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![Page 1: Hormonal Action and Feedback Loops Understanding how certain hormones work in the body What exactly is “feedback”?](https://reader037.fdocuments.us/reader037/viewer/2022110209/56649e0c5503460f94af42ce/html5/thumbnails/1.jpg)
Hormonal Action and Feedback Loops
Understanding how certain hormones work in the body
What exactly is “feedback”?
![Page 2: Hormonal Action and Feedback Loops Understanding how certain hormones work in the body What exactly is “feedback”?](https://reader037.fdocuments.us/reader037/viewer/2022110209/56649e0c5503460f94af42ce/html5/thumbnails/2.jpg)
Thyroid Gland
• Found at the base of the throat• Consists of two lobes and a connecting
isthmus• Produces two hormones– Thyroid hormone– Calcitonin
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Thyroid Gland
Figure 9.7a
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Thyroid Gland
• Thyroid hormone– Major metabolic hormone– Composed of two active iodine-containing
hormones• Thyroxine (T4)—secreted by thyroid follicles
• Triiodothyronine (T3)—conversion of T4 at target tissues
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Thyroid Gland
• Thyroid hormone disorders– Goiters • Thyroid gland enlarges due to lack of iodine• Salt is iodized to prevent goiters
– Cretinism• Caused by hyposecretion of thyroxine• Results in dwarfism during childhood
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Thyroid Gland
• Thyroid hormone disorders (continued)– Myxedema• Caused by hypothyroidism in adults• Results in physical and mental slugishness
– Graves’ disease• Caused by hyperthyroidism• Results in increased metabolism, heat intolerance,
rapid heartbeat, weight loss, and exophthalmos
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Thyroid Gland
• Calcitonin– Decreases blood calcium levels by causing its
deposition on bone– Antagonistic to parathyroid hormone– Produced by parafollicular cells– Parafollicular cells are found between the follicles
![Page 8: Hormonal Action and Feedback Loops Understanding how certain hormones work in the body What exactly is “feedback”?](https://reader037.fdocuments.us/reader037/viewer/2022110209/56649e0c5503460f94af42ce/html5/thumbnails/8.jpg)
Parathyroid Glands
• Tiny masses on the posterior of the thyroid• Secrete parathyroid hormone (PTH)– Stimulate osteoclasts to remove calcium from
bone– Stimulate the kidneys and intestine to absorb
more calcium– Raise calcium levels in the blood
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Regulation of Calciumlevels in the blood….
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Hormonal Regulation of Calcium in Blood
Figure 9.10, step 1
Calcium homeostasis of blood9–11 mg/100 ml
RisingbloodCa2+
levels
Imbalance
Imbalance
![Page 11: Hormonal Action and Feedback Loops Understanding how certain hormones work in the body What exactly is “feedback”?](https://reader037.fdocuments.us/reader037/viewer/2022110209/56649e0c5503460f94af42ce/html5/thumbnails/11.jpg)
Hormonal Regulation of Calcium in Blood
Figure 9.10, step 2
Calcium homeostasis of blood9–11 mg/100 ml
RisingbloodCa2+
levels
Thyroidgland
Imbalance
Imbalance
![Page 12: Hormonal Action and Feedback Loops Understanding how certain hormones work in the body What exactly is “feedback”?](https://reader037.fdocuments.us/reader037/viewer/2022110209/56649e0c5503460f94af42ce/html5/thumbnails/12.jpg)
Hormonal Regulation of Calcium in Blood
Figure 9.10, step 3
Calcium homeostasis of blood9–11 mg/100 ml
RisingbloodCa2+
levels
Thyroid glandreleasescalcitonin
Calcitonin
Thyroidgland
Imbalance
Imbalance
![Page 13: Hormonal Action and Feedback Loops Understanding how certain hormones work in the body What exactly is “feedback”?](https://reader037.fdocuments.us/reader037/viewer/2022110209/56649e0c5503460f94af42ce/html5/thumbnails/13.jpg)
Hormonal Regulation of Calcium in Blood
Figure 9.10, step 4
Calcium homeostasis of blood9–11 mg/100 ml
RisingbloodCa2+
levels
Thyroid glandreleasescalcitonin
Calcitonin Calcitoninstimulatescalcium saltdepositin bone
Thyroidgland
Imbalance
Imbalance
![Page 14: Hormonal Action and Feedback Loops Understanding how certain hormones work in the body What exactly is “feedback”?](https://reader037.fdocuments.us/reader037/viewer/2022110209/56649e0c5503460f94af42ce/html5/thumbnails/14.jpg)
Hormonal Regulation of Calcium in Blood
Figure 9.10, step 5
Calcium homeostasis of blood9–11 mg/100 ml
RisingbloodCa2+
levels
Thyroid glandreleasescalcitonin
Calcitonin Calcitoninstimulatescalcium saltdepositin bone
Thyroidgland
![Page 15: Hormonal Action and Feedback Loops Understanding how certain hormones work in the body What exactly is “feedback”?](https://reader037.fdocuments.us/reader037/viewer/2022110209/56649e0c5503460f94af42ce/html5/thumbnails/15.jpg)
Figure 9.10, step 6
Calcium homeostasis of blood9–11 mg/100 ml
FallingbloodCa2+
levels
Imbalance
Imbalance
Hormonal Regulation of Calcium in Blood
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Figure 9.10, step 7
Calcium homeostasis of blood9–11 mg/100 ml
Thyroidgland
Parathyroidglands
FallingbloodCa2+
levels
Imbalance
Imbalance
Hormonal Regulation of Calcium in Blood
