Introduction to physiology and homeostasis Flashcards
What are control systems
-Mechanisms that exist within the human body to maintain homeostasis by monitoring key functions and variables
-Can be local or reflex
What is dynamic steady state
the internal environment is in a relatively steady state but is dynamic in that materials are constantly moving back and forth between extracellular and intracellular fluid
-Not the same as equilibrium but stable disequilibrium
-Aimed to maintain each respective compartment stable but not the same as each other
What are emergent properties
-Properties of a complex system that cannot be explained by a knowledge of a systems individual components
-greater than the simple sum of the system’s individual parts
-result from complex, nonlinear interaction of different components
-Emotion or intelligence cannot be predicted from knowing the individual properties of nerve cells
What is homeostasis
-Coined by Walter B. Cannon in 1929
-the ability to maintain a relatively stable internal environment (ECF) despite exposure to external variability (Blood pressure, body temp, ion/molecule concentration, gas partial pressures, etc.)
What is physiology
-The study of the normal functioning of all living organism and its components, parts, including all its chemical and physical processes
-Literally means “knowledge of nature”
-Key principles include homeostasis and regulation of the internal environment
What is a set point
the ideal value or range of values for a physiological parameter
What are all the levels of organization studied in physiology
-Molecules
-Cells
-Tissues
-Organs
-Organ systems
-Organisms
-Populations of one species
Name the 10 physiological organs of the body
-Circulatory
-Digestive
-Endocrine
-Immune
-Integumentary
-Muscoskeletal
-Nervous
-Reproductive
-Respiratory
-Urinary
What two systems are shown as a continuum rather than two distinct systems? Why?
-Nervous and endocrine systems
-Carry similar functions and have blurred as we have learned more about the integrative nature of physiological function
What are the two approaches when studying physiological processes? How do they differ?
Teleological (functional) approach:
-The ‘why’ or adaptive significance behind a system or event
-Explains why processes occur without elaborating on it’s function
The mechanistic approach:
-the ‘how’ of a system or process
-Provides concrete answer that explains exactly how a process works but does not explain the significance behind it
What is a pathological condition?
The result of a diseased state when the body fails to maintain homeostasis and normal function is disrupted
What are the two general groups of disease based on their origin?
Internal:
-Abnormal growth of cells (causing cancer or benign tumors)
-Production of antibodies against its own tissues (autoimmune diseases)
-The premature death of cells or the failure of cell processes
-Inherited disorders
External:
-Toxic chemicals
-Physical trauma
-Foreign invaders (bacteria and viruses)
What composes the body’s internal environment?
-Extracellular fluid (ECF): watery internal environment that surrounds the cell
-Serves as the transition between an organism’s external environment (Buffer zone)
-Intracellular fluid (ICF): Fluid inside cells
How does the ECF maintain homeostasis?
When ECF composition varies outside its normal range of values, compensatory mechanisms activate and try to return the fluid to the normal state
What is Mass Balance and why is it important to homeostasis?
-Law of Mass Balance: If the amount of substance in the body is to remain constant, any gain must be offset by an equal loss (Body’s load or ‘sodium load’)
-Maintains concentrations of substances such as oxygen, carbon dioxide, salts and hydroged ions (pH)
-Equation: Total amount of substance X in body = intake + production - excretion -metabolism
What are the two output options to maintain mass balance?
Excretion
-The elimination of material from the body, usually through the urine, feces, lungs or skin
-Many foreign substances that enter the body, such as drugs or artificial food additives (xenobiotics), are excreted by the liver and kidneys
Metabolism
-Converting the substance to a different substance through metabolism
-Nutrients that enter the body become the starting point for metabolic pathways that convert the original nutrient to a different molecule (Creates a new mass balance disturbance by adding a new metabolite)
What is mass flow?
-Describes the rate of transport of a substance x as it moves through body fluids or into and out of the body
-Mass flow(amount x/min) = concentration of (x) x volume flow (amount of x/vol) x (vol/min)
Describe local control
-Cells in close vicinity of the change initiate the response
-Includes Input signal, integrating center, output signal and a response
Describe reflex control
-Uses long-distance signaling
-Is systemic and uses more complex control systems to maintain homeostasis through the nervous, endocrine system or both
-Broken into response loop and feedback loop
-Feedback loop modulates response loop and influences the input
-Can be antagonistic
What are the 3 types of feedback loops and their functions?
Negative feedback loop:
-Homeostatic
-Response opposes or removes signal to stabilize system
-Can restore initial state but cannot prevent initial disturbance
Positive feedback loops:
-Not homeostatic
-Reinforce a stimulus to drive system away from normal value (childbirth)
-Requires intervention or outside event to cease response
Feedforward control:
-Anticipatory change that enables functions to prematurely begin
What are biological rhythms and how do they change individuals set point?
-Set points vary from person to person or may vary over time
-Can be due to genetics or constant exposure to a new condition
-Biorhythms: variables that change predictably and create repeating patterns or cycles of changes (circadian rhythm)
-May create anticipatory response to predictable environment changes
What are the seven steps in reflex control?
-Stimulus
-Sensor
-Input signal
-Integrating center
-Output signal
-Target
-Response
