Lecture 3 Flashcards
1
Q
What is the difference between a neurotransmitter and a hormone?
A
Neurotransmitters go from neurons to act locally, while hormones travel throughout the body from glands to their target organs.
2
Q
What are some examples of paracrine signaling pathways?
A
Our responses to allergens
Tissue repair
Scar tissue formation
Blood clotting
Ovaries with estrogen
3
Q
What are some examples of autocrine signaling pathways?
A
Il-1
T lymphocytes
Metastasis of cancer
4
Q
What are the cytokine peptides?
A
IL, lymphokines, monokines, IFNs, colony stimulating factors, and chemokines
5
Q
What functions of the body do hormones generally cover?
A
Metabolism
Growth and Development
Water and electrolyte balance
Reproduction
Behavior
6
Q
What are the major endocrine glands/tissues of the body?
A
Hypothalamus
Pineal gland
Pituitary gland
Thyroid gland
Parathyroid gland
Thymus gland
Adrenal glands
Stomach
Pancreas
Kidneys
Adipose tissue
Small Intestine
Ovaries/Testes
7
Q
What glands/tissues secrete protein and polypeptide hormones?
A
Anterior and Posterior pituitary glands
Pancreas
Parathyroid gland
8
Q
Where are protein and polypeptide hormones produced?
A
Rough ER of endocrine cells. Generally stored or bound to cell membrane until needed.
9
Q
What hormones are steroids?
A
Aldosterone and Cortisol (adrenal cortex)
Estrogen and Progesterone (Ovaries & Placenta)
Testosterone (Testes)
10
Q
What are some characteristics of steroids?
A
Derivatives of cholesterol
Fat soluble
Diffuse easily over cell membranes and then to the blood to go to their targets.
Not stored
11
Q
What are the tyrosine derivatives?
A
T4 & T3
Epinephrine/Norepinephrine
12
Q
How are T3 and T4 stored?
A
Synthesized by the thyroid and then made into a protein called thyroglobulin. Thyroglobulin is stored in large vesicles in the thyroid gland until needed.
13
Q
How does the secretion of T3 and T4 occur?
A
Amines are split off of thyroglobulin, releasing free hormones into the bloodstream.
The hormones combine with plasma proteins ad then are slowly released to their target organ.
14
Q
Does the adrenal medulla produce more epinephrine or norepinephrine?
A
Epinephrine
15
Q
How does the adrenal medulla store its hormones?
A
Epi/Norepi are stored in preformed vesicles until they are secreted.
16
Q
What are the neuroendocrine hormones released by the hypothalamus?
A
Thyrotrophin-releasing hormone (TRH -> TSH & prolactin)
Corticotropin-releasing hormone (CRH -> ACTH)
Growth hormone-releasing factor (GHRH)
Growth hormone-inhibiting factor (GHIH)
Gonadotropin-releasing hormone (GnRH -> LH & FSH)
Dopamine/prolactin-inhibiting factor (PIF)
17
Q
What are the hormones secreted by the anterior pituitary gland?
A
Growth Hormone (somatotropin)
Thyroid stimulating hormone (TSH)
Adrenocorticotropin hormone (ACTH)
Prolactin
Follicle-stimulating hormone (FSH)
Luteinzing hormone (LH)
18
Q
Which anterior pituitary hormones cause effects directly?
A
Prolactin -> breasts
Growth Hormone -> many organs
19
Q
What is another name for triacylglycerol?
A
Triglyceride
20
Q
What is the effect of growth hormone on blood sugar levels?
A
Anti-insulin, so it increases blood sugar.
21
Q
What is released by the liver when growth hormone acts on it?
A
Somatomedins
22
Q
What are the effects of somatomedins?
A
Skeletal: Increase cartilage formation and skeletal growth.
Non-skeletal: Increase protein synthesis and cell growth.
23
Q
What releases triglycerides?
A
Adipose tissue
24
Q
What stimulates the release of GH?
A
Starvation (especially protein deficiency)
Hypoglycemia
Low fatty acid concentrations in blood
Exercise
Excitement
Trauma
Ghrelin
25
What are the hormones secreted by the posterior pituitary gland?
Antidiuretic hormone (ADH) aka vasopressin
Oxytocin
26
What hormones are secreted by the thyroid gland?
T4
T3
Calcitonin (lower blood calcium levels)
27
In what part of the cell do thyroid hormones act?
Nucleus. They cause the synthesis of new proteins to carry out a variety of metabolic effects.
