Introductory Physiology PSL250 - Key Concepts Flashcards

What is Physiology?

• Physiology is the study of how the body works.

• It covers normal function from cells to the organism as a whole.

• Emphasizes mechanisms—the hows and why behind bodily function.

• Explained using cause-and-effect sequences.

• Derived from scientific experiments.

Subdisciplines of Physiology

• Pathophysiology:

  • Disease or injury affects physiological processes.

  • Aids understanding of normal processes.

  • Example: Phineas Gage – injury to the frontal lobe.

• Comparative Physiology:

  • Differences and similarities in functions across invertebrates and vertebrates.

  • Includes extreme examples and limits of the system.

• Subfields (examples):

  • Respiratory Physiology

  • Cardiovascular Physiology

  • Muscle Physiology

  • Neurophysiology

Levels of Organization in the Human Body

• There are 6 levels of organization, from simplest to most complex:

  1. Chemical (atoms and molecules)

  2. Cellular (cells)

  3. Tissue (group of similar cells)

  4. Organ (composed of two or more tissues)

  5. Organ system (group of organs with a common function)

  6. Organism (the whole living being)

• Figure 1.2 illustrates the progression from simple to complex, then from small to large.

Learning Objectives (as stated in the slides)

1. Describe the science of physiology and list the subdivisions of physiology.

   • Physiology: The scientific study of how the body works, covering normal function from cells to the organism as a whole, emphasizing mechanisms (the hows and whys), explained using cause-and-effect sequences, and derived from scientific experiments.

   • Subdivisions: Pathophysiology, Comparative Physiology, Respiratory Physiology, Cardiovascular Physiology, Muscle Physiology, and Neurophysiology.

2. Describe the 6 levels of organization in the human body.

   • The 6 levels, from simplest to most complex, are: Chemical (atoms and molecules), Cellular (cells), Tissue (groups of similar cells), Organ (composed of two or more tissues), Organ System (groups of organs with a common function), and Organism (the whole living being).

3. Define homeostasis and the components of a homeostatic system.

   • Homeostasis: The ability of an organism to maintain a relatively constant internal environment despite changing internal or external conditions.

   • Components of a homeostatic system: Receptor (detects a change), Control Center (processes information and determines response), and Effector (carries out the response).

4. List the 10 regulated variables of the human body.

   • The 10 regulated variables are: Arterial $PO<em>2$, Arterial $PCO</em>2$, $[K^+]$ (potassium), $[Ca^{2+}]$ (calcium), Blood acidity or $pH$ (i.e., $[H^+]$), Blood glucose (blood sugar), Body temperature ($T$), Blood pressure (BP), Blood volume (BV), and Blood osmolarity. Each is maintained within a narrow range to support life.

5. Identify the features that determine if a variable is regulated.

   • A variable is regulated if it is found in the blood (or directly affects blood-borne processes), is essential for the life of the organism, and has a sensor (a mechanism that detects changes in the variable).

6. Define negative feedback.

   • Negative Feedback: A mechanism where the resulting action is in the opposite direction of the initial stimulus, acting to reduce the deviation from the set point and restore balance. It is the most common homeostatic regulatory mechanism.

7. Be able to recognize each component of a homeostatic system in representative systems.

   • To recognize components, identify the Receptor (senses a change/stimulus), the Control Center (processes the information and determines an appropriate response, e.g., hypothalamus, pancreas), and the Effector(s) (carry out the response, e.g., blood vessels, skeletal muscles, or target tissues like liver/muscle for insulin). Examples like the glucose homeostasis loop or a home thermostat analogy illustrate this recognition.

8. Explain how homeostatic mechanisms regulated by negative feedback detect and respond to environmental changes.

   • Homeostatic mechanisms detect environmental changes via receptors (sensors) that monitor regulated variables. When a change (stimulus) moves the variable away from its set point, the receptor sends this information to a control center. The control center processes the information and determines an appropriate response. This response is then carried out by effectors, which act to counteract the initial change. In negative feedback, the effector's action is in the opposite direction of the stimulus, bringing the variable back towards its set point and restoring internal stability (homeostasis).

9. Define positive feedback and describe the actions of a positive feedback loop.

   • The provided notes do not offer a definition or full description of positive feedback. They only mention that diagrams might ask to indicate whether a response is negative or positive feedback.

Homeostasis: Keeping Internal Conditions Stable

• Homeostasis is the ability of an organism to maintain a relatively constant internal environment despite changing internal or external conditions.

• Hundreds of anatomic structures and physiologic processes are continuously monitored and adjusted.

• Homeostasis is controlled by the nervous and endocrine systems (endocrine and nervous system).

• A homeostatic system has three key components: receptor, control center, and effector.

What is Regulated? The 10 Regulated Variables

• The following variables are regulated in the human body:

  • Arterial $PO<em>2$, arterial $PCO</em>2$

  • $[K^+]$ (potassium)

  • $[Ca^{2+}]$ (calcium)

  • Blood acidity or $pH$ (i.e., $[H^+]$)

  • Blood glucose (blood sugar)

  • Body temperature ($T$)

  • Blood pressure (BP)

  • Blood volume (BV)

  • Blood osmolarity

• Each variable is maintained within a narrow range to support life.

