Exam 1 Flashcards
The number of cells in the human body?
35 trillion
25 trillion are red blood cells
Define homeostasis?
The healthy balance constantly maintained by the body’s cellular processes.
All the body systems work together to maintain homestasis
“what goes in must go out”
What are the components of energy?
Work, heat, and potential energy
How does anesthesia impair homestasis?
Anesthetics impairs almost all control sensors - so the body will no longer maintain it’s own homeostasis (that is now our job).
Describe how peripheral circulatory beds maintain homeostasis?
Increased cellular metabolism causes a nutrient deficency, blood flow increases to supply more nutrients (breakdown of ATP and release of adenosine). The increased inflow of nutrients also causes an increased outflow of blood and waste products.
DELIVER ONLY ENOUGH TO MEET TISSUE NEEDS
“what goes in must go out”
Describe how the GI system can maintain homeostasis?
Returns depleted nutrients to the bloodstream
Describe how the kidneys can maintain homeostasis?
The kidneys buffer the pH when out of range and assist in blood pressure control.
Describe how the liver can maintain homeostasis?
By riding toxins from the blood stream, esp. ethanol.
Liver contains many peroxisomes.
What is the major feedback system in the body and describe how it functions?
The negative feedback system. The body has sensors that detect a change, the controller is alerted of this change and initiates a negative/opposing change to counteract the effects and maintain homeostasis. Once returned to normal, the contoller stops.
Think of an air conditioning thermostat (turns on when temperature is out of normal, tells the AC/heater to turn on to return the temperature to normal range.)
Describe 4 ways the body can regulate a decrease in MAP?
- Increase sympathetic outflow (norepinephrine).
- Decrease parasympathetic outflow.
- Increase AVP/ADH (vasopressin)
- Decrease ANP (vasodilatory hormone).
These can all be working simultaneously to maintain homeostasis.
Define postive feedback?
The stimulus produces a change and the body responds by amplifying this change.
What are the 2 types of postitive feedback?
Physiologic and pathologic
Why would a physiologic postive feedback be less likely to enter a vicious cycle?
Physiologic feedback contains checkpoints/safty valves to control respones.
Describe how birth is an example of good positive physiologic feedback?
Oxytocin is released which causes uterine contractions, the baby is pushed onto the cervix and causes it to stretch, and the cervical stretch causes more oxytocin release.
Birth is the checkpoint that ends the positive feedback loop.
Describe how the clotting cascade can be a good positve physiologic feedback?
Endothelial injury begins the clotting cascade and the platelet plug is formed, TXA 2 helps vasospasm. Clotting speeds up as time goes on and the feedback stops when bleeding is controlled.
How would not having a checkpoint in positive feedback effect the outcome?
Without a checkpoint the response will continue and eventually cause deaths or other bad effects (ex: cornary artery blockages and massive blood loss).
Describe positive feedback in sepsis/necrosis?
Cells begin dying faster than the body can replicate them/get rid of them. The toxic byproducts of cell death leak into the environment and other cells begin to die.
Describe positive feedback in severe acidosis?
The CNS is affected and can no longer compensate with hyperventilation, the reduced respiratory drive worsens the acidosis, and continues to worsen the CNS.
Describe positive feedback in diabetic renal inflammation/hyperfiltration?
Nephrons begin to die and they don’t regenerate, putting more strain on the remaining nephrons. With the increased work and with age, these nephrons also die.
Describe positive feedback in severe hemorrhage?
Blood loss leads to decreased MAP which causes reduced coronary blood flow. The low coronary blood flow causes decreased cardiac output which further reduces the MAP.
With less severe hemmohage, negative feeback will compensate. After more than 20% blood loss, negative feedback can’t keep up and positive feedback will lead to death.
Describe the relationship between physiologic systems and and anesthetics?
Alterations in physiologic systems (someone who is not healthy) changes how they responed to anesthetics.
Administiring anestheics alters a systems physiology (“takes control systems offline”).
Describe the function of a lysosome?
Reside within the cell and destroy things when no longer needed with acidity.
The byproducts of breakdown can be recycled.
Describe the function of a peroxisome?
They neutralize toxins by oxidation reactions.
Primary toxin being ethanol. Many peroxisomes are in the liver.
Think rust leading to malfunction.
Describe the structure of the cell membrane?
It is made up of a phospholipid bilayer. The heads are polar and hydrophilic, the tails are nonpolar and hydrophobic (made of lipids).
The intracellular fluid is primarily what?
70-85% water
Except fat cells
The nuclear envelope (or membrane) protects the nucleus how?
It is comprised of a double phospholipid bilayer with small pores that are highly selective.
Why is the nucleus highly protected?
Because it contains DNA. It is protecting it from virus and bacteria.
What class of drug can enter the nucleus?
Steroids
Where is the endoplasmic reticulum located?
It is an extension of the nucleus.
What is the purposes of the endoplasmic reticulum?
Used for storage (calcium), and producing protiens and lipids.
Describe how a protien is created in the cell?
DNA contains the protein code sequence. DNA is transcribed to RNA. RNA transports the code out of the nucleus to the ribosome. The ribosome takes these instructions and forms an amino acid chain and forms the protien. Proteins that will leave the cell go to the Golgi apparatus for final modifications and packaging.
What occurs in the granular/rough endoplasmic reticulum?
Protein production by ribosomes.
These protiens are not ready after this stage.
What occurs in the smooth endoplasmic reticulum?
Fat production
What occurs in the golgi apparatus?
The proteins that arrive from the rough ER are modified to their final state and then packaged to leave the cell.
How are protiens transported to the golgi apparatus and out of the cell?
By transport vesicles and secretory vesicles, respectively.
What is the purpose of proteins on the cell wall?
