2025 Physiology Exam 1 Flashcards

Question

Ion Channels

Answer 1

Permeability of axon membrane to ions is determined by the: number of open channels. Ion channels are usually selectively permeable permeable to specific ions: some pass only Na ions and are generally called “Na channels” some pass only K ions = “K channels” some pass only Ca ions = “Ca channels” (important in synaptic transmission) some pass only Cl ions = “Cl channels” permeable to classes of ion: Some channels are selective only for cations (Na, K and Ca) over anions (e.g., Cl-) These are called ‘non-selective cation channels’ Ion channel gating (using voltage-gated as example) Most voltage-gated channels open in response to depolarization. The terms “gate” and “gating” refer to transitions between different states. These “different states” reflect different conformational states of the channel protein Has minimum of two gating transitions. activation = opening of channel when membrane is depolarized deactivation = closure of channel when membrane repolarizes

Answer 2

Myelination Schwann cells surround the nerve axon forming a myelin sheath. Sphingomyelin decreases membrane capacitance and ion flow 5000-fold. Sheath is interrupted every 1–3 mm by a node of Ranvier.

Answer 3

MS is an immune-mediated inflammatory DEMYLINATING disease of the CNS

Answer 4

Point of communication between neurones Most synapses involve transmitter substances. Synapses can be: - Excitatory - Inhibitory Neurons communicate with specialized structures - synapses. An action potential in the presynaptic cell causes transmitter to be released. In fast synapses, transmitter substances bind to receptors on postsynaptic cell to directly open ion channels (ligand-gated) The permeability of this region of the “postsynaptic” membrane to ions is increased. The selectivity of the channels for particular ions determines whether the membrane is hyperpolarized or depolarized. The membrane potential will move towards the equilibrium potential for the permeant ion(s) Excitatory transmitters depolarize the membrane. Synaptic responses that reach threshold initiate an action potential. Subthreshold responses can summate with others.

Answer 5

Subthreshold potential change (electrotonic) proportional to stimulus strength (graded) not propagated but decremental with distance exhibits summation Action potential independent of stimulus strength (all or none) propagated unchanged in magnitude summation not possible

Answer 6

Examples—nAChR, Glutamate Permeable to cations (Na+, K+, and Ca2+) Equilibrium potential ~ 0 mV Depolarizes postsynaptic cell Enhances excitability

Answer 7

Examples—GABA, Glycine Permeable to anions (Cl-) Equilibrium potential ~ -90 mV Hyperpolarizes post-synaptic cell Depresses excitability

Answer 8

Partial pressure Depends on percentage of gas Driving force for diffusion Saturation % Hb that has oxygen bound (note: no units) Content Absolute quantity (mL O2/100 mL blood)

Answer 9

Decreased ability for the body to carry O2 in the body

Answer 10

External Respiration happening in the lungs ***Internal Respiration is within the tissue

Answer 11

Greatest amount of O2 PICKED UP in Pulmonary Capillaries Greatest amount of O2 LOST in the Systemic Capillaries Moves via Diffusion

Answer 12

O2 wants to join onto the Hb (hemoglobin) as it moves through Pulmonary Capillaries

Answer 13

Even with no Hb the O2 will still diffuse across

Answer 14

Exercising increases O2 consumption... body needs O2 diffusion increases Tissue PO2 is determined by balance of delivery and usage

Answer 15

Cellular CO2 is higher than Capillary... diffuse in to be removed

Answer 16

Partial pressure (mm Hg) driving force for diffusion Percent saturation (no units) HbO2/(Hb+HbO2) (DONT NEED TO KNOW FORMULA) Content (mL O2/100 mL blood) absolute quantity of oxygen in blood

Answer 17

Dissolved Oxygen Solubility 0.003 mL O2/100 mL blood mm Hg Normal blood 0.3 mL O2/100 mL blood Normal oxygen consumption 250 mL O2/min Would require 831/min blood flow *** Very low amount Hemoglobin 97% transported by Hb O2 + HB ~= HBO2 1.34 mL O2/g Hb Normal 15 g Hb/100 mL blood 20 mL O2/100 mL blood Anemic 10 g Hb/100 mL blood 13 mL O2/100 mL blood

