Homeostasis Principles and Feedback Loops

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Questions and Answers

What is defined as the process of maintaining an internal environment to ensure functional integrity?

Metabolism

Homeostasis (correct)

Homeostatic imbalance

Physiological adaptation

Which of the following statements accurately describes a negative feedback loop?

It enhances the output of a system which leads to more production.

It amplifies the original stimulus to drive a process to completion.

It maintains a constant increase in system output.

It counteracts a change, reducing the output of the system. (correct)

Which factor is NOT typically under homeostatic control?

Personal preferences (correct)

Body temperature

Waste products

Gases

How do behavioral activities affect physiological responses?

They can trigger compensatory regulatory responses. Signup and view all the answers

Which of the following examples illustrates a positive feedback loop?

Release of oxytocin during childbirth. Signup and view all the answers

What component is part of a physiological feedback loop?

Receptor Signup and view all the answers

What is the effect of a system's output acting to reduce the processes that lead to that output?

It stabilizes the system towards equilibrium. Signup and view all the answers

Which homeostatic control mechanism best describes the role of central chemoreceptors in response to pCO2?

They adjust respiratory rate. Signup and view all the answers

What is the main function of antidiuretic hormone (ADH) in the body?

Regulates water content by increasing permeability in kidney tubules Signup and view all the answers

Where are the cell bodies of the neurons that produce oxytocin located?

In the supraoptic and paraventricular nuclei of the hypothalamus Signup and view all the answers

How does an increase in plasma osmolality affect ADH secretion?

It stimulates increased ADH secretion Signup and view all the answers

What is the effect of ADH binding to V1 receptors?

Stimulates vasoconstriction in arterioles Signup and view all the answers

What triggers the secretion of oxytocin during breastfeeding?

Mechanical stimulation from suckling Signup and view all the answers

What condition results from abnormally low levels of ADH?

Diabetes insipidus Signup and view all the answers

What is the primary role of V2 receptors in the kidneys?

To promote the insertion of water channels in nephron membranes Signup and view all the answers

Which hormone acts as a neuromodulator and promotes the release of ACTH?

ADH Signup and view all the answers

What causes the release of ADH during stress?

Decreased blood volume Signup and view all the answers

Which of the following is a consequence of elevated ADH levels?

High urine osmolality Signup and view all the answers

Which receptors are primarily responsible for physiological actions of ADH in the kidneys?

V2 receptors Signup and view all the answers

What effect does ADH have on the smooth muscle of blood vessels when in high concentrations?

Induces vasoconstriction Signup and view all the answers

In addition to its role in osmoregulation, ADH can also affect which other physiological aspect?

Promotes platelet aggregation Signup and view all the answers

Which of the following correctly describes the secretion of oxytocin during childbirth?

It promotes contractions of the uterus Signup and view all the answers

What is the primary role of central chemoreceptors in regulating breathing?

To monitor pCO2 levels Signup and view all the answers

What physiological response occurs when body temperature drops?

Vasoconstriction Signup and view all the answers

Which feedback loop mechanism typically amplifies a response?

Positive feedback Signup and view all the answers

What initiates the physiological responses when body temperature rises?

Increased sweat production Signup and view all the answers

What is a characteristic of positive feedback loops?

They often lead to unstable systems Signup and view all the answers

What role do peripheral chemoreceptors primarily play?

Monitoring pCO2, pO2, and H+ levels Signup and view all the answers

How does the hypothalamus respond to a decrease in body temperature?

Increases muscle activity through shivering Signup and view all the answers

What initiates the positive feedback loop during childbirth?

Stretching of the cervix Signup and view all the answers

What is the first step in the feedback loop process?

Detection by the sensor Signup and view all the answers

Which type of pathway regulates physiological responses through internal mechanisms without external influence?

Intrinsic pathway Signup and view all the answers

In a negative feedback loop, what happens when the variable returns to set points?

The effector no longer receives signals to change Signup and view all the answers

During which physiological condition might the body engage feedforward mechanisms?

Anticipation of physical activity Signup and view all the answers

Which hormone is released by the pituitary gland to facilitate milk ejection during nursing?

Oxytocin Signup and view all the answers

What best describes the relationship between a comparator and an effector in feedback loops?

The comparator only detects changes, while the effector initiates a response. Signup and view all the answers

What is the main consequence of chronic glucocorticoid administration on adrenal cortical cells?

