Nervous vs. Endocrine System Overview

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Questions and Answers

Which of the following best describes a key difference in the way the nervous and endocrine systems regulate the body?

  • The nervous system is associated with slow, long-lasting responses, while the endocrine system is associated with rapid, short-lived responses.
  • The nervous system primarily controls metabolic activity, while the endocrine system directly controls muscle contraction.
  • The nervous system uses hormones for signaling, while the endocrine system uses electrical signals.
  • The nervous system uses neurotransmitters for signaling while the endocrine system uses hormones. (correct)

Which of the following is NOT a primary function of the endocrine system?

  • Maintaining homeostasis of electrolytes, water, and nutrients
  • Coordinating reproduction
  • Regulating growth and development
  • Rapidly controlling muscle movements (correct)

The pineal gland, which is located in the brain, is primarily associated with the production of what hormone?

  • Pinealocytes (correct)
  • Insulin
  • T3 and T4
  • Cortisol

Which of these descriptions accurately reflects the structure of the adrenal gland?

<p>Formed of a cortex containing three separate layers and a medulla. (C)</p> Signup and view all the answers

A change in blood calcium levels directly causes the release of a hormone. Which type of stimulus is this an example of?

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

What is the primary function of the hypophyseal portal system?

<p>To transport releasing and inhibiting hormones from the hypothalamus to the anterior pituitary (A)</p> Signup and view all the answers

Paracrine hormones are best described as local hormones that:

<p>Affect nearby cells. (C)</p> Signup and view all the answers

How do water-soluble hormones typically circulate in the bloodstream?

<p>They travel freely in the plasma. (D)</p> Signup and view all the answers

Which of the following best describes the effect of calcitonin?

<p>It lowers blood calcium levels by inhibiting the activity of osteoclasts. (A)</p> Signup and view all the answers

Which characteristic best describes a lipid-soluble hormone?

<p>It diffuses into cells and binds to intracellular receptors to affect gene transcription. (C)</p> Signup and view all the answers

Which of the following best describes the communication method of the endocrine system?

<p>Hormones transported via the bloodstream (B)</p> Signup and view all the answers

Which of the following is NOT a hormone produced by the adrenal cortex?

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

A rise in blood calcium levels would most likely trigger the release of what hormone? This is an example of what kind of stimulation?

<p>Parathyroid hormone (PTH), humoral stimulation (A)</p> Signup and view all the answers

Which pancreatic cell type is responsible for producing glucagon?

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

Which of the following is characteristic of steroid hormones?

<p>They can diffuse directly into cells. (C)</p> Signup and view all the answers

What is the role of thymosins?

<p>Promoting the maturation of T-cells. (A)</p> Signup and view all the answers

Which of the following is a common hormonal change associated with aging?

<p>Reduced levels of growth hormone, estrogen and testosterone (D)</p> Signup and view all the answers

Which scenario exemplifies a synergistic hormone interaction?

<p>Glucagon and epinephrine both increasing blood glucose levels. (B)</p> Signup and view all the answers

Which of the following hormones are synthesized directly by the hypothalamus?

<p>Antidiuretic hormone (ADH), oxytocin (B)</p> Signup and view all the answers

Which hormone directly stimulates the thyroid gland to produce T3 and T4?

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

What is the primary function of the hormone produced by the pineal gland?

<p>To help regulate sleep-wake cycles (C)</p> Signup and view all the answers

Which of the following hormones is NOT produced by the anterior pituitary?

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

What is the main function of the posterior pituitary gland?

<p>To store and release ADH and oxytocin (D)</p> Signup and view all the answers

Which of the following is NOT a disorder associated with abnormal endocrine function listed in the text?

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

Flashcards

Up-regulation

The process of increasing the number of receptors on a cell to enhance its sensitivity to a hormone.

Down-regulation

The process of decreasing the number of receptors on a cell to reduce its sensitivity to a hormone.

Hypothalamus-Pituitary Relationship

The hypothalamus controls the pituitary gland through releasing and inhibiting hormones, the hypophyseal portal system (anterior pituitary), and neural connections (posterior pituitary).

Growth Hormone

A hormone produced by the pituitary gland that stimulates growth, protein synthesis, and fat breakdown. Regulated by growth hormone-releasing hormone (GHRH) and somatostatin.