![Page 17: Hormonal Action and Feedback Loops Understanding how certain hormones work in the body What exactly is “feedback”?](https://reader037.fdocuments.us/reader037/viewer/2022110209/56649e0c5503460f94af42ce/html5/thumbnails/17.jpg)
Figure 9.10, step 8
Calcium homeostasis of blood9–11 mg/100 ml
PTHParathyroidglands releaseparathyroidhormone (PTH)
Thyroidgland
Parathyroidglands
FallingbloodCa2+
levels
Imbalance
Imbalance
Hormonal Regulation of Calcium in Blood
![Page 18: Hormonal Action and Feedback Loops Understanding how certain hormones work in the body What exactly is “feedback”?](https://reader037.fdocuments.us/reader037/viewer/2022110209/56649e0c5503460f94af42ce/html5/thumbnails/18.jpg)
Figure 9.10, step 9
Calcium homeostasis of blood9–11 mg/100 ml
Osteoclastsdegrade bonematrix and releaseCa2+ into blood
PTHParathyroidglands releaseparathyroidhormone (PTH)
Thyroidgland
Parathyroidglands
FallingbloodCa2+
levels
Imbalance
Imbalance
Hormonal Regulation of Calcium in Blood
![Page 19: Hormonal Action and Feedback Loops Understanding how certain hormones work in the body What exactly is “feedback”?](https://reader037.fdocuments.us/reader037/viewer/2022110209/56649e0c5503460f94af42ce/html5/thumbnails/19.jpg)
Figure 9.10, step 10
Calcium homeostasis of blood9–11 mg/100 ml
Osteoclastsdegrade bonematrix and releaseCa2+ into blood
PTHParathyroidglands releaseparathyroidhormone (PTH)
Thyroidgland
Parathyroidglands
Hormonal Regulation of Calcium in Blood
![Page 20: Hormonal Action and Feedback Loops Understanding how certain hormones work in the body What exactly is “feedback”?](https://reader037.fdocuments.us/reader037/viewer/2022110209/56649e0c5503460f94af42ce/html5/thumbnails/20.jpg)
Figure 9.10, step 11
Calcium homeostasis of blood9–11 mg/100 ml
RisingbloodCa2+
levels
Thyroid glandreleasescalcitonin
Osteoclastsdegrade bonematrix and releaseCa2+ into blood
PTH
Calcitonin Calcitoninstimulatescalcium saltdepositin bone
Parathyroidglands releaseparathyroidhormone (PTH)
Thyroidgland
Thyroidgland
Parathyroidglands
FallingbloodCa2+
levels
Imbalance
Imbalance
Hormonal Regulation of Calcium in Blood
![Page 21: Hormonal Action and Feedback Loops Understanding how certain hormones work in the body What exactly is “feedback”?](https://reader037.fdocuments.us/reader037/viewer/2022110209/56649e0c5503460f94af42ce/html5/thumbnails/21.jpg)
Hormones of the Adrenal Gland…
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Adrenal Glands
• Sit on top of the kidneys• Two regions– Adrenal cortex—outer glandular region has three
layers• Mineralocorticoids secreting area• Glucocorticoids secreting area• Sex hormones secreting area
– Adrenal medulla—inner neural tissue region
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Hormones of the Adrenal Cortex
Figure 9.11
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Hormones of the Adrenal Cortex
• Mineralocorticoids (mainly aldosterone)– Produced in outer adrenal cortex– Regulate mineral content in blood– Regulate water and electrolyte balance– Target organ is the kidney– Production stimulated by renin and aldosterone– Production inhibited by atrial natriuretic peptide
(ANP)
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Action Within the Adrenal Cortex
Figure 9.12
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Hormones of the Adrenal Cortex
• Glucocorticoids (including cortisone and cortisol)– Produced in the middle layer of the adrenal cortex– Promote normal cell metabolism– Help resist long-term stressors– Released in response to increased blood levels of
ACTH
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Hormones of the Adrenal Cortex
• Sex hormones– Produced in the inner layer of the adrenal cortex– Small amounts are made throughout life– Mostly androgens (male sex hormones) are made
but some estrogens (female sex hormones) are also formed
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Adrenal Gland Disorders
• Adrenal cortex disorders– Addison’s disease• Results from hyposecretion of all adrenal cortex
hormones• Bronze skin tone, muscles are weak, burnout,
susceptibility to infection
– Hyperaldosteronism• May result from an ACTH-releasing tumor• Excess water and sodium are retained leading to high
blood pressure and edema
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Adrenal Gland Disorders
• Adrenal cortex disorders– Cushing’s syndrome• Results from a tumor in the middle cortical area of the
adrenal cortex• “Moon face,” “buffalo hump” on the upper back, high
blood pressure, hyperglycemia, weakening of bones, depression
– Masculinization• Results from hypersecretion of sex hormones• Beard and male distribution of hair growth
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Hormones of the Adrenal Medulla
• Produces two similar hormones (catecholamines)– Epinephrine (adrenaline)– Norepinephrine (noradrenaline)
• These hormones prepare the body to deal with short-term stress (“fight or flight”) by– Increasing heart rate, blood pressure, blood
glucose levels– Dilating small passageways of lungs
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Hormones of the Adrenal Cortex
Figure 9.11
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How important is the Pancreas??