Adrenal atrophy Signup and view all the answers

What effect does cortisol have on adrenal cortex growth?

Promotes growth and structural maintenance of adrenal cortex cells Signup and view all the answers

Which hormone inhibits the secretion of growth hormone?

Somatostatin Signup and view all the answers

What is a primary physiological effect of growth hormone (GH)?

Stimulates growth and anabolic functions Signup and view all the answers

What condition is characterized by excessive growth hormone production in adults?

Acromegaly Signup and view all the answers

What triggers increased secretion of prolactin during lactation?

Neural reflexes from suckling Signup and view all the answers

What effect do estrogen levels have on prolactin secretion?

Stimulate prolactin release Signup and view all the answers

Which hormone is responsible for regulating thyroid function through stimulation of the TSH receptor?

Thyroid stimulating hormone (TSH) Signup and view all the answers

What is a common side effect of bromocriptine, a dopamine receptor stimulant?

Nausea and vomiting Signup and view all the answers

What is the primary role of T3 in the secretion regulation of TSH?

Inhibits secretion of TSH Signup and view all the answers

Which factor leads to the secretion of FSH and LH from the anterior pituitary?

Gonadotropin-releasing hormone (GnRH) Signup and view all the answers

Which substance acts as the main inhibitory mediator for prolactin secretion?

Dopamine Signup and view all the answers

How does FSH affect ovarian follicle development?

Stimulates growth and maturation of follicles Signup and view all the answers

What is the result of IGF-1's action on growth hormone production?

Inhibits GH release through somatostatin Signup and view all the answers

What is the effect of cortisol on ACTH secretion?

Cortisol negatively feeds back to inhibit ACTH secretion Signup and view all the answers

Which hormone is primarily involved in the regulation of mineralocorticoid production?

Renin-angiotensin system Signup and view all the answers

How does inhibin specifically affect hormone production?

Inhibits only FSH production Signup and view all the answers

Which of the following actions of ACTH is a primary physiological response?

Stimulation of synthesis and release of glucocorticoids Signup and view all the answers

What is the primary role of MSH in the body?

Promotes formation of melanin Signup and view all the answers

What physiological effect does an increase in aldosterone primarily have?

Increases potassium excretion Signup and view all the answers

Which cells in the ovary are primarily stimulated by LH?

Thecal cells Signup and view all the answers

What general physiological pattern do ACTH levels follow during the day?

Shows a diurnal pattern Signup and view all the answers

In hyperthyroidism, what happens to the production of T3 and T4 levels?

Increased due to low TSH levels Signup and view all the answers

What is the primary physiological feedback mechanism for controlling TSH secretion?

Negative feedback from thyroid hormones Signup and view all the answers

What is the effect of anticipatory increases in breathing frequency during exercise-induced hypoxia?

It reduces the time course of the response Signup and view all the answers

Which response helps the body maintain homeostasis during a body temperature increase?

Increased sweating and vasodilation Signup and view all the answers

What is the role of hormones in compensatory regulatory responses?

They act as messengers to facilitate long-term response changes. Signup and view all the answers

What does the term 'gain of control system' refer to?

The degree of effectiveness of a control system in maintaining homeostasis. Signup and view all the answers

In the context of homeostasis, what condition is associated with COPD?

Persistent hypoxaemia and modified set points Signup and view all the answers

What triggers the fever response in the body?

Prostaglandin E2 acting on the thermoregulatory center Signup and view all the answers

What is the primary function of melanocyte-stimulating hormone (MSH)?

Stimulates production of melanin Signup and view all the answers

What differentiates the anterior pituitary from the posterior pituitary?

It is composed of neural tissue in contrast to glandular tissue in the anterior pituitary. Signup and view all the answers

What is a consequence of excessive alpha-MSH production?

Increased risk of melanoma Signup and view all the answers

What is the primary function of the hormones produced by the anterior pituitary?

To control the functions of other endocrine glands Signup and view all the answers

Which hormones are secreted by the adenohypophysis?

Thyroid-stimulating hormone and growth hormone Signup and view all the answers

What is the role of the hypothalamus regarding the pituitary gland?

It controls the release of hormones from both anterior and posterior glands. Signup and view all the answers

What is a significant role of the thyroid gland?

Regulates metabolism and growth Signup and view all the answers

What is the effect of thyroid hormones on metabolic control?

Regulates gene expression for energy metabolism Signup and view all the answers

What is the result of the body adapting to a high altitude over time?

