Exam 1 Flashcards
1
Q
What is Physiology?
A
- study of how your body works
- incorporates many different areas of study (chem, anatomy, biology, etc…)
2
Q
Neurons
A
- supported by neuroglial cells
- neuroglial cells (glial cells) don’t do much except support neurons
- 5:1
3
Q
Long Neurons in Leg
A
- run entire length, think sciatic
- functionally if it’s damaged (spine area or lower) you won’t be able to move your foot/leg)
4
Q
Organs that contract involuntarily and contain smooth muscle
A
- GI tract
- airways into lungs-asthma is the inappropriate contraction
- gallbladder
5
Q
Intercalated Discs
A
- present in cardiac muscle
- makes all fibers connected electrically
- if these aren’t coordinated the heart won’t pump blood efficiently which means you die
6
Q
Diaphragm
A
- largest and most important muscle of breathing
- skeletal muscle
- voluntary and involuntary
- voluntary: holding breath, singing/talking-controls volume and flow rate
- involuntary: sleep, hiccups
7
Q
Epithelial Tissues
A
- form membranes that cover the surfaces of the body and various glands
- classified by shape of cells and number of layers
8
Q
Endocrine and Exocrine Glands
A
- endocrine are internal
- exocrine open to the external environment
- endocrine: hormones
- exocrine: sweat and oil, mammary, tears, salivary
9
Q
Total Body Water
A
- extracellular and intracellular
- plasma is part of extracellular
- interstitial is also part of extracellular
- everything except GI tract (technically outside of the body) and what’s been filtered in the kidney and air in lungs
10
Q
Intracellular Fluid
A
- cells have very specific and known concentrations
- fluid inside cells
- all cells pretty much have same composition
11
Q
Interstitial Fluid
A
- between cells and blood
- between blood vessels
- extracellular
12
Q
Extracellular Fluid
A
- blood and fluid surrounding cells always kept constant
- outside of cells
- plasma is part
- pretty much all alike in composition
- salty
13
Q
Blood Plasma
A
- in blood vessels
- not including the cells
14
Q
Homeostasis
A
- negative feedback loop
- if something changes you negate the initial change
- set point is normal condition
- change in set point happen which is the error signal
- error signal detected at an integration center and a regulatory mechanism/sensory pathway is activated which sets in motion an effector response and this reduces the change and returns the body to a set point.
15
Q
Where is the too hot error signal located?
A
-hypothalamus
16
Q
What are some temperature effector responses that help increase body temperature under cold conditions, and explain why they are effective.
A
- decrease in temperature initiates the hypothalamus
- in response it may cause you to shiver which contracts muscles to generate heat
- it may control skin blood flow and send more warm blood internally or constrict skin blood vessels
- or it may change your behavior to seek out warmer places or wear warmer clothes
17
Q
What are some temperature effector responses that help decrease body temperature under hot conditions, and explain why they are effective.
A
- increase in temperature initiates hypothalamus
- in response it may cause you to sweat which cools by evaporation-has to do with water vapor in air–humid is harder to stay cool
- or it may control skin blood flow and send more warm blood to skin to dissipate heat
18
Q
Blood Glucose Regulation
A
- kept constant
- change in regulated variable-increase in blood glucose
- integrating center-beta cells of pancreas increase signal to effectors
- effectors are cells throughout the body and they take up the blood glucose and decrease levels
19
Q
Role of Insulin
A
- opens doors of cells so glucose can go into skeletal muscles and adipose tissue-frees up energy
- then blood glucose decreases
- negative feedback
20
Q
What happens if insulin is absent or ineffective?
A
-nothing to put the breaks on blood glucose levels so blood sugar gets too high
21
Q
Type 1 Diabetes
A
- insulin absent
- destroyed cells that make insulin
- autoimmune
22
Q
Type 2 Diabetes
A
- have insulin but has become ineffective over time-cells don’t respond
- link between weight and this
- sedentary living (obesity and inactivity) cause insulin to be ineffective
- cells don’t want more glucose so they are being poisoned by excess glucose
23
Q
Treatments for type 1 diabetes
A
- exogenous insulin treatment
- problems: timing of eating and insulin spikes and monitoring of blood glucose
- have to kinda guess how much you need based on how much you’ve eaten
24
Q
What do the drugs do that treat type 2 diabetes?
A
- bind to cell (adipose or skeletal) to let glucose into cell
- drug to lower glucose levels in the body
25
Treatments for type 2 diabetes
- exercise-most effective, makes cells need more sugar and allows glucose into cells without dependence on insulin
- healthier diet consisting of less sugars
26
Covalent Bonds
- share electrons evenly
- don't break
- stable
27
Polar Molecules and Hydrogen Bonds
- covalent bonds not shared evenly one hogs electrons
- weak bonds
- negative energy bonds stronger (liquid)
- positive energy bonds break (water vapor)
28
Why do molecules with polar covalent bonds so readily dissolve in water?
