretion

A

Thyroid hormone inhibits the release of TRH by the hypothalamus and the release of TSH by the anterior pituitary

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58
Q

Give an example of positive feedback in pituitary secretion

A

Stretching of the uterus increases OT (oxytocin) release, causes contractions, causing more stretching of uterus, etc. until delivery

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59
Q

After age __ the pineal gland undergoes involution (shrinkage); it loses __% of its size by the end of puberty

A

Age 7; 75%

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60
Q

What two glands undergo involution, and at what ages?

A

1) The pineal gland starting at age 7
2) The thymus starting after puberty

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61
Q

What does the pineal gland do?

A

-May play a role in circadian rhythms since it synthesizes melatonin during the night and fluctuates seasonally with changes in day length
-May influence timing of puberty

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62
Q

What synthesizes melationin at night?

A

Pineal gland

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63
Q

The thymus plays a role in what 3 organ systems?

A

Endocrine, lymphatic, and immune

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64
Q

Describe the location of the thymus and what it does

A

1) It’s a bilobed gland in the mediastinum superior to the heart
2) It’s the site of the maturation of T cells; important in immune defense

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65
Q

What 3 hormones are secreted by the thymus?

A

Thymopoietin, thymosin, and thymulin

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66
Q

What is the largest gland that is purely endocrine?

A

Thymus

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67
Q

What color is the thymus and what gives it its color?

A

It’s dark red due to its rich blood supply

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68
Q

Describe the anatomy of the thymus

A

-Bi-lobed: It’s composed of two lobes and an isthmus below the larynx.
-Thyroid follicles: sacs that make up most of thyroid that contain protein-rich colloid

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69
Q

Describe the thyroid follicles

A

-They’re sacs lined with simple cuboidal epithelial cells (follicular cells)
-They make up most of thyroid and contain protein-rich colloid.

70
Q

The thyroid secretes ___________ and ____________ in response to TSH

A

thyroxine (T4) and triiodothyronine (T3)

71
Q

When thyroxine (T4) and triiodothyronine (T3) in are secreted in response to TSH, what increases?

A

Increases:
1) Metabolic rate
2) O2 consumption
3) Heat production
4) Appetite
5) Growth hormone secretion
6) Alertness
7) Reflex speed

72
Q

Parafollicular (C or clear) cells secrete ______________ with rising blood calcium

A

calcitonin

73
Q

What secretes calcitonin, and what does it do?

A

-Secreted by the parafollicular (C or clear) cells of the thyroid
-It stimulates osteoblast activity and bone formation in children

74
Q

Name 3 thyroid disorders

A

1) Grave’s disease (toxic goiter)
2) Congenital hypothyroidism (Cretinism)
3) Myxedema

75
Q

Describe Grave’s disease (toxic goiter)

A

-The most common form of hyperthyroidism
-Occurs when autoantibodies mimic the effect of TSH on the thyroid (bind and activate TSH receptor), causing thyroid hypersecretion

76
Q

Describe congenital hypothyroidism (Cretinism)

A

-Thyroid hyposecretion present at birth
-Treat with oral thyroid hormone

77
Q

Describe myxedema (what is it and how is it treated?)

A

-Adult hypothyroidism
-Treat with oral thyroid hormone

78
Q

How many parathyroid glands are there, and where are they?

A

-Usually four glands partially embedded in the posterior surface of thyroid gland

79
Q

What do the parathyroid glands secrete?

A

Parathyroid hormone (PTH)

80
Q

What does parathyroid hormone (PTH) do, and what 4 things does it trigger to accomplish this?

A

A) It increases blood Ca(2+) levels
B) It does this by:
1) Promoting synthesis of calcitriol
2) Increasing absorption of Ca^(2+) from digestive system
3) Decreasing urinary excretion
4) Increasing bone resorption

81
Q

Name 2 parathyroid disorders

A

Hypoparathyroidism and hyperparathyroidism

82
Q

How does hypoparathyroidism happen? What does it result in?

A

Happens due to surgical excision during thyroid surgery
Results in fatal tetany (spasms in larynx) in just a few days due to rapid decline in blood calcium level

83
Q

Define and describe hyperparathyroidism (what is it due to, what 3 things does it result in?)

