Chapter 18: The Endocrine System Flashcards
1
Q
Nervous System vs. Endocrine System: Mediator Molecules
A
Nervous System: Neurotransmitters released locally in response to nerve impulses
Endocrine System: Hormones delivered to tissue throughout the body by blood.
2
Q
Nervous System vs. Endocrine System: Site of Mediator Action
A
Nervous System: close to site of release, at synapse; binds to receptors in postsynaptic membrane
Endocrine System: far from site of release (usually); binds to receptors on or in target cells
3
Q
Nervous System vs. Endocrine System: Types of Target Cells
A
Nervous System: muscle (smooth, cardiac, and skeletal) cells, gland cells, other neurons
Endocrine System: cells throughout the body
4
Q
Nervous System vs. Endocrine System: Time to onset of action
A
Nervous System: typically within milliseconds (thousandths of a second)
Endocrine System: seconds to hours or days
5
Q
Nervous System vs. Endocrine System: Duration of action
A
Nervous System: generally briefer than endocrine system (milliseconds)
Endocrine System: generally longer than nervous system (seconds to days)
6
Q
Endocrine Glands
A
- composed of endocrine cells and tissues.
- produce and secrete hormones that move through the bloodstream to reach their target cells.
7
Q
In order for a hormone to affect a target cell, a hormone must first
A
bind to a specific receptor
8
Q
target cells
A
tissues that must have specific receptors to which a specific hormone binds.
9
Q
List the endocrine glands
A
- hypothalamus (in the brain)
- pituitary gland: anterior and posterior pituitary (in the brain)
- thyroid gland (around trachea)
- parathyroid gland (on thyroid gland)
- adrenal gland: adrenal cortex and medulla (on top of kidneys)
- pancreas (tucked behind stomach)
- gonads: testes (in scrotum) and ovaries (lower abdomen)
- thymus gland (in front of the heart)
- pineal gland (in the brain)
10
Q
Gastrin
A
- promotes secretion of gastric juice
- increases movements of the stomach
11
Q
Glucose-dependent insulinotropic peptide (GIIP)
A
stimulates release of insulin by pancreatic beta cells
12
Q
Secretin
A
stimulates secretion of pancreatic juice and bile
13
Q
Cholecystokinin (CCK)
A
- stimulates secretion of pancreatic juice
- regulates release of bile from gallbladder
- causes feeling of fullness after eating
14
Q
Human chorionic gonadotropin (hCG)
A
stimulates corpus luteum in ovary to continue production of estrogen’s and progesterone to maintain pregnancy
15
Q
Estrogens and progesterone
A
- maintain pregnancy
- help prepare mammary glands to secrete milk
16
Q
Hyman chorionic somatomammotropin (hCS)
A
stimulates development of mammary glands for lactation
17
Q
Renin
A
part of reaction sequence that raises blood pressure by bringing about vasoconstriction and secretion of aldosterone
18
Q
Erythropoietin (EPO)
A
increases rate of red blood cell formation
19
Q
Calcitriol (active form of Vit D)
A
aids in absorption of dietary calcium and phosphorus
20
Q
Atrial Natriueretic
A
decreases blood pressure
21
Q
Leptin
A
- suppresses appetite
- may increase FSH and LH activity
22
Q
Hormones
A
long distance chemical signals; travel in blood or lymph
23
Q
Autocrines
A
chemicals that exert effects on same cells that secrete them
24
Q
Paracrines
A
-locally acting chemicals that affect cells other than those that secrete them
25
What are the 3 chemical messengers?
1. hormones
2. autrocrines
3. paracrines
26
Paracrines and Autrocrines are referred to as
local chemical messengers; not considered part of endocrine system
27
What are the 6 functions of hormones?
1. Control cellular metabolism, growth and division (e.g. stimulate mitosis)
2. Stimulate synthesis of enzymes &/or other proteins
3. Control body fluids and electrolyte balance
4. Control the secretion of other hormones
5. Regulate reproductive cycles
6. Regulate homeostasis by negative or positive feedback loop
28
What are the four types of hormones?