- like molecules dissolve like molecules
| - dispersal and dissolve
29
Fats
- don't dissolve in water
- nonpolar
- hydrophobic
30
What kind of molecules can easily move through the membrane?
- hydrophobic, nonpolar
- small
- lipid soluble
- has to be dissolved by membrane to get in
31
Major atoms
- 99% of you is made of these
- carbon, oxygen, hydrogen, nitrogen
- carbon and hydrogen bond with single or double covalent bonds
- super stable so lots of you is chemically stable
32
Functional Groups
-reactive, make chemical changes to do stuff in the body
33
Reactive Oxygen Species and Antioxidants
-excessive amounts of ROS cause damage to biomolecules and have been linked to diseases
-antioxidants combine with free radical electrons to make more stable species
0reacting with antioxidant and not critical body pieces like DNA
34
Carbohydrates
- class of molecules made from carbon and water
- general formula CnH2nOn
- monosaccharaides are glucose, fructose, and galactose and can be combined in chains to make polysaccharides
35
What is the use of storing polysaccharides in the liver and skeletal muscle?
- skeletal muscles=quick energy for muscle movement
| - liver glycogen-pump around body as needed, convert polysaccharides into glucose to make blood glucose
36
Glycemic Index
- per serving of food, not fixed unit of carbohydrates
- crude measure of how much glucose will rise
- rise in blood sugar produced by a type of food is related to this
- defined as increase in blood sugar that results from eating a defined quantity of carbohydrates from food
37
Factors that influence glycemic index of foods
- complexity of carbs
| - how readily the body breaks it down in the GI tract, amount of fats/proteins->slow down absorption
38
Glycemic Load Effect
- glycemic load is classification of different carbs that measures their impact on body and body sugar
- measurement of the amount a serving of a specific food will alter your blood sugar
39
Lipids
- 4 main classes
- triglycerides
- phospholipids
- eicosanoids
- steroids
- insoluble in water
- triglycerides are higher in energy density than glycogen
- additional type is ketone bodies
40
Why is it efficient to make triglyceride the primary stored form of energy for the body?
- energy dense molecules in almost no water
| - skeletal muscle glycogen is heavy and not efficient in calories, increased calories will also increase weight
41
Phospholipids
- hydrophilic polar head
- hydrophobic nonpolar tails
- glycerol backbone
- this allows them to survive in water by having the hydrophilic part
- micelle is in GI tract; arranged with heads toward the outside and tails toward center in a circle
42
Anabolic Steroids
- produce more muscle strength in body
| - makes muscle grow rapidly
43
Proteins
- made up of amino acids
- all have nitrogen-builds individual proteins
- proteins are specialized
44
Protein Structure
- primary sequence of amino acids tacked together
- secondary: individual amino acids twisted into helix (alpha helix)
- tertiary: beta pleated sheet; alpha helix wrapped around to tertiary, won't work unless this structure is right
- quaternary: very complex and specific twisted structure important to hemoglobin
45
Prosthetic Group
-has something in it that's not a protein
46
Why is there a daily protein requirement but not similar ones for carbs or fats?
- proteins contain amino acids and our body can't make them on their own
- bod already has stores of fats and carbs
- if you're only eating fats and carbs you're not getting nitrogen
47
Lipoproteins
- combo of lipid and protein
| - key for transport of cholesterol in blood
48
Protein Function
- structural/contractile: stringy long proteins in muscle (actin and myosin)
- catalytic: enable reactions to run faster than they would on their own (enzymes)
- immunological: cells designed to remember viruses so they can create antibodies (proteins) to destroy cells infected with virus
- transporters and carriers: most important in cell membrane; carries things in that couldn't get in otherwise
- regulatory: manage speed of important processes (DNA replication)
49
Nucleotides and Nucleic Acids
- proteins determine so much
- each of us has 30,000 different proteins
- each protein is coded for by a gene
- two things that matter: which genes came from biological parents and of those genes which do you have that are chosen to make significant amounts of proteins
50
What cellular events had to happen to increase muscle mass?
- using up and making more protein
- muscle damage
- cells hypertrophy (enlarge) or hyperplasia (cells divide)
- make more actin and myosin (specific proteins
51
Explain how genes and gene expression changed when increasing loads were placed on muscles.