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Thyroid Structure and Histology

The thyroid gland is composed of follicles containing colloid. Follicular cells produce thyroid hormones (T3 and T4). Parafollicular cells produce calcitonin.

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Thyroid Hormone Regulation and Effects

Thyroid hormone production is regulated by thyroid-stimulating hormone (TSH) from the anterior pituitary. Thyroid hormones increase metabolic rate, protein synthesis, and energy usage.

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Parathyroid Hormone (PTH)

A hormone produced by the parathyroid gland that raises blood calcium levels. Stimulated by low blood calcium levels.

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Sex Hormones

Hormones produced by the testes (testosterone) and ovaries (estrogen and progesterone) regulate male and female secondary sexual characteristics and reproductive functions.

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Nervous vs. Endocrine System Communication

Nervous system uses electrical signals and neurotransmitters for fast, short-term, and specific communication. Endocrine system uses hormones in the bloodstream for slow, long-term, and broad communication.

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Types of Hormone Stimulation

Humoral: Blood composition changes trigger hormone release (e.g., low calcium triggers PTH). Neural: Nerve signals stimulate hormone release (e.g., sympathetic nerves stimulate adrenaline). Hormonal: Hormones trigger other hormones (e.g., hypothalamus releases factors for pituitary hormones).

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Types of Circulating Hormones

Steroid hormones, like cortisol, are lipid-soluble and can pass through cell membranes. Peptide hormones, like insulin, are water-soluble and bind to surface receptors. Biogenic amines, like adrenaline, are derived from amino acids.

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Local vs. Circulating Hormones

Local hormones act in a nearby area (e.g., prostaglandins). Circulating hormones travel through the blood to distant targets.

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Target Cell Responsiveness

Hormone concentration, receptor density, and influences from other hormones determine how responsive a target cell is.

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Hormone Interactions

Permissive: One hormone allows another to act (e.g., thyroid hormone is needed for adrenaline to work fully). Synergistic: Hormones amplify effects (e.g., glucagon and adrenaline both raise blood sugar). Antagonistic: Hormones oppose each other (e.g., insulin lowers blood sugar, glucagon raises it).

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Hypothalamus Role

The hypothalamus, located in the brain, synthesizes ADH and oxytocin and controls the release of hormones from the pituitary gland.

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Anterior Pituitary Role

The anterior pituitary, located below the hypothalamus, produces growth hormone (GH), thyroid-stimuating hormone (TSH), adrenocorticotropic hormone (ACTH), follicle-stimulating hormone (FSH), luteinizing hormone (LH), and prolactin (PRL). These hormones affect growth, metabolism, and reproduction.

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Nervous vs. Endocrine System

The nervous system uses electrical signals (action potentials) for rapid and short-lived responses, directly controlling muscles and glands via neurotransmitters. The endocrine system utilizes chemical signals (hormones) released into the bloodstream for slower but longer-lasting effects on metabolic activity and homeostasis.

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Endocrine System's Major Functions

The endocrine system plays a crucial role in regulating growth and development, maintaining electrolyte, water, and nutrient balance, controlling metabolism and energy, coordinating reproduction, and helping the body respond to stress.

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Pituitary Gland's Role

The pituitary gland, located below the hypothalamus, is responsible for producing and releasing hormones that regulate various bodily functions. It's often called the "master gland" because it controls other endocrine glands.

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Thyroid Gland Structure and Function

The thyroid gland, situated in the neck below the larynx, produces thyroid hormones (T3 and T4) that regulate metabolism and energy production. Its structure is characterized by follicles containing colloid.

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Hormone Release Triggers

Hormones are released in response to changes in blood levels (humoral stimuli), nerve stimulation (neural stimuli), or other hormones (hormonal stimuli).

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Hormone Transport

Water-soluble hormones travel freely in plasma, binding to surface receptors, while lipid-soluble hormones require carrier proteins for transport and can readily pass through cell membranes.

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Water-Soluble vs. Lipid-Soluble Hormone Mechanisms

Water-soluble hormones, like insulin and epinephrine, are amino-acid based and bind to surface receptors, activating second messengers. Lipid-soluble hormones, such as cortisol, T3, and T4, are steroids or thyroid hormones that diffuse into cells and bind to intracellular receptors to affect gene transcription.

