Week 1

Question 1

what is the extracellular environment

Answer 1

includes all constituents of the body located outside of the cells. Cells receive nourishment from and release waste into the extracellular environment. Cells interact with each other via chemical regulators secreted into extracellular environment

Question 2

What are primary cilia

Answer 2

non-motile cilia are on every type of cell except blood cells. They have important functions in communication, signal transduction, and cell growth control. They can have huge effects on growth and development, kidney disease, obesity, wound healing, and cancer

Question 3

what are some ciliopathies

Answer 3

Diseases cause by dysfunction of cilia include polycystic kidney disease, congenital heart disease, mitral valve prolapse, retinal degeneration.

Question 4

Describe the water content of the body

Answer 4

67% of total body water is WITHIN cells. 33% is extracellular. About 20% of the extracellular fluid is in blood plasma and the remaining 80% is the interstitial fluid in tissues

Question 5

describe the interstitial fluid (where is it)

Answer 5

it is contained in the gel-like extracellular matrix. Molecules must pass through the interstitial fluid to get between blood and body cells

Question 6

What composes the extracellular matrix and what does each component do

Answer 6

collagen, elastin, and gel-like ground substance (contains glycoproteins and proteoglycans with high content of water bound molecules)

collagen and elastin provide structural strength to the connective tissues (Collagen IV contributes to the basement membrane)

glycoproteins and proteoglycans form bonds with carbohydrates on membrane of cells making a basement membrane which weds the epithelium to its connective tissues

Question 7

What are integrins

Answer 7

a class of glycoproteins that extend from the cytoskeleton in a cell through its plasma membrane and into the extracellular matrix. Serve to provide adhesion, polarity, signaling, and motility

“Integrate” the two compartments

Question 8

why is it called the plasma membrane?

Answer 8

because the extracellular fluid is either blood plasma or derived from it. The membrane separates extracellular from intracellular

Question 9

explain how the plasma membrane is selectively permeable

Answer 9

It only allows some molecules to penetrate the membrane because it has a large non polar region so only non polar molecules can pass. Generally proteins, nucleic acids, and other large polar molecules are not permeable. But certain ions or small non polar molecules are permeable

This is relevant to PHARMACOLOGY

Question 10

categories of transport through the plasma membrane

Answer 10

Carrier-mediated transport includes facilitated diffusion and active transport

Non-carrier-mediated transport includes simple diffusion, simple diffusion through channel proteins, and aquaporin channels

Can also categorize by PASSIVE and ACTIVE transport. Passive moves with concentration gradient and uses no energy. Active moves agains gradient and requires energy (PUMPS!)

Question 11

difference between carrier and channel proteins

Answer 11

carrier proteins are membrane proteins that change their configuration (3D structure) in some way to ferry a molecule or ion across the membrane

channel proteins are membrane proteins with structures that provide selective channels for the movement of specific ions or water molecules across the membrane

Question 12

what are the components of an aqueous solution

Answer 12

solvent: liquid doing the dissolving (usually water)
solute: molecule being dissolved (like salt, sugar, etc)

Question 13

What is Brownian Motion

Answer 13

the visible manifestation of random electromotion of a solution. The molecules of a solution are in a constant state of random motion as a result of their thermal energy

This is the driving force for diffusion!

Question 14

define diffusion

Answer 14

If there is a concentration difference or concentration gradient between two regions of a solution, random motion (Brownian motion) tends to eliminate the concentration difference as the molecule become more diffuses spread out

Question 15

define NET diffusion

Answer 15

as a result of random molecular motion, molecules in the part of the solution with a higher concentration will enter the area of lower concentration. There is motion in both directions, but more move in the high to low direction so there is a NET MOVEMENT from the region of higher concentration to lower until the difference no longer exists

Question 16

when does net diffusion occur?

Answer 16

whenever there is a concentration difference across a membrane AND that membrane is permeable to the diffusing substance

Question 17

what molecules can pass through the plasma membrane easily and why?