- for hyperplasia regulatory genes must be expressed to make proteins divide
- express more gens for actin and myosin; don't change structure just make lots more
52
Nucleic Acid Structure
-make up instruction booklet that is DNA
53
Plasma Membrane
- barrier
- phospholipid bilayer
- keeps extracellular and intracellular different because they have different compositions
- membrane proteins function as channels
54
Why do water-soluble substance require a channel to get though plasma membrane while lipid soluble substances
- polar molecules can't get through-channel made out of proteins
- aquaporins-small enough to allow one water molecule at a time-always passive
- common ions that require membrane channels: Na+, Ca2+, K+, Cl-, water, glucose
55
What are some ways a drug can block activation of pain receptor (happens when membrane channel for sodium ions opens) and act as a local anesthetic?
- give a drug that occludes Na+ channels or doesn't allow them to open
- morphine allows pain receptors to activate but that pain is interpreted as not that bad
56
Cytoskeleton and microtubules
- give structure
- some cells this moves the cell
- also aid in division
57
Lysosomes and Perixosomes
- l: recycles old and worn out parts, breaks down to remove
| - peroxisome: has enzymes that deal with reactive oxygen species-->makes less toxic
58
Mitochondria and ribosomes
- energy from oxidative metabolism
| - R: makes new proteins
59
Rough ER and Smooth ER
- rough makes protein hormones
| - smooth makes steroid hormones
60
Golgi Apparatus
- details final protein product
| - shapes, sized, clipped, and sorted just right
61
Protein Synthesis
- happens in cell nucleus and DNA
- never leaves the nucleus, it's copied and that's whats taken out
- have double strand of DNA with the gene of interest on it, then you sense the strand of DNA and transcribe the triplets that make the gene of interest, mRNA is the complementary pair of this section that leaves the nucleus-transcribed as complementary copy that can be interpreted by cells
- ex: insulin-all cells have this gene but only beta cells of the pancreas can activate
62
Transcription
-photocopy of DNA instructions onto mRNA
63
Translation
- building protein amino acid by amino acid from the mRNA instructions
- uses tRNA
- has anticodon that matches up to what's on mRNA
- ex: increase in actin gene expression leads to increase in actin mRNA which increases ribosomes that increase efficient binding to mRNA to ribosomes
64
Factors that increase or decrease rate of transcription of genes for the major contractile proteins actin and myosin in skeltal muscle
- increase: working out
- decrease: injury/illness-body preoccupied with something different or disuse of muscle
- sensed by cell via energy use, stress/force, inflammation, damage to muscle (microtears) stimulates actin and myosin gene expression-energy goes where needed, replenishes, grows, and strengthens
65
Prolonged weightlessness causes rapid reduction in mass and strength of bone. Why does this happen in terms of regulation of gene transcription?
- no stress or signal (gravity) to the cells that they need to grow so no transcription is activated
- no bearing of weight by bones says that force stimulates protein/matrix production
66
How is mRNA different from simple photocopy of specific portion (gene) on DNA
- complementary to photocopy of DNA
| - bases are slightly different
67
How does tRNA differ from mRNA in terms of base sequences and codons?
- tRNA has a set of anticodons that match up to mRNA's set of codons
- tRNA has the same base sequence as DNA
68
Metabolism and Metabolic Pathways
- the chemical processes that occur within a living organism in order to maintain life
- A+X-->B-->C-->D+Y
- examples: hydrolysis, phosphorylation and dephosphorylation, oxidation-reduction
69
Catabolic Reaction
- breaking things down and releasing available energy
- A-->B+energy
- taking complicated molecule and change them and release energy
70
Anabolic Reaction
- building things up and using available energy
| - C+energy--->D
71
Law of Mass Action
- if you've got a whole lot of product it slows stuff down
| - if you have a whole lot of substrate it speeds stuff up
72
During aerobic exercise the reactions involved in energy metabolism in the working skeletal muscles would be classified as what kind of reactions?
- catabolic
| - increased hunger due to increased need for substrate/energy
73
Activation Energy
- biological reactions won't proceed fast enough on the basis of just pure chemistry
- biological reactions need catalysts-chemical or molecule that increases the rate of reaction without being changed itself
- enzymes lower energy barrier
- enzymes can help you build and break down
- can lower forward activation energy or reverse activation energy
74
How enzymes work
- enzyme is free to bind with substrate molecule
- substrate binds to enzyme molecule and substrate may leave active site unchanged
- enzyme may be converted to product by enzyme-product is changed and can't fint with "coach" or enzyme any more
- once product leaves enzyme is free to bind again
- can be used over and over
75
Substrate Specificity
-only one kind of substrate will fit with enzyme
76
Substrate Affinity
- some substrates bind better even though they have same specificity
- high affinity produces a quicker reaction
77
Enzymes in blood
-medical significance is that the cells are damaged which means damage to whole body
78
Isozymes
- slightly different versions of same molecule
- ex: two different basketball coaches-do the same thing but a little differently
- ex: heart enzyme is different from skeletal enzyme but have same function (contraction)
79
Factors that affect reaction rates
- catalytic rate
- temperature and pH (warmer speeds things up, and have optimal acidities)
- substrate concentration-increase causes increase in rate of reaction but eventually levels off because no more available enzymes; enzymes become saturated and work at maximum possible rate
80
Why does reaction rate eventually plateaus at a very high substrate concentration that is the same for two enzymes performing the same reaction but with different affinities?
