Endocrine System

LECTURE EXAM

I. The Endocrine System

1. What system often works in conjunction with the endocrine system?

2. How does the endocrine system communicate with target cells?

1. The nervous system

2. It secretes hormones into the blood

1. How do endocrine responses compare with nervous system responses?

2. Where are most hormones secreted from?

1. Endocrine responses are generally slower and longer-lasting

2. Endocrine glands, although other cells can also secrete hormones

1. Which glands have dual endocrine and exocrine functions?

2. What are the hypothalamus's two functions?

1. The pancreas and gonads

2. It has endocrine and neuronal functions

II. Extracellular Chemical Communication

1. What is autocrine communication?

2. What example of autocrine communication appears in the notes?

1. Chemical communication that activates the cell that released the signal

2. The macrophage IL-1 response

1. What is paracrine communication?

2. What example of paracrine communication appears in the notes?

1. Chemical communication that activates adjacent cells

2. B-cell activation

1. What is endocrine communication?

2. Why don't all cells respond to every hormone in the blood?

1. Hormones travel through the blood to distant target cells

2. Only cells with the appropriate receptors respond to a particular hormone

• What determines tissue specificity in hormonal communication?

  • What does receptor up-regulation mean?

    • What does receptor down-regulation mean?

• The presence of appropriate hormone receptors

  • An increase in the number of receptors

    • A decrease in the number of receptors

How can hormonal signals be terminated?

Hormones can be degraded by enzymes or removed by the kidneys and liver

III. Classes of Hormones

• What are the three broad hormone categories identified in the overview?

  • What forms can amino acid-based hormones take?

    • What are the main characteristics of amino acid-based hormones?

• Peptide hormones, steroid hormones, and amino acid hormones

  • Amino acids, peptides, or proteins

    • They are polar, hydrophilic, and water-soluble

• How are amino acid-based hormones stored and released?

  • How do amino acid-based hormones travel through the body?

    • Where are the receptors for amino acid-based hormones located?

• They are stored in vesicles and released by exocytosis

  • They travel in the blood plasma

    • On the target-cell surface.

• Why can't amino acid-based hormones directly pass through the cell membrane?

  • What is a first messenger?

    • What is a second messenger?

• They cannot pass through the cell membrane, so they bind to surface receptors

  • The hormone that binds to a receptor on the target cell

    • An intracellular signal triggered by hormone-receptor activation

• How do second messengers produce a cellular response?

What are the main steps of the signal-transduction pathway?

• They activate enzymes, producing a generally rapid response

First messenger → G-protein-coupled receptor → amplifier enzyme → second messenger

1. Which hormone is derived from tryptophan?

2. What hormones are derived from tyrosine?

3. Which hormone group acts like peptide hormones?

4. Which hormone group acts like steroid hormones?

5. What are steroid hormones produced from?

1. Melatonin

2. Catecholamines and thyroid hormones

3. Catecholamines

4. Thyroid hormones

5. Cholesterol

• What type of hormones are lipid-soluble (lipophilic) hormones?

  • Can steroid hormones be stored?

    • How are steroid hormones transported in plasma?

• Steroid hormones, including adrenocortical and gonadal hormones

  • No. They are synthesized as needed and released by diffusion

    • They attach to carrier molecules in the plasma

• How do steroid hormones enter their target cells?

  • Where are the receptors for steroid hormones located?

    • How do steroid hormones produce their effects?

• They diffuse through the target cell's membrane

  • Inside the target cell, in the cytoplasm or nucleus

    • They initiate gene activity and protein production, producing a slow response

D. Hormone interactions

• What is synergism?

  • What is permissiveness?

• The combined effect of hormones is greater than the sum of their individual effects

  • A second hormone is needed for another hormone to exert its full effect

• What is competitive antagonism?

  • What is a functional antagonist?

• A competitive inhibitor blocks the hormone receptor on the target cell

  • A hormone or substance that produces the opposite physiological effect

II. Endocrine reflex pathways

• What is a simple endocrine (humoral) reflex?

  • What hormone is given as an example of a simple endocrine reflex?

• What is a neuroendocrine reflex?

  • How may neurons influence hormone release in a neuroendocrine reflex?

• The endocrine gland acts as both the sensor and integration center

  • Parathyroid hormone (PTH).

• A reflex involving the nervous system in hormone release.

  • Through efferent neurons or by releasing neurohormones into the blood

• What is a trophic hormone reflex?

  • What two mechanisms are listed under trophic hormone reflexes?

• A reflex in which hormone release is triggered by another hormone.

  • Neurons may influence release through efferent neurons or release neurohormones into the blood.

• How is hormone release usually controlled?

  • Which hormone is listed with hyposecretion?

    • Which hormone is listed with hypersecretion?

• By negative feedback loops

  • Testosterone

    • Thyroid-stimulating hormone (TSH)

VI. Hypothalamus and Pituitary Glands

• What does the hypothalamus produce for the posterior pituitary?

  • How does the hypothalamus regulate the anterior pituitary?

What connects the hypothalamus to the anterior pituitary through the blood?

• Neurohormones that are stored and released

  • It releases neurohormones that stimulate hormone release

The hypothalamic-hypophyseal portal system

• What type of tissue makes up the posterior pituitary?

  • Does the posterior pituitary produce its own hormones?

Which two hormones are released by the posterior pituitary?