Answer 17

PM has a thick non polar core, so non polar molecules can easily pass through it. This includes oxygen gas and steroid hormones. Small, uncharged, polar molecules such as CO2 and H2O can also pass through.

Question 18

explain the distribution of O2 and CO2 concentrations inside and outside cells

Answer 18

Oxygen concentration is high in the extracellular fluid because oxygen is carried from lungs to tissues in blood. During cell respiration (metabolism, ETC) oxygen is constantly being depleted and made into water, so intracellular oxygen is low.

Carbon dioxide is higher inside the cell. Cells produce CO2 during cell respiration (metabolism, CAC) so intracellular CO2 is constantly being produced.

This contributes to Gas Exchange

Question 19

how does water diffuse through the membrane

Answer 19

water can diffuse through membrane to a limited degree because of the small size and lack of net charge. However, most membranes have greatly aided water passage through AQUAPORIN water channels.

Question 20

define osmosis

Answer 20

Net diffusion of water molecules (the solvent instead of solute) across membrane

Question 21

define ion channels

Answer 21

transmembrane proteins that provide passage for impermeable charged inorganic ions (Na+ and K+ for example). They are relatively selective. Some are always open and many are gated so they can open or close

Question 22

What determines the rate of diffusion (4 things)

Answer 22

1. The magnitude of the concentration difference across the membrane
2. the permeability of the membrane to the substance
3. the temperature of the solution
4. the surface area of the membrane

Can you explain why all of these things contribute to diffusion rate? Page 008

Question 23

what are microvilli

Answer 23

tiny fingerlike projections in the epithelial membranes in the small intestine which aid in increasing cell surface area and therefore increasing rapid diffusion of digestion products across membranes

Question 24

2 criteria for osmosis to occur

Answer 24

1. There must be a difference in the concentration of a solute on the two sides of a selectively permeable membrane
2. The membrane must be relatively impermeable to the solute

Question 25

define osmotically active

Answer 25

solutes that cannot freely pass through the membrane can promote the osmotic movement of water are osmotically active. Basically if they cause osmosis

Question 26

when are aquaporins present? what organ as special importance in aquaporin regulation

Answer 26

some cells always have aquaporins present while others have those channels inserted into the membrane in response to regulatory molecules. This regulation is especially important to the KIDNEYS which are the major organs regulating total body water balance IMPORTANT: aquaporins do not open and close, they are inserted and removed!

Question 27

explain osmotic pressure

Answer 27

The pressure needed to stop osmosis. E.g. in plant cells, the cell walls provide a rigid box that will prevent further expansion. Animal cells don't have this and will LYSE (burst) if placed in pure water the greater the solute concentration of a solution, the greater its osmotic pressure. Measures the force required to stop osmosis, so measures how strongly a solution draws water by osmosis

Question 28

explain molarity and molality

Answer 28

molarity is a measure of mol/liter so when making a solution you add the weight of 1 mol to a total volume of 1 liter. This means you DO NOT KNOW the exact ratio of solute to water because you don't know how much water exactly is added molality is a measure of mol/kg water so you would add the weight of 1 mol to 1 kg of water. Now you know the EXACT ratio of solute to solvent because you know how much water is added!

Question 29

what is osmolality

Answer 29

the TOTAL MOLALITY of a solution. Depends on ratio of solute to solvent, NOT chemical nature of solute molecules. Add the molality of everything in the solution together for osmolality. NOTE: for electrolytes like NaCl, they will ionize in water and dissociate. So if a solution is 1 molal NaCl it ends up being 2 osmolal because the Na and Cl ionize

Question 30

how to measure osmolality

Answer 30

freezing point depression occurs because the freezing point of a solution is affected by total concentration. So by seeing how much freezing point is changed from 0 C, we know the osmolality! Through this we know that plasma is 0.3 Osm or 300 milliosmolal (mOsm)

Question 31

describe 2 common isosmotic solutions

Answer 31

5% dextrose or D5W: 0.3 m glucose solution is 0.3 Osm. made by 5 g of glucose per 100 ml. physiologic saline or normal saline: 0.15 m NaCl solution is 0.3 Osm. made by 0.85 g of NaCl per 100 ml. (NOTE: 0.9 g NaCl is commonly used but 0.85 is the exact number!)