- working as hard as possible and enzyme is fully saturated
| - eventually all enzyme will be used up no matter what the affinity, one will just proceed faster
81
Cofactors and Coenzymes
-some enzymes require other enzymes or other factors for them to work
82
Through a series of reactions the liver produces cholesterol. How could the body regulate how much cholesterol is to be made?
- block or regulate enzymes in the reaction once you reach a certain amount of cholesterol
- A--E1-->B--E2-->C--E3-->D--E4-->cholesterol goes back and inhibits E3 by binding to it to make it less efficient
- called allosteric regulation
- feedback on rate limiting enzyme which is the slowest that sets the pace for the reaction
83
Covalent Regulation
- donor molecule provides part that modifies properties of enzyme
- most are reversible
- ex: phosphorylation and dephosphorylation
84
Feedback Inhibition
- happens on slowest enzyme
- gives more control of things
- one part of reaction goes back and inhibits slowest enzyme
85
Feed-forward Activation
- speeds things up
| - activation or stimulation of an enzyme by a precursor of the substrate of that enzyme
86
Body needs constant amount of cholesterol even as dietary intake varies. How could the body modify activity of rate-limiting enzyme HMG-CoA reductase to maintain a constant cholesterol level?
- feedback inhibition
- cholesterol gos back and inhibits HMG-CoA reductase
- or a drug could do this
- diet low in cholesterol then feed back stops and more is made
- ex: lipitor and zocor
87
Energy metabolism
- burning vs. cellular breakdown
| - breakdown into simple products/molecules and liberate energy then capture it to do stuff
88
Energy Capture
- ATP
| - release energy from food and capture it briefly on a specialized molecule (ATP)
89
Substrate Level Phosphorylation
- creatine phosphate+ADP-->creatine+ATP
- immediate quick-money/free money
- requires no special anything
- primarily found in muscles
90
Oxidative Phosphorylation
- ADP+Pi-->ATP
- much more effective way to make money; it's your actual job
- by coupling energy-releasing and energy-requiring reactions, energy in the glucose molecule can be captured in ATP and used elsewhere in the cell
- net overall reaction releases 38 ATP for every 1 glucose
- can also do this from triglycerides
91
If there is no carbohydrate available in the body, can the body continue to generate ATP? Think of one way to do so without O2 being available
- yes, substrate level phosphorylation
- no O2 only creatine phosphate and takes a few seconds at most
- if you have O2, oxidative phosphorylation is the better route
92
Stages of Glucose Oxidation: Glycolysis
- glucose breakdown into pyruvic aid
- little energy released-net of 2 ATP for each glucose
- no oxygen required to run this set of reactions: "anaerobic metabolism"
- Glucose in-->glycolysis-->2 pyruvate and during glycolysis 2 ATP captured
93
No O2 is consumed and no CO2 is produced during glycolysis, yet some ATP is generated. List some reasons why glycolysis might not be the best way to provide for all of our energy requirements.
- very few ATP produced
- buildup of lactic acid
- lack of O2 for cells
- only use glucose
94
Lactic Acid
- produced when glycolysis proceeds very rapidly
- comes from the 2 pyruvate
- blood pH is 7.4
- outside the range death can occur at 7.0 or 7.8
95
One driving force for glycolysis is a rising level of ADP inside of cells. ADP is a breakdown product of ATP. WHy is it reasonable to drive glycolysis with ADP?
- ADP activates enzyme
- allosterically available
- cycles-ADP-->ATP-->ADP
96
Glycogenesis and Glycolysis
- enzymes can go either direction because you can modulate them or mass action them
- muscle and liver stores carbs so this happens in those
- look at diagram on page 40
- happens in cytoplasm
- pyruvate enters mitochondria and is turned into Acetyl-CoA
97
What metabolic principles are being followed by practice of "carbohydrate loading" prior to long-term severe endurance exercise event?
