Cell-Surface Receptors and Second Messenger Systems Quiz

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Questions and Answers

Match the following with their effect on behavior:

Oxytocin = Maternal behavior Vasopressin = Sex-related behavioral characteristics Trophic hormones = Nesting activity Antidiuretic hormone = Broodiness

Match the following with their primary role in hormone release:

Environmental cues = Triggering hormone release Cell-surface receptors = Interaction with peptide and protein hormones Specific receptors = Determining tissue response to hormones Hormone delivery method = Determining selectivity of hormone action

Match the following hormones with their effect on smooth muscle contraction:

Oxytocin = Stimulates myoepithelium contraction in mammary gland Secretin = Stimulates pancreatic secretions ADH (vasopressin) = Increases water reabsorption by the kidney Trophic hormones = Can stimulate or inhibit hormone secretion from target organs

What is the major structural group of hormones made from cholesterol?

Prostaglandins Signup and view all the answers

How do paracrine hormones function?

Diffuse to neighboring cells Signup and view all the answers

Which type of hormones are synthesized by nervous tissue and carried in the blood to the target tissue?

Neuroendocrine hormones Signup and view all the answers

Who first recognized homeostasis and its importance in the 19th century?

Claude Bernard Signup and view all the answers

What is the primary function of autocrine hormones?

Feedback on the cell of origin Signup and view all the answers

Which type of hormone is synthesized from highly active lipids?

Prostaglandins Signup and view all the answers

What is the primary role of hormones in altering cellular metabolism?

Influencing gene expression and protein synthesis Signup and view all the answers

How do hormones affect enzyme catalytic rates?

By phosphorylation and dephosphorylation of proteins Signup and view all the answers

Which process can hormones affect to alter muscle contraction?

Altering membrane permeability Signup and view all the answers

What is a possible effect of hormones acting as mitogens?

Accelerating cell division Signup and view all the answers

How do hormones potentially influence exocrine secretion?

By altering membrane permeability Signup and view all the answers

What distinguishes the effects of hormones from nervous signals?

Hormones modulate the activity of the target tissue long after their levels return to basal values. Signup and view all the answers

Which statement best describes the regulation of hormone production by nervous signals?

Nervous signals regulate hormone production through short-lasting effects. Signup and view all the answers

What is the role of hormones before eliciting a response in the target tissue?

To maintain receptors in the target tissue and keep it primed for a response. Signup and view all the answers

In what range are hormones typically present in plasma?

$10^{-9}$ to $10^{-6}$ g ml$^{-1}$ Signup and view all the answers

What does it mean when hormones exhibit 'Permissive Action'?

They have no effect on their own but must be present for another hormone to have an effect. Signup and view all the answers

What is meant by the term 'Synergistic' regarding hormone effects?

When the combined effect of two hormones is more than the sum of their separate effects. Signup and view all the answers

What is the reason for a hypophysectomized winter flounder turning grey?

Absence of melanocyte stimulating hormone (MSH) Signup and view all the answers

How is induced diabetes through alloxan treatment related to endocrine function?

Destroys insulin-producing cells in the pancreas Signup and view all the answers

What effect does cobalt chloride treatment have on the pancreas?

Destroys glucagon-secreting cells Signup and view all the answers

How does deafferentation of the vagus nerve impact gastrin secretion?

Disrupts gastrin release Signup and view all the answers

Why are tissues transplanted to an ectopic site, like beneath the kidney capsule?

To avoid rejection and ensure blood supply Signup and view all the answers

What method can be used to check for the presence of a hormone without surgical removal of tissues?

Injection of an extract of the gland Signup and view all the answers

Which type of cells respond rapidly upon subsequent exposure to the same antigen?

Memory cells Signup and view all the answers

What is the main purpose of an adjuvant when given with an antigen in the context of immune response stimulation?

Enhances immune response Signup and view all the answers

What is the critical requirement for a substance (Ag) to elicit an antibody response?

Complexity and foreignness Signup and view all the answers

What distinguishes a secondary immune response from a primary immune response?

Higher antibody titres in secondary response Signup and view all the answers

What occurs during the primary immune response to an antigen?

Memory cells differentiate into plasma cells Signup and view all the answers

What type of antibodies are produced during the immunization process?

Polyclonal antibodies Signup and view all the answers

Study Notes

Hormone Action Mechanisms

Two primary mechanisms: Direct gene activation and second-messenger system.
Direct gene activation is used by steroid hormones and thyroid hormones.
Protein and peptide hormones utilize the second-messenger system for signal transmission.

Direct Gene Activation

Steroid hormones can diffuse through the plasma membrane of target cells.
Once inside the cell, steroid hormones enter the nucleus.
The hormone binds to a specific protein in the nucleus, forming a hormone-receptor complex.
This complex interacts with specific DNA sites, leading to the transcription of messenger RNA.
New proteins are synthesized as a result of gene activation.

Second-Messenger System

Hormone acts as a first messenger by binding to a membrane receptor.
Binding activates the receptor and initiates a cascade of reactions, activating an enzyme.
The enzyme produces a second messenger molecule (e.g., cyclic AMP or cAMP).
cAMP oversees additional intracellular changes for a specific target cell response.

Stimuli for Hormone Release

Hormone levels are primarily regulated by negative feedback mechanisms.
Low hormone levels trigger the release of more hormones until an appropriate level is reached.
Stimuli for endocrine glands fall into three categories: Hormonal, Humoral, and Neural.

Hormonal Stimuli

Most common stimulus type for hormone release.
Endocrine organs activate in response to other hormones.
Example: Hormones from the hypothalamus stimulate the anterior pituitary.

Humoral Stimuli

Hormone release is stimulated by changing blood levels of ions and nutrients.
Humoral refers to body fluids like blood and bile.
Examples:
- Parathyroid hormone and calcitonin respond to blood calcium levels.
- Insulin is released in response to blood glucose levels.

Neural Stimuli

Nerve fibers directly stimulate hormone release, mainly influenced by the sympathetic nervous system.
Example: Sympathetic stimulation leads to the adrenal medulla releasing epinephrine and norepinephrine.

Location and Release of Hormones

Steroid hormones are not stored; they diffuse out of cells immediately after synthesis.
Protein and peptide hormones are stored in granules and released upon stimulation.
Trophic hormones like TSH, FSH, LH, and ACTH stimulate the release of other hormones.
Hormonal release can be influenced by environmental stimuli, such as light, sound, and temperature.

Metabolism and Excretion of Hormones

Hormones follow exponential decay kinetics for removal and inactivation.
The half-life indicates the duration of hormone action in circulation.
Synthetic hormones are designed with longer half-lives for prolonged effectiveness compared to natural hormones.
Rapid metabolism and removal of hormones are essential for effective feedback regulation and cellular function management.

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Description

Test your knowledge on how some cell-surface receptors require a second messenger system to transmit hormone response signals. Learn about the two mechanisms of hormone action: direct gene activation and second-messenger system.