Homeostasis in Animals Quiz

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Questions and Answers

What are the three components of all homeostatic control mechanisms?

Effector, nervous system, endocrine system

Receptor, control center, effector (correct)

Stimulus, control center, variable

Receptor, sensor, effector

Which system responds to changes in the environment and sends information to the control center along an afferent pathway?

Homeostatic system

Endocrine system

Nervous system (correct)

Excretory system

What is the main function of the effector in a homeostatic control system?

Determines set point

Produces change in variable (correct)

Detect changes in the environment

Analyze information

What results from a disturbance in homeostasis according to the text?

Disease Signup and view all the answers

In a homeostatic imbalance, what happens to the equilibrium state of an organism?

It disturbs the equilibrium and leads to disease Signup and view all the answers

What is the role of the control center in a homeostatic control system?

Determines set point, analyzes information, and determines response Signup and view all the answers

What is the main function of negative feedback mechanisms?

Shuts off the original stimulus or reduces its intensity Signup and view all the answers

In what process does positive feedback occur in the human body?

Blood clotting Signup and view all the answers

How do hormones and nervous signals differ in terms of duration and immediacy of effects?

Hormones have short-lasting effects, while nervous signals are more immediate Signup and view all the answers

What is the role of hormones in target tissue?

To increase receptor sensitivity Signup and view all the answers

How does a positive feedback system differ from a negative feedback system?

Positive feedback increases stimulus intensity, while negative feedback shuts off the stimulus Signup and view all the answers

What characterizes the effects of hormones in the body?

Hormones return to basal levels long after effects are seen Signup and view all the answers

What is the main factor determining the sensitivity of a tissue to a hormone?

The presence of specific receptors in the target cells Signup and view all the answers

How do peptide and protein hormones generally interact with target cells?

By binding to cell-surface receptors Signup and view all the answers

What is the role of a second messenger system for some cell-surface receptors?

To transmit the hormone response signal into the cell Signup and view all the answers

How do steroid hormones enter target cells?

Through the plasma membrane Signup and view all the answers

What happens once a hormone-receptor complex binds to specific sites on the cell’s DNA?

Activation of certain genes to transcribe messenger RNA Signup and view all the answers

Which type of hormones are used in direct gene activation through binding to a specific protein within the nucleus?

Steroid hormones Signup and view all the answers

What is the biological half-life of a hormone?

The time it takes for the hormone to lose half of its physiological activity Signup and view all the answers

How are peptide hormones primarily degraded?

By exopeptidases at the carboxy-terminal end Signup and view all the answers

What regulates parathyroid hormone and calcitonin secretion?

Extracellular Ca2+ Signup and view all the answers

Why are many synthetic hormones designed to have a longer half-life?

To increase their effectiveness over a longer period Signup and view all the answers

What follows exponential decay kinetics regarding hormone removal or inactivation?

Removal or inactivation of hormones Signup and view all the answers

What is the primary role of somatotrophin stimulation?

Increase in amino acid uptake Signup and view all the answers

What is the main reason that steroid hormones are bound to protein carriers in blood?

To increase their half-life Signup and view all the answers

What percentage of the hormone is typically present in the free or unbound form physiologically?

5–10% Signup and view all the answers

Which enzyme adds functional groups such as hydroxyl groups to steroids during the first phase of their degradation process?

Cytochrome P450 (CYP) Signup and view all the answers

How are the more water-soluble metabolites of steroids excreted from the body?

In the urine or bile salts Signup and view all the answers

What is the primary role of phase one in the degradation process of steroids?

To add functional groups like hydroxyl groups Signup and view all the answers

Which hormone has a shorter half-life than that of human chorionic gonadotropin?

Luteinizing hormone Signup and view all the answers

Study Notes

Homeostatic Control Mechanisms

Three components: receptor (sensor), control center, and effector.
Receptors respond to environmental changes and send information to the control center via afferent pathways.

Effectors and Homeostasis

Effectors are responsible for executing responses that restore balance in homeostatic control systems.
Disturbance in homeostasis can lead to disease or dysfunction within the organism.

Homeostatic Imbalance

Homeostatic imbalance disrupts the equilibrium state, making the organism vulnerable to health issues.

Control Center Function

The control center processes information received from receptors and determines necessary responses.

Feedback Mechanisms

Negative feedback mechanisms work to reverse changes back to a set point, maintaining stability.
Positive feedback amplifies responses, often occurring in processes like childbirth.

Hormonal and Nervous Responses

Hormones typically have longer-lasting effects compared to the immediate responses of nervous signals.

Hormonal Action

Hormones bind to specific receptors on target tissues to elicit physiological responses.
Sensitivity of a target tissue to a hormone is primarily determined by the number of available receptors.

Hormone Interaction

Peptide and protein hormones interact with cell-surface receptors and typically utilize second messenger systems.
Steroid hormones enter target cells directly due to their lipid solubility and interact with intracellular receptors.

Gene Activation

A hormone-receptor complex can bind to DNA’s specific sites, influencing gene expression and function.
Steroid hormones achieve direct gene activation through binding to nuclear proteins.

Hormone Half-Life and Degradation

The biological half-life of a hormone is the time it takes for its concentration to reduce by half.
Peptide hormones are mainly degraded through enzymatic processes.
Synthetic hormones often have longer half-lives to maintain therapeutic effectiveness.

Hormone Removal and Kinetics

Hormone removal typically follows exponential decay kinetics, influencing the duration of hormone action.

Somatotrophin and Hormonal Binding

Somatotrophin stimulation plays a significant role in growth and metabolism.
Steroid hormones are often bound to protein carriers in blood to enhance solubility and extend circulation.

Hormone Concentration

About 1-10% of hormones exist in their free, unbound form within the physiological environment.

Degradation Enzymes

Specific enzymes, such as hydroxylases, add functional groups to steroids during their degradation process.

Excretion of Steroid Metabolites

More water-soluble steroid metabolites are excreted through urine or bile after processing by the liver.

Phase One Degradation Role

Phase one in steroid degradation changes steroid solubility, preparing them for further metabolic processes.

Short Half-Life Hormones

A hormone like insulin has a shorter half-life compared to human chorionic gonadotropin.

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Description

Test your knowledge about the concept of homeostasis in animals, which enables them to regulate and maintain their internal environment despite external changes. Learn about the components of homeostatic control mechanisms and the importance of maintaining stable internal conditions in living organisms.