• Nervous tissue; it is a downward growth of the hypothalamus

  • No. It releases neurohormones produced by the hypothalamus

Oxytocin and vasopressin (ADH)

Which hormones does the anterior pituitary produce and release?

• thyrotrophin, (TSH)

• adrenocorticotropin, (ACTH)

• gonadotrophins, (FSH & LH)

• growth hormone, (GH)

• prolactin

Hypothalamic Hormones

1. What does TRH stand for?

2. What does CRH stand for?

3. What does GHRH stand for?

4. What does GnRH stand for?

1. Thyrotropin-releasing hormone

2. Corticotropin-releasing hormone

3. Growth hormone-releasing hormone

4. Gonadotropin-releasing hormone

• What is the effect of dopamine on prolactin release?

  • What is the effect of somatostatin on growth hormone release?

• It inhibits prolactin release

  • It inhibits growth hormone release

VIII. Posterior Pituitary Hormones

• What stimulates ADH (vasopressin) release?

  • What is the primary effect of ADH on the kidneys?

What stimulates oxytocin release?

• Low blood pressure

  • It causes the kidneys to retain water

Stretching of the cervix

• What does oxytocin do to the uterus?

  • What does oxytocin do in the mammary glands?

• It causes the uterus to contract

  • It causes the mammary glands to release milk

IX. Anterior Pituitary Hormones

• What stimulates thyrotrophin TSH release from the anterior pituitary?

  • What does TSH stimulate?

What are the effects of thyroid hormones on metabolism?

• TRH released by the hypothalamus

  • The release of T3 and T4 from the thyroid gland

They increase metabolic activity and help maintain metabolism

• What stimulates adrenocorticotropin, ACTH release?

  • What does ACTH stimulate?

What are the effects of cortisol?

• CRH, Corticotropin-releasing hormone released by the hypothalamus

  • Cortisol release from the adrenal cortex

It increases metabolism, supports long-term stress responses, and impairs the immune response

• What stimulates LH and FSH release?

  • What are the two main effects of LH and FSH on the gonads?

What stimulates growth hormone release?

• GnRH, Gonadotropin-releasing hormone released by the hypothalamus

  • stimulate sex hormone release & gamete production

GHRH released by the hypothalamus

• What do growth hormone and insulin-like growth factors promote?

  • What does prolactin do?

• Growth of muscle, bone, and cartilage

  • It stimulates milk production by the mammary glands and plays a role in milk ejection

X. Thyroid and Parathyroid Hormones

• What stimulates T3 and T4 release?

  • What is the primary role of T3 and T4?

What type of hormone interaction do T3 and T4 demonstrate ?

• TSH from the anterior pituitary

  • Maintaining metabolism

Permissiveness

• What stimulates calcitonin release?

What are the effects of calcitonin on calcium?

• High calcium levels in the plasma

It decreases bone calcium resorption and increases calcium excretion by the kidneys

• What stimulates parathyroid hormone (PTH) release?

  • What are the effects of PTH on calcium?

• Low calcium levels in the plasma

  • It increases bone calcium resorption and kidney calcium reabsorption

XI. Adrenal Gland Hormones

• Which hormones are produced by the adrenal medulla?

  • What stimulates adrenal medulla hormone release?

• Epinephrine (adrenaline) and norepinephrine

  • Short-term stress, producing the fight-or-flight response.

• What effect do epinephrine and norepinephrine have on blood glucose?

  • Which hormone is associated with long-term stress?

    • What are the effects of cortisol?

• They increase blood glucose levels

  • Cortisol

    • It increases metabolism and impairs the immune response

• What stimulates aldosterone release?

  • What does aldosterone do to sodium and potassium?

• Low blood pressure or high potassium concentration

  • It increases sodium reabsorption and potassium secretion

XII. Pancreatic Hormones

• Which pancreatic cells produce insulin?

  • What stimulates insulin production?

How does insulin affect glucose storage?

• Beta cells

  • High glucose levels in the plasma

It promotes storage of glucose as glycogen and triglycerides

• Which pancreatic cells produce glucagon?

  • What stimulates glucagon production?

What does glucagon do?

• Alpha cells

  • Low glucose levels in the plasma

It increases glucose production from glycogen and triglycerides

• Which pancreatic cells produce somatostatin?

  • What does pancreatic somatostatin do?

• Delta cells

  • It inhibits digestion and the release of pancreatic hormones, thereby inhibiting metabolism

XIII. Gonads, Thymus, and Pineal Gland

• What are the primary sex hormones produced by the testes ?

  • What are the effects of testosterone?

• Androgens, including testosterone

  • It contributes to male primary and secondary sex characteristics

• What hormone is produced by the ovaries?

  • What are the effects of estrogen?

What are thymosins responsible for?

• Estrogen

  • It contributes to female primary and secondary sex characteristics

T-cell development

• What is the primary function of melatonin?

What happens to melatonin production in response to light?

• Regulation of the daily sleep-wake cycle

Light suppresses melatonin production

XIV. Endocrine Disorders

What disorders are associated with growth hormone imbalance?

• Which thyroid disorders ?

Pituitary dwarfism, gigantism, and acromegaly

• Cretinism (underdevelopment),

• goiter ( with excess TSH),

• exophthalmia (associated with a hyperactive thyroid)

• What causes diabetes mellitus ?

What is the result of diabetes mellitus ?

• Insulin deficiency

An inability to regulate blood glucose levels