Improved efficiency in oxygen transport through increased RBC production Signup and view all the answers

How does the body react to excess caloric intake?

It enhances fat storage for energy reserves. Signup and view all the answers

Which cells in the thyroid gland synthesize and release T3 and T4?

Follicular cells Signup and view all the answers

What can result from pituitary tumours affecting the optic chiasm?

Visual field defects Signup and view all the answers

How does the hypothalamic-pituitary axis contribute to stress response regulation?

By regulating multiple endocrine functions related to stress Signup and view all the answers

What does steady-state gain indicate in a control system?

Constant effectiveness in maintaining homeostasis without variation. Signup and view all the answers

How are T3 and T4 levels primarily regulated in the body?

Through negative feedback by thyroid-stimulating hormone Signup and view all the answers

What is rT3 and its relationship to T3?

It is an inactive form of T3 produced in peripheral tissues. Signup and view all the answers

What effect do antipyretic drugs have during a fever?

They inhibit cyclo-oxygenase 2 (COX-2), limiting the fever response. Signup and view all the answers

What is the primary structural component of thyroid follicles?

Follicular cells Signup and view all the answers

What primary role does oxytocin play during childbirth?

Induces regular uterine contractions Signup and view all the answers

Which hormone is primarily responsible for stimulating the production of breast milk?

Prolactin Signup and view all the answers

What does dopamine inhibit in relation to lactotrophs in the anterior pituitary?

Release of prolactin Signup and view all the answers

What is the function of Folliculostellate cells in the anterior pituitary?

Regulate hormone-secreting endocrine cells Signup and view all the answers

Which hypothalamic hormone stimulates the secretion of growth hormone?

Growth hormone-releasing factor Signup and view all the answers

Which of the following hormone pathways is indicated as a long negative feedback mechanism?

Adrenal corticotropic hormone influencing the hypothalamus Signup and view all the answers

What primarily stimulates the release of oxytocin from the posterior pituitary during breastfeeding?

Nipple stimulation by the infant's latch Signup and view all the answers

What effect does somatostatin have on growth hormone?

Inhibits its release Signup and view all the answers

What role does the primary plexus play in the hormone regulation system?

It facilitates hormone transport from hypothalamus to anterior pituitary Signup and view all the answers

Which hormone is responsible for regulating the integrity of the thyroid gland?

Thyroid-stimulating hormone Signup and view all the answers

What is the primary role of the adenohypophysis?

To secrete hormones that regulate various physiological processes Signup and view all the answers

What initiates the physiological response leading to oxytocin release during childbirth?

Vaginal distention and cervical stimulation Signup and view all the answers

What is the effect of prolactin during the postpartum period?

It promotes development of mammary tissue Signup and view all the answers

What pathway is responsible for transporting hormones from the hypothalamus to the anterior pituitary?

Hypophyseal portal system Signup and view all the answers

Which hormone is primarily responsible for regulating the metabolism of carbohydrates, fats, and proteins?

Thyroid hormones (T3 and T4) Signup and view all the answers

What is one significant effect of T3 and T4 on carbohydrate metabolism?

Stimulate glycogenolysis Signup and view all the answers

How do T3 and T4 influence fat metabolism?

They stimulate fat breakdown and oxidation. Signup and view all the answers

What is the primary function of the thyroid-stimulating hormone (TSH)?

To stimulate growth and activity of the thyroid gland Signup and view all the answers

Which type of goitre is uniformly enlarged without changes in hormone levels?

Non-toxic goitre Signup and view all the answers

What role do thyroid hormones play during development and growth?

They are essential for normal neurogenesis and maturation of the CNS. Signup and view all the answers

What is a common consequence of mutations in the MCT8 gene?

Impaired T3 transport into brain cells Signup and view all the answers

In what way do thyroid hormones affect the basal metabolic rate (BMR)?

They enhance ATP consumption and energy expenditure. Signup and view all the answers

What is the initial treatment option for hypothyroidism?

Synthetic T4 oral tablets Signup and view all the answers

What effect do thyroid hormones have on the autonomic nervous system (ANS)?

They increase the number of adrenergic receptors. Signup and view all the answers

Which of the following statements is true about T3 and T4 during early development?

They are crucial for synaptic plasticity and neurotransmitter regulation. Signup and view all the answers

What defines a toxic goitre?

