Endocrine System 1 Flashcards
(98 cards)
1
Q
Name the 2 types of glands in the body
A
- Exocrine glands
2. Endocrine glands
2
Q
Differentiate between exocrine glands and endocrine glands
A
Exocrine- secretes substances through ducts into body cavities , lumen of organs or body surface
Endocrine glands- ductless glands that secrete products into interstitial fluid, diffuses into blood
3
Q
Give some examples of exocrine glands
A
Salivary and digestive glands, sweat pores
4
Q
Give some examples of endocrine glands
A
Placenta, kidney, heart, liver, thyroid and adrenal, pituitary and pineal glands
5
Q
How does the nervous system play a role in the function in the endocrine system?
A
Nerve impulses cause the release of neurotransmitters. Neurotransmitters excite or inhibit nerve, muscle and gland cells
6
Q
What is the down-regulation of hormones?
A
Excess hormone leads to a decrease in number of receptors; receptors undergo endocytosis and are degraded
7
Q
What is up-regulation of hormone receptors?
A
Deficiency of hormone leads to an increase in receptors, target tissue becomes more sensitive to the hormone
8
Q
What are the 2 chemical classes of hormones?
A
Lipid soluble hormones
Water soluble hormones
9
Q
List 3 lipid soluble hormones
A
Steroids, thyroid hormones and nitric oxide
10
Q
List 4 water soluble hormones
A
Amines
Peptide
protein hormones
Eicosanoids
11
Q
What are the 2 types of eicosanoids?
A
Prostaglandins and leukotrienes
12
Q
How are lipid soluble hormones transported?
A
Must attach to transport proteins synthesized by the liver
13
Q
How do lipid soluble affect hormone loss in kidneys?
A
Slow loss of hormone by filtration
14
Q
Describe the action of lipid soluble hormones
A
- Hormone diffuses through phospholipid bilayer into cell
- receptor-hormone complex activates/inhibits specific genes
- New mRNA is formed and allows for synthesis of new proteins
- new protein changes cell activity
15
Q
Describe the action of water soluble hormones
A
- Hormones binds (first messsanger) to receptors in the plasma membrane of target cell
- Adenylate Cyclase converts ATP to cyclic AMP(second messenger) which activates protein kinases
- These protein kinases phosphorylation enzymes which catalyze reactions that produce the physiological response
16
Q
How are protein hormones administered and why?
A
By injection, the digestive enzymes destroy them by breaking their peptide bonds
17
Q
How are steroid and thyroid hormones administered and why?
A
Orally because they do no split by digestion and easily cross the intestinal lining because they are lipid soluble
18
Q
Name 3 hormonal interactions
A
Permissive effect
Synergistic effect
Antagonist effect
19
Q
Describe the permissive effect- hormonal interaction
A
A second hormone strengthens the weak effects of the first hormone
20
Q
Describe the synergistic effect- hormonal interaction
A
The effect of 2 hormones acting together is greater than the effect of each hormone acting alone
21
Q
Describe the antagonistic effect- hormonal interactions
A
2 hormones with opposite effects
22
Q
Give an example of the permissible effect- hormonal interaction
A
Thyroid hormone strengthens epinephrine effect on lipolysis
23
Q
Give an example of the synergistic effect
A
Before ovulation, estrogen has a positive feedback on the release of FSH and LH
24
Q
Give 4 major examples of hormonal control
A
Regulated signals(nervous, chemical/blood, other hormones)
Negative feedback
Positive feedback
Hypo-secretion and hyper-secretion
25
What are the general functions of hormones?
- control growth and development
Regulate reproductive system
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Help regulate:
Extracellular fluid
Metabolism
Biological clock
Contraction of cardiac and smooth muscle
Glandular secretion
Some immune functions
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26
What do hormones affect while traveling in the blood?
Target cells with specific protein or glycoprotein receptors to which the hormones bind?
27
What is the pharmaceutical application of creating synthetic hormones to block receptors for particularly naturally occurring hormones?
-these synthetic hormones that block natural hormones are available as drugs
RU486(Mifepristone) is used to induce abortion which binds to its receptors for progesterone and prevents progesterone from exerting it’s normal effect
28
Hormones can be local or circulating(endocrine) Specify what is meant by local
Local hormones are produced by nerve or gland cells and bind to either neighboring cells or same type of cell that produced them
29
What are examples of local hormones?
Auto cringe and paracrine
30
What is autocrine regulation?
Mode of hormone action to which hormones bind to receptors on the very cell that produced it
31
What is paracrine regulation?
Form of cell to cell communication, hormones affect nearby cells
32
Are local hormones using the exocrine or endocrine cell signaling method?
Exocrine, as endocrine uses circulatory means
33
Describe the lipid soluble hormone class- steroids
-lipid soluble derived from cholesterol
34
Describe the lipid-soluble hormone class- thyroid hormone
Tyrosine ring plus attached iodine’s are lipid soluble ( T3, T4)
35
Describe the lipid soluble hormone, nitric oxide
A gas, both a hormone and a neurotransmitter
36
Describe the water soluble hormone- Amines
They are comprised of ccatecholamines- epinephrine and nonepinephrine
As well as melatonin, Seratonine, histamine
37
Describe the water soluble hormone- peptide and protein hormones
Modified amino acids or amino acids put together.