1. Amino Acid Derivatives
2. Peptide Hormones
3. Lipid Derivatives
4. Gas
29
Amino Acid Derivatives
- modified amino acid: tyrosine and tryptophan
| ex) epinephrine, norepinephrine, dopamine, melatonin, histamine, serotonin, thyroid hormones (T3, and T4)
30
Peptide Hormones
-glycoproteins and short/small proteins
31
glycoproteins
- more than 200 amino acids long with carbohydrate side chains
ex) thyroid-stimulating hormone (TSH), luteinizing hormone (LH), follicle-stimulating hormone (FSH)
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short/small proteins
- less than 200 amino acids
| ex) antidiuretic hormone (ADH), oxytocin (OXT), growth hormone (GH), prolactin (PRL)
33
Lipid Derivatives
eicosanoids and steroids
34
eicosanoids
- derived from arachidonic acid
| ex) leukotrienes, prostaglandins, thromboxanes, prostacyclins
35
steroids
- derived from cholesterol
| ex) androgens, estrogens, progestins, corticosteroids, calcitriol
36
Gas Hormones
Nitric Oxide (NO): (produced by endothelial cells lining blood vessels)
37
Hormones act in one of 2 ways:
1. Water-Soluble Hormones
| 2. Lipid-soluble Hormones
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Water-soluble Hormones
- (all amino acid–based hormones except thyroid hormone)
- Act on plasma membrane receptors
- Act via G protein second messengers
- Cannot enter cell
39
Lipid-soluble Hormones
- (steroid and thyroid hormones)
- Act on intracellular receptors that directly activate genes
- Can enter cell
40
Steps when water-soluble hormone binds to receptor:
1. binding of hormone (1st messenger) to its receptor activates G protein, which activates adenlyate cyclase
2. activated adenylate cyclase converts ATP to cAMP
3. cAMP serves as a 2nd messenger to activate protein kinases
4. activated protein kinases phosphorylate cellular proteins
5. millions of phosphorylated proteins cause reactions that produce physiological responses
6. phosphodiesterase inactivates cAMP
41
Steps when lipid-soluble hormones binds to receptor:
1. lipid-soluble hormone diffuses into cell and binds to intraccellular receptor
2. the receptor-hormone complex enters the nucleus and binds to a specific DNA region
3. binding initiates transcription of the gene to mRNA
4. the mRNA directs protein synthesis
42
cAMP
- Cyclic adenosine monophosphate
| - a second messenger important in many biological processes
43
What are the 3 stimuli that controls the release of hormones?
1. humoral stimulus
2. neural stimulus
3. hormonal stimulus
44
Humoral Stimulus
hormone release caused by altered levels of certain critical ions or nutrients.
45
Neural Stimulus
hormone release caused by neural input
46
Hormonal Stimulus
hormone release caused by another hormone (a tropic hormone)
47
Blood levels of hormones are controlled by
negative feedback systems:
- increased hormone effects on target organs can inhibit further hormone release
- levels vary only within narrow, desirable range
48
What is the stimulus and response that occurs during a humoral stimulus?
Stimulus: low concentration of Ca2+ in capillary blood
Response: parathyroid glands secrete parathyroid hormone, which increases Ca2+
49
What is the stimulus and response that occurs during a neural stimulus?
Stimulus: action potentials in preganglionic sympathetic fibers to adrenal medulla
Response: adrenal medulla cells secrete epinephrine and norepinephrine.
50
What is the stimulus and response that occurs during a hormonal stimulus?
Stimulus: hormones from hypothalamus
Response: anterior pituitary gland secretes hormones that stimulate other endocrine glands to secrete hormones.