- storing of carbs to make glycogen so you don't run out
| - major energy store
98
Krebs Cycle
- pyruvic acid: from cytosol to mitochondria
- when we were single cells we ate up an aerobic organism which is now the mitochondrion-whyc has own DNA
- set of reactions breaks off pieces to generate ATP
- look at image drawn and printed
- happens in mitochondria
99
Electron Transport Chain
- mitochondrial ATP production
- when you break apart take component parts in gradual steps* that each release some energy that you capture and make ATP until you get to the simple products like water and carbon dioxide.
- *Krebs cycle, oxidative phosphorylation, electron transport chain
- happens in mitochondria
100
Summary of Glucose Oxidation
-Glucose in-->Glycolysis (releases 2 ATP)-->2 pyruvate-->Krebs cycle (releases 2 ATP) and other things that go on to Oxidative Phosphorylation (releases 34 ATP)
101
In terms of molecular complexity and free energy why does it make sense that more energy is liberated by converting glucose to CO2 and H2o than by converting glucose to pyruvic or lactic acid?
- energy efficient
| - easier to break down CO2 and H2O than pyruvate or lactic acid
102
Why does someone get hot and sweaty when exercising?
- glucose broken down into carbon dioxide and water and 38 ATP but also releases heat
- rapidly go through cycle so lots of heat is released
103
In terms of cellular respiration why does cessation of breathing cause death in just a few minutes?
-cells need oxygen for oxidative phosphorylation without it rely on glycolysis which means you get acidotic very quickly
104
Cyanide blocks the ETC and thus oxidative phosphorylation. How is cyanide a lethal poison?
-can't make ATP-can't survive
105
Most every transported electron gets coupled to ATP production; but if there is a parallel uncoupling then ATP production will be less per unit O2 consumed. Why are uncoupling compounds a potential treatment for obesity?
- have to work harder to make energy to exercise
| - burn through fat stores
106
Metabolism of Lipids and Proteins
- lipids are the major energy source of the resting body
| - can end up oxidatively phosphorylating fats to release ATP
107
Gluconeogenesis
- with the right modulation of enzymes we can make glucose from proteins
- protein breakdown for energy (generates glucose)
108
Under what conditions is gluconeogenesis an important process?
- hyperglycemic conditions
- when you can't break down carbs-rare
- diabetes
- diet with no carbs/low carbs
- diet: storage of glycogen in the liver but this needs replenishing (can be used in blood-blood glucose) or muscle (in muscle only, no blood glucose)
109
Under what conditions is protein breakdown for energy an important process?
- when you lack enough carbohydrates in your diet
| - glycogen stores depleted-next muscles are eaten and then body fat.
110
How is it possible to gain weight as adipose tissue while eating a 100% carbohydrate diet? A 100% protein diet?
-proteins can be converted into glycogen and then into triglycerides as can carbohydrates directly.
111
The blood glucose remains in the normal range even while eating a 100% fat diet. How is this possible?
- take glycerol from the triglycerides to make glucose for the blood
- body does lots of interconversions
112
During starvation or semi-starvation the basal metabolic rate (number of kcal burned while at rest) falls. How does this enhance the ability to survive under such conditions?
- expending less energy on metabolism which conserves energy and allows less usage of glucose and conserving kcals of energy means longer survival
- daily kcal requirement=decreased BMR + activity
113
Diffusion
- slow process
- random molecular motion and go where less crowded.
- more concentration in a cell means solute will diffuse out and vice versa
114
Chemical Driving Force
-concentration difference of the inside of the cell vs. the outside
115
Rates of Diffusion are dependent on...
- magnitude of the driving force
- membrane surface area
- membrane permeability-lipid solubility, thickness
116
Explain why oxygen gas always diffuses into cells while carbon dioxide gas always diffuses out of cells.
- cells are always using up oxygen which means oxygen levels in the cell are lower inside and higher outside which means oxygen will constantly be diffusing into the cell
- cells make carbon dioxide as a byproduct of cellular activities so there will be higher levels inside the cell than outside so it diffuses out
117
Oxygen diffuses from the tiny air sacs deep in the lungs across a then membrane into the blood. Explain why alterations in each of the factors of diffusion can cause lung disease.