Examples: FSH, LH, TSH,hGH, insulin, glucagon, parathyroid hormone, oxytocin
38
Describe the water soluble hormone- eicosanoids
Derived from arachadonic acid (20 carbon fatty acid)
39
How does water soluble hormones circulate in blood?
Circulates in free form
40
How are lipid soluble hormones transported in blood?
Must be attached to transport proteins synthesized by the liver
41
How is hormone lost while being transported in the blood?
Slow loss of hormone by filtration within kidney
42
How much hormones travel by free fraction?
0.1%-10%
43
Contrast how liver and adipocytes respond to insulin
Liver cells- insulin stimulates glycogen synthesis
Adipocytes- insulin stimulates triglyceride synthesis
44
Describe the action of water-soluble hormones
Binding of hormone(first hormone) to receptors embedded in the plasma membranes of target cells .
This activates G-proteins which turns on adenylate cyclase
Adenylate cyclase converts ATP into cyclic AMP(second messenger) which activates protein kinases
Protein kinases phosphorylate enzymes which catalyze reactions that produce the physiological response
45
Give some examples by which the endocrine is controlled
Nervous system, chemical changes in the blood, other hormones, both positive and negative feedback and disorders in hypo-secretion and hyper-secretion
46
Describe the role of the hypothalamus
It is the interface between the endocrine, autonomic and limbus systems.
It controls the pituitary gland with nine different releasing and inhibiting hormones
47
Name the functions of the pituitary gland/hypophysis
Secretes hormones that regulate other endocrine hormones
48
What regulates the pituitary gland?
Stimulated and inhibited by hypothalamus and feedback mechanisms from target organs
49
What connects the hypothalamus to the pituitary gland?
Infundibulum
50
Name and describe the parts of the anterior pituitary
Pars distalis (anterior lobe)
Pars tuberalis(forms a sheath around the infundibulum)
51
What kind of axons are in the anterior pituitary gland( adrenohypophysis)
Neurosecretory
52
How are hormones made by neurosecretory cells transported ?
Hypophyseal transport system
53
What is the purpose of anterior pituitary hormones?
They act on other endocrine glands(tropic hormones) , hormone production and secretion controlled by releasing and inhibitory hormones from hypothalamus and feedback mechanisms
54
Describe the general pathway of hormones through circulatory system to leave the anterior pituitary
- Controlling hormones enter blood at primary plexus
- travel through portal veins
- Leave anterior pituitary through secondary plexus
55
What are the 5 different cell types of the adrenohypophysis and the hormones they produce
1. Somatotrophs- human growth hormone(hGH)
2. Thyrotrophs-thyroid-stimulating hormone (TSH)
3. Gonadotrophs-FSH and LH
4. Lactotrophs- prolactin (PRL)
5. Corticotrophs - adrenocorticotropic hormone(ACTH) and melanocyte-stimulating hormone(MSH)
56
Describe how human growth hormone allows for cell growth
Increases cell growth and cell division by increasing their uptake of amino acids and synthesis of proteins
57
Describe how human growth hormone stimulates lypolysis
Causes fat to be used for energy in preference to carbohydrates and proteins
58
Why does human growth hormone prevent the uptake of glucose in skeleton muscle and fat?
So blood glucose levels remain high enough in the brain by decreasing glucose uptake in skeletal muscle and fat
59
List the functions of human growth hormone
Increase cell growth and division
Stimulate lypolysis
Decreases glucose uptake in skeletal muscle and fat
60
How does low blood sugar stimulate release of Growth releasing hormone(GHRH) ?
Stimulates release of GHRH from hypothalamus
Anterior pituitary releases more hGH which, along with insulin growth factor, speed up breakdown of liver, glycogen into glucose , which enters the blood more rapidly
Blood glucose raises back to normal
If blood continues to rise, hyperglycemia inhibits release of GHRH
61
How does high blood sugar affect the regulation of hGH?
High blood sugar stimulates release of GHIH(somatostatin) from the hypothalamus
Anterior pituitary secretes less hGH
Low levels of hGH and IGF decrease the rate of glycogen breakdown in the liver and glucose enters the blood more slowly
Blood glucose falls back to normal
If blood glucose continues to fall hypoglycemia inhibits release of GHIH
62
What are the results of excess of hGH?
- Raises blood glucose concentration
- Pancreas releases insulin continually
- beta-cell burnout
63
What is the diabetogenic effect of hGH?
Causes diabetes myelitis if no insulin activity can occur eventually
64
What is acromegaly?
Disease due to hyper secretion of growth hormone by the pituitary (remember Andre the gentle giant)
65
What are the signs and symptoms of acromegaly?
- excessive soft tissue growth
- growth of hand and feet
- increased ring and shoe size
- large tongue
- Thickened skin
- enlarged jaw and forehead
66
What is dwarfism?
Hyposecretion of growth hormone
67
What are the signs and symptoms of dwarfism?