Answer 18

Alveoli Over wide range hemoglobin will be highly saturated example: PO2 of 60 saturation is 89%. Tissue Normal: 5 mL O2/100 mL blood (20 mm Hg) Exercise: 15 O2/100 mL blood (40 mm Hg)

Answer 19

Increased cardiac output Decreased transit time Increased diffusing capacity Opening up of additional capillaries Better ventilation/perfusion match Equilibration even with shorter time (previous graph)

Answer 20

Right shift at tissue increased carbon dioxide in blood (associate with increased H+) decreased affinity for oxygen... enter into tissue maintain partial pressure gradient Left shift at lungs loss of carbon dioxide at lungs increased affinity of oxygen

Answer 21

Regional V/Q ratios vary throughout lung. Pathologic conditions include asthma, emphysema, and atelectasis. Low V/Q regions contribute to hypoxemia (KNOW THIS) Hypoxemia responsive to increasing FIO2 Regions with V/Q > 1.0 do not contribute to hypoxemia

Answer 22

Dissolved solubility 20× oxygen venous blood: 2.7 mL/100 mL blood arterial blood: 2.4 mL/100 mL blood transported : 0.3 mL/100 mL blood 7% total in the plasma (KNOW THIS) Most CO2 Enters RBC Joins with H2O... goes into process shown in picture HCO3- can serve as a Ph buffer... leaves RBC into plasma Cl- enters RBC to maintain neutrality (Cl shift) H+ joins with Hgb to form HHgb (deoxygenated or met hemoglobin) 3 Ways CO2 Transported Directly in Plasma = 7% Directly to Hgb = 23% Process to HHgb = 70%

Answer 23

Hgb has a greater affinity for O2 than H+. So when O2 comes in it kicks the H+ off and joins to O2 The process goes in reverse than at the tissue

Answer 24

Sensors gather information Central controller integrate signals Effectors muscles

Answer 25

Peripheral Chemoreceptors = Arterial Chemoreceptors (monitor O2 and CO2) Central chemoreceptors = Medulla Oblongata

Answer 26

Know the Fourth Ventricle Pneumotaxic center: limit inspiration increase respiratory rate modulate respiratory system The apneustic center is a group of nerve cells in the brain that controls the depth and intensity of breathing Vagus and Glossopharyngeal bringing information from the chemoreceptors to the brain Respiratory motor pathways control breathing muscles Dorsal respiratory group Inspiration Intrinsic nerve activity Ventral respiratory group Inactive during quiet respiration Active respiration Projections from the dorsal respiratory group

Answer 27

Stretch receptors Located in smooth muscle of large and small airways Minimize work of breathing by inhibiting large tidal volumes Hering–Breuer reflex Irritant receptors (KNOW THESE) Nasal mucosa, upper airways, possibly alveoli Bronchoconstriction Cough, sneeze J receptors Located in the capillary wall, interstitium Lung disease and edema (pulmonary congestion) Rapid shallow breathing (tachypnea)

Answer 28

Arterial chemoreceptors Hyperpnea, increased blood pressure Arterial baroreceptors Stimulation by elevated blood pressure results in brief apnea and bronchodilation. Muscles and tendons Muscles of respiration as well as skeletal muscles, joints, and tendons. Adjust ventilation to elevated workloads.

Answer 29

Carbon dioxide central Most sensitive chemical to create respiration change Hydrogen ions central Oxygen peripheral (specifically in the Carotid Sinus) They are "sensing" these chemicals for pass of information to regulate respiration

Answer 30

In the brain, the result of too much CO2 ultimately means too much H+. The high H+ in brain stimulates the chemoreceptors to stimulate the efferent motor neurons to increase breathing to blow off CO2

Answer 31

Carbon dioxide is major stimulus for increased respiration... more than O2 Acts on chemosensitive area through pH Chemoreceptors are mainly affected by oxygen. If PCO2 is constant low oxygen can be important. Questions: Why is oxygen’s effect on respiration blunted? Explain ventilatory drive during severe lung disease.