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Pancreatic Islets
• The pancreas is a mixed gland and has both endocrine and exocrine functions
• The pancreatic islets produce hormones– Insulin—allows glucose to cross plasma
membranes into cells from beta cells– Glucagon—allows glucose to enter the blood from
alpha cells– These hormones are antagonists that maintain
blood sugar homeostasis
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Figure 9.15, step 1
Homeostasis: Normal blood glucoselevels (90 mg/100ml)
![Page 35: Hormonal Action and Feedback Loops Understanding how certain hormones work in the body What exactly is “feedback”?](https://reader037.fdocuments.us/reader037/viewer/2022110209/56649e0c5503460f94af42ce/html5/thumbnails/35.jpg)
Stimulus:rising bloodglucose levels(e.g., aftereating fourjelly doughnuts)
Homeostasis: Normal blood glucoselevels (90 mg/100ml)
Imbalance
Imbalance
Figure 9.15, step 2
![Page 36: Hormonal Action and Feedback Loops Understanding how certain hormones work in the body What exactly is “feedback”?](https://reader037.fdocuments.us/reader037/viewer/2022110209/56649e0c5503460f94af42ce/html5/thumbnails/36.jpg)
Elevatedblood sugarlevels
Stimulus:rising bloodglucose levels(e.g., aftereating fourjelly doughnuts)
Homeostasis: Normal blood glucoselevels (90 mg/100ml)
Imbalance
Imbalance
Figure 9.15, step 3
![Page 37: Hormonal Action and Feedback Loops Understanding how certain hormones work in the body What exactly is “feedback”?](https://reader037.fdocuments.us/reader037/viewer/2022110209/56649e0c5503460f94af42ce/html5/thumbnails/37.jpg)
Insulin-secretingcells of the pancreasactivated; releaseinsulin into theblood
Elevatedblood sugarlevels
Stimulus:rising bloodglucose levels(e.g., aftereating fourjelly doughnuts)
Homeostasis: Normal blood glucoselevels (90 mg/100ml)
Imbalance
Imbalance
Figure 9.15, step 4
![Page 38: Hormonal Action and Feedback Loops Understanding how certain hormones work in the body What exactly is “feedback”?](https://reader037.fdocuments.us/reader037/viewer/2022110209/56649e0c5503460f94af42ce/html5/thumbnails/38.jpg)
Insulin-secretingcells of the pancreasactivated; releaseinsulin into theblood
Elevatedblood sugarlevels
Stimulus:rising bloodglucose levels(e.g., aftereating fourjelly doughnuts)
Uptake of glucosefrom blood is en-hanced in mostbody cells
Homeostasis: Normal blood glucoselevels (90 mg/100ml)
Imbalance
Imbalance
Figure 9.15, step 5
![Page 39: Hormonal Action and Feedback Loops Understanding how certain hormones work in the body What exactly is “feedback”?](https://reader037.fdocuments.us/reader037/viewer/2022110209/56649e0c5503460f94af42ce/html5/thumbnails/39.jpg)
Insulin-secretingcells of the pancreasactivated; releaseinsulin into theblood
Elevatedblood sugarlevels
Stimulus:rising bloodglucose levels(e.g., aftereating fourjelly doughnuts)
Uptake of glucosefrom blood is en-hanced in mostbody cells
Liver takes upglucose and storesit as glycogen
Homeostasis: Normal blood glucoselevels (90 mg/100ml)
Imbalance
Imbalance
Figure 9.15, step 6
![Page 40: Hormonal Action and Feedback Loops Understanding how certain hormones work in the body What exactly is “feedback”?](https://reader037.fdocuments.us/reader037/viewer/2022110209/56649e0c5503460f94af42ce/html5/thumbnails/40.jpg)
Figure 9.15, step 7
Insulin-secretingcells of the pancreasactivated; releaseinsulin into theblood
Elevatedblood sugarlevels
Stimulus:rising bloodglucose levels(e.g., aftereating fourjelly doughnuts)
Blood glucoselevels declineto set point;stimulus forinsulin releasediminishes
Uptake of glucosefrom blood is en-hanced in mostbody cells
Liver takes upglucose and storesit as glycogen