Question 32

describe tonicity

Answer 32

Tonicity is the effect of a solution on the osmotic movement of water. Isotonic: no net movement of water occurs, both solutions have the same osmolality Hypotonic: water moves into cells because solution has a lower total concentration of solutes than plasma. Cells may burst (hemolysis or cytolysis) Hypertonic: water moves out of cells because solution has higher total concentration of solutes than plasma. Cells shrink (crenation)

Question 33

describe some of the mechanisms that prevent extracellular fluid osmolality from changing more than 1 - 3% in response to Dehydration

Answer 33

Dehydration increases plasma osmolality and the increases osmotic pressure stimulates osmoreceptors (neurons located by hypothalamus) to shrink and increase nerve impulses, causing thirst and water drinking! Dehydrated person will also excrete less urine because the osmoreceptors trigger hypothalamus which also triggers posterior pituitary to release antidiuretic hormone (ADH) or vasopressin into blood. antidiuretic hormone acts on kidneys to promote high water retention and less urine excretion.

Question 34

describe the osmotic effect of eating salts and not eating salts and the pathways that are triggered

Answer 34

Eat salty food: increases plasma osmolality but is not dehydrated (not low blood volume), so antidiuretic hormone is released and person drinks more, urinates less to restore correct osmolality. Result is blood volume high and blood pressure high. Salt deprivation: lowered plasma osmolality so less osmoreceptor and antidiuretic hormone stimulation. More water excreted in urine to restore proper plasma concentration but at a lower blood volume and low blood pressure, can be fatal!

Question 35

common characteristics of carrier proteins (and enzymes)

Answer 35

1. Specificity: only interact with specific molecules 2. Competition: if two molecules are transported by same carrier, rate of transport is lower when they are present together 3. Saturation: as concentration of a transported molecule increases, so does rate of transport, but only up to a TRANSPORT MAXIMUM (Tm)

Question 36

How is glucose transported from blood across plasma membrane

Answer 36

by facilitated diffusion which is passive and powered by the thermal energy of the diffusing molecule (Brownian motion) down a concentration gradient. Uses a carrier. 1. glucose binds to a specific site in its carrier protein 2. this binding causes a conformation (shape ) change in this carrier that brings the glucose to the cytoplasmic side of the membrane 3. Glucose is released into the cell (to the side of lower concentration)

Question 37

Types of glucose carriers

Answer 37

GLUT1: central nervous system and is increased under certain conditions GLUT2: pancreatic beta cells and hepatocytes of liver GLUT3: major glucose transporter in neurons GLUT4: adipose tissue and skeletal muscles. Insertion of GLUT4 carriers into plasma membrane of adipocytes and skeletal muscle fibers is regulated by exercise and insulin (important for health/diabetes) (these two maybe less important to memorize) GLUT5: small intestine sugar absorption SGLUT1: small intestine/kidneys

Question 38

when is glucose transported against its gradient

Answer 38

in the epithelial cells of the kidney tubules and small intestine glucose is transported against gradient by a secondary active transporter that moves Na+ with its gradient

Question 39

how are fatty acids transported

Answer 39

through carriers similar to GLUT carriers. The uptake of fatty acids likewise increases with exercise and insulin (like GLUT4)

Question 40

define active transport

Answer 40

movement of molecules and ions agains their concentration gradients from lower to higher concentrations. requires energy obtained from ATP (Primary) or coupling with favorable second molecule gradient (Secondary) PUMPS or ATPase enzymes refer to primary active transport carriers

Question 41

describe the Ca2+ pump

Answer 41

a Primary Active transporter (pump, ATPase enzyme) located on plasma membrane of all cells and in membrane of ER of striated muscle cells. Removes Ca2+ from cytoplasm by pumping into extracellular fluid or ER. creates high concentration outside cell ( and in ER). so when ion channels open, calcium rapidly diffuses into cytoplasm. Rise of calcium signals diverse processes, like neurotransmitters and muscle contraction.