A

-Defined as excess PTH secretion
-Often due to a parathyroid tumor
-Result:
a) Bones become soft, fragile, and deformed
b) Ca^(2+) and phosphate blood levels increase
c) Promotes renal calculi formation

84
Q

Define the adrenal medulla and what organ systems it’s a part of

A

-The inner core, 10% to 20% of adrenal gland
-It’s both an endocrine gland and a ganglion of the sympathetic nervous system

85
Q

What is the adrenal medulla innervated by, what is it made out of, and what does it do when stimulated?

A

1) Innervated by sympathetic preganglionic fibers
2) Consists of modified sympathetic postganglionic neurons called chromaffin cells
3) When stimulated, it releases catecholamines (epinephrine and norepinephrine) directly into the bloodstream

86
Q

What hormones are released by the adrenal medulla

A

Catecholamines (epinephrine and norepinephrine) are released directly into the bloodstream

87
Q

When is the adrenal medulla activated, and what does it mobilize when activated?

A

-It increases alertness and prepares the body for physical activity
-It does this by mobilizing high-energy fuels, lactate, fatty acids, and glucose (glycogenolysis and gluconeogenesis by liver)

88
Q

Describe how the adrenal medulla relates to glucose

A

It mobilizes glucose through glycogenolysis and gluconeogenesis by liver

89
Q

What does epinephrine do before physical activity? Why?

A

-Epinephrine inhibits insulin secretion (glucose-sparing effect)
-This is because muscles use fatty acids, saving glucose for brain

90
Q

What 5 things does the adrenal medulla increase, and what 2 things does it decrease?

A

Increases:
1) Blood pressure
2) Heart rate
3) Blood flow to muscles
4) Pulmonary airflow
5) Metabolic rate
Decreases:
1) Digestion
2) Urine production

91
Q

Describe the mineralocorticoids of the adrenal cortex (what is the main mineralocorticoid, what do they do, and what are they a part of)

A

1) Primarily aldosterone
2) They stimulate Na^+ retention and K^+ excretion
-Water is retained with sodium by osmosis
-Blood volume and blood pressure are maintained
3) Part of the renin-angiotensin-aldosterone (RAA) system

92
Q

Describe the glucocorticoids of the adrenal cortex (what is the main glucocorticoid, when are they released, and what do they do?)

A

1) Primarily cortisol
2) Release stimulated by ACTH
3) Effects:
-Stimulate fat and protein catabolism
-Gluconeogenesis
-Help body adapt to stress and repair tissues
-Anti-inflammatory effect becomes immune suppression with long-term use

93
Q

Name the 2 sex steroids of the adrenal cortex and describe what they do

A

1) Androgens: set libido throughout life; large role in prenatal male development
2) Estradiol: important after menopause

94
Q

What 3 things are released by the adrenal cortex?

A

1) Mineralocorticoids (primarily aldosterone)
2) Glucocorticoids (primarily cortisol)
3) Sex steroids (androgens and estradiol)

95
Q

Name 3 adrenal disorders

A

1) Adrenogenital syndrome (AGS)
2) Cushing’s syndrome
3) Addison’s disease

96
Q

What disorder is characterized by excess cortisol secretion, and what organ controls the release of cortisol?

A

Cushing syndrome; adrenal cortex

97
Q

Define and describe the symptoms of cushing syndrome

A

-Defined as excess cortisol secretion
-Results in:
a) Hyperglycemia, hypertension, weakness, edema
b) Rapid muscle and bone loss due to protein catabolism
c) Abnormal fat deposition; moon face and buffalo hump

98
Q

Define and describe the symptoms of adrenogenital syndrome (AGS)

A

1) Defined as adrenal androgen hypersecretion (accompanies Cushing)
2) Characterized by:
-Enlargement of external sexual organs in children and early onset of puberty
-Newborn girls exhibit masculinized genitalia
-Masculinizing effects on women
-Increased body hair, deeper voice, beard growth

99
Q

Define and describe the symptoms of Addison’s disease

A

1) Defined as deficient cortisol and/or aldosterone
2) Characterized by:
Hypoglycemia
Hypotension
Weakness
Weight loss
Hyperpigmentation

100
Q

What two things are secreted from the pancreatic islets, and what types of cells are they secreted from?