- magnitude of driving force: amount of oxygen in the atmosphere; lower at higher elevations
- membrane surface area: loss of membranes of alveoli; if they expand loss of surface area happens and they're less effective at gas transfer--emphysema
- membrane permeability: thicken membrane-smoking does this
118
Ion Channels
- specialized
- want to regulate these
- allow charged molecules through membrane
- salt ionizes into Na+ and Cl- outside the cell and are allowed in thorough ion channels
119
Osmosis
- water traveling on its concentration gradient
- high water concentration to low water concentration
- going from dilute concentrations/solutions to high solute concentrations/solutions
120
Osmotic pressure
- semipermeable membrane separates solution from solvent and only the solvent molecules can move through thus raising the fluid level on the side they flow toward
- osmotic pressure of a solution is the pressure difference needed to stop the flow of solvent across a semipermeable membrane
121
Moles, Molarity, and Osmoles
- NaCl is 1M
| - Na+ and Cl- is 2 osmoles per solution in your body
122
Tonicity
- stuff inside cell is non permeable
| - urea is permeable so when it enters urea is now equalized and water flows in cell
123
If cell contains 300 mOsm of non-permeating solute, how will it change insize when exposed to infinite solution containing
- 150 mOsm of these same non-permeating solutes
- 300 mOsm urea
- 150 mOsm non-permeating solutes+300 mOsm urea
- hypotonic-water goes in
- hypotonic
- urea moves first so also hypotonic
124
Why is rapid excessive consumption of water potentially fatal?
-too much water consumed means too much water taken up by cells which dilutes their contents and affects their functioning
125
Sweat Osmolarity ranges from 70 to 150 mOsmol/L. What fluid shifts between cells and ECF would be expected after prolonged sweating?
- you sweat from ECF
- lose water and electrolytes but you lose more water than salt because osmolarity of sweat is relatively low
- this means ECF increases in salt concentration and cells shrink because water is moving to the ECF
- this decreases blood plasma, which decreases blood volume, which decreases blood pressure with is bad
- need to reestablish proper levels of salt in ECF and water in cells and ECF
126
In uremic poisoning the kidney's inability to eliminate urea allows urea levels to climb to toxic levels. Why don't cells shrink or swell during uremic poisoning?
- concentrations are always equal
- equilibrates without water movement
- urea moves faster than water-so it always balances right away and water has no driving force making it have to move into or out of cell
127
Facilitated Diffusion
- only goes by concentration gradient, high to low
- has a specialized channel designed to bind with only one molecule and when molecule binds it triggers a conformational change and the molecule can be let into the cell
- no energy required
128
why does rate of facilitated diffusion plateau while rate of simple diffusion continues to increase linearly?
-facilitated proteins become saturated and can't move any faster while simple doesn't have to rely on carrier proteins
129
Electrical Driving Force
- tendency of positives and negatives to be attracted to each other
- positive outside attracted to negative inside or negative inside moving to positive outside
- high charge to low charge
130
Electrochemical Driving Force
- ex: outside: lots of NaCl and no K+ inside: no NaCl and lots of K+ so K+ wants to go out (chemical driving force) which results in a potential difference across the membrane; so K+ leaks out a little and is balanced out by electrical force which creates a tiny voltage which is called the equilibrium voltage
- takes very few K+ to reach equilibrium
- depends on potential difference and gradient of permeant ion across membrane
131
Na+ K+ ATPase
- ATPase is an enzyme that breaks apart ATP and liberates energy for use and it is a membrane protein
- Na+ is in intracellular fluid and goes into protein to be moved outside by combustion of ATP that releases energy then K+ enters
- constantly pumping
132
Secondary Active Transport-Co-transport and Countertransport
- depends on ATPase pump being active to make the secondary protein work because ATPase system is busy constantly pumping Na+ out to keep gradient inside low
- co-transport Na+ and glucose come in together through special secondary protein and is dependent on ATPase pump constantly pumping Na+ out
- countertransport: exchange one molecule for another one through the special secondary protein channel
133
Drug or hormone increases rate of activity of membrane Na+ K+ ATPase. What would be some consequences?
- increase in K+ inside and decrease outside
- increase in Na+ outside and decrease inside
- more effective secondary active co-transport
- requires more energy
134
Xylose, Fructose, and Glucose absorption in small intestine
- Xylose: passive-less easily absorbed, no help/energy; very little actually absorbed or any at all
- fructose: facilitated-faster than xylose but saturates channels and eventually can't go any faster
- glucose: secondary active co-transport-fastest, takes energy, higher glucose concentration inside cell
135
Mechanisms of Intercellure Communication
- direct communication through gap junctions-something changes on one side it must change on other
- chemical messengers
136
Possible advantages of direct electrical communication or chemical messengers
- direct: faster, more efficient, less room for error
| - messengers: more widespread, can go far away, can go to multiple cells, longer lasting effects
137
Paracrines, neurotransmitters, and hormones
- all signal changes in other cells
- act as chemical messengers
- wherever you want to put the receptor is where you get the effect
138
Take away about receptors
- different receptors have different responses even though the hormone/paracrine/neurotransmitters are the same
- multiple histamine effects on the body, there is no specific effect it's all reliant on responses
- ex: antihistamines in block histamines neurotransmitter actions in brain and makes you drowsy
- histamine released locally in skin or nasal mucosa makes you sneezy, sniffly, itchy, red, swollen, hives, inflammation, vasodilation etc.