Question 42

describe the sodium potassium pump

Answer 42

A primary active transporter (pump, ATPase enzyme) in all body cells. 3 Na+ ions in cytoplasm move partway into pump and bind, activates ATPase to hydrolyze ATP and block both exits. ADP released, producing shape change that opens passage for the Na+ ions to enter extracellular fluid. 2 K+ ions in extracellular fluid bind and Pi is released, allowing pump to return to initial state and release K+ inside cytoplasm. Summary: pump transports 3 Na+ out of cell for every 2 K+ transported inside cytoplasm (both against gradient)

Question 43

why do cells spend so much energy maintaining the steep Na+ and K+ gradient? 3 reasons

Answer 43

1. Na+ gradient used to provide energy for coupled transport of other molecules 2. both gradients are used to produce electrochemical impulses needed for nerve and heart muscles 3. extrusion of Na+ is osmotically important. if intracellular Na+ is too high, water flows inside cell and damages it

Question 44

explain hypokalemic periodic paralysis

Answer 44

a mutation in the calcium channels screws up calcium ion flow. This causes there to be low extracellular potassium ion concentration (hypokalemia) and so the muscle cells repolarize more quickly, so calcium conductance can't be sustained if it even occurs. The threshold for muscle contraction is hard to reach and maintain. Increasing extracellular potassium concentration would help

Question 45

describe secondary active transport or coupled transport

Answer 45

the energy needed for the uphill movement of a molecule or ion is obtained from the downhill transport of Na+ into the cell. ATP is only INDIRECTLY required (to maintain the Na+ gradient) cotransport or symport: molecules move in same direction into cell counter transport or anti port: molecules move in opposite direction (Na+ into and other out of)

Question 46

describe cotransport of Na+ and glucose into intestine or kidney cells

Answer 46

Sodium Coupled Glucose Transporters (SGLTs) downhill movement of Na+ into the cell furnishes energy for uphill movement of glucose into cell. carrier has conformation change that transports molecules SGLT1 is in small intestine and moves 2 Na+ for every 1 glucose SGLT2 is in kidney and moves 1 Na+ for every 1 glucose

Question 47

describe the sodium calcium exchanger / Na+ - Ca2+ exchanger / NCX

Answer 47

a counter transport of uphill movement of Ca+ out of cell with downhill movement of Na+ into cell. no direct use of ATP, but needs ATP to maintain Na+ gradient. NOTE: this exchanger can work in REVERSE depending on the concentration gradients

Question 48

how does Digitalis or Digoxin (from foxglove) work?

Answer 48

the drug induces stronger contractions of the heart. It binds to and inactivates Na+/K+ ATPase pumps in the heart cells. Na+ accumulates inside the cell. This increases the REVERSE direction activity of the Na+ Ca2+ exchanger so Na+ pumps out and Ca2+ pumps in. As intracellular Ca2+ increases, a stronger contraction is possible in the heart cells! improves blood flow and reduces congestion in heart/lungs

Question 49

how does cyanide affect active transport

Answer 49

Cyanide interferes with the electron transport chain and halts ATP production. After primary pumps stop working (they have no ATP to hydrolyze) the concentration gradient for Na+ decreases. Transport of glucose from the intestinal lumen into the epithelial cells (as well as other secondary transports) declines.

Question 50

define exocytosis and endocytosis

Answer 50

exocytosis: fusion of a membrane bound vesicle that contains large cellular products with the plasma membrane so the products are released into the extracellular space endocytosis: same thing but in reverse. vesicles from extracellular space fuse with plasma membrane and bring vesicle into cell. (cholesterol example) together, these provide BULK TRANSPORT

Question 50

define exocytosis and endocytosis

Answer 50

exocytosis: fusion of a membrane bound vesicle that contains large cellular products with the plasma membrane so the products are released into the extracellular space endocytosis: same thing but in reverse. vesicles from extracellular space fuse with plasma membrane and release materials into cell. (cholesterol example)

Question 51

3 factors that contribute to the unequal Na+ K+ gradient

Answer 51

1. the Na+ / K+ pump moves 3 sodium out and 2 potassium in 2. fixed anions inside cell attract positively charged cations from extracellular fluid 3. the plasma membrane is more permeable to K+ than any other cation so accumulates inside the cell (towards anions) the most

Question 52

what are the potassium concentrations? Net result on cell charge?