A

1) Glucagon: secreted by A or alpha (α) cells
2) Insulin: secreted by B or beta (β) cells

101
Q

________: secreted by A or alpha (α) cells
________: secreted by B or beta (β) cells

A

Glucagon: secreted by A or alpha (α) cells
Insulin: secreted by B or beta (β) cells

102
Q

Describe glucagon and what it stimulates

A

-Secreted by A or alpha (α) cells; released between meals when blood glucose falls
-In liver, stimulates gluconeogenesis & glycogenolysis and stimulates the lipolysis of adipose tissue

103
Q

Describe insulin and what it stimulates

A

-Secreted by B or beta (β) cells during and after meal
-Promotes synthesis of glycogen, fat, and protein
>Brain, liver, kidneys, and RBCs absorb glucose without insulin, but other tissues require insulin
>Insufficiency or inaction is cause of diabetes insipidus (*)

104
Q

What 4 things in the body don’t require insulin to absorb glucose?

A

Brain, liver, kidneys, and RBCs absorb glucose without insulin

105
Q

What is the most prevalent metabolic disease in the world?

A

Diabetes mellitus

106
Q

Define diabetes mellitus and its symptoms. What tests are done to indicate these symptoms?

A

1) Defined as the disruption of metabolism due to hyposecretion or inaction of insulin (insulin resistance)
2) Symptoms: Polyuria, polydipsia, and polyphagia
-Revealed by elevated blood glucose, glucose in urine, and ketones in the urine

107
Q

Why does polyuria occur in diabetes mellitus?

A

-Polyuria (with thirst and dehydration) occurs because kidneys exhibit a transport maximum-limit to how fast the glucose transporters can work to reabsorb
-Excess glucose enters urine and water follows it

108
Q

What are the two types of diabetes, and how common are they?

A

1) Type 1 diabetes mellitus (IDDM): 5% to 10% of cases in United States
2) Type 2 (NIDDM): 90% to 95% of diabetics

109
Q

Describe what is used to treat type 1 diabetes mellitus and its causes

A

-Insulin is always used to treat type 1
-Hereditary susceptibility: if a susceptible individual is infected with certain viruses (rubella, cytomegalovirus), autoantibodies attack and destroy pancreatic beta cells

110
Q

Describe the main problem, risk factors, and treatments of type 2 diabetes (diabetes insipidus)

A

1) The main problem is insulin insufficiency (**); the failure of target cells to respond to insulin
2) Risk factors are heredity, age (40+), obesity, and ethnicity (Native American, Hispanic, and Asian)
3) Treated with weight-loss program and exercise since:
-Loss of muscle mass causes difficulty with regulation of glycemia
-Adipose signals interfere with glucose uptake into most cells
3) If necessary, also use glycemia-lowering oral medications and, if still not enough, use insulin

111
Q

Define hyperglycemic hormones and give examples (includes hormones from any gland)

A

-Defined as hormones that raise blood glucose concentration
-Glucagon, growth hormone, epinephrine, norepinephrine, and cortisol

112
Q

Define hypoglycemic hormones and name the one hormone in this category

A

Hypoglycemic hormones lower blood glucose; insulin

113
Q

Are ovaries and testes endocrine, exocrine, or both?

A

Ovaries and testes are both endocrine and exocrine

114
Q

Name the endocrine and exocrine products of the ovaries and testes

A

Exocrine product (cytogenic glands): eggs and sperm
Endocrine product: gonadal hormones

115
Q

Name the 3 ovarian hormones and the 4 testicular hormones

A

Ovarian hormones: Estrogen (Estradiol), progesterone, and inhibin
Testicular hormones: Testosterone, weaker androgens, estrogen, and inhibin

116
Q

List the 3 general functions of estrogens and progesterone for females

A

1) Development of female reproductive system and physique including adolescent bone growth
2) Regulate menstrual cycle, sustain pregnancy
3) Prepare mammary glands for lactation

117
Q

List the 2 general functions of testosterone for males

A

1) Stimulates development of male reproductive system in fetus and adolescence, and sex drive
2) Sustains sperm production

118
Q

What suppresses FSH secretion from anterior pituitary in both sexes?

A

Inhibin

119
Q

What does inhibin do?