51
Target cell activation depends on 3 factors:
1. blood levels of hormone
2. relative number of receptors on/in target cell
3. affinity (strength) of binding between receptor and hormone
52
Amount of hormone can influence the
number of receptors for that hormone
53
Up-regulation
target cells form more receptors or increase affinity in response to low hormone levels
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Down-regulation
- target cells lose receptors or decrease affinity in response to high hormone levels
- desensitizes target cells to prevent them from overreacting to persistently high levels of hormone
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Interaction of Hormones at Target Cells: 3 Types
1. Permissiveness
2. Synergism
3. Antagonism
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Permissiveness
- one hormone cannot exert its full effects without another hormone being present
ex) reproductive system development largely regulated by reproductive system hormones but need thyroid hormone for timely development of reproductive system structures
57
Synergism
- more than one hormone produces same effects on target cell, causing amplification
ex) glucagon and epinephrine both cause liver to release glucos
58
Antagonism
- one or more hormones oppose(s) action of another hormone
| ex) insulin and glucagon
59
How does the hypothalamus regulate the internal environment through the autonomic nervous system? (4)
1. helps control water balance
2. controls glandular secretions
3. helps control heartbeat
4. helps control body temperature
60
What 3 ways does the hypothalamus link the nervous system and the endocrine system?
1. Acts as an Endocrine Organ. Neurosecretory cells within the hypothalamus produces the hormone which then passes through the axons into the posterior pituitary where they are stored in the ends of the axon and released when needed.
2. Secretes Regulatory Hormones that control the endocrine cells in the anterior pituitary.
3. Exerts direct control over the endocrine cells of the adrenal gland (adrenal medulla) by means of actions potentials (sending nerve impulses, rather than through regulatory hormone
61
Hormones produced by the hypothalamus
ADH and Oxytocin (OXT)
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What are the two regulatory hormones that control the endocrine cells in the anterior pituitary?
1. Hypothalamic Releasing Hormone (RH)
| 2. Hypothalamic Inhibiting Hormone (IH)
63
Hypothalamic Releasing Hormone (RH)
- stimulates the anterior pituitary to secrete hormones
| - produced by neurosecretory (neuroendocrine) cells
64
Hypothalamic Inhibiting Hormone (IH)
- inhibits the anterior pituitary to not secrete hormones
| - produced by neurosecretory (neuroendocrine) cells
65
The hypothalamus will stimulate the adrenal medulla to secrete
epinephrine and norepinephrine from chromaffin cells
66
hypophysis
the pituitary gland
67
neurohypophysis
- the posterior pituitary
- is the posterior lobe of the pituitary gland which is part of the endocrine system.
- not glandular
68
adenohypophysis
- the anterior pituitary
| - the glandular, anterior lobe that together with the posterior lobe makes up the pituitary gland
69
neuroendocrine
relating to or involving both nervous stimulation and endocrine secretion
70
tropic hormone
hormone release caused by another hormone
71
neurosecretory cells
- a type of neuron, or nerve cell, whose function is to translate neural signals into chemical stimuli (neuron that secretes hormones)
- secretes a hypothalamic-releasing hormone or inhibiting hormone into blood capillaries of the hypothalamus
72
myxedema
- caused by hyposecretion of TH in an adult
- Symptoms: low metabolic rate, thick and/or dry skin, puffy eyes, feeling chilled, constipation, edema, mental sluggishness, letharg
73
goiter
- a swelling of the neck from enlargement of the thyroid gland
74
What causes goiter?
1. caused by lack of iodine which decreases TH levels
2. low TH levels triggers increased TSH secretion
3. increased TSH secretion triggers thyroid to synthesize more and more unusable thyroglobulin --> thyroid enlarges
75
cretinism
- caused by hypersecretion in infants
| - symptoms include intellectual disabilities, short and disproportionately sized body, thick tongue and neck
76
Grave's disease
- caused by hypersecretion of TH: most common type
- Autoimmune disease: body makes abnormal antibodies directed against thyroid follicular cells
- Antibodies mimic TSH, stimulating TH release
77
Grave's disease: Symptoms
- include elevated metabolic rate, sweating, rapid and irregular heartbeats, nervousness, and weight loss despite adequate food
• Exophthalmos may result: eyes protrude as tissue behind eyes becomes edematous (swollen) and fibrous
78
Grave's disease: Treatment
include surgical removal of thyroid or radioactive iodine to destroy active thyroid cell
79
hypersecretion of growth hormone is usually caused by
- anterior pituitary tumor.