Answer 52

Potassium intracellular 150 mEq/L and extracellular 5 mEq/L | Inside of cell is negative and outside is positive, called the potential difference or membrane potential

Question 53

the extent to which an ion contributes to the potential difference across the membrane (membrane potential) depends on:

Answer 53

1. its concentration gradient 2. its membrane permeability K+ is the most permeable so membrane potential is primarily determined by K+

Question 54

what is the resting membrane potential (-70 mV) determined by

Answer 54

many ions contribute to the resting membrane potential including K+, Na+, Ca+, and Cl- and the extent to which they contribute is determined by their concentration differences and membrane permeabilities. Changing either of those two factors will change the resting membrane potential. K+ is the most permeable ion and so changes in its concentration have the greatest effect on membrane potential

Question 55

what would be the effect of inhibiting Na+ channels? specifically in relation to membrane potential and impulses

Answer 55

inhibiting Na+ channels would prevent action potentials (when increased permeability to Na+ drives membrane potential to a positive value) and so would stop neurons from firing and no pain would be felt.

Question 56

describe the role of the Na+ / K+ pump on membrane resting potential

Answer 56

sodium and potassium concentrations are not a equilibrium, but they are kept constant due to the constant expenditure of energy in active transport by the pump. The pump counters leaks and maintains membrane potential. it also has a net effect of increasing the negative charge inside the cell (3 out, only 2 in) which adds 3 mV to the membrane potential

Question 57

how can cell signals travel directly from one cell to another and example of cells that use this signaling system

Answer 57

through gap junctions which are tiny links between the cytoplasms of two cells made by proteins called connexins. allows signals to travel by diffusion Present in smooth muscle and cardiac muscle (allows for all cells in the heart to contract together)

Question 58

three categories of cell signaling

Answer 58

paracrine: local signal to same organ. cells secrete regulatory molecules that diffuse to nearby targets with receptors autocrine: regulatory molecules act on the same cells that released them synaptic: refers to neurons. axon innervates its target organ through a functional connection (synapse) between axon ending and target cell endocrine: cells of endocrine glands secrete chemical regulators called hormones into extracellular fluid. effects the whole body, but only cells with receptors for signal.

Question 59

explain oral rehydration therapy

Answer 59

drink a solution with equal amounts Na+ and glucose to promote the cotransport of sodium and glucose into intestine. Helps with rehydrating cholera patients who have excessive loss of sodium and water

Question 60

explain how diabetes messes with osmolality and the effects of that

Answer 60

high blood sugar (HYPERGLYCEMIA) caused by diabetes means high plasma osmolality and osmotic pressure, this causes osmoreceptors to signal hypothalamus and thirst. there is also more glucose in the urine (GLYCOSURIA) caused by the high blood sugar exceeding glucose carriers maximum so glucose remains in the urine. This increases osmosis of water into urine and loss of water.

Question 61

what are matrix metalloproteinases and what diseases are they related to

Answer 61

Matrix metalloproteinases break down extracellular matrix proteins. If they are over active they can allow for tumor cells to easily metastasize and migrate through the body. TIMPs (tissue inhibitors of metalloproteinases) inhibit MMPs to prevent this

Question 62

explain dialysis treatments

Answer 62

If kidneys fail to filter out waste molecules of blood we can manually remove them by a dialysis bag which has a semipermeable membrane and a dialysate solution that will draw the molecules out of the person into the bag. Can be done outside the body with bags or inside the person (PERITONEAL dialysis)

Question 63

what causes cystic fibrosis

Answer 63

A defective Cystic Fibrosis Transmembrane Conductance Regulator (CFTCR) causes abnormal NaCl and water movement across epithelial membranes

Question 64

what causes Edema

Answer 64

low blood plasma proteins that cause there to be too much water accumulating in interstitial fluid (tissues). Normally blood plasma proteins are osmotically active and draw water out into blood stream. Liver disease interferes with producing Albumin, the primary blood plasma protein, and causes edema treatment can therefore be to provide blood plasma proteins such as in a Mannitol intravenous solution.