A

Suppresses FSH secretion from anterior pituitary in both sexes

120
Q

Describe an endocrine function of the skin

A

Keratinocytes produce cholecalciferol using UV from sun (first step in making vitamin D)

121
Q

Describe two endocrine functions of the kidneys; name what two endocrine things they secrete and what their targets and actions are

A

1) Kidneys secrete erythropoietin
-Target: red bone marrow
-Action: stimulates production of RBC’s
2) Kidneys secrete renin
-Target: cortex of adrenal gland
-Action: stimulates production of aldosterone

122
Q

Describe the endocrine function of the heart; name what endocrine thing it secretes and what its target and action is

A

Secretes Atrial natriuretic peptides
-Target: kidneys
-Action: reduces blood volume and BP by increasing Na^+ and H_2 O excretion

123
Q

Describe the endocrine function of the stomach and small intestine; name what endocrine-like cell it has and what it does

A

-Has enteroendocrine cells
-Action: Coordinate digestive motility and glandular secretion of cholecystokinin, gastrin, and secretin

124
Q

Enteroendocrine cells coordinate digestive motility and glandular secretion of what 3 hormones?

A

Cholecystokinin, gastrin, and secretin

125
Q

Describe the endocrine function of the adipose tissue; name what hormone it secretes and what its action

A

Secretes leptin
-Action: Slows appetite

126
Q

Describe the endocrine function of the placenta; name 2 examples of hormones it secretes and what their action is

A

-Secretes estrogen, progesterone, and others
Action: Regulate pregnancy, stimulate development of fetus and mammary glands

127
Q

What are the 3 chemical classes of hormones?

A

1) Steroids
2) Peptides (and glycoproteins)
3) Monoamines (biogenic amines)

128
Q

What are steroids derived from? Give 2 examples of steroids

A

-Derived from cholesterol
-Exs: Sex steroids and corticosteroids

129
Q

What are peptides (and glycoproteins) made of? Give 3 examples of hormones from this class

A

-Made of chains of amino acids
-Ex: hormones from pituitary, hypothalamus, insulin

130
Q

What are monoamines (biogenic amines) made from? Give 3 examples of hormones from this class

A

-Made from amino acids
-Exs: Catecholamines, melatonin, thyroid hormone

131
Q

Thyroid hormone is composed of what two things?

A

1) Thyroxine (T4)
2) Triiodothyronine (T3)

132
Q

Describe how thyroid hormone is synthesized and secreted (3 steps)

A

1) Thyroid follicles absorb iodine from blood.
2) The follicular cells produce T3 (contains three iodines) and T4 (contains four iodines) when stimulated (by TSH)
3) Thyroid Hormone (mostly T4) is released to the blood.

133
Q

True or false: Hormones are not secreted at steady rates and levels in bloodstream fluctuate throughout the day

A

True

134
Q

True or false: Some hormones are on a daily or monthly rhythm

A

True

135
Q

Describe 2 common ways hormones can fluctuate

A

1) Daily or monthly rhythms
2) Influence of stimuli

136
Q

What are the 3 hormone secretion stimuli categories?

A

1) Neural stimuli
2) Hormonal stimuli
3) Humoral stimuli

137
Q

Give 2 examples of neural stimuli

A

1) Sympathetic N.S. stimulates adrenal medulla during stress
2) In childbirth, stretch receptors stimulate release of oxytocin

138
Q

Give an example of hormonal stimuli (Tropic hormones)

A

Releasing & inhibiting hormones from the hypothalamus (TSH, ACTH, FSH, LH)

139
Q

Define humoral stimuli and give 2 examples

A

-Refers to blood-borne stimuli
Examples:
1) High blood glucose stimulates release of insulin
2) Low blood calcium stimulates secretion of parathyroid hormone

140
Q

Most monoamines and peptides are hydro______. Describe the importance of this.

A

-Most monoamines and peptides are hydrophilic
-This is important because it allows them to mix easily with blood plasma

141
Q

Steroids and thyroid hormone are hydro_____. How are they transported through plasma?

A

-Steroids and thyroid hormone are hydrophobic
-They bind to transport proteins (albumins and globulins)

142
Q

What type of hormones have a longer half-life? Why?

A

-Bound (Hydrophobic) hormones have longer half-life
-Because they’re protected from liver enzymes and kidney filtration

143
Q

Only _______ hormones leaves capillaries to reach target cell

A

unbound

144
Q

What is the exception to the rule about bound (hydrophobic) hormones having a longer half-life?