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Study Notes

Nervous vs. Endocrine System Regulation

  • The nervous system uses electrical signals (action potentials) and neurotransmitters for regulation.
  • Nervous system responses are fast and short-lived.
  • The nervous system directly controls muscles and glands.
  • The endocrine system uses chemical signals (hormones) for regulation.
  • Endocrine system responses are slower but longer-lasting.
  • The endocrine system controls metabolic activity and homeostasis.
  • Hormones are released into the bloodstream.

General Functions of the Endocrine System

  • Regulates growth and development.
  • Maintains homeostasis of electrolytes, water, and nutrients.
  • Controls metabolic activity and energy balance.
  • Coordinates reproduction.
  • Helps the body respond to stress.

Locations of Endocrine Glands

  • Hypothalamus (brain)
  • Pituitary gland (below hypothalamus)
  • Thyroid gland (neck, below larynx)
  • Parathyroid glands (posterior thyroid)
  • Adrenal glands (on top of kidneys)
  • Pancreas (behind stomach)
  • Pineal gland (brain)
  • Thymus (upper chest, behind sternum)
  • Gonads (testes in males, ovaries in females)

Gland Tissues and Histology

  • Pituitary gland: Anterior (glandular) and posterior (neural) lobes
  • Thyroid gland: Follicles with colloid (T3, T4 production)
  • Adrenal gland: Cortex (three layers) and medulla
  • Pancreas: Islets of Langerhans (endocrine function)
  • Pineal gland: Pinealocytes

Stimulation of Hormone Synthesis and Release

  • Humoral stimuli: Response to changes in blood levels (e.g., calcium)
  • Neural stimuli: Nerve fibers stimulate release (e.g., adrenal medulla)
  • Hormonal stimuli: One hormone stimulates another gland (e.g., hypothalamic-pituitary axis)

Local vs. Circulating Hormones

  • Local Hormones
    • Paracrine: Affect nearby cells
    • Autocrine: Affect the same cell that secretes them
  • Circulating Hormones
    • Travel through the bloodstream to distant targets

Hormone Transport in Blood

  • Water-Soluble Hormones
    • Travel freely in plasma
    • Bind to surface receptors
  • Lipid-Soluble Hormones
    • Bind to transport proteins
    • Diffuse through cell membranes

Water-Soluble vs. Lipid-Soluble Hormones

  • Water-Soluble Hormones
    • Structure: Amino-acid based
    • Function: Bind to surface receptors; activate second messengers
    • Examples: Insulin, epinephrine
  • Lipid-Soluble Hormones
    • Structure: Steroids and thyroid hormones
    • Function: Diffuse into cells; bind to intracellular receptors to affect gene transcription
    • Examples: Cortisol, T3, T4

Up and Down Regulation

  • Up-Regulation: Increase in receptor numbers to enhance sensitivity
  • Down-Regulation: Decrease in receptor numbers to reduce sensitivity

Hypothalamus and Pituitary Gland Relationship

  • Hypothalamus controls pituitary via:
    • Releasing/inhibiting hormones
    • Hypophyseal portal system (anterior pituitary)
    • Neural connections (posterior pituitary)
  • Pituitary secretes hormones that regulate other endocrine glands.

Growth Hormones

  • Regulation: Stimulated by GHRH; inhibited by somatostatin
  • Effects: Stimulates growth of tissues, protein synthesis, and fat breakdown

Thyroid Structure and Histology

  • Composed of follicles filled with colloid.
  • Follicular cells produce T3 and T4.
  • Parafollicular cells produce calcitonin.

Thyroid Hormone Regulation and Effects

  • Regulation: TSH from anterior pituitary.
  • Effects: Increases metabolic rate, protein synthesis, and energy usage.

Calcitonin Regulation and Effects

  • Regulation: Stimulated by high blood calcium levels.
  • Effects: Lowers calcium levels by inhibiting osteoclasts.