Answer 32

Voluntary control Activity from vasomotor center Body temperature increased production of carbon dioxide has direct effect on respiratory center Irritants Anesthesia

Answer 33

Water: 70–85% of cell mass Ions: 1% Proteins: 10–20% Lipids: 2–95% Carbohydrates: 1–6%

Answer 34

Provide “specificity” to a membrane Defined by mode of association with the lipid bilayer Integral: channels, pores, carriers, enzymes, etc. Peripheral: enzymes, intracellular signal mediators

Answer 35

Network of tubular and flat vesicular structures Membrane is similar to (and contiguous with) the plasma membrane. Space inside the tubules is called the endoplasmic matrix.

Answer 36

Outer membrane surface covered with ribosomes Newly synthesized proteins are extruded into the ER matrix Proteins are “processed” inside the matrix: crosslinked folded glycosylated (N-linked) cleaved

Answer 37

Site of lipid synthesis Phospholipids cholesterol Growing ER membrane buds continuously forming transport vesicles, most of which migrate to the Golgi apparatus

Answer 38

Membrane composition similar to that of the smooth ER and plasma membrane Composed of four or more stacked layers of flat vesicular structures Receives transport vesicles from smooth ER Substances formed in the ER are: “processed” phosphorylated glycosylated Substances are concentrated, sorted, and packaged for secretion.

Answer 39

Secretory vesicles diffuse through the cytosol and fuse to the plasma membrane Secretory vesicles containing proteins synthesized in the RER bud from the Golgi apparatus Fuse with plasma membrane to release contents constitutive secretion—happens randomly stimulated secretion—requires trigger Lysosomes fuse with internal endocytotic vesicles. Vesicular organelle formed from budding Golgi Contain hydrolytic enzymes (acid hydrolases) phosphatases nucleases proteases lipid-degrading enzymes lysozymes digest bacteria Fuse with pinocytotic or phagocytotic vesicles to form digestive vesicles

Answer 40

Primary function: extraction of energy from nutrients "Power house of the cell"

Answer 41

The double nuclear membrane and matrix are contiguous with the endoplasmic reticulum

Answer 42

Molecules attach to cell-surface receptors concentrated in clathrin-coated pits Receptor binding induces invagination Also ATP-dependent and involves recruitment of actin and myosin

Answer 43

Step 1 Carbohydrates are converted into glucose. Proteins are converted into amino acids. Fats are converted into fatty acids. Step 2 Glucose, AA, and FA are processed into Acetyl-CoA. Step 3 Acetyl-CoA reacts with O2 to produce ATP. A maximum of 38 molecules of ATP are formed per molecule of glucose degraded.

Answer 44

Continual endocytosis at the “tail” and exocytosis at the leading edge of the pseudopodium Attachment of the pseudopodium is facilitated by receptor proteins carried by vesicles Forward movement results through interaction of actin and myosin (ATP-dependent)

Answer 45

Passive diffusion: molecules dissolve in phospholipid bilayer. Sometimes transport through a channel protein is considered facilitated diffusion (see The Cell: A molecular approach). Facilitated diffusion allows movement of both polar and nonpolar molecules to move through membrane: ions, carbohydrates, amino acids, nucleosides. Channel proteins (porins) allow movement of ions and other small polar molecules to move through membrane in bacteria. Aquaporins are protein channels that allow movement of water through membrane.

Answer 46

Ungated channels Transport is determined by size, shape, and charge of channel and ion. Gated channels Voltage (e.g., voltage-gated Na+ channels) Chemical (e.g., nicotinic acetylcholine receptor channels)

Answer 47

Also called carrier-mediated diffusion

Answer 48

Concentration Difference Electrical Potential Hydrostatic Pressure Difference

Answer 49

Primary Active Transport Molecules are “pumped” against an electrochemical gradient at the expense of energy (ATP). direct use of energy Secondary Active Transport Transport is driven by the energy stored in the electrochemical gradient of another molecule (usually Na+). indirect use of energy

Answer 50

Na+-K+ ATPase Located on the plasma membrane of all animal cells Pumps sodium ions out of cells and pumps potassium ions into cells against electrochemical gradients Plays a critical role in regulating osmotic balance by maintaining Na+ and K+ balance (inhibition of pump by ouabain causes cell to swell and burst!) Pump is activated by an increase in cell volume. Requires about 1/5 of typical cell’s energy and up to 2/3 of neuron’s energy.