A

Aldosterone (hydrophobic): short half-life; 85% unbound, 15% binds weakly to albumin and others

145
Q

Hydro_____ hormones are bound, and hydro______ hormones are unbound

A

Hydrophobic are bound, hydrophilic are unbound

146
Q

True or false: Hormones stimulate all cells they touch

A

False; hormones stimulate only those cells that have receptors for them

147
Q

Define receptors and name the 3 places they can be found

A

-Defined as protein (or glycoprotein) molecules
-Located on plasma membrane, in the cytoplasm, or in the nucleus

148
Q

What do receptors do?

A

Act like switches turning on metabolic pathways when hormone binds to them

149
Q

A target cell has about how many receptors for a given hormone?

A

A few thousand receptors for a given hormone

150
Q

Receptor–hormone interactions exhibit what two properties? How so?

A

They exhibit specificity and saturation
-Specific receptor for each hormone
-Saturated when all receptor molecules are occupied by hormone molecules

151
Q

Describe the mode of action of peptide hormones

A

Cannot penetrate target cell, so they bind to surface receptors and activate intracellular processes through second messengers

152
Q

What type of hormones use second messengers?

A

Peptide hormones

153
Q

Describe the mode of action of steroid hormones and how long it takes

A

-Penetrate plasma membrane and bind to internal receptors (usually in nucleus) to influence expression of genes of target cell
-Take several hours to days to show effect due to lag for protein synthesis

154
Q

Describe the mode of action of thyroid hormone (3 steps)

A

1) It enters the target cell by means of an ATP-dependent transport protein
2) Within target cell, T4 is converted to more potent T3
3) Then T3 binds to nuclear receptors and activates genes; one gene is for the sodium-potassium pump

155
Q

Describe the potency of hormones

A

-Hormones are extraordinarily potent chemicals; one hormone molecule can activate many enzyme molecules
-Very small stimulus can produce very large effect
-Therefore, hormone concentrations in blood are low

156
Q

Are hormone concentrations in the blood low or high?

A

Low

157
Q

How is target-cell sensitivity adjusted?

A

By changing the number of receptors

158
Q

What are the two ways in which target-cell sensitivity can be regulated?

A

Up-regulation and down-regulation

159
Q

Define and describe what happens after up-regulation and down-regulation

A

1) Up-regulation: number of receptors is increased
-Which means sensitivity is increased
2) Down-regulation reduces number of receptors
-Which means sensitivity is decreased

160
Q

When does down-regulation happen?

A

Happens with long-term exposure to high hormone concentrations

161
Q

Are most cells sensitive to one hormone or more?

A

Most cells sensitive to more than one hormone and exhibit interactive effects

162
Q

What are the 3 kinds of effects of hormone interaction? Give a brief definition for each

A

1) Synergistic effects: multiple hormones enhance each other
2) Permissive effects: one hormone enhances an organ’s response to another hormone
3) Antagonistic effects: one hormone opposes the action of another

163
Q

Define and give an example of synegistic effects

A

-When multiple hormones act together for greater effect
-Ex: Synergism between FSH and testosterone on sperm production

164
Q

Define and give an example of permissive effects

A

-When one hormone enhances the target organ’s response to a second later hormone
-Ex: Estrogen prepares uterus for action of progesterone

165
Q

Define and give an example of antagonistic effects

A

-When one hormone opposes the action of another
-Ex: Insulin lowers blood glucose and glycogen raises it

166
Q

True or false: Hormone signals must be turned off when they have served their purpose

A

True

167
Q

Most hormones are taken up and degraded by _________ and ______________. Where are they then excreted?

A

-Most hormones are taken up and degraded by the liver and kidneys
-Excreted in bile or urine

168
Q

List the 6 hypothalamic hormones that inhibit or stimulate the release of another hormone, and state what hormone they stimulate or inhibit

A

1) TRH promotes secretion of TSH and PRL
2) CRH promotes secretion of ACTH
3) GnRH promotes secretion of FSH
4) GHRH promotes secretion of GH
5) PIH inhibits secretion of prolactin
6) Somatostatin inhibits secretion of GH and TSH

169
Q

What are the 5 steroid hormones that can cross the phospholipid bilayer (i.e. are not water soluble)?
What is the one water soluble hormone that acts like it’s not?

A

1) Testosterone
2) Estrogen
3) Progesterone
4) Aldosterone
5) Cortisol
1) Thyroid hormone (TH) acts lipid-soluble

170
Q

The receptors of _______ hormones and ________ hormone are inside the cell, since they can cross the phospholipid bilayer to enter the cell.

A

steroid; thyroid

Anatomy and Physiology II (40 decks)

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