Physiology Exam 1 Review Notes

Physiology Review: Exam 1

Introduction to Physiology

• Physiology is the study of how the body works to maintain life, focusing on function.

Scientific Method

• Steps:
  1. Form a testable hypothesis based on observations.
     • Involves experimental and control groups.
     • Quantitative measures are used.
     • Data analysis using statistics.
  2. Conduct and analyze experiments to test the hypothesis.
  3. Draw conclusions about whether results support the hypothesis.
  4. Develop a theory.
     • A general statement explaining natural phenomena based on proven hypotheses.

Homeostasis

• Definition: The condition in which blood pressure, pH, temperature, fluids, and other factors of the internal environment are maintained within a range of values suitable to support life.
• It is a dynamic state where all the body’s systems are constantly adjusting to changing internal and external conditions.

Homeostasis Response Loop

1. Stimulus.
2. Sensor.
3. Afferent pathway.
4. Integration center.
5. Efferent pathway.
6. Effector.
7. Response (opposite to stimulus).

Negative Feedback

• Definition: A body mechanism by which any change from an ideal normal value is made smaller or is resisted.
• Leads to a compensated, healthy state and maintains homeostasis.
• The response subtracts from the stimulus, moving the system back to the set point.
• Negative feedback loops are continuous, ongoing processes.
• Examples:
  • Hormonal regulation.
  • Body temperature control via antagonistic effectors (sweating and shivering).
  • Blood pressure control.

Positive Feedback

• Definition: A body mechanism by which any change from an ideal normal value is made greater.
• Leads to a decompensated, disease state and away from homeostasis.
• The response adds to the stimulus, moving the system away from the set point.
• Positive feedback is rare because it amplifies changes.
• Examples:
  • Producing blood clots.
  • LH surge causing ovulation in females.
  • Positive feedback between the uterus and oxytocin secretion during labor.

Baroreceptors

• Located in arterial walls, aortic arch, and carotid sinus.
• Important for rapid control of blood pressure.
• Mechanoreceptors sensitive to stretch located in the internal carotid artery.

Antagonistic Effectors in Homeostasis

• Tonic Control: Varies a parameter via ONE mechanism on and off and in between.
  • Example: Adjusting water flow from a faucet.
• Antagonistic Control: Varies a parameter through TWO mechanisms that work in opposition to each other, providing precise and balanced control.
  • Sometimes described as “push-pull”.
  • Example: Mixing hot and cold water to achieve a desired temperature.

Role of Nervous and Endocrine Systems in Homeostasis

• Nervous and endocrine systems provide extrinsic regulation of other body systems to maintain homeostasis.
• Hormone secretion is stimulated by specific chemicals and inhibited by negative feedback mechanisms.
• Nerve activity and hormone concentration may decrease in response to deviations of the internal environment in one direction.
• Examples:
  • Hormones control blood glucose levels.
  • Heart rate is controlled by sympathetic and parasympathetic nerve fibers producing opposite effects: stimulation of one group increases heart rate, while stimulation of another group slows it.

Basic Tissue Types in the Human Body

1. Muscle Tissue
   • Cardiac
   • Smooth
   • Skeletal
2. Nervous Tissue
3. Epithelial Tissue
   • Squamous
   • Columnar
   • Cuboidal
4. Connective Tissue
   • Connective tissue proper
   • Cartilage
   • Adipose
   • Bone