28
What condition typically is associated with elevated TSH?
Hypothyroidism
29
What condition typically is associated with abnormally low TSH?
Hyperthyroidism
30
What are the symptoms of hyperthyroidism?
Weakness
Fatigue
Excitability
Sweating
Weight loss
Diarrhea
Muscle weakness
Nervousness
Hand tremors
31
What are the symptoms of hypothyroidism?
Fatigue
Weakness
Depression
Irritability
Weight gain
Coarse, dry hair and skin
Sensitivity to cold
Muscle cramps and aches
32
Which thyroid disorder is more common, hyper or hypothyroidism?
Hypothyroidism.
33
What hormones does the adrenal cortex secrete?
Aldosterone
Cortisol
Androgens
34
What are the layers of the Adrenal Cortex (Superficial to deep)
Zona Glomerulosa (15%)
Zona Fasciculata
Zona Reticularis
35
What layer of the adrenal cortex is aldosterone made in?
Zona Glomerulosa
36
What stimulates the secretion of aldosterone?
Angiotensin II
Potassium
37
Where are cortisol and androgens made in the adrenal cortex?
Zona Fasciculata
Zona Reticularis
38
What is the function of PTH?
Increases blood calcium, releasing it from bones and absorbing it from food.
39
What cells of the pancreas secrete insulin and glucagon?
Insulin is made by beta cells
Glucagon is made by alpha cells
40
What hormones does a placenta release?
Progesterone
Estrogen
Human chorionic gonadotropin (HCG)
Human somatomammotropin
41
What hormones does a kidney release?
Renin
1,25-dihydroxycholecalciferol (Vitamin D)
Erythropoeitin
42
What hormone does the heart secrete?
Atrial natriuretic peptide.
43
What hormone does the stomach secerete?
Gastrin
44
What hormone does the small intestine serete?
Secretin and cholecystokinin.
45
What hormone do adipocytes secerete?
Leptin
46
What is the fastest hormone secreted?
Epi and norepi, which is released within seconds.
47
What is the fastest hormone secreted?
Epi and norepi, which is released within seconds.
48
Which hormones typically have long onsets and durations of action?
Thyroxine
Growth hormone
49
How big are hormone concentrations?
Incredibly tiny!
One millionth of one millionth of a gram (picogram) per mL of blood.
A few millionths of a gram per mL
50
What is an example of a positive feedback loop for hormones?
Secretion of estrogen causes a surge in LH. LH then goes to the ovaries, causing more estrogen to be secreted. More estrogen then leads to more LH until ovulation is complete.
51
Why does the body use negative feedback loops for hormones?
It helps ensure a proper level of hormone activity at the target tissue.
The hormone/its products will prevent oversecretion/overactivity at the target tissue.
52
What are some cyclical variations of hormone release?
Seasonal changes
Various stages of development and aging
Diurnal cycles
Sleep
53
How is growth hormone affected by sleep?
Most of our GH is secreted in the beginning half of our sleep, getting reduced in the 2nd half of sleeping.
54
Which type of hormones are water-soluble?
Peptides and catecholamines, which dissolve in plasma.
55
How do steroids and thyroid hormones travel in the blood?
They stay bound to plasma proteins until they dissociate, so they are reservoirs.
56
What is the clearance rate of a hormone?
It is the rate at which it is removed from the body.
57
What two properties determine a hormone's concentration in the blood?
Rate of hormone secretion into blood
Clearance rate
58
In what ways can hormones be cleared from the bloodstream?
Metabolism by tissues
Binding with tissues
Excretion by liver into bile
Excretion by kidneys into urine
59
How long does it take hormones that bind to plasma proteins to be cleared?
several hours to days
60
In what locations of a cell do I find hormone receptors and what hormone types do they respond to?
Cell surface (protein, peptide, and catecholamines)
Cell cytoplasm (steroids)
Cell nucleus (thyroid)
61
Describe the basic process of a GPCR.
A hormone binds to the receptor on the surface.
The G protein, with its 3 subunits and GDP attached, it phosphorylated to GTP.
The now GTP activated alpha subunit can split off and bind to a different enzyme or receptor.
62
What are the typical effects of a G protein?
Open/closing of cell membrane ion channels
Changing the activity of an enzyme.
63
What hormones use the adenylyl cyclase cAMP second messenger system?