Linked to increased thyroid hormone production Signup and view all the answers

What are the effects of administering too high a dose of thyroid hormones?

Cardiac dysfunction Signup and view all the answers

What triggers the process of thermoregulation in relation to thyroid hormones?

Enhanced Na/K ATPase activity. Signup and view all the answers

Which physiological aspect is influenced by thyroid hormones during starvation?

Accelerated response to starvation. Signup and view all the answers

In which condition is T3 typically used as a treatment option?

Hypothyroid coma Signup and view all the answers

How do thyroid hormones affect growth plate activity in long bones?

They stimulate proliferation of osteoblasts and maturation of chondrocytes. Signup and view all the answers

What condition results in severe neurodevelopmental defects due to impaired T3 transport?

Allan-Herndon-Dudley syndrome Signup and view all the answers

What factor often contributes to the development of multinodular goitre?

Iodine deficiency Signup and view all the answers

What role does the MCT10 transporter play in the context of thyroid hormones?

Facilitates entry of T3 and rT3 into brain Signup and view all the answers

What is the primary role of T3 and T4 in the body?

To increase metabolism in peripheral tissue Signup and view all the answers

What triggers the release of TSH from the anterior pituitary?

Increased TRH from hypothalamus Signup and view all the answers

Which condition can result from iodine deficiency?

Hypothyroidism Signup and view all the answers

In which condition is the thyroid gland continuously stimulated to produce hormones?

Graves disease Signup and view all the answers

What is a characteristic symptom of hyperthyroidism?

Increased heat production and sweating Signup and view all the answers

How does the feedback loop function in regulating thyroid hormone secretion?

Low levels of T3 increase TRH and TSH secretion Signup and view all the answers

What mechanism does TSH use to act on thyroid follicle cells?

Activation of second messengers Signup and view all the answers

Which of the following hypothesized connections contributes to the pathophysiology of Graves disease?

Immune system producing thyroid-stimulating immunoglobulin Signup and view all the answers

What is a common side effect of antithyroid medication?

Potential for relapse after cessation Signup and view all the answers

Which of the following is a possible treatment for hyperthyroidism?

Surgical removal of the thyroid gland Signup and view all the answers

What role does iodine play in thyroid hormone synthesis?

It is essential for the synthesis of T3 and T4 Signup and view all the answers

Which hormone has a regulatory role in the TRH-TSH pathway?

Protirelin Signup and view all the answers

Which physiological effect is due to hyperthyroidism?

Weight loss despite high appetite Signup and view all the answers

What factors contribute to the regulation of TH secretion?

Feedback loops among endocrine glands Signup and view all the answers

What role does reverse T3 (rT3) serve in the body?

It has no physiological role and is cleared from circulation. Signup and view all the answers

Which deiodinase type is primarily responsible for converting T4 to T3 in the liver and kidneys?

Type 1 deiodinase Signup and view all the answers

What is the primary function of calcitonin?

To inhibit bone resorption and decrease blood calcium levels. Signup and view all the answers

What is the main role of type 3 deiodinase?

Inactivation of thyroid hormones. Signup and view all the answers

What is synthesized by thyroid epithelial cells and serves as a scaffold for thyroid hormone synthesis?

Thyroglobulin (TG) Signup and view all the answers

How does thyroid hormone (TH) affect gene expression?

By activating or repressing gene transcription through nuclear receptors. Signup and view all the answers

Which type of deiodinase is expressed primarily in the CNS and provides T3 during low T4 levels?

Type 2 deiodinase Signup and view all the answers

What stimulates all aspects of thyroid hormone synthesis and release?

Thyroid-stimulating hormone (TSH) Signup and view all the answers

What is a consequence of altered deiodinase activity in thyroid disorders?

Development of hypothyroidism or hyperthyroidism Signup and view all the answers

Which thyroid hormones remain stored within thyroglobulin in the colloid until needed?

Both T3 and T4 Signup and view all the answers

Which enzyme catalyzes the production of thyroid hormones by oxidizing iodide to iodine?

Thyroid peroxidase Signup and view all the answers

What is a therapeutic implication of deiodinase inhibitors?

Manage thyroid hormone-related disorders Signup and view all the answers

What is the primary mechanism of action for type 1 deiodinase?

Activating T4 to T3 by removing outer ring iodine Signup and view all the answers

What is the minor carrier protein that is important for thyroid hormone delivery to the CNS?