Homeostasis: Normal blood glucoselevels (90 mg/100ml)
![Page 41: Hormonal Action and Feedback Loops Understanding how certain hormones work in the body What exactly is “feedback”?](https://reader037.fdocuments.us/reader037/viewer/2022110209/56649e0c5503460f94af42ce/html5/thumbnails/41.jpg)
Figure 9.15, step 8
Stimulus:declining bloodglucose levels(e.g., afterskipping a meal)
Homeostasis: Normal blood glucoselevels (90 mg/100ml)
Imbalance
Imbalance
![Page 42: Hormonal Action and Feedback Loops Understanding how certain hormones work in the body What exactly is “feedback”?](https://reader037.fdocuments.us/reader037/viewer/2022110209/56649e0c5503460f94af42ce/html5/thumbnails/42.jpg)
Figure 9.15, step 9
Stimulus:declining bloodglucose levels(e.g., afterskipping a meal)
Low bloodsugar levels
Homeostasis: Normal blood glucoselevels (90 mg/100ml)
Imbalance
Imbalance
![Page 43: Hormonal Action and Feedback Loops Understanding how certain hormones work in the body What exactly is “feedback”?](https://reader037.fdocuments.us/reader037/viewer/2022110209/56649e0c5503460f94af42ce/html5/thumbnails/43.jpg)
Figure 9.15, step 10
Stimulus:declining bloodglucose levels(e.g., afterskipping a meal)
Low bloodsugar levels
Glucagon-releasingcells of pancreasactivated;release glucagoninto blood; targetis the liver
Homeostasis: Normal blood glucoselevels (90 mg/100ml)
Imbalance
Imbalance
![Page 44: Hormonal Action and Feedback Loops Understanding how certain hormones work in the body What exactly is “feedback”?](https://reader037.fdocuments.us/reader037/viewer/2022110209/56649e0c5503460f94af42ce/html5/thumbnails/44.jpg)
Figure 9.15, step 11
Stimulus:declining bloodglucose levels(e.g., afterskipping a meal)
Low bloodsugar levels
Glucagon-releasingcells of pancreasactivated;release glucagoninto blood; targetis the liverLiver breaks down
glycogen stores andreleases glucose tothe blood
Homeostasis: Normal blood glucoselevels (90 mg/100ml)
Imbalance
Imbalance
![Page 45: Hormonal Action and Feedback Loops Understanding how certain hormones work in the body What exactly is “feedback”?](https://reader037.fdocuments.us/reader037/viewer/2022110209/56649e0c5503460f94af42ce/html5/thumbnails/45.jpg)
Figure 9.15, step 12
Rising bloodglucose levelsreturn blood sugarto homeostatic setpoint; stimulus forglucagon releasediminishes
Stimulus:declining bloodglucose levels(e.g., afterskipping a meal)
Low bloodsugar levels
Glucagon-releasingcells of pancreasactivated;release glucagoninto blood; targetis the liverLiver breaks down
glycogen stores andreleases glucose tothe blood
Homeostasis: Normal blood glucoselevels (90 mg/100ml)
![Page 46: Hormonal Action and Feedback Loops Understanding how certain hormones work in the body What exactly is “feedback”?](https://reader037.fdocuments.us/reader037/viewer/2022110209/56649e0c5503460f94af42ce/html5/thumbnails/46.jpg)
Figure 9.15, step 13
Insulin-secretingcells of the pancreasactivated; releaseinsulin into theblood
Elevatedblood sugarlevels
Stimulus:rising bloodglucose levels(e.g., aftereating fourjelly doughnuts)
Rising bloodglucose levelsreturn blood sugarto homeostatic setpoint; stimulus forglucagon releasediminishes
Blood glucoselevels declineto set point;stimulus forinsulin releasediminishes
Stimulus:declining bloodglucose levels(e.g., afterskipping a meal)
Low bloodsugar levels
Glucagon-releasingcells of pancreasactivated;release glucagoninto blood; targetis the liver
Uptake of glucosefrom blood is en-hanced in mostbody cells
Liver breaks downglycogen stores andreleases glucose tothe blood
Liver takes upglucose and storesit as glycogen
Homeostasis: Normal blood glucoselevels (90 mg/100ml)
Imbalance
Imbalance