Excitable Cells and Endocrine Systems
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Questions and Answers

What is the term used for electrical signals that might or might not cause an action potential?

  • Resting Membrane Potential
  • Graded Potential (correct)
  • Action Potential
  • Threshold Potential

    • What is the main ion responsible for establishing the resting membrane potential?

  • Sodium
  • Chloride
  • Calcium
  • Potassium (correct)

    • How does an increase in extracellular potassium concentration affect the resting membrane potential?

  • It makes the cell more positive (correct)
  • It makes the cell more permeable to sodium
  • It has no effect on the resting membrane potential
  • It makes the cell more negative

    • What is the impact of low calcium levels on the threshold potential?

    <p>Threshold potential decreases (becomes more negative) (B)</p> Signup and view all the answers

    How does increasing the extracellular potassium concentration affect the cell's excitability?

    <p>Increases excitability (C)</p> Signup and view all the answers

    What is the primary mechanism by which beta blockers lower blood pressure?

    <p>Decreasing calcium levels (A)</p> Signup and view all the answers

    What is the theoretical equilibrium potential for potassium (E_K)?

    <p>-90 mV (B)</p> Signup and view all the answers

    Which of the following is NOT a strategy to decrease the excitability of brain regions during a seizure?

    <p>Increase calcium levels (A)</p> Signup and view all the answers

    A patient is prescribed a prednisone pack for 2 weeks but stops taking the full dose after 4 days. Which of the following symptoms would they likely experience due to low cortisol levels?

    <p>Hypoglycemia (A)</p> Signup and view all the answers

    Which of the following is a cause of secondary hyperaldosteronism?

    <p>High activity of the RAAS (D)</p> Signup and view all the answers

    Which of the following is NOT a symptom of primary hyperaldosteronism?

    <p>Hypoglycemia (A)</p> Signup and view all the answers

    What is the primary symptom of Cushing's syndrome, caused by hypersecretion of cortisol?

    <p>Excessive gluconeogenesis (C)</p> Signup and view all the answers

    Which of the following is a symptom associated with the excessive DHEA production in females?

    <p>Irregular menstrual periods (C)</p> Signup and view all the answers

    What is the primary cause of hyperpigmentation in Addison's disease?

    <p>Increased levels of ACTH, POMC, and MSH (A)</p> Signup and view all the answers

    What is the main difference between primary and secondary adrenocortical insufficiency?

    <p>Primary is caused by an adrenal gland issue, secondary is caused by a pituitary issue. (A)</p> Signup and view all the answers

    Which of the following is NOT a potential cause of secondary adrenocortical insufficiency?

    <p>High levels of cortisol (D)</p> Signup and view all the answers

    Which of the following is a potential side effect of long-term cortisol use?

    <p>Suppression of the HPA axis (A)</p> Signup and view all the answers

    Which of the following hormones contributes to vasoconstriction and helps sustain blood pressure during acute plasma volume loss?

    <p>Vasopressin (C)</p> Signup and view all the answers

    In the context of adrenocortical insufficiency, what is the relationship between ACTH and cortisol levels?

    <p>ACTH levels are low, cortisol levels are low. (B)</p> Signup and view all the answers

    Which of the following is a common symptom of Addison's disease?

    <p>Hypoglycemia (A)</p> Signup and view all the answers

    What is the typical signalment for Addison's disease?

    <p>30-50 year old female (B)</p> Signup and view all the answers

    What is the primary role of the thyroid gland in the body?

    <p>Regulation of metabolism and energy expenditure (C)</p> Signup and view all the answers

    Which of the following is TRUE about the thyroid gland's role in metabolism?

    <p>Thyroid hormones increase the production of heat. (B)</p> Signup and view all the answers

    What is the precursor molecule for the synthesis of thyroid hormones?

    <p>Tyrosine (A)</p> Signup and view all the answers

    Which of the following hormones is released from the anterior pituitary gland and acts on the thyroid gland?

    <p>Thyroid-stimulating hormone (TSH) (D)</p> Signup and view all the answers

    What is the active form of thyroid hormone?

    <p>Triiodothyronine (T3) (C)</p> Signup and view all the answers

    Identify the correct sequence of events in the regulation of thyroid hormone secretion.