Features That Determine If a Variable Is Regulated

• It must be found in the blood (or directly affect blood-borne processes).

• It must be essential for the life of the organism.

• It must have a sensor (a mechanism that detects changes in the variable).

Receptor, Control Center, and Effector: The Homeostatic Trio

• Receptor (sensor): detects a change in a variable.

• Control Center: processes the information and determines the appropriate response.

• Effector: carries out the response to restore the variable toward its set point.

• Classic analogy: a home thermostat (receptor senses temperature, control center makes a decision, heater/AC acts as the effector).

• Figure 1.11 illustrates the three components in a homeostatic mechanism.

Negative Feedback and Homeostatic Regulation

• Negative Feedback: the resulting action is in the opposite direction of the stimulus; this is the most common mechanism.

• Homeostasis is primarily regulated by the endocrine and nervous systems.

• Negative feedback acts to reduce the deviation from the set point, restoring balance.

• Practice questions in the slides reinforce recognizing components and how the loop operates.

Recognizing Homeostatic Systems in Representative Systems

• Example components: Receptor (senses change), Control Center (e.g., hypothalamus), Effectors (e.g., blood vessels in skin, skeletal muscles) that produce responses to adjust the variable.

• Negative feedback loops detect environmental changes and respond to restore homeostasis.

• Diagrammatic practice: identify stimulus, receptor, control center, effector, and indicate whether the response is negative or positive feedback.

Glucose Homeostasis (An Illustrative Example)

• Stimulus: Blood glucose rises after a meal.

• Sensor: Pancreas detects elevated glucose.

• Control Center: Pancreas responds by secreting insulin.

• Effector: Insulin acts on target tissues (e.g., skeletal muscle, liver) to promote glucose uptake.

• Outcome: Blood glucose decreases toward the set point.

• In the diagram, identify the stimulus, receptor, control center, and effector, and indicate in the center whether the response is negative or positive feedback.

• This example demonstrates how a negative feedback loop maintains blood glucose within a narrow range.

Figure References (from the slides)

• Figure 1.2: Levels of organization from small to large; simple to complex.

• Figure 1.11: Three components of the homeostatic control mechanism (Receptor, Control Center, Effector).

• Figure 1.13a & 1.13b: Receptor, Control Center, and Effectors organized in representative systems.

Concept Mapping and Study Tools

• Concept maps help organize components of the homeostatic control mechanism and their relationships.

• Use concept maps to connect receptors, control centers, effectors, and the outcomes of feedback loops.

Plan for Today and Course Structure (Overview)

• Introductions to classmates and teaching team.

• Course overview and Chapter 1 content: Sciences of Anatomy & Physiology.

• Topics: Physiology defined, organization/language of anatomy and physiology, homeostasis.

• Learn about syllabus, practice quizzes, and D2L navigation (Content → Quizzes).

Tips for Success in PSL250 (Active vs Passive Learning)

• Passive Learning:

  • Listening to lectures.

  • Reading textbooks or notes.

• Active Learning:

  • Rewrite notes in your own words.

  • Compare/contrast concepts.

  • Create concept maps.

  • Draw and label diagrams.

  • Apply concepts to health issues.

  • Explain concepts to someone else.

Method for Studying PSL250 (Recommended Schedule)

• Pre-class: Read recommended sections in textbook or SmartBook.

• In/Just After Class: Attend lecture and take notes.

• Within 1–5 days:

  • Review notes.

  • Rewrite notes in your own words.

  • Write answers to learning objectives.

  • Complete weekly homework assignments.

  • Create concept maps.

  • Use supplemental material.

• Within 3 days of the exam:

  • Review homework questions.

  • Review concept maps.

  • Take Practice Quiz.

• Keep a steady study routine to maximize retention.

Today’s Big Questions (Takeaways)

• What is physiology and how do we study physiology?

• How does the human body maintain a relatively constant internal environment despite external challenges such as temperature changes or eating?

Practice Questions from the Slides (Examples)

• Q: What subdiscipline of physiology deals with similarities and differences between different animals?

  • A: Comparative physiology.

• Q: What subdiscipline deals with the heart and blood vessels?

  • A: Cardiovascular physiology.

• Q: What is the simplest level of organization in a human?

  • A: The answer is typically the cellular level (though some questions consider atoms as the simplest chemical level; the quiz asks to choose from options: Cellular, Organismal, Atoms, Chemical).

• Q: What is the component of a homeostatic system that detects a change in the stimulus?

  • A: Receptor.

Connections to Foundational Principles

• Physiology builds on anatomy: structure relates to function.

• Homeostasis underpins health and disease; disruption leads to pathophysiology.

• Negative feedback loops illustrate how systems stabilize after perturbations.

• Phineas Gage example

Practical and Ethical Considerations

• Ethical implications are context-dependent (in clinical physiology and biomedical imaging). While the slides touch on training and research contexts, the core content focuses on foundational physiological principles rather than ethical debates.