- in children results in gigantism
- in adults, results in acromegaly
80
gigantism
- a result of hypersecretion of growth hormone in children
- is usually caused by an anterior pituitary tumor
- can reach heights of 8 feet
81
acromegaly
- a result of hypersecretion of the growth hormone in adults
- is usually caused by an anterior pituitary tumor
- overgrowth of hands, feet and face
82
pituitary dwarfism
- caused by hyposecretion of growth hormone in children
| - may reach height of only feet
83
hypersecretion of prolactin is more common than
- hyposecretion.
| * Hyposecretion is not a problem in anyone except women who choose to nurse.
84
hyperprolactinemia
- the most frequent abnormality of anterior pituitary tumors
| - Clinical signs include galactorrhea, amenorrhea, infertility in females, and impotence in males (erectile dysfunction)
85
galactorrhea
inappropriate lactation
86
amenorrhea
abnormal absence of menstruation
87
exocrine glands
- are glands that secrete their products into ducts
- they are the counterparts to endocrine glands, which secrete their products directly into the bloodstream
- include sweat glands, salivary glands, mammary glands, and many glands of the digestive system.
88
ketoacidosis
Ketones are acidic, and their build-up in blood can cause ketoacidosis.
89
ketonuria
- ketone bodies in urine.
| - can be caused build-up of ketones (acidic) in the blood along with ketoacidosis.
90
lipidemia
high levels of fatty acids in blood
91
When sugars cannot be used as fuel, as in DM, fats are used, causing ________.
lipidemia
92
Fatty acid metabolism results in formation of _________.
ketones (ketone bodies)
93
Untreated ketoacidosis causes
hyperpnea, disrupted heart activity and O2 transport, and severe depression of nervous system that can possibly lead to coma and death
94
Pancreas
Regulates Glucose concentrations in blood
95
Pancreas: Structure
Composed of 2 Types of Tissues:
1. Exocrine Gland (Acinar Cells)
2. Endocrine Glands (Islets of Langerhans)
96
Beta-cells of Langerhans
- produces Insulin
| - stimulates uptake of glucose by cells (liver, muscle, adipose)
97
Alpha-cells of Langerhans
- produces Glucagon
| - stimulates breakdown of glycogen (storage form of glucose) in liver
98
Adrenal Gland (Adrenal Cortex)
- helps regulate blood pressure
| - produces Mineralocorticoids
99
Thyroid Gland
- produces and secretes Calcitonin
- decreases osteoclast activity (results in more calcium absorbed in bone)
- increases calcium excretion in urine (more calcium is found in urine)
100
Parathyroid Glands
- produces Parathyroid Hormone (PTH):
- increases osteoclast activity (bone is destroyed releasing more calcium into blood)
- decreases calcium excretion, while increasing calcium reabsorption (less calcium is found in urine)
101
What endocrine glands regulate the concentration of Ca2+ in the blood?
thyroid and parathyroid glands
102
Thyroid-Stimulating Hormone (TSH) are secreted by and target what tissues?
secreted by: thyrotrophs (cells in anterior pituitary)
| target tissues: the thyroid gland
103
Thyrotropin-Releasing Hormone (TRH)
Secreted by: hypothalamus
Target tissue: anterior pituitary
Function: a releasing hormone that stimulates the release of thyrotropin and prolactin from the anterior pituitary.