    <p>TRH → TSH → T3/T4 (C)</p> Signup and view all the answers

    What is the role of the colloid-filled lumen within the thyroid follicular cells?

    <p>Storage of thyroid hormone precursors (D)</p> Signup and view all the answers

    What is the role of the adrenal medulla in the body?

    <p>Production of catecholamines, such as epinephrine and norepinephrine (A)</p> Signup and view all the answers

    Which of the following hormones are glycoproteins?

    <p>TSH, FSH, and LH (B)</p> Signup and view all the answers

    What is the primary function of the suprachiasmatic nucleus (SCN)?

    <p>To control the body's circadian rhythms (B)</p> Signup and view all the answers

    Which of the following is NOT an example of a negative feedback loop in the Hypothalamic-Pituitary Axis?

    <p>The release of oxytocin from the posterior pituitary (A)</p> Signup and view all the answers

    What is the role of angiotensin II in the Renin-Angiotensin-Aldosterone System (RAAS)?

    <p>It causes vasoconstriction and stimulates aldosterone release (A)</p> Signup and view all the answers

    What is the primary function of cortisol in the body?

    <p>To regulate blood glucose levels (C)</p> Signup and view all the answers

    Which of the following is NOT a direct effect of aldosterone?

    <p>Vasoconstriction (C)</p> Signup and view all the answers

    Which of the following statements about receptor sequestration is TRUE?

    <p>The signal molecule is pulled into the cell's endosome and remains there. (D)</p> Signup and view all the answers

    What is the role of melanopsin in the regulation of circadian rhythms?

    <p>It senses light changes and stimulates the SCN (D)</p> Signup and view all the answers

    Which of the following hormones is responsible for the contraction of myoepithelial cells surrounding alveoli during breastfeeding?

    <p>Oxytocin (C)</p> Signup and view all the answers

    What is the primary function of vasopressin (ADH)?

    <p>To increase water reabsorption in the kidneys (D)</p> Signup and view all the answers

    Which of the following describes the pattern of hormone secretion that is most common?

    <p>Basal (D)</p> Signup and view all the answers

    Which of the following statements about the release of oxytocin is TRUE?

    <p>It plays a role in uterine contractions during childbirth. (A)</p> Signup and view all the answers

    Which of the following hormones is produced by the adrenal medulla?

    <p>Epinephrine (B)</p> Signup and view all the answers

    Which of the following is a precursor to both aldosterone and cortisol?

    <p>Pregnenolone (C)</p> Signup and view all the answers

    Which of the following correctly describes the effect of bright late-night light on circadian rhythms?

    <p>It advances the rhythm (A)</p> Signup and view all the answers

    Which of the following is a common example of feed-forward signaling in the body?

    <p>Insulin (C)</p> Signup and view all the answers

    What is the effect of increasing extracellular calcium concentration on the excitability of a cell?

    <p>Decreased excitability due to an increase in threshold potential. (D)</p> Signup and view all the answers

    What is the primary mechanism by which parasympathetic stimulation affects heart rate?

    <p>Increasing acetylcholine release from postganglionic fibers. (A)</p> Signup and view all the answers

    What is the role of the hypothalamus in the autonomic nervous system?

    <p>It serves as the central control center for autonomic activity. (C)</p> Signup and view all the answers

    Which of the following correctly describes the characteristics of sympathetic preganglionic fibers?

    <p>Short, originate in the thoracolumbar spinal cord, release acetylcholine. (D)</p> Signup and view all the answers

    Which of the following is NOT a characteristic of steroid hormones?

    <p>Stored in secretory vesicles before release. (C)</p> Signup and view all the answers

    What is the primary function of the second messenger cAMP in 7 transmembrane loop receptor signaling?

    <p>It activates protein kinase A, which phosphorylates target proteins. (B)</p> Signup and view all the answers

    Which of the following is an example of a neurohormone?

    <p>Antidiuretic hormone released from the posterior pituitary. (C)</p> Signup and view all the answers

    What is the primary difference between paracrine and endocrine signaling?

    <p>Paracrine signaling involves the release of local mediators, while endocrine signaling involves the release of hormones into the bloodstream. (A)</p> Signup and view all the answers

    What is the effect of sympathetic stimulation on blood vessels in skeletal muscle?

