SHARC Comprehensive

• What is tonicity?


  the ability of a surrounding solution to cause a cell to gain or lose water
• What is a hypertonic solution?

  solute concentration is greater outside the cell than inside the cell

  
  

  cell loses water; crenation
• What is a hypotonic solution?

  solute concentration is lesser outside the cell than that inside the cell

  
  

  cell gains water; lysis
• What is simple diffusion?


  movement of molecules from high to low concentration through the cell membrane
• What is facilitated diffusion?

  the passive movement of a particle across a cell membrane via protein channels
• What is active transport?


  the movement of ions or molecules across a cell membrane from low to high concentration, using energy
• What is hydrolysis?


  the chemical breakdown of a compound due to the addition of water
• Why do you need O2?

  O2 is the final electron acceptor in cellular respiration so we need it to make ATP
• How is O2 transported in the blood?

  about 1.5% is dissolved into plasma

  
  

  the majority is carried by hemoglobin
• Why do we need to get rid of CO2? What happens to pH if we have too much CO2?

  CO2 loves water

  
  

  CO2 + H2O --> HCO3 + H+

  
  

  H+ is a product which lowers pH and makes blood acidic
• How is pH measured?

  pH is the measure of H+ ions
• Which organs help you to maintain pH homeostasis?

  kidneys and lungs
• How is the resting potential determined? Which ions are involved? Which transporters?

  Resting potential is determined by negatively charged organic phosphates and proteins in the cell

  
  

  ATPase pumps move 3Na+ out and 2K+ in the cell to maintain the negative charge
• Where is the pacemaker of your heart? What does it determine?

  sinoatrial node

  
  

  determines the rate of heart contractions
• Describe blood flow through the heart.

  superior & inferior vena cava --> right atrium --> tricuspid valve --> right ventricle --> pulmonary valve --> pulmonary artery --> lungs --> pulmonary veins --> left atrium --> mitral valve --> left ventricle --> aortic valve --> aorta --> body
• Why do we need valves?


  To prevent backflow and keep blood moving in one direction
• Which organ systems have similar functions?

  nervous and endocrine (communication)

  
  

  lymphatic, skeletal, integumentary, respiratory, muscular, cardiovascular, digestive, urinary (protection)

  
  

  skeletal, muscle, nervous (movement)

  
  

  nervous, cardiovascular, muscular, integumentary (temperature regulation)

  
  

  urinary, respiratory, digestive, cardiovascular (acid-base balance)
• Which hormones are involved in calcium homeostasis? What specifically do they do?

  high blood Ca+ levels ---> thyroid releases calcitonin ---> stimulates movement of Ca+ into bone ---> inhibits osteoclast activity and promotes osteoblast activity

  
  

  calcitonin ---> kidneys pee out Ca+

  
  

  low blood Ca+ levels ---> parathyroid secretes parathyroid hormone (PTH) ---> increased osteoclast activity and decreased osteoblast activity

  
  

  PTH ---> Ca+ is retained and not peed out by kidneys
• Which hormone helps to maintain water homeostasis? How?

  antidiuretic hormone (ADH)

  
  

  stimulates kidneys to reabsorb more water

  
  

  stimulates thirst from the hypothalamus

  
  

  decreases water lost through sweating

  
  

  constricts arterioles (vasoconstriction) which increases blood pressure
• Why is calcium the most important ion?

  calcium ions strengthen bones and stimulate muscle contraction
• How is an action potential brought about? What are the ions involved? How?

  Voltage gated Na+ ion channels open and Na+ ions diffuse in ---> cell depolarizes ---> Na+ channels close and potassium channels open ---> K+ ions diffuse out ---> cell repolarizes ---> K+ flow out past resting membrane potential ---> cell goes through hyperpolarization ---> Na+, K+ ATPase restores resting potential
• What neurotransmitters are released by the sympathetic nervous system?

  norepinephrine and epinephrine
• What neurotransmitters are released by the parasympathetic nervous system ie Vagus?

  acetylcholine
• Why are enzymes important?

  they speed up chemical reactions
• How do you carry CO2 to the lungs?