Answer 51

Ca2+ ATPase Present on the cell membrane and the sarcoplasmic reticulum in muscle fibers Maintains a low cytosolic Ca2+ concentration H+ ATPase Found in parietal cells of gastric glands (HCl secretion) and intercalated cells of renal tubules (controls blood pH) Concentrates H+ ions up to 1 million-fold

Answer 52

Involves the use of an electrochemical gradient (usually for sodium). Protein cotransporters are classified as symporters or antiporters. Transport substance in same direction as a “driver” ion like Na+.

Answer 53

Transport substance in opposite direction of a “driver” ion like Na+

Answer 54

Osmosis occurs from pure water toward a water/salt solution. Water moves down its concentration gradient.

Answer 55

The amount of pressure required to counter osmosis Osmotic pressure is attributed to the osmolarity of a solution.

Answer 56

The tonicity of any solution used to bathe tissue is totally dependent on its effective osmotic pressure. If the effective osmotic pressure of the bathing solution is the same as that of the tissue, there will be no net movement of fluid. The tonicity (also called effective osmotic pressure) depends on the properties of both the membrane and the solute. Osmolarity is merely another way of expressing the concentration of a solution.

Answer 57

Step 1. RNA polymerase binds to the promoter sequence. Step 2. The RNA polymerase temporarily “unwinds” the DNA double helix. Step 3. The polymerase “reads” the DNA strand and adds complementary RNA molecules to the DNA template. Step 4. “Activated” RNA molecules react with the growing end of the RNA strand and are added (3′ end). Step 5. Transcription ends when the RNA polymerase reaches a chain terminating sequence, releasing both the polymerase and the RNA strand.

Answer 58

Complementary in sequence to the DNA coding strand 100s to 1000s of nucleotides per strand Organized in codons - triplet bases each codon “codes” for one amino acid (AA) each AA—except met—is coded for by multiple codons start codon: AUG (specific for met) stop codons: UAA, UAG, UGA

Answer 59

Acts as a carrier molecule during protein synthesis Each transfer RNA (tRNA) combines with one AA. Each tRNA recognizes a specific codon by way of a complementary anticodon on the tRNA molecule.

Answer 60

Polyribosomes: multiple ribosomes can simultaneously translate a single mRNA

Answer 61

Genomics—the large-scale study of the genome Recent estimates suggest ~ 30,000 genes. Humans are 99.8% identical at the genome level, 99.999% identical in the coding regions.

Answer 62

Following replication and prior to mitosis, DNA polymerase “proofreads” the “new” DNA, and cuts out mismatches. DNA ligase replaces the mismatches with complementary nucleotides. A “mistake” during transcription results in a mutation causing the formation of an abnormal protein. Approximately 10 DNA mutations are passed to the next generation; however, two copies of each chromosome almost always ensures the presence of a functional gene.

Answer 63

Different from reproduction... Changes in physical and functional properties of cells as they proliferate Results not from the loss of genes but from the selective repression/expression of specific genes. Development occurs in large part as a result of “inductions,” one part of the body affecting another.

Answer 64

Light speed decreases when it passes through a transparent substance. The refractive index is the ratio of speed in air to speed in the substance. Light rays bend when passing through an angulated interface with a different refractive index. These light rays are eventually focused on retina.

Answer 65

Convex lens focuses light rays.

Answer 66

Concave lens diverges light rays.

Answer 67

Note that a point source of light has a longer focal length compared to light from a distant source; this is why an object comes into focus as it moves closer to the eye in a person with myopia (nearsightedness, long eyeball).

Answer 68

Lens has less refractive power, but it’s adjustable. a diopter is a measure of the power of a lens. 1 diopter is the ability to focus parallel light rays at a distance of 1 meter. the retina is considered to be 17 mm behind refractive center of eye. hence, the eye has a total refractive power of 59 diopters (1000/17).