104
Action of the Thryoid-Stimulating Hormone (aka thyrotropin)
stimulates synthesis and secretion of thyroid hormones by thyroid gland
105
Growth Hormone Releasing Hormone (GHRH)
- aka Somatocrinin
- produced in the hypothalamus
- target tissue: anterior pituitary
- function: Stimulates secretion of Growth Hormone (hGH)
- release is stimulated by low blood glucose (hypoglycemia)
106
Which gland secretes Growth Hormone Inhibiting Hormone (GHIH), what is the target tissue, and what is its function?
- aka Somatostatin
- produced in the hypothalamus
- Target tissue: anterior pituitary
- Function: Inhibits secretion of Growth Hormone (hGH) and Thyroid Stimulating Hormone (TSH)
107
Human Growth Hormone (hGH)
- aka Somatotropin
- Secreted by: somatotrophs (cells in anterior pituitary)
- Target tissues: bone, skeletal muscle, cartilage, liver
108
Insulin-like Growth Factors (IGFs)
- aka Somatomedins
| - a polypeptide hormone produced mainly by the liver in response to the endocrine GH stimulus
109
Action of Human Growth Hormone (hGH)
Stimulates liver, muscle, cartilage, bone and other tissues to synthesize and secrete (IGF’s)
110
Action of Insulin-like Growth Factors (IGFs)
Promotes growth of body cells, protein synthesis, tissue repair, lipolysis and elevation of blood glucose concentration
111
Action of the Growth Hormone Releasing Hormone (GHRH)
stimulates the pituitary gland to produce and release hGH into the bloodstream
112
Action of the Growth Hormone Inhibiting Hormone (GHIH)
inhibits secretion of hGH by somatotrophs (cells in anterior pituitary)
113
Corticotropin Releasing Hormone (CRH)
produced by: hypothalamus
target cells/tissues: corticotrophs, anterior pituitary
inhibited by: glucocorticoids via negative feedback
114
Adrenocorticotropic Hormone (ACTH)
Secreted by: anterior pituitary
| Target tissues: adrenal cortex
115
Actions of the Adrenocorticotropic Hormone (ACTH)
controls the production and secretion of cortisol and other glucocorticoids by the adrenal cortex
116
Actions of the Corticotropin Releasing Hormone (CRH)
Stimulates secretion of Adrenocorticotropic Hormone (ACTH) and Melanocyte Stimulating Hormone (MSH)
117
Glucocorticoids
produced by: adrenal cortex
| target cells/tissues:
118
Actions of Glucocorticoids
- regulate metabolism and resistance to stress
| - includes cortisol, corticosterone and cortisone.
119
Gonadotropin-Releasing Hormone (GnRH)
produced by: hypothalamus
target cells/tissues: anterior pituitary
inhibited by: estrogens in females and by testosterone in males through negative feedback
120
Actions of Luteinizing Hormone (LH)
- In females, stimulates secretion of estrogens and progesterone, ovulation and formation of corpus luteum.
- In males, stimulates testes to produce testosterone.
121
Actions Follicle Stimulating Hormone (FSH)
- In females, initiates development of oocytes and induces ovarian secretion of estrogens.
- In males, stimulates testes to produce sperm
122
Actions of Progesterone and Estrogen
together with gonadotropic hormones of anterior pituitary:
- regulates female reproductive cycle
- maintains pregnancy
- prepare mammary glands for lactation
- development and maintenance of female secondary sex characteristics
123
Actions of Testosterone
- stimulates descent of testes before birth
- regulates sperm production
- promotes development and maintenance of male secondary sex characteristics
124
Luteinizing Hormone (LH)
- stimulated by GnRH
- inhibited by feedback inhibition exerted by estrogens, progesterone, and testosterone
- secreted by gonadotrophs, anterior pituitary
- target organs: ovaries and testes
125
Follicle Stimulating Hormone (FSH)
- stimulated by GnRH
- inhibited by feedback inhibition exerted by inhibin, estrogens and testosterone.