Transthyretin Signup and view all the answers

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

To serve as a scaffold for the synthesis of thyroid hormones Signup and view all the answers

Which of the following best describes the energy dependency of iodine uptake in the thyroid gland?

Iodine uptake requires energy to move against a concentration gradient Signup and view all the answers

What is the primary function of thyroid peroxidase in thyroid hormone synthesis?

To oxidize iodine and iodinate tyrosine residues Signup and view all the answers

Which thyroid hormone is produced when two diiodotyrosine (DIT) molecules are coupled?

Thyroxine (T4) Signup and view all the answers

Which thyroid hormone receptor isoform is primarily involved in regulating metabolism in the heart?

TRa1 Signup and view all the answers

What triggers the release of co-activator complexes during transcription regulation by thyroid receptors?

Binding of thyroid hormones Signup and view all the answers

What is the minimum daily requirement of iodine for adults?

150 ug Signup and view all the answers

Which of the following accurately describes the structural domain organization of thyroid receptors?

It consists of four domains including N-terminal, DNA-binding, and ligand-binding domains Signup and view all the answers

How does thyroid hormone receptor (TR) interact with retinoid acid X receptor (RXR)?

They form a heterodimer that binds to thyroid response elements Signup and view all the answers

Which physiological effect is primarily associated with thyroid hormones on cellular development?

Enhanced differentiation of nerve cells Signup and view all the answers

What is the role of the Na+/I- symporter (NIS) in the thyroid gland?

To enable iodine uptake into thyroid follicular cells Signup and view all the answers

Which component of the thyroid hormone synthesis process requires hydrogen peroxide?

Oxidation of iodine and iodination Signup and view all the answers

Which thyroid hormone is formed through the coupling of monoiodotyrosine (MIT) and diiodotyrosine (DIT)?

Triiodothyronine (T3) Signup and view all the answers

What is the primary mechanism by which thioureylenes inhibit thyroid hormone synthesis?

They prevent iodination of tyrosine residues. Signup and view all the answers

Which of the following describes the main action of propylthiouracil in the treatment of hyperthyroidism?

It inhibits the deiodinase enzyme converting T4 to T3. Signup and view all the answers

What is a significant side effect of carbimazole/methimazole that often leads patients to switch medications?

Skin rash. Signup and view all the answers

What is the function of radioiodine (I-131) in treating hyperthyroidism?

It selectively destroys thyroid follicular cells. Signup and view all the answers

What occurs when iodine intake exceeds 2 mg/day concerning thyroid hormone synthesis?

NADPH oxidase activity and TPO gene expressions are suppressed. Signup and view all the answers

What is the Wolff-Chaikoff effect related to high concentrations of iodine?

Inhibits thyroid hormone synthesis acutely. Signup and view all the answers

How do beta-blockers like propranolol work in the context of hyperthyroidism?

They competitively inhibit beta-adrenergic receptors. Signup and view all the answers

What is a potential effect of using I-131 for hyperthyroidism treatment?

It may require thyroid hormone replacement therapy. Signup and view all the answers

What is the most common cause of hypothyroidism?

Inflammatory/autoimmune disease like Hashimoto's disease. Signup and view all the answers

What symptom is most commonly associated with hyperthyroidism?

Anxiety and tremors. Signup and view all the answers

In hypothyroidism, what happens to TSH levels due to decreased levels of thyroid hormones?

TSH levels increase above normal levels. Signup and view all the answers

What characterizes myxedema coma?

Severe form of hypothyroidism. Signup and view all the answers

What is a primary metabolic consequence of inadequate thyroid hormone production?

Generalized slowing of metabolic processes. Signup and view all the answers

Study Notes

Homeostasis: Principles, Factors, and Feedback Loops

Homeostasis is the process of maintaining a stable internal environment despite external changes. This involves regulating factors like body temperature, blood pressure, blood sugar, electrolytes, hormones, oxygen levels, and protein concentrations.

