Lesson 2 (homeostasis-positive and Negative Feedback)

Question 1

What is homeostasis?

Answer 1

The ability to maintain a constant internal environment in response to environmental changes.

Homeostasis involves physiological constancy despite fluctuations in external conditions.

Question 2

What challenges do fluctuating environments create for organisms?

Answer 2

They create a challenge to maintain cellular environments in optimum conditions.

Question 3

What is essential for maintaining homeostasis in animals?

Answer 3

Organ systems.

Question 4

Name three examples of homeostasis in the human body.

Answer 4

• Blood pH
• Blood pressure
• Body Temperature
• Blood [Glucose]

Question 5

What is the normal range for blood pH?

Answer 5

7.35 to 7.45

Question 6

What is the normal range for blood pressure?

Answer 6

120/40

Question 7

What are the three functional components of homeostatic control systems?

Answer 7

• A receptor
• A control center
• An effector

Question 8

What is the role of a receptor in homeostatic control systems?

Answer 8

To detect change (detecting the stimulus).

Question 9

What does the control center do in homeostatic control systems?

Answer 9

Processes information from the receptor.

Question 10

What is the function of an effector in homeostatic control systems?

Answer 10

Produces an appropriate response (responds to the command of the control center).

Question 11

What does a feedback system involve?

Answer 11

A stimulus from one part of the body invoking a response from another part which acts to alter the original stimulus.

Question 12

True or False: Body systems are regulated by feedback systems.

Answer 12

True

Question 13

What does homeostasis rely on for control?

Answer 13

Feedback mechanisms

Feedback mechanisms are essential for maintaining stable internal conditions.

Question 14

What is the role of receptors in the negative feedback process?

Answer 14

Detect unacceptable levels and signal the control center

Receptors are distributed throughout the body to monitor changes.

Question 15

What is the function of the control center in homeostasis?

Answer 15

Monitor and control body conditions

Examples include the hypothalamus, which regulates pH, temperature, blood pressure, and glucose levels.

Question 16

Fill in the blank: Negative feedback _____ or counteracts the stimulus to re-establish homeostasis.

Answer 16

diminishes

Question 17

What is an adaptive response in the context of homeostasis?

Answer 17

The behavior of the effector to regain normal state

For example, shivering in response to cold.

Question 18

What happens once the normal state is regained in a negative feedback loop?

Answer 18

The receptor stops signaling the control center

This cessation of signaling halts the adaptive response.

Question 19

What results from the negative feedback mechanism?

Answer 19

Fluctuation between two levels

For instance, glucose concentration in blood averages around a set point.

Question 20

What does the effector do in a negative feedback loop?

Answer 20

Brings about a change or response to alter the controlled condition

Effectors are the organs or cells that enact the necessary changes.

Question 21

True or False: The concentration of glucose in the blood is always exactly 0.1%.

Answer 21

False

Glucose levels fluctuate around the average of 0.1% throughout the day.

Question 22

What is the pathway that sends information from the receptor to the control center called?

Answer 22

Afferent pathway

Question 23

What is the pathway that sends information from the control center to the effector called?

Answer 23

Efferent pathway

Question 24

What is a classic example of negative feedback?

Answer 24

Temperature control in a house

This analogy illustrates how systems regulate temperature to maintain comfort.

Question 25

What is the main characteristic of positive feedback?

Answer 25

It causes the stimulus to be increased ## Footnote Positive feedback amplifies the original stimulus rather than canceling it.

Question 26

How does positive feedback differ from negative feedback?

Answer 26

Positive feedback does not bring about an adaptive response that cancels the stimulus ## Footnote Negative feedback aims to restore homeostasis by counteracting changes.

Question 27

What is a common outcome of a positive feedback cycle?

Answer 27

Ejection of something from the body ## Footnote Positive feedback cycles typically lead to a significant change or event.

Question 28

In which biological system is positive feedback less common?

Answer 28

The human body ## Footnote Positive feedback systems are less prevalent compared to negative feedback systems.

Question 29

What forms a looped system in positive feedback?

Answer 29

The stimulus from one part of the body enhances the effect of the stimulus ## Footnote This creates a cycle that amplifies the response.

Question 30

What makes positive feedback systems unstable?

Answer 30

They cause an escalation in the original condition ## Footnote This instability can lead to significant departures from homeostasis.

Question 31

What is the specific example of positive feedback mentioned in Biology 12?

Answer 31

The positive feedback loop during labour involving oxytocin ## Footnote This example illustrates how positive feedback operates in a physiological context.

Question 32

Where is oxytocin produced and stored?

Answer 32

Produced in the hypothalamus and stored in the posterior pituitary gland ## Footnote Oxytocin plays a crucial role in childbirth.

Question 33

What triggers the release of oxytocin during childbirth?

Answer 33

Pressure from the baby's head against the cervix ## Footnote This pressure activates sensory nerves that signal the release of oxytocin.

Question 34

What effect does oxytocin have on the uterus during childbirth?

Answer 34

It causes stronger uterine contractions ## Footnote These contractions further stimulate the release of more oxytocin.

Question 35

The cycle of oxytocin release during childbirth continues until what event?

Answer 35

The baby is pushed out of the uterus ## Footnote This event stops the stimulation of sensory nerves to the pituitary.