  small amount dissolved in plasma

  
  

  some are bound to hemoglobin (carbaminohemoglobin)

  
  

  most are carried as bicarbonate ions in plasma
• Why do you need hemoglobin?

  to transport oxygen and CO2
• Which organelle makes ATP?

  the mitochondria
• What is the function of myelin?

  protects and insulates axon to increase the speed of action potentials
• Where are all blood cells made?


  in red bone marrow
• Where did you see Acetylcholine? Was it stimulatory or inhibitory?

  acetylcholine can be found in neuron synapses and neuromuscular junctions

  
  

  stimulatory in skeletal muscle

  
  

  inhibitory in the heart
• Describe the steps of muscle contraction.

  1) action potential arrives at neuromuscular junction

  2) this opens voltage gated Ca2+ channels and Ca2+ rushes in

  3) Ca2+ stimulates vesicles to release ACh by exocytosis

  4) ACh binds to receptors on the motor end plate

  5) this opens ligand-gated channels

  6) Na+ channels open and Na+ enters the cell, making it more positive (depolarization)

  7) Na+ channels close and K+ channels open, allowing K+ to exit the cell, making it more negative (repolarization)

  8) K+ channels stay open too long and becomes even more negative (hyperpolarization) before returning to resting membrane potential through Na+/K+ pumps

  9) after reaching the voltage threshold, graded depolarization leads to an action potential in the muscle which zooms down the T-tubules

  10) this opens voltage-gated Ca2+ channels

  11) Ca2+ binds to troponin, which moves tropomyosin to expose the myosin binding site on actin

  12) myosin binds to actin but detaches when ATP binds to myosin

  13) myosin hydrolyzes ATP which allows it to reset / rebind to actin
• How is blood pressure regulated? Why do we regulate blood pressure?

  blood viscosity:

  increased BV = decreased flow & increased BP

  
  

  total blood vessel length:

  greater length = slower flow & increased BP

  
  

  blood vessel radius:

  increased radius = increased flow & decreased BP

  
  

  we regulate blood pressure because high BP requires heart to work harder and low BP may decrease O2 to the brain
• Define hydrophobic and hydrophilic messengers.

  hydrophobic messengers

  can cross the cell membrane by simple diffusion

  
  

  ex: steroid hormones, thyroid hormones and nitric oxide (NO)

  
  

  hydrophilic messengers

  cannot cross the target cell membrane
• Describe glucose homeostasis.


  when glucose levels are low alpha cells secrete glucagon

  
  

  when glucose levels are high beta cells secrete insulin
• What are the actions of Thyroid hormones?

  increases metabolic rate and protein synthesis in the target

  
  

  stimulates the synthesis of Na+/K+ pumps

  
  

  raises temperature (calorigenic)

  
  

  stimulates increased amino acid and glucose uptake (make more ATP)

  
  

  increases number of cellular respiration enzymes in mitochondria
• What stimulates the release of Thyroid Hormones?

  Stimulus:

  Cold temperature, pregnancy, high altitude, hypoglycemia, or

  low TH

  
  

  TRH (from hypothalamus) ---> TSH (from AP) ---> binds to follicular cell receptors (thyroid) ---> TH ---> bind to target cell receptors inside the cell
• What is calcitriol? Where is it released?

  low blood Ca2+ levels ---> in the kidneys, vitamin D3 is activated to create calcidiol ----> calcidriol is activated to create calcitriol ---> calcitriol is released by the kidneys --->

  
  

  increased activity of osteoclasts (release Ca2+ from bone)

  
  

  inhibits osteoblasts

  
  

  enhances Ca2+ and PO₄³⁻ absorption by digestive tract
• What is albumin? What does it do?

  a plasma protein that makes up 60% of blood plasma

  
  

  transports substances such as fatty acids, thyroid hormones, and steroid hormones
• What are actions of growth hormone? Tropic versus non-tropic.

  Tropic effect:

  muscle, cell, and bone growth

  
  

  Non-tropic effect:

  stimulate gluconeogenesis in liver

  
  

  stimulate lipolysis in adipose tissue
• What is a tropic hormone?

  control secretion of hormones from other endocrine glands