Adrenal Gland Structure and Histology

  • Cortex: Three zones
    • Zona glomerulosa: Produces mineralocorticoids (aldosterone)
    • Zona fasciculata: Produces glucocorticoids (cortisol)
    • Zona reticularis: Produces androgens
  • Medulla: Produces catecholamines (epinephrine, norepinephrine)

Pancreas Structure and Histology

  • Structure: Exocrine (acinar cells) and endocrine (islets of Langerhans)
  • Histology: Islets contain alpha (glucagon), beta (insulin), delta (somatostatin) cells

Pancreas Hormones Regulation and Effects

  • Insulin: Lowers blood glucose; regulated by high glucose levels
  • Glucagon: Raises blood glucose; regulated by low glucose levels

Other Endocrine Organs

  • Pineal Gland:
    • Hormone: Melatonin
    • Function: Regulates sleep-wake cycles.
  • Parathyroid Gland:
    • Hormone: Parathyroid hormone (PTH)
    • Function: Raises blood calcium levels
  • Thymus
    • Hormone: Thymosins
    • Function: Maturation of T-cells (immune response)
  • Testes
    • Hormone: Testosterone
    • Function: Male secondary sexual characteristics and spermatogenesis
  • Ovaries
    • Hormones: Estrogen and progesterone
    • Function: Female secondary sexual characteristics and menstrual cycle regulation

Hormonal Changes with Aging

  • Reduced hormone levels (e.g., growth hormone, estrogen, testosterone)
  • Reduced sensitivity to hormones
  • Increased risk of endocrine disorders

Diseases and Disorders of the Endocrine System

  • Diabetes Mellitus: Insulin deficiency or resistance
  • Hyperthyroidism: Excess thyroid hormone (e.g., Graves' disease)
  • Hypothyroidism: Insufficient thyroid hormone (e.g., Hashimoto's)
  • Cushing's Syndrome: Excess cortisol
  • Addison's Disease: Insufficient cortisol and aldosterone
  • Acromegaly/Gigantism: Excess growth hormone in adults/children
  • Pituitary Dwarfism: Insufficient growth hormone
  • Diabetes Insipidus: Deficiency of ADH

Nervous vs. Endocrine System Control

  • Communication Method:
    • Nervous: Electrical signals and neurotransmitters
    • Endocrine: Hormones in bloodstream
  • Target:
    • Nervous: Specific cells (neurons, muscles)
    • Endocrine: Broad (cells with receptors)
  • Response:
    • Nervous: Rapid
    • Endocrine: Slow

Three Types of Stimulation

  • Humoral: Blood composition triggers hormone release
  • Neural: Nerves stimulate release
  • Hormonal: Hormones trigger other hormones

Circulating Hormones

  • Types:
    • Steroid Hormones: Lipid-soluble
    • Peptide Hormones: Water-soluble
    • Biogenic Amines: Derived from amino acids
  • Differences:
    • Lipid-soluble diffuse into cells, water-soluble bind to surface receptors

Local vs. Circulating Hormones

  • Local: Act nearby
  • Circulating: Travel in blood to distant targets

Target Cell Responsiveness

  • Depends on:
    • Hormone concentration
    • Receptor density
    • Influence of other hormones

Hormone Interactions

  • Permissive: One hormone allows another to act
  • Synergistic: Hormones amplify effects
  • Antagonistic: Hormones counteract

Hypothalamus Role

  • Synthesizes: ADH, oxytocin
  • Controls: Pituitary hormone release

Anterior Pituitary Role

  • Hormones: GH, TSH, ACTH, FSH, LH, PRL
  • Effects: Growth, metabolism, reproduction

Posterior Pituitary Role

  • Stores/releases: ADH, oxytocin

Thyroid Role

  • Hormones: T3, T4, calcitonin
  • Effects: Metabolism, calcium regulation

Parathyroid Role

  • Hormone: PTH
  • Effect: Raises blood calcium

Adrenal Cortex Role

  • Hormones: Aldosterone, cortisol, androgens
  • Effects: Electrolytes, stress response

Stress Response Stages

  • Alarm, resistance, exhaustion

Adrenal Medulla Role

  • Hormones: Epinephrine, norepinephrine
  • Effects: Fight-or-flight response

Pancreas Role

  • Hormones: Insulin, glucagon
  • Effects: Glucose regulation

Pineal Gland Role

  • Hormone: Melatonin
  • Effect: Circadian rhythms

Other Organs

  • Include all of the organs, hormones, and function stated in the notes.

Clinical Disorders

  • List all disorders along with associated problems.

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