Answer 69

Refractive power of lens is 20 diopters. Refractive power can be increased to 34 diopters by making lens thicker. This is called accommodation. Accommodation is necessary to focus image on retina. Contraction of ciliary muscle attached to ligament pulls ligament forward causing lens to become thicker (which increases refractive power of lens). Under control of parasympathetic nervous system.

Answer 70

Intraocular fluid keeps eyeball round and distended. 2 fluid chambers. aqueous humor, in front of lens. (freely flowing fluid). vitreous humor, behind lens (gelatinous mass with little fluid flow). Produced by ciliary body at rate of 2–3 microliters/min. (~3–4 mL/day)

Answer 71

Normally 15 mm Hg (range: 2–20 mm Hg). Level of pressure is determined by resistance to outflow of aqueous humor in canal of schlemm. Rate of production of aqueous humor is constant. Increased pressure can cause blindness due to compression of axons of optic nerve as well as blood vessels.

Answer 72

Light sensitive portion of eye Contains cones for color vision. Contains rods for night vision. Contains neural architecture.

Answer 73

It is a small area at center of retina ~1 mm2. Center of fovea, called “central fovea” or “fovea centralis” contains only cones. These cones have special structure. Aid in detecting detail. In central fovea, neuronal cells and blood vessels are displaced to each side so light can strike cones with less obstruction. This is area of greatest visual acuity. At central fovea: no rods, and ratio of cones to ganglion cells is 1:1. May explain high degree of visual acuity in central retina.

Answer 74

Contains black pigment called melanin. Prevents light reflection in globe of eye. Without pigment, light would scatter diffusely; normal contrast between dark and light would be lost.

Answer 75

Rods and cones contain chemicals that decompose on exposure to light. This excites nerve fibers leading from eye. Membranes of outer segment of rods contain rhodopsin or visual purple.

Answer 76

Vitamin A1 (aka, all-trans retinal) is converted into 11-cis retinal within the retinal pigment epithelium. Night blindness (nyctalopia): Lack of vitamin A1 causes a decrease in retinal, which results in decreased production of rhodopsin; and a lower sensitivity of retina to light.

Answer 77

Transmission of signals in retina is by electrotonic conduction. Allows graded response proportional to light intensity. Only ganglion cells have action potentials. Send signals to brain.

Answer 78

Processing the visual image begins in the retina. One example is lateral inhibition. Horizontal cells provide inhibitory feedback to rods and cones and bipolar cells. Output of horizontal cells is always inhibitory. Prevents lateral spread of light excitation on retina.

Answer 79

Point where ganglion cell axons (~1 million) exit the eye to form the optic nerve (2nd cranial nerve). Entry point for retinal blood vessels Creates a blind spot since there are no rods or cones. Located 3–4 mm to nasal side of fovea Size: 1.76 mm (horizontally) × 1.92 mm vertically Has a central depression called the optic cup.

Answer 80

About 30 different types. Some involved in the direct pathway from rods to bipolar to amacrine to ganglion cells Some amacrine cells respond strongly to the onset of the visual signal, some to the extinguishment of the signal. Some respond to movement of light signal across the retina. Amacrine cells are a type of interneuron that aid in the beginning of visual signal analysis.

Answer 81

Only ganglion cells have action potentials. Send signals to brain. Spontaneously active with continuous action potentials Visual signals are superimposed on this background. Many excited by changes in light intensity. Respond to contrast borders, this is the way the pattern of the scene is transmitted to brain.

Answer 82

Two principle functions: Relay of information to primary visual cortex “Gate control” of information to primary visual cortex

Answer 83

Primary visual cortex lies in calcarine fissure. Distribution from eye is shown. Note large area of representation of macula (which includes fovea). Fovea has several 100x more representation in cortex compared to peripheral portions of retina. Secondary visual areas are visual association areas, where the visual image is dissected and analyzed. Separation of the signals from the two eyes is lost in the primary visual cortex. Signals from one eye enter every other column, alternating with signals from the other eye. Allows the cortex to decipher whether the two signals match. The visual signal in the primary visual cortex is concerned mainly with contrasts in the visual scene. The greater the sharpness of the contrast, the greater the degree of stimulation. How the brain perceives a visual image is not understood well.