- secreted by gonadotrophs, anterior pituitary
- target organs: ovaries and testes
126
Actions of Inhibin
inhibits secretion of FSH from anterior pituitary
127
Prolactin Releasing Hormone (PRH)
Secreted by: hypothalamus
Target tissue: anterior pituitary
Function: Stimulates secretion of Prolactin (PRL)
128
Prolactin Inhibiting Hormone (PIH)
Secreted by: hypothalamus
Target tissue: anterior pituitary
Function: Inhibits secretion of Prolactin (PRL) and Melanocyte Stimulating Hormone (MSH)
129
Actions of Prolactin (PRL)
together with other hormones, promotes milk production by mammary glands
130
Adrenal Glands: Structure
2 Parts: Adrenal Cortex and Adrenal Medulla
1. cortex (outer layer): controlled by the pituitary gland
2. The medulla (core): influences ANS by releasing the hormones epinephrine (adrenaline) and norepinephrine (noradrenaline), which increase heart activity and blood flow in response to excitement or stress
131
Adrenal Cortex Hormones
1. Mineralocorticoids (mainly aldosterone) from zona glomerulosa cells
2. Glucocorticoids (mainly cortisol) from zona fasciculata cells
3. Androgens (mainly dehydroepiandrosterone, or DHEA) from zona reticularis cells
132
Prolactin (PRL)
- stimulated by decreased PIH
- release enhanced by estrogens, birth control pills, breast-feeding, and dopamine-blocking drugs
- inhibited by PIH (dopamine)
- secreted by lactotrophs, anterior pituitary
- target organ/tissues: mammary glands
133
3 Cardinal Signs of Diabetes Mellitus
1. polyuria
2. polydipsia
3. polyphagia
134
polyuria
- huge urine output
| - glucose acts as osmotic diuretic
135
polydipsia
- excessive thirst
| - from water loss due to polyuria
136
polyphagia
- excessive hunger and food consumption
| - cells cannot take up glucose and are "starving"
137
Type 1 Diabetes Mellitus
(Insulin-Dependent)
- usually early-onset
- autoimmune disorder that tends to run in families
138
Type 1 Diabetes Mellitus is caused when
- pancreatic islet of langerhans are attacked and cannot produce insulin
- requires insulin injections to live
139
Type 2 Diabetes Mellitus
(Insulin-Independent)
- usually adult-onset and most common type
- tends to occur in obese, sedentary individuals
140
Type 2 Diabetes Mellitus is caused when
- cells do not respond to normal levels insulin produced (cells become tolerant called insulin resistance)
- weight loss, diet and exercise have been shown to control and may even prevent the onset
141
Actions of Gonadotropin-Releasing Hormone (GnRH)
controls the secretion of follicle stimulating hormone (FSH) and luteinizing hormone (LH) from the anterior pituitary
142
What factors inhibit release of GHRH?
High levels of growth hormone (hGH) in the blood
143
What factors stimulate the release of GHIH?
release is stimulated by high blood glucose levels (hyperglycemia)
144
What inhibits ACTH release?
Increased cortisol levels
145
What inhibits CRH release?
Increased cortisol levels
146
Which gland secretes Thyroxine (T4) and Triiodothyronine (T3), what are the target tissues?
Secreted by: thyroid
| Target tissues: most body cells
147
What is the function of Thyroxine (T4) and Triiodothyronine (T3)?
- increases metabolism and basal metabolic rate by stimulating glycolysis
- beta oxidation, and lipolysis
- increases heat production by increasing the synthesis of Na/K ATPase
- enhances the actions of the sympathetic NS by up-regulating beta adrenergic receptors
148
Adrenal Medulla is responsible for which stress response system?
Short term stress.
149
Which hormone would increase to reduce stress over the long term?
Cortisol
150
Aldosterone
specific type of mineralocorticoid that helps regulate blood pressure
151
Acinar Cells (Pancreas)
produces and secretes digestive enzymes into the small intestines (duodenum)
152
Islets of Langerhans (Pancreas)
produces and secretes hormones into the bloodstream (Beta-cells and Alpha-cells of Langerhans)