- histamine as paracrine in stomach and activates acid cell secretion so histamine blockers decrease secretion of stomach acid which reduces acid reflux and acts as ulcer prevention
139
Amines
- chemical messenger class
| - includes dopamine, norepinephrine, and epinephrine
140
What are some effects of peripheral release (outside CNS) of adrenaline?
- dilated eyes, agitated, increase heart rate, loss of control over some bodily functions, increase in blood pressure
- fight or flight response
141
Norepinephrine has similar actions to epinephrine. What effects of norepinephrine in the brain would be appropriate for a situation that stimulates peripheral epinephrine release (fight or flight)?
-become hyper alert and super focused
142
How is one cell able to synthesize dopamine without making any norepinephrine, while another cell is able to make norepinephrine without producing any dopamine as a final product?
- can't reverse cycle to go back to dopamine but can't make norepinephrine without enzyme to hydroxylate dopamine
- norepinephrine is hydrosylated dopamine
143
Steroids, Peptides and Proteins
- can be chemical messengers
| - ex: growth hormone and insulin
144
Chemical Receptors
- detect chemical messengers
- can be adapted: up regulated in which they become more sensitive or more abundant or they can be down regulated in which they become less sensitive or less abundant
145
What are some ways the body could alter receptor structure or function to modify the cellular response to a messenger?
- block it
- change shape or affinity of receptor
- increase or decrease number of receptors
- change placement in cell-could be in cell and unaccessible then moved to outside so they can function
- change responsiveness/sensitivity to how its bound
146
Why does Benadryl stop treating insomnia after the first few days?
- receptors adapt
- become less sensitive to drug and don't perform at same rate so responsiveness to drug decreases and histamine receptor becomes more sensitive
- body says it wants to be normal and responds accordingly to drug so that having it in your system is the new normal
147
An inactive 57-year old man has gained a pound of weight every year for 35 years. His insulin is having less and less effect over time. What changes are occurring in his cell membrane insulin receptors and why?
- receptors have change in responsiveness (decrease) and decrease in number of receptors
- body is aiming for constancy and is being overloaded with glucose so it turns off response in insulin receptors so as to not uptake any more glucose
148
22 year old takes Xanax for two years. Drug binds and acts as agonist of GABA receptor. Why is she more anxious than ever before when she suddenly stops taking the drug?
- GABA receptors become less sensitive so when you remove the drug the sensors become hypersensitive which means you're less calm
- agonist means it binds to receptor and acts as a neurotransmitter would
149
Enzyme-linked receptors and channel linked receptors
- enzyme: when messengers bind it activates enzyme
| - channel: when messenger binds it opens the channel; also called ligand gated channel
150
Intracellular receptors
-have to have lipophilic messenger that diffuses through membrane to activate process used to make new proteins
151
Testosterone is lipophilic messenger that is converted to DHT once inside cell. DHT binds to intracellular androgen receptor. In hair follicles androgen receptor binding by DHt shortens hair growth cycle leading to male pattern baldness. What are some treatments for this?
- decrease/block DHT affinity on receptors
- decrease DHT binding to it's receptor-antagonist (blocks normal ligand)
- block/inhibit/destroy enzyme that converts testosterone into DHT
152
ER + (tumor growing in response to estrogen) vs. ER - in breast cancer.
- give estrogen blockers to ER+ patient
| - ER- patient has one less treatment option would could cause more problems
153
HGH and testosterone cause skeletal muscle to grow. Where are some organs where receptors for these two hormones might be found
- HGH: tends to make everything grow; proportional growth; but specifically brain and smooth and skeletal muscles
- Testosterone: mostly growth of skeletal muscle and secondary sexual characteristics; specifically brain, skeletal muscle, testes
154
Receptors for HGH and testosterone are different in structure. Why?
- testosterone is made from cholesterol and is big and bulky while HGH made from peptide chain and is small
- receptors are different because messengers that bind are different in shape
155
Are genes activated by receptor binding of HGH and testosterone similar? Why/why not?
-similar because they have same kind of genes that turn on-both stimulate muscle hypertrophy (growth)
156
Posterior Pituitary Gland
- synthesized by cells with cell body in hypothalamus so they're neurons but have axon that goes directly into the blood-like a neurotransmitter but it's a hormone
- makes ADH and oxytocin
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ADH
- controls water excretion from kidney in response to changing concentrations of water (plasma osmolarity) in blood
- to save water ADH is signaled to absorb more which results in concentrated urine
- too much water ADH is slowed down or stops and results in more dilute urine
158
Why is releasing ADH and oxytocin directly into the blood useful?