Answer 84

Parasympathetic preganglionic fibers arise from Edinger-Westphal nucleus and synapse with postganglionic fibers in ciliary ganglion as shown. The postganglionic fibers send action potentials through ciliary nerves to eyeball to control 1. ciliary muscle (lens focusing). 2. sphincter of iris (constricts pupil). Parasympathetic nerves excite pupillary sphincter muscle, decreasing pupillary aperture (miosis). Sympathetic preganglionic fibers originate in intermediolateral horn of 1st thoracic segment of cord and synapse with postganglionic fibers in superior cervical ganglion as shown. The postganglionic fibers innervate radial fibers of iris (which open pupil), plus several extraocular muscles. Sympathetic nerves excite radial fibers of iris causing pupillary dilation (mydriasis).

Answer 85

System of three coiled tubes separated by membranes into the scala tympani, scala media, scala vestibuli. Sound waves cause back and forth movement of the tympanic membrane which moves the stapes back and forth. This causes displacement of fluid in the cochlea and induces vibration in the basilar membrane. Organ of Corti lies on surface of basilar membrane; contains hair cells which are electromechanically sensitive.

Answer 86

Two muscles attach to the ossicles: Stapedius (stapes) Tensor tympani (malleus) Attenuation reflex: a loud noise initiates reflex contraction, causing ossicular system to develop rigidity. Both muscles involved.

Answer 87

Receptor organ that generates nerve impulses Contains rows of hair cells that have stereocilia Stereocilia, when bent in one direction cause hair cells to depolarize; when bent in opposite direction hyperpolarize. This is what begins neural transduction of auditory signal Hair cells are the receptor organs that generate APs in response to sound vibrations. The tectorial membrane lies above the stereocilia of the hair cells. Movement of the basilar membrane causes the stereocilia of the hair cells to shear back and forth against the tectorial membrane.

Answer 88

Arranged by tonotopic maps High frequency sounds at one end of map Low frequency sounds at other end Discrimination of sound patterns is lost when auditory cortex is destroyed.

Answer 89

Goal of respiratory system is to provide O2 and remove CO2. Functions which accomplish this goal … Ventilation Diffusion O2/CO2 transport Regulation of ventilation

Answer 90

Boyle’s Law: For a given quantity of gas in a chamber, the pressure is inversely proportional to the volume of the container. P1V1 = P2V2 PV = nRT P = nRT/V P = gas pressure (atm) V = volume in which the gas is contained (L) N = moles of the gas R = universal gas constant (L*atm/mole* K) T = temperature (K)

Answer 91

In a gas mixture the pressure exerted by each individual gas in a space is independent of the pressure exerted by other gases. Patm = PH2O+PO2+PN2 Pgas = % total gases * Ptotal

Answer 92

Capillary endothelial cells Alveoli epithelial cells Type 1 cells Type II cells Fibroblasts (surfactant) Macrophages Mast cells

Answer 93

Nervous Sympathetics β2 receptors dilate Parasympathetics Acetylcholine constrict Humoral Histamine, acetylcholine >> Constrict Adrenergic (β agonists) >> Relax

Answer 94

Pleural pressures Resting −5 cm H20 Inspiration −8 cm H20 Alveolar pressure Resting 0 cm H20 Inspiration −1 cm H20 Expiration 1 cm H20 Compliance ∆V/∆P 200 mL/cm H20 (1 cm H20 ~ 0.7 mm Hg)

Answer 95

Flow = ∆P π r4/(8 μL) Resistance = 8 μL/(πr4) Upper airways major resistance Decrease in lung volume results in an increase in resistance.

