Human Physiology Quiz

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Questions and Answers

What happens to enzymes when the temperature exceeds 45°C?

They enhance blood flow regulation.

They promote heat retention in cells.

They function optimally, increasing metabolic rates.

They become inactive due to denaturation. (correct)

How do blood vessels respond to a drop in temperature below the set core temperature?

They cause muscle relaxation to warm up.

They dilate to increase heat loss.

They restrict blood flow to conserve heat. (correct)

They remain unchanged to maintain blood pressure.

What is the primary function of sweat glands during elevated temperatures?

To conserve water within the body.

To promote blood flow to the brain.

To facilitate heat loss through evaporation. (correct)

To increase internal body temperature.

Which hormone is primarily responsible for lowering blood glucose levels?

Insulin Signup and view all the answers

What adverse effect occurs to cells at temperatures below freezing point?

Formation of ice crystals causing cellular damage. Signup and view all the answers

What role do effectors play in a feedback loop?

They cause a change to reverse the situation and return the value to the normal range. Signup and view all the answers

Which component of a feedback loop is responsible for monitoring changes in physiological parameters?

Sensors / Receptors Signup and view all the answers

What is the primary function of the Control Center in a feedback loop?

To compare sensory input to the set point and determine necessary actions. Signup and view all the answers

Which of the following statements is true regarding feedback loops in the body?

Only a few systems demonstrate negative feedback loops. Signup and view all the answers

What characterizes negative feedback in physiological systems?

The effector response is in the opposite direction to the stimulus. Signup and view all the answers

If the Control Center detects that a physiological parameter is too far from the set point, what is the most likely action it will take?

Activate effectors to correct the deviation. Signup and view all the answers

In which scenario would positive feedback be more likely to occur?

During childbirth to facilitate labor progression. Signup and view all the answers

What is the primary function of feedback loops in maintaining homeostasis?

To resist significant deviations from normal physiological ranges. Signup and view all the answers

Which of the following statements is true regarding feedback mechanisms?

Negative feedback mechanisms activate systems to counteract the initial stimulus. Signup and view all the answers

How does the body generally respond when a stimulus increases?

By activating a negative feedback loop to decrease the stimulus. Signup and view all the answers

What role does insulin play in glucose regulation?

It promotes the uptake of glucose by cells from the bloodstream. Signup and view all the answers

In what circumstance does glucagon release glucose into the bloodstream?

When blood glucose levels are too low. Signup and view all the answers

Which of the following statements about glycogen is correct?

Glycogen is a form of energy storage in the liver. Signup and view all the answers

How does the body respond to an increase in blood glucose levels after eating?

Insulin is released to promote cellular glucose uptake. Signup and view all the answers

Which cellular response occurs when blood glucose levels are low?

Alphas cells in the pancreas release glucagon. Signup and view all the answers

Study Notes

Course Information

Faculty of Medicine
Academic Year: 2024-2025
Year: 1
Semester: 1
Module: Human Body Function (HBF) 102

Physiology of Homeostasis

Defined as the body's ability to maintain a stable, relatively constant internal environment despite external fluctuations.
Homeostasis is crucial for all living organisms.
Homeostasis helps maintain constant internal conditions such as temperature, glucose, potassium and others.
The body shivers as an example to maintain a relatively constant body temperature in cold environments.
The normal range of body temperature is between approximately 36.5-37.5°C (97.7-99.5°F).

Objectives

Define and discuss the concept of homeostasis and its importance to living organisms.
Discuss how physiologic control mechanisms maintain the body's normal steady state.
Define a feedback mechanism and describe its components.
Differentiate between positive and negative feedback mechanisms and give examples.

Pathophysiology

Disruption of homeostasis leads to disease.
Failure of homeostasis can result in death.

Control Systems

Nervous System: Controls rapid body responses. It detects and initiates reactions to changes in the environment, such as regulating blood pressure.
Endocrine System: Regulates activities that require duration, such as hormone regulation of calcium levels and control of blood glucose. Examples include parathyroid hormones, thyroid hormones and insulin.

Feedback Loops

Control Centers: Found in the brain, these centers play a vital role in regulating physiological parameters.
Feedback Loops: Continuously monitor and adjust conditions in the body to maintain homeostasis. This process is crucial to return the body to its normal state by restoring physiological parameters.
Example: The body's response to temperature changes to maintain a set point.

Feedback Mechanisms

Positive Feedback: Action is in the same direction as the stimulus. Continuously reinforces a change in the system, resulting in further change (e.g. blood clot formation, childbirth)
Negative Feedback: Action in the opposite direction to the stimulus. Counteracts the change, returning the system to its previous state, in order to prevent severe outcomes. (e.g. regulation of blood glucose, body temperature)

Types of Feedback Mechanisms

Negative Feedback: The effector's response is opposite to the stimulus, maintaining homeostasis. Most body systems use negative feedback (e.g., blood glucose levels).
Positive Feedback: The effector's response is in the same direction as the stimulus and is often only needed for specific outcomes or until an endpoint is reached (e.g., blood clotting, childbirth).

Feedback Loops Components

Sensors/Receptors: Monitors internal conditions and report changes to the control center.
Control Center: Receives sensory input, compares to the set point, and sends signals to effectors.
Effectors: Executes the command to change internal conditions. Example includes muscles and glands.

Temperature Regulation

The body maintains its core temperature (thermoregulation) through negative feedback mechanisms between 36.5-37.5°C (97.7-99.5°F).
The hypothalamus plays a crucial role as a body thermostat.
The body reacts to maintain temperature when it exceeds a set core temperature. For higher temperature, it dilates blood vessels to allow more heat loss through the skin, sweat to evaporate.
When temperature is too low, blood vessels constrict to reduce heat loss, and shivering generates heat within the body.

Blood Glucose Regulation

The pancreas regulates blood glucose levels through insulin and glucagon.
High blood glucose triggers insulin release, promoting removal of glucose from blood to storage as glycogen in liver cells.
Low blood glucose triggers glucagon release from pancreas to stimulate liver cells to release glucose.

Diabetes

Diabetes occurs when the body does not produce enough insulin, causing glucose levels to remain elevated.
Diabetics need to inject insulin to regulate glucose levels.

Blood Pressure Regulation

Baroreceptors monitor blood pressure.
When blood pressure rises: blood vessels dilate to reduce blood pressure.
When blood pressure falls: blood vessels constrict and cardiac output increases.

Calcium Regulation

The thyroid gland regulates calcium through calcitonin.
When calcium levels rise: calcitonin is released to promote calcium deposition in bones.
When calcium levels fall: parathyroid hormone (PTH) is released to promote calcium release from bones.

Kidney and Water Regulation

The nephrons in kidneys filter nutrients to maintain water balance.
Antidiuretic hormone (ADH) is crucial for water balance.

Positive Feedback Loops

Positive feedback mechanisms amplify changes within a system, moving it farther from its normal range (e.g., childbirth, blood clotting.). -These mechanisms are critical for specific and rapid processes like blood clot formation, but they are not for general homeostasis.
In most cases, a mechanism like a counter-signal stops or suppresses the loop once the purpose has been fulfilled (e.g., childbirth, lactation).

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Description

Test your knowledge on human physiology with this quiz that covers topics such as enzyme activity, thermoregulation, and hormonal responses. Answer questions about how temperature affects biological functions and the role of various systems in maintaining homeostasis.