Physio

Physiology

Physiology

• the study of body functions; how the body carries out its life-sustaining activities

• Focuses on events happening on the cellular and molecular levels

Why should we study physiology

• Learn about yourself!

• How to stay healthy

• Understand & appreciate emerging discoveries in genetic engineering

• New medications & treatments for disease

Anatomy

• structure determines function

  • Physiological mechanisms are only possible through structural design

  • A slight change in anatomy can have a significant effect on physiology

• Chemistry

• Acid / Bases

• Osmolarity

• Biochemistry

Physics

• Electrical currents

• Blood pressure

• Flow rates

• Gas Laws

Homeostasis

• State of balance in which the body’s internal environment remains relatively stable despite changes in the internal and external environments.

What types of things change the cell’s environment?

• Lactic acid & heat from muscles

• CO2  from respiration, ↓pH

• Glucose going into cells

Negative Feedback

output or response of the effector counteracts the original stimulus, returning the variable to normal limits.

• Can be an immediate short-term response or a long-term adaptation

  • Ex: Heart’s response to exercise

    • Short-term- ↑ HR

    • Long-term- ↑ Stroke volume with a lower rate (trained heart)

compensatory responses

Deviation from a stable condition will trigger a sequence of events that will counteract the change

Law of Maximum and Minimum

effects of various conditions that the body can function efficiently

Optimal range

• functions most efficiently

Range of tolerance

• can still function

• Minimum or Maximum condition

• Moving past max or min may result in death

Homeostatic Control Mechanisms

• Variable

• Stimulus

• Receptor

• Control Center

• Effector

• Response

Extrinsic

• control from outside the organ/tissue

  • Accomplished by the nervous and endocrine systems (Reflex control)

  • Several systems working towards a common goal

  • Ex: sympathetic regulation of blood pressure

Intrinsic

• control from within the organ/tissue

  • Self-serving the organ it occurs in (Local control)

  • Ex: Decreased oxygen levels in skeletal muscle causes vasodilation of blood vessels

Extrinsic Control \n Reflex Loops

• Neural Reflex

• Endocrine Reflex

• Neuroendocrine Reflex

Positive Feedback

• Output of effector is amplified or the original stimulus is intensified

• Variable moves further from set value

• Tends to be destabilizing if not self limiting (eventually shuts off)

Feed forward control

• reflex that starts the response loop in anticipation of the stimulus

  • Examples:

    • Thought or smell of food triggers salivation

    • Increased respiratory rate in anticipation of exercise

Teleological

• explanation is based on purpose, meeting body needs

  • Does not consider how it occurs. Focus on why.

Mechanistic

• in terms of cause and effect, sequence of events

physiology as an integrative science

Physiology integrates function across many levels of organization and information from different body systems

Levels of Organization

Chemical, Cellular, Tissue, Organ, Body system, Organism

Emergent properties

• properties that cannot be predicted based only on the knowledge of individual systems

• Important to look at the human body as a whole and how the different systems work together and affect each other

• Also depends on internal and external factors

  • Genetics, age, overall health, etc