They help water soluble or polar compounds cross the cell membrane.
Each protien has specific task
These molecules need help because without it they cannot cross the hydrophobic center of the cell membrane.
What is the purpose of sugars in the cell?
On the cell wall they are attached to proteins and:
1. They help identify other cells.
2. They are “sticky” and help the cell attach to other cells around it.
3. They typically have (-) charge and will repel protiens (-).
Intracellularly:
They are a source of energy via glycolysis.
Are all protiens produced in ribosomes within the rough ER?
About 95% are, the other 5% are made in ribosomes within the cytosol that do not require packaging or modification.
What is an enzyme and what is its purpose?
Typically a protien, ending in “-ase” that catalyze chemical reactions.
What is the purpose of filaments and proteins in the cell wall?
They are structural components that help the cell maintain it’s shape.
What are organelles?
Distinct structures that perform specific tasks within the cell.
Can all cells replicate themselves?
No, RBC contain no nucleus and therefore cannot replicate themselves.
Cells that cannot regenerate have nearby progenerator tissues that aid in replication.
What are some cells that do not replicate or do not replicate very fast?
RBC, neurons, cardiac cells, and nephrons.
RBC need progenitor cell to replicate.
After this age, nephrons begin die off more rapidly?
40-45 years old.
How many nephrons are there per kidney?
~1 million
What are some motility mechanisms for a cell?
Flagella help move the cell. Cilia are structures on the outside of the cell that move the environment around the cell.
Cilia - mucous in the airway.
Where is genetic material located within the cell?
In the nucleus as DNA, RNA, and as mitochondrial DNA.
Mitochondrial DNA comes from?
Inherited maternally.
What are some compounds that are typically insoluble in water?
Cholesterol, steroid hormones, lipids, nitrous gas
What are some water soluble substances?
Ions, proteins (some), carbohydrates (sugar), gases like CO2, buffers, some drugs
How much water is in a healthy adult?
60% of their body weight.
Where is most of the body’s water located?
The intracellular fluid (ICF).
How much of the body’s water is in the ICF?
2/3 of the water is in the ICF
How much of the body’s water is in the ECF?
1/3 of the total body water is in the ECF
How much of the ECF is the plasma volume?
1/4-1/5 of the ECF volume
What are the components of the ECF?
Plasma and interstitial fluid.
What is plasma?
The fluid in the vasculare system not including blood cells.
How much of the ECF is the interstitial fluid?
3/4-4/5 of the ECF is interstital fluid.
What seperates the intracellular fluid from the interstitial fluid?
Cell membrane
What seperates the interstital fluid from the plasma?
Capillary membrane
What is the difference in permeability between the capillary and cell membrane?
The cell membrane is much more selective, needs pumps or controllers for polar molecules to cross. The capillary membrane allows small molecules like ions to cross but does not allow larger molecules like proteins to cross- they stay in the plasma.
Water can cross both easily in order to maintain osmolarity.
What is the difference between steady state and equilibrium?
Steady state describes the regulated differences and equilibrium means the same inside as outside.
What is the normal plasma sodium level?
140 or 142
What is the relationship between plasma and intracellular concentrations of sodium?
There is 10 times more sodium in the plasma than the ICF.
10:1
How can you quickly estimate serum osmolarity?
Multiple the plasma sodium concentration by 2.
What is the relationship between plasma and intracellular potassium?
There is 30 times more potassium intracellularly.
30:1
What is the normal potassium level in the plasma?
4.0
What is the relationship between ECF and ICF concentrations of calcium?
There is almost no calcium in the ICF. The ratio is 1:10,000
What is the relationship of magnesium present in the ECF and ICF?
There is much more magnesium in the ICF
Why is the ICF so low in calcium and what is calciums function?
It is so that the cell has a low threshold for activation by extracellular calcium for things like muscle movement. Calcium turns cell functions on.
What is the function of magnesium in the ICF?
It is a cofactor for many reactions intracellularly.
What is chloride’s role in the chemistry of ECF?
Chloride is the primary anion in the ECF.
Describe the prostaglandin formation pathway?
1.Arachidonic Acid becomes PGG2 and then PGH2 in sequential reactions by COX 1/COX 2.
2.PGH2 becomes a number of prostaglandins and TXA2 by prostaglandin synthases.
What is simple diffusion and what are some examples?
Where molecules move across the membrane without the use of energy or binding.
Examples: gases move independently across the cell, Na+, Cl-, and H2O move across via channel protiens.
Describe facilitated diffusion?
Molecules bind to a membrane protein, cause a conformation change, and moves from one side to the other. This does not require energy; molecules are still moving with the chemical/electrical gradient.
How does the Na+/K+/ATPase pump function? Why is this pump important?
1.The pump attaches 3 Na+ intracellularly and 2 K+ extracellularly - then uses the dephosphorylation of ATP to transport the ions against their concentration gradients.
2. It is important in setting up action potentials. Also sets up the gradient (stored energy) that secondary active transporters utilize to perform their function.
Describe the action of a voltage gated Na+ channel?
At rest, the M-gate is closed and the H-gate is open. Once activated the M-gate opens first (activated), then immediately followed by the H-gate closing (inactivated). The cell then must repolarize to open the H-gate or reset the channel.
Describe the structure and function of the voltage gated K+ channel?
It has only and inner gate that is closed at rest. It also has a selectivity filter for the K+ ion. The gate opens to repolarize the cell and is slower (to open and close) than the voltage gated Na+ channel. It closes when Vrm is restored.
What position’s are the M-gate and H-gate in at rest in a VG Na+ channel?
The M-gate is closed and the H-gate is open.
What position’s are the M-gate and H-gate during inactivation in a VG Na+ channel?
M-gate open and H-gate closed.