ACTH
Glucagon
Catecholamines
TSH
LH
FSH
Angiotensin II
64
Describe the process of the adenylyl cyclase cAMP second messenger system
A GPCR is activated, with the activated G protein binding to adenylyl cyclase, which is an enzyme in the cell membrane.
ATP is dephosphorylated and turned into cAMP.
The phosphate groups from the ATP are used to activate a protein kinase that is dependent on cAMP.
A protein + ATP is phosphorylated by the protein kinase, which transfer the phosphate group from the ATP to the protein, which can then to go to its targets.
65
Describe the process of insulin binding.
Insulin receptors are composed of 2 alpha subunits that lie outside the membrane and 2 beta subunits that can penetrate the cell membrane.
These beta subunits undergo autophosphorylation when insulin binds, which removes their dimerization. This then activates a tyrosine kinase.
Tyrosine kinase activates Insulin Receptor Substrates (IRS), which go out and phosphorylate to do the various cellular effects of insulin.
66
What is the key difference between Glut-1 and Glut-4 when it comes to insulin?
Both are transporters, but Glut-1 is insulin independent.
67
What is the function of Glut-1 and Glut-4?
Transporting glucose into a cell.
68
Insulin is a hormone of _________
Abundance
69
What are most cells of the pancreas called?
Acini/Acinar cells
70
What are the islets of Langerhans and what do they have?
They hold the alpha and beta cells of the pancreas.
Beta cells secrete insulin
Alpha cells secrete glucagon
71
What is the basic chemical structure of insulin?
Insulin, in its proinsulin form, begins as an A chain connected to a C-chain connected to a B chain.
A - C - B, with A and B also connected by sulfide bridges.
C-peptide is cleaved in the golgi apparatus when insulin is packaged, leaving the A and B chain bound to each other by disulfide bridges.
72
How does insulin lose its function?
If the A and B chain are cleaved and the disulfide bridges are broken. Insulin needs to be injected for this reason.
73
What is the significance of a C-peptide?
C chains are always secreted in the same amount of human-made insulin. We can measure how much C-peptide has to see how much natural insulin they are producing.
74
Describe the role of GLUT-2
GLUT-2 transporters are found in beta cells. When the blood contains excess glucose, it will enter the beta cell, becoming phosphorylated to G6P and then becoming oxidized to ATP. This closes K+ channels and opens Ca++ channels. This change causes insulin containing vesicles to be exocytosed.
75
What factors can increase insulin secretion?
Elevated blood glucose
Elevated free fatty acids and amino acids (FFA, AA)
GI Hormones such as gastrin & secretin
Parasympathetic stimulation
Insulin resistance/obesity
Sulfonylurea drugs (Victoza)
76
How do sulfonylurea drugs work?
Sulfonylurea drugs have a subtance known as glucagon-like-peptide 1, or GLP-1 agonists. It is a neuropeptide and it released when you eat a meal.
It competes with gluacagon receptors but does not have the same function. It helps suppress liver glycogenolysis, increases the release of insulin from the pancreas, and decreases gastric emptying. We feel full longer as a result.
77
What factors decrease insulin secretion?
Decreased blood glucose
Fasting
Leptin
Exercise
78
What are all the effects of insulin?
Promoting the uptake and metabolism of glucose by muscles.
Promoting the uptake, storage, and use of glucose by the liver.
Promoting the conversion of excess glucose into fatty acids.
Promoting the synthesis of fat.
Promoting the synthesis and storage of proteins.
Inhibition of gluconeogenesis.
79
What are the effects of glucagon?
Glycogenolysis
Gluconeogenesis
Stimulation of adipose tissue lipase
Hormone sensitive lipase
80
When do we usually start seeing glucagon being secreted?
Around a blood sugar of 90 ml/dl or lower.
81
What is HSL?
Hormone sensitive lipase. It is the enzyme that hydrolyzes glycerols and is expressed highly in adipose tissues. It frees up FFAs from adipose tissue.
It is activated not just by glucagon, but also ACTH and catecholamines.
82
What are the effects of ADH?
Increases water reabsorption by the kidneys and causes vasoconstriction, raising blood pressure.
Peptide
83
What are the effects of oxytocin?
Stimulates milk ejection from breasts and uterine contractions.
Peptide
84
What are the effects of T4 and T3?
T4: thyroxine
T3: triiodothyronine
Increases the rates of chemical reactions in most cells, increasing body metabolic rate
Amine
85
What are the effects of calcintonin?
Promotes deposition of calcium in the bones and decreases extracellular fluid calcium ion concentration
Peptide
86
What are the effects of TSH?