- slow bone,organ and tissue growth
- slow growth rate
- early closure of epiphyseal plate
- proportions normal
- intelligence normal
- appears younger than normal
68
How is dwarfism treated?
Give hGH
69
Explain the process of thyroid stimulating hormone increasing metabolism
Low blood levels of T3 and T4 or low metabolism stimulates release of Thyrotropin releasing hormone (TRH) in the hypothalamus
This causes release of TSH by thyrotropin cells
TSH stimulates the synthesis and secretion of T3 and T4 by thyroid gland by binding to thyroid follicular cells
Metabolic rate is then stimulated
Elevated T3 stimulates release of TRH and TSH (negative feedback)
70
What are the functions of FSH?
- initiates the formation of follicles within the ovary
- stimulates follicle cells to secrete estrogen
- stimulates sperm production in testes
71
How is FSH and LH released?
Hypothalamus releases GnRH which stimulates gonadotrophs to release FSH and LH
72
What are the functions of LH in females?
- secretion of estrogen
- triggers ovulation
- formation of corpus luteum
- secretion of progesterone
73
What are the functions of LH in males
Stimulates interstitial cells of the testes to secrete testosterone
74
What is the function of prolactin?
Along with other hormones, it initiates and maintains milk production and secretion by the mammary glands
75
How does the hypothalamus prevent prolactin secretion?
Hypothalamus produces prolactin inhibiting hormone( dopamine) which inhibits prolactin production by lactotroph cells
76
What are the effects of suckling on prolactin levels?
Suckling reduces levels of hypothalamic inhibition and prolactin levels rise among with milk secretion
77
What does adrenocorticotropic hormone control?
ACTH controls the production and secretion of hormones called glucocorticoids by the cortex of the adrenal gland
78
Describe the regulation of adrenocorticotropic hormone ACTH
1. Hypothalamus releases corticotropin releasing hormone
2. Corticotropin releasing hormone stimulates the release of corticotropin/ ACTH by
3. ACTH stimulates release of cortisol by the adrenal cortex
4. Cortisol inhibits release of corticotropin releasing hormone in hypothalamus and inhibits corticotropin release in anterior pituitary
79
What is the name of the posterior pituitary?
Neurophysis
80
What is a function of the neurophysis and thus a difference between the neurophysis and adrenophysis?
Do not synthesize hormones but stores and releases hormones produced by the hypothalamus
81
What makes up the neurophysis?
Consists of axons and axon terminals of hypothalamic neurons
82
What 2 neurotransmitters do the neurophysis release into the capillary plexus
Antidiuretic hormone
Oxytocin
83
What is the function of oxytocin during delivery?
Stretching of cervix stimulates release of oxytocin
Oxytocin enhances smooth muscle contraction of the uterus
84
What is the function of oxytocin after delivery?
- Oxytocin stimulates uterus contraction and ejection of milk from the breasts
- Nursing a babybafter delivery causes oxytocin release which promotes uterine contraction and placenta expulsion
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85
What are the functions of ADH?
Water reabsorption in the kidneys
Decreased perspiration
Arteriolar constriction
86
What internal stimuli controls ADH?
Mainly osmotic pressure in blood
87
What is the effect of ADH?
Decrease urine volume and conserve body water
88
What are 2 things which inhibit ADH ?
Over hydration and alcohol intake
89
Explain ADH regulation when there is high blood osmotic pressure
1. High blood osmotic pressure stimulates hypothalamic osmoreceptors
2. Osmoreceptors activate the neurosecretory cells that synthesize and release ADH
3. Nerve impulses liberate ADH from axon terminals in posterior pituitary into the bloodstream where they effect target cells (kidneys retain water, sudoriferous/sweat glands and arterioles constrict)
90
Explain ADH regulation when blood osmotic pressure is low
1. Low blood osmotic pressure inhibits hypothalamic osmoreceptors
2. Inhibition of osmoreceptors reduces or stops ADH secretion
91
Aside from osmotic blood pressure, what are other stimulants of ADH?
Dehydration and hypovolemia
92
What are some pituitary posterior disorders?
Diabetes insipidus-DI
hyposecretion of ADH
Neurogenic DI-brain tumor, head trauma affecting hypothalamus or posterior pituitary
Nephrogenic DI- kidneys do not respond to ADH
Excessive volumes of urine , dehydration, thirst
Hormone replacement therapy for life
93
Describe the time to onset of hormones
Most take several minutes or more but some seconds
94
Describe the duration of action for hormones
Anywhere from seconds to days
95
Describe the time to action and duration of neurotransmitters
Results are immediate, milliseconds
Brief duration of effects
96
Explain the amplifications hormone effects, specifically water soluble
A single molecule activates about 100 G proteins
Each G protein molecule activates an adenylate cyclist molecule which then produce about 1000 to 100,000 cAMP liberated in the cell
This may end up in the activation of 100ls of substrate molecules
97
What are common target cells of hGH?
Liver, skeletal muscle, adipose tissue, cartilage and bone
98
What can stimulate milk ejection in mother’s?
Hearing baby’s crying and suckling
