Lecture 1

Question 1

Define the term physiology

Answer 1

• the study of living things and how they function
• helps us understand how the body works, from the smallest part all the way to the whole body
• helps us understand how different parts of the body work together

Question 2

what is homeostasis

Answer 2

• maintenance of a relatively stable internal environment
• we have a set point and the goal is to maintain these variables within a tight range
• maintenance of a dynamic steady state

Question 3

explain negative feedback loop and give an example

Answer 3

• ex. regulation of body temperature
  stimulus = decrease in temp
  sensor = nerve endings
  signal = nerve signals send signal to integrating center about decrease in temp
  integrating center = hypothalamus
  signal = nerve signal to effector to initiate change
  effector = skeletal muscles or blood vessels (shivering)
  output = levels to back to normal

Question 4

explain negative vs positive feedback loops

Answer 4

negative feedback loop = the feedback reduces the difference between the desired setpoint and the actual value -> it works to reduce the initial stimulus and regain homeostasis

positive feedback loop = the feedback increases the difference between the normal setpoint and the actual value -> it enhances the stimulus and moves the system away from homeostasis

Question 5

explain and give an example of a positive feedback loop

Answer 5

• ex. labor and childbirth
  stimulus = baby drops and presses on cervix
  sensor = stretch receptors in cervix
  integrating center = brain, oxytocin release
  effector = smooth muscles of the uterus (contractions)
  response = increased contractions until baby is delivered

Question 6

what is feedforward control

Answer 6

• initiation of a response in anticipation of the stimulus (things happening before the change)
• ex. sight, smell, or thought of food is enough to initiate salivation and digestion
• ex. increase in ventilation (breathing) as soon as exercise begins

Question 7

what is the biological hierarchy of organization

Answer 7

atoms -> molecules -> cells -> tissues -> organs -> organ systems -> organisms -> populations of one species -> ecosystem of different species -> biosphere
- compartmentalization allows for separation of complex processes

Question 8

describe the functional compartments
organs -> tissues -> cells

Answer 8

• heart is surrounded by a pericardial sac (tissue)
• the pericardial membrane is a layer of flattened cells supported by connective tissue
• each cell of the pericardial membrane has a cell membrane surrounding it
• the cell membrane is a phospholipid bilayer

Question 9

describe the body fluid compartments

Answer 9

• 2 compartments
• ECF and ICF are in osmotic equilibrium but have very different chemical composition
• ICF = 2/3 of the total body water volume
• ECF = 1/3 of the total body water volume -> consists of interstitial fluid and blood plasma
• interstitial fluid = between the circulatory system and the cells

Question 10

what is the body fluid distribution (numbers)

Answer 10

volumes for standard 70 kg male
- ECF = 1/3
- plasma = 3L
- interstitial fluid = 11L
- ICF = 2/3 = 28L

Question 11

explain the structure and components of the cell

Answer 11

cell membrane = plasma membrane
- provides structural support
- physical barrier between ICF/ECF
- selectively permeable
- regulates exchange
- regulates communication

cytosol = intracellular fluid
cytoplasm = intracellular fluid + organelles, inclusions, proteins

Question 12

explain components of the cell membrane

Answer 12

• mostly phospholipid bilayer
• also contains proteins (transmembrane, peripheral (non-covalent), lipid anchored (covalent)
• carbohydrates (glycoproteins and glycolipids)
• cholesterol -> affects membrane fluidity and permeability

Question 13

cells are physically and functionally grouped together by ____

Answer 13

• extracellular matrix and specialized cell adhesion proteins
• ECM can have variability consistency
• proteoglycans
• insoluble protein fibers (collagen, laminin, elastin)

Question 14

name and describe the 3 different cell junctions

Answer 14

• gap junctions -> enable communication between cytoplasms of adjacent cells
• tight junctions -> adjacent cell membranes are partly fused together making a barrier
• anchoring junctions (desmosome) -> anchor cells to each other or ECM, provides strength when tissue is under mechanical stress

Question 15

what proteins are involved in the different cell junctions

Answer 15

• gap junctions (communicating junctions) -> connexin proteins ex. action potential
• tight junctions (occluding junctions) -> claudin and occludin proteins, ex. blood brain barrier
• desmosome (cell to cell anchoring junction) -> cadherin proteins
• hemidesmosomes anchor cells to ECM

Question 16

which proteins can be removed without disrupting the integrity of the membrane

Answer 16

• peripheral proteins

Question 17

what is the concentration of Na+ and Cl- outside the cell

Answer 17

• 140 mmol/L (Na+)
• 100 mmol/L (Cl-)

Question 18

what is the concentration of K+ inside the cell

Answer 18

• 140 mmol/L