    <p>Dilation due to the release of norepinephrine from postganglionic fibers. (C)</p> Signup and view all the answers

    What is the primary function of the autonomic nervous system?

    <p>Regulate the body's internal environment (homeostasis). (C)</p> Signup and view all the answers

    Which of the following is true regarding the sympathetic and parasympathetic nervous systems?

    <p>They can work antagonistically or synergistically depending on the target organ and context. (D)</p> Signup and view all the answers

    Which of the following hormones is responsible for the development of Addison's disease?

    <p>Cortisol. (A)</p> Signup and view all the answers

    What is the primary role of transport proteins in the bioavailability of steroid hormones?

    <p>They protect steroid hormones from degradation in the bloodstream. (D)</p> Signup and view all the answers

    What is the primary difference between the nervous system and the endocrine system in terms of their response characteristics?

    <p>The nervous system is rapid and short-lived, while the endocrine system is slower and longer-lasting. (B)</p> Signup and view all the answers

    What is the primary mechanism by which the sympathetic nervous system increases heart rate?

    <p>By releasing norepinephrine from postganglionic fibers. (C)</p> Signup and view all the answers

    What is the primary function of the varicosities at the end of sympathetic postganglionic fibers?

    <p>To store and release neurotransmitters. (B)</p> Signup and view all the answers

    Study Notes

    Excitable Cells

    • Action potentials result in neurotransmitter (NT) release. NT release isn't always consistent in amount; more NT equals a stronger signal, less a weaker one.
    • Graded potentials may or may not trigger an action potential (AP).
    • Resting membrane potential (RMP) relies on potassium ion (K+) concentration differences across the membrane. High potassium can cause excitation, muscle spasms, and twitching.
    • Low potassium lowers the threshold for excitation.
    • High calcium raises the threshold for excitation; beta blockers lower heart rate by affecting calcium.
    • Equilibrium potential (E) calculation: E = 61 log ([outside]/[inside]). The permeability of the membrane to a specific ion factors into these calculations. Potassium has the greatest effect on RMP.
    • Increased extracellular potassium causes the cell to become more excitable.
    • Decreased extracellular potassium causes the cell to become less excitable.

    Endocrine Systems (Hormones)

    • Hormones are classified as membrane-receptor binding or intracellular-receptor binding, based on how they bind to cells.
    • Different hormone classes include polypeptides (amino acid chains produced by the rough ER), and steroids (derived from cholesterol).
    • Hormones work through different ways such as paracrine neurotransmitters, endocrine hormones, and neurohormones.
    • The nervous system can induce rapid, brief effects, while endocrine responses are slower and have long-lasting effects.
    • Hormones often bind to receptors on the cell membrane (hydrophilic) or inside the cell (lipophilic).
    • Feedback loops regulate hormone release.
    • The hypothalamus-pituitary axis (HPA) is a crucial endocrine system component. It includes the hypothalamus, anterior pituitary, and various target endocrine organs and controls many physiological functions.

    Circadian Rhythms

    • The pineal gland and suprachiasmatic nucleus (SCN) regulate circadian rhythms.
    • Melanopsin, part of retinal ganglion cells, senses light and regulates the SCN.
    • The SCN establishes a daily clock and the pineal gland responds to the SCN by releasing melatonin (regulates the light/dark cycle rhythm)
    • Light and dark cycles influence the SCN and endocrine organs, causing daily fluctuations in hormone production and other biological functions.

    Thyroid and Growth

    • The thyroid gland is located below the larynx. It regulates metabolism.
    • The thyroid releases thyroid hormone (T3 and T4).
    • T3 and T4 increase metabolic rate and heat production, and enhance growth and central nervous system development.
    • T4 is converted to T3 before T3 can be utilized by most tissues.
    • Hormones are actively transported using carrier proteins.
    • Thyroid hormone effects depend on the tissue target and receptor types present.
    • Iodine deficiency can lead to goiter formation due to disruptions in thyroid hormone production.
    • A large set of processes regulates how the thyroid gland functions, including TSH production by the pituitary, feedback, and iodine import.

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    Description

    This quiz covers key concepts on excitable cells, including action potentials, graded potentials, and the influence of ions on resting membrane potential. Additionally, it delves into the role of hormones in endocrine systems, emphasizing their impact on physiological processes.

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