Stimulates synthesis and secretion of thyroid hormones (T4 and T3)
Peptide
87
What are the effects of ACTH?
Stimulates synthesis and secretion of adrenocortical hormones (aldosterone, cortisol, and androgens)
Peptide
88
What are the effects of prolactin?
Promotes development of the female breasts and secretion of milk.
Peptide
89
What are the effects of FSH?
Causes growth of follicles in the ovaries and sperm maturation in the Sertoli cells of the testes.
Peptide
90
What are the effects of LH?
Stimulates testosterone synthesis in Leydig cells of the testes; stimulates ovulation, formation of corpus luteum, and estrogen and progesterone synthesis in ovaries.
Peptide
91
What is another name for the posterior pituitary gland?
Neurohypophysis
92
What is the main difference between the anterior and posterior pituitary gland?
The hypothalamus sends its hormones to the anterior pituitary via the hypothalamic-hypophyseal portal vessels. The anterior then secretes its hormones into the capillary bed surrounding it.
The posterior pituitary is considered an extension of the hypothalamus, so it simply sends its signals via the hypothalamic-hypophyseal tract, where it releases vesicles at the end of the axons.
93
What is another term for insulin-like growth factor 1?
Somatomedins
94
What is the effeect of aldosterone?
Increases sodium reabsorption by the kidneys
Increases potassium excretion by the kidneys
Increases hydrogen ion excretion by the kidneys.
Steroid
95
What happens if an infant is deficient in T3 and T$?
Neurological impairments.
Thyroid hormones are essential in the development of synapses and neurons.
96
What is the effect of cortisol?
Controls metabolism of proteins, fats, and carbohydrates. Has anti-inflammatory effects.
Steroid
97
What is the effect of parathyroid hormone?
Controls serum calcium ion concentration by increasing calcium absorption by the gut and kidneys and releasing calcium from the bones.
Peptide
98
What is the effect of Testosterone?
Promotes development of male reproductive system and male secondary sexual characteristics.
Steroid
99
What is the effect of Estrogen?
Promotes development and growth of the female reproductive system, female breasts, and female secondary sexual characteristics.
Steroid
100
What is the effect of Progesterone?
Stimulates secretion of "uterine milk" by the uterine endometrial glands and promotes development of secretory apparatus of the breasts.
Steroid
101
What are the effects of Human Chorionic Gonadotropin (HCG)?
Promotes growth of corpus luteum and secretion of estrogens and progesterone by corpus luteum.
Peptide
102
What are the effects of Human sommatomammotropin?
Probably helps promote development of some fetal tissues as well as the mother's breasts.
Peptide
103
What are the effects of Renin?
Catalyzes the conversion of angiotensinogen to angiotensin I (enzyme)
Peptide
104
What are the effects of 1,25-dihydroxycholecalciferol?
Increases intestinal absorption of calcium and bone mineralization.
Steroid
105
What are the effects of erythropoeitin?
Increases erythrocyte production.
Peptide
106
What are the effects of ANP?
Atrial natriuretic peptide.
Increases sodium excretion by the kidneys, decreasing blood pressure.
Peptide
107
What are the effects of gastrin?
Stimulate HCl secretion by parietal cells
Peptide
108
What are the effects of secretin?
Stimulates pancreatic acinar cells to release bicarbonate and water.
Peptide
109
What are the effects of cholecystokinin? (CCK)
Stimulates gallbladder contraction and release of pancreatic enzymes.
Peptide
110
What are the effects of Leptin?
Inhibits appetite and stimulates thermogenesis.
Peptide
111
How do Professor Shepherd measure metabolic rate?
He analyzes the oxygen they breathe in/out and calculate how much they should be burning based on their age, weight, etc...
112
What are the two drugs mentioned that release GLP-1 agonists?
Victoza and Ozempic
113
When should exercise be done for diabetics and why?
Morning, because then they can titrate their insulin throughout the day.
114
What is the key difference between Type 1 and Type 2 diabetes?
Type 1 is genetic and involves an autoimmune condition that destroys the beta cells of the pancreas, preventing any natural insulin production.
Type 2 is obtained and involves decreasing insulin sensitivity, with the most common risk factor being obesity.
115
How exactly does exercise cause upregulation of GLUT-4?
The release of calcium from muscle contraction works on a protein called calmodulin, which will increase the number of GLUT-4 transporters. The consistent increase of calcium will also upregulate GLUT-4.