Answer 96

Alveolar Ventilation (Tidal volume − dead space)*respiratory rate Dead Space Anatomical 150 mL Physiological Depends on ventilation-perfusion ratio

Answer 97

Fick Principle VO2=Q(Cao2−Cvo2) VO2 = Oxygen consumption Q = Blood flow Cao2 = Arterial content Cvo2 = Venous content

Answer 98

Pressure drop of 12 mm Hg Flow of 5 l/min Resistance 1/7 systemic circulation

Answer 99

Outward forces Pulmonary capillary pressure 7 mm Hg Interstitial osmotic pressure 14 mm Hg Negative interstitial pressure 8 mm Hg Total 29 mm Hg Inward forces Plasma osmotic pressure 28 mm Hg Net filtration pressure 1 mm Hg Negative interstitial pressure keeps alveoli dry.

Answer 100

Pulmonary Edema–fluid accumulation in pulmonary interstitial space Causes Increase in pulmonary venous and capillary pressure (left-sided heart failure, mitral valve stenosis) outward force Increased capillary membrane permeability (damage to associated with infections, noxious gases (chlorine, sulfur dioxide). Decrease in plasma osmotic pressure (liver failure). inward force Large decrease in intrapleural pressure (inspiring heavily against a closed airway, i.e., severe laryngeal spasm). Negative pleural pressure is transmitted to interstitial and alveolar spaces, favoring fluid movement out of pulmonary capillaries. Pulmonary edema safety factor: protection against edema until pulmonary capillary pressure equals capillary osmotic pressure. Causes of pulmonary edema Left heart failure Damage to pulmonary membrane Safety factor Negative interstitial pressure Lymphatic pumping Decreased interstitial osmotic pressure

Answer 101

Diffusion in response to concentration gradient Pressure proportional to concentration Gas contributes to total pressure in direct proportion to concentration. CO2 20 times as soluble as O2 Diffusion depends on partial pressure of gas. Air is humidified yielding a vapor pressure of 47 mm Hg. Determinate of Diffusion Fick's Law

Answer 102

PO2 = (760 − 47) * 0.21 = 713 * 0.21 = 149

Answer 103

PAO2= PIO2 − (PCO2/R) PAO2 = 149 − (40/0.8) = 99 R is respiratory exchange ratio ~0.8 Remember in a normal person alveolar PO2 = arterial PO2, and alveolar PCO2 = arterial PCO2.

Answer 104

Hyperventilation Increased ventilation beyond metabolic (O2 demand, CO2 production). Results in drop in arterial CO2. Hypoventilation Ventilation below needs. PaCO2 rises.

Answer 105

CO2 diffusing capacity is 20 times the diffusing capacity of O2.

Answer 106

Relationship between adequate flow and adequate ventilation Defined as V/Q V/Q = (4 L/min)/ (5 L/min) = 0.8 Va/Q = 8.63 * R * (CAO2 − CVO2)/PACO2 If there is no diffusion impairment then the PO2 and PCO2 between an alveolus and end capillary blood are usually the same.

Answer 107

Differences in airway and lung expansion produce uneven regional ventilation. Differences in vascular geometry and hydrostatic pressures produce uneven regional blood flow. V/Q ratios vary across regions within normal healthy lung. Pathologies that lead to regional changes in ventilation (e.g., asthma) or changes in perfusion (e.g., pulmonary embolism) will increase V/Q mismatch.

Answer 108

CO2 returns from the Tissue to Lungs ~23% directly to HGb ~7% in plasma of Blood ~70% is dissolved (bicarbonate)

Answer 109

The glycocalyx is a thin, gel-like layer that covers the surface of many cells, including endothelial cells (lining blood vessels) and epithelial cells (lining organs and body surfaces). It consists of a complex mixture of molecules, including: Glycoproteins: Proteins with attached sugar molecules (glycans) Proteoglycans: Glycoproteins with long chains of sugar molecules (glycosaminoglycans) Glycolipids: Lipids with attached sugar molecules

Answer 110

Calcium is needed to release neurotransmitters

Answer 111

Do I have char with more of them???

Answer 112

CO2 enters brain, but H+ is the direct stimulator of the brain respiratory system pH homeostasis: 7.35-7.4 0-6 = acidic 7 = neutral 8-14 = basic

2025 Physiology Exam 1 Flashcards

Lectures 1-5: Intro/Cell/Membrane, Membrane Transport/Protein Synthesis, Vision/Hearing/Balance, Pulmonary Phys 1, Pulmonary Phys 2 (184 cards)