Homeostasis

• Anatomy


  The scientific discipline that investigates the body's structures and the relationship between the structure of a body part and its function
• Physiology


  The science of the normal function of living systems, to understand and predict the body's responses to stimuli and how the body maintains conditions within a narrow range of values in a constantly changing environment
• Homeostasis


  The tendency of biological systems to maintain relatively constant conditions in the internal environment while continuously interacting with and adjusting to changes originating within or outside the system
• Homeostasis


  The maintenance of a variable around an ideal normal value or set point, where the value of the variable fluctuates around the set point to establish a normal range of values
• Stressors


  Changes in the internal and the external environment that affect the normal conditions of the body
• How is homeostasis achieved?

  • Structural
  • Functional
  • Behavioral

  
• Feedback Mechanism/Feedback Loop


  A physiological loop that brings the body either toward or away from the normal, steady state, either amplifying or inhibiting a certain biological pathway
• Basic Components of Control Mechanisms


  • Receptor
  • Control center
  • Effector
• Negative feedback


  A feedback loop in which the output of a system reduces the activity that causes that output
• Negative feedback


  • Blood glucose concentrations rise after a sugary meal, insulin is released which speeds up the transport of glucose out of the blood, blood glucose concentrations decrease
  • Exercise creates metabolic heat which raises the body temperature, cooling mechanisms such as vasodilation and sweating begin, body temperature falls
• Positive feedback


  A feedback loop in which the output of a system is increased by the mechanism's own influence on the system that creates that output
• Positive feedback

  • Blood Clotting - Substances released by the injured blood vessel wall begin the process of blood clotting, platelets in the blood start to cling to the injured site and release chemicals that attract additional platelets, accelerating the process of clotting
• Anatomical position


  A person standing erect with the face directed forward, the upper limbs hanging to the sides, and the palms of the hands facing forward
• Anatomical positions

  • Prone - facing down
  • Supine - facing up
• Directional terms

  • Anterior - goes before
  • Posterior - goes behind
  • Dorsal - the back
  • Ventral - the belly
  • Superior - up
  • Inferior - down
  • Superficial - towards the surface
  • Deep - towards the interior
  • Proximal - near the main body axis
  • Distal - away from the main body axis
  • Medial - near the midline
  • Lateral - away from the midline
• Planes


  • Frontal plane/coronal plane - divides the body into dorsal and ventral halves
  • Transverse/horizontal plane - divides the body into superior and inferior halves
  • Sagittal plane - divides the body into left and right halves
• The human body is composed of various systems for support and movement, regulation and maintenance, integration and control, reproduction and development, and sense organs