Physiological Feedback Loops

Feedback loops are crucial for maintaining homeostasis. They consist of:
- Sensors: Detect changes in a variable (e.g., temperature).
- Integrators/Comparators: Compare the sensed variable to a set point and signal a response.
- Effectors: Produce the response to adjust the variable (e.g., shivering, sweating).
Negative feedback loops are common in homeostasis. In these loops, a change in a variable triggers a response that opposes the initial change, restoring the variable to the set point (e.g., temperature regulation). The loop continuously monitors and adjusts.
- Sensors → Comparator → Effector → Variable (repeats).
Positive feedback loops amplify a change in a variable. This can lead to rapid and dramatic responses, although they are less stable than negative feedback loops (e.g., labor contractions). There is a cascade effect and continued deviation from steady state, leading away from equilibrium state.
- Stimuli → Activates stretch receptors → generates signals → promotes uterine contractions.
- Suckling → Activates mechanoreceptors → triggers prolactin and oxytocin release → stimulates milk production and ejection.
Extrinsic pathway: relies on the endocrine or nervous system for regulation (e.g., adrenaline release in response to stress).
Intrinsic pathway: the organ/tissue regulates itself using local chemical signals (e.g., blood flow to muscles during exercise).

Factors Under Homeostatic Control

Nutrients: Essential for cell function
Gases: Oxygen and carbon dioxide
Waste products: Removal of metabolic by-products
pH: Maintaining acidic/alkaline balance
Salt and electrolytes: Maintaining proper ion levels
Temperature: Maintaining body temperature
Volume and pressure: Maintaining appropriate fluid balance

Compensatory Regulatory Responses

These self-protective mechanisms help maintain homeostasis when challenged:
- Neuronal responses: Nervous system response to environmental changes (e.g., sweating, shivering).
- Hormonal responses: Endocrine system response (e.g., glucagon release to raise blood sugar).
- Metabolic adjustments: Compensating for energy deficits (e.g., fat breakdown during fasting).
- Behavioral responses: Changing behavior to compensate (e.g., seeking cool environments).
- Adaptive responses: Long-term changes in an organism to better cope with stresses (e.g., high altitude adaptation).

Modification of Set Points

Set points can change in certain conditions (e.g., fever, acclimatization to high altitude). These are responses to illness or disease that need to be tolerated by the body until the physiological function is again at the original standard.

Hypothalamic-Pituitary Axis (HPA)

Anatomical connection between the hypothalamus and pituitary gland.
Anterior pituitary (adenohypophysis) and posterior pituitary (neurohypophysis) differ in cell composition, vascular supply, and hypothalamic innervation.

Neurohypophysis

Neural tissue; made of axons from hypothalamic neurons which synthesize and release hormones.
Antidiuretic hormone (ADH): Regulates water balance by controlling water reabsorption in the kidneys (stimulated via increased plasma osmolality or decreased blood pressure).
Oxytocin: Stimulates uterine contractions and milk ejection.

Adenohypophysis

True endocrine organ; composed of specialized cells.
Releasing hormones (from hypothalamus) stimulate or inhibit hormone release from the anterior pituitary.
Six key hormones are produced:
- Thyroid-stimulating hormone (TSH): Stimulates thyroid hormone production.
- Adrenocorticotropic hormone (ACTH): Stimulates cortisol production in the adrenal cortex.
- Growth hormone (GH): Regulates growth and metabolism.
- Follicle-stimulating hormone (FSH) and Luteinizing hormone (LH) : regulate gonadal function.
- Prolactin: Stimulates milk production.
- Melanocyte-stimulating hormone (MSH): Involved in melanin production.
Feedback loops: Target hormones from the peripheral glands, negatively feedback to the hypothalamus and anterior pituitary (long loop feedback), or directly to the hypothalamus to regulate release of the pituitary hormones.

Thyroid Gland

Produces thyroid hormones (T3 and T4) and calcitonin.
Thyroid hormones regulate metabolism, growth, and development.
Calcitonin regulates calcium levels.

Thyroid Hormone Synthesis and Effects

Iodine uptake and incorporation into thyroglobulin are paramount for TH synthesis in the thyroid follicle cells.
Deiodinases activate (T4 to T3) and inactivate (T4 to reverse T3) thyroid hormones.
T3 and T4 bind to receptors in the cytosol and/or nucleus, effecting gene expression, and have permissive and metabolic effects and influence cardiovascular and nervous systems
Hyperthyroidism results from excessive thyroid hormone production; symptoms include weight loss, restlessness, elevated heart rate.
Hypothyroidism occurs from inadequate thyroid hormone production; symptoms include weight gain, lethargy, constipation, and cold intolerance.

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Description

Explore the essential concepts of homeostasis, including the factors that regulate it and the critical role of feedback loops. This quiz covers sensors, integrators, and effectors involved in maintaining stable internal conditions. Test your knowledge on how negative feedback mechanisms work to restore balance.