Question 65

what is the effect of a diuretic drug

Answer 65

cause increased urination and so increase plasma osmolality (?)

Question 66

effect of hypoglycemia

Answer 66

hypoglycemia is very low blood sugar. Causes decreased glucose in tissues and so no energy, leads to unconsciousness and death

Question 67

what is sexual reproduction

Answer 67

when genes from two individuals are combined in random and novel ways with each new generation. This offers the further advantage of introducing great variability into a population

Question 68

review reproduction terminology: germ cells, gametes, gonads, meiosis, fertilization, zygote, mitosis

Answer 68

germs cells or gametes include the sperm and ova gonads include testes and ovaries, where gametes are formed meiosis is reduction division and is the process by which the gonads form gametes fertilization is the fusion of sperm and ovum cells zygote is the fertilized egg with the full 46 chromosomes mitosis is duplication division and contributes to growth of the zygote into an adult

Question 69

describe chromosome numbers throughout the process of reproduction

Answer 69

The germ cells (gametes) have half the normal number of chromosomes (23) and are haploid. They then fuse during sexual reproduction and have the normal 46 chromosomes, 23 from mom and 23 from dad in homologous pairs. This is called diploid. All cells besides the gametes are diploid

Question 70

autosomal vs sex chromosomes

Answer 70

The first 22 pairs of chromosomes are autosomal. They are homologous pairs with similar gene content. They can recombine The final pair are the sex chromosomes X and Y. They are not homologous and don't contain similar genes. Males have XY and females have XX. In the testes, X and Y can't recombine except for at the tips of the X.

Question 71

explain X linked genes

Answer 71

Because X and Y don't really recombine, there are a large number of genes which are restricted to the solitary X chromosome in males. These are X linked genes. Many of them can be responsible for diseases which are more common in males than in females because the genes responsible (recessive genes) don't have an additional copy to overwrite

Question 72

describe testes specific genes and their origin

Answer 72

Genes on the Y chromosome from X-transposed sequences. Most are found to be located in huge palindromes, which enable the Y chromosome to have gene conversions where defects in one region of the palindrome can be corrected by a corresponding region (substitutes crossing over)

Question 73

what determines the sex of a zygote

Answer 73

The fertilizing SPERM. The chromosomes are randomly divided during meiosis and the creation of the gametes, but in a female only X chromosomes are available to end up in the ova (egg). In males, either the X or Y chromosome can end up in the sperm. So sperm determines the sex of the zygote

Question 74

explain the importance of X chromosome inactivation

Answer 74

Each diploid cell in a woman's body has two X chromosomes, but only one is fully active. The result is expression of only one allele of X chromosome genes. Which X chromosome is inactivated is completely random, so a woman's cells are a mosaic

Question 75

what are Barr Bodies

Answer 75

The inactive X chromosome in a woman's cells forms a clump of heterochromatin which can be seen as a dark spot (Barr body). This is seen in cheek cells. It's also seen as a drumstick appendage in the nucleus of some neutrophils Provides a microscopic test for chromosomal sex of a person!

Question 76

describe formation of testes and ovaries

Answer 76

Gonads of males and females look the same for the first 40 days or so of development. This is a "primordial germ cell" with potential to become either testes or ovaries. The hypothetical substance that promotes conversion to testis is called Testis Determining Factor (TDF) encoded by the Sex-Determining Region Y (SRY) gene on the short arm of the Y chromosome. Otherwise, female is the default formation during development.

Question 77

Are males always XY? And females XX?

Answer 77

Some rare cases of XX males occur when one of the X chromosomes contains a segment of the Y chromosome Similarly, XY females occur when they are missing the same portion of the Y chromosome. This portion of the Y chromosome is the Sex Determining Region Y (SRY) gene.