- less regulation means faster response which means more efficiency
- oxytocin: able to provide milk for baby as soon as possible; secondary effect is for bonding with child
- ADH: maintain plasma osmolarity quickly
159
Anterior Pituitary Gland
- same neurosecretory cells that send a hormone that then stimulates another hormone to be produced
- many made here like GH, LSH, FSH, TSH, ACTH and Prolactin
160
Why does it make sense to link brain directly with cortisol, prolactin and FSH and LH, growth hormones, and thyroid hormone?
- cortisol: can't have stress if you're not conscious so linking cortisol to brain means decreased strss during consciousness
- prolactin, LSH, FSH: brain has to know about milk production/pregnancy/puberty; brain maturation has to happen before puberty so it can decide when these should start production
- growth hormone: you grow as brain grows or after; never before
- thyroid hormone: part of development as well; essential for everything growing in child
161
Feedback control
- most hormones do this to keep things constant
- can have short loop negative feedback or long loop negative feedback-look at image
- ex: control and dysregulation of thyroid hormone-common issue; primary hypersecretion or secondary hypersecretion
- primary you're making excess TH and the regulation of thyroid stimulating secretion (TSH) is inadequate
- secondary you're making excess TH and regulation of TSH is inadequate and so is regulation of thyrotropin releasing hormone (TRH)
162
Primary vs. Secondary Hyperthyroidism
- primary affects the gland or organ that makes the hormone that is out of control so the thyroid gland is the issue
- secondary affects the gland or organ that stimulates the other gland or organ to produce the hormone that is out of control so the anterior pituitary gland is the issue
163
Bound vs. Free Hormones in Blood
-free hormones are not bound within the blood and can bind to a target cell to initiate a response
164
Cortisol
- major action is to respond to stress
- keeps you alive when starving and breaks down muscle and increases blood glucose
- negative feedback loop can be superseded because stress trumps its process as is the case for chronic stress
- pathway: stress-->hypothalamus increases release of CRH-->anterior pituitary increases release of ACTH-->adrenal cortex releases cortisol
- cortisol increases blood pressure, blood glucose, wakefulness, and vigilance
165
What changes would be seen in components of cortisol control system if synthetic cortisol-like drug is given for many months? Prednisone
- all the effects of cortisol become super strong and rampant which triggers negative feedback. CRH is decreased and so is ACTH.
- your ability to make cortisol yourself is significantly lowered so you have to be tapered off of it it so your adrenal glands can go back to normal
- this drug is used for a pharmacological effect-reduces inflammation like in organ transplants
- should only be used in the short term
166
PTSD patients often have lower than normal cortisol levels when not exposed to stressors. Why?
- system is so overloaded with the severe flashback stress that when this isn't happening it just doesn't respond.
- similar to receptor sensitivity with drugs
167
Synergistic vs. Antagonistic Hormones
- synergistic work together like epinephrine and norepinephrine
- antagonistic work against each other like hormones to increase or decreases blood calcium levels
168
Hormone concentrations and tissue responses
- half life: time it takes to go down 1/2 previous level of drug; every drug is different so these differences matter; longer half life=slower change
- physiological vs. pharmacological effects: above physiological range; molecule has new effects that you normally would never encounter
- down regulation and desensitization
169
Afferent vs. Efferent
- afferent: input/info from senses and organs
| - efferent: output/effects
170
Resting Membrane Potential
- how neurons transmit info
- in cell: high K+ and A- outside: High Na+ and Cl-
- K+ is leakiest and leaves the cell due to chemical force of concentration but electrical force is now saying it should go back in to establish electrical balance
- wavering of membrane like this establishes a resting membrane potential and because K+ is leakiest it is a negative membrane potential
- if Na+ were to go into cell because of chemical driving force electrical driving force would want it to go back out and the resting membrane potential would then be negative
- Na+ K+ ATPase pump is the reason for intracellular/extracellular segregation of Na+ and K+; always pumps regardless of potentials of cell; just keeps pumping
171
Action Potential
- stereotypical, predictable, unchangeable effect
- fluctuation of cell going from potential to negative back to positive
- in excitable cell membrane potential rises slightly to threshold and Na+ permeability rises sharply; happens because voltage gated Na+ channels open which makes Na+ most dominant which changes the potential to positive and increases it
- but then when potential rises more K+ channels open which lowers membrane potential back down into the negative which is even lower than before
- the constant up and down is the action potential and hthis is how neurons send messages
