Cross House Human Phys

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Pyruvate Dehydrogenase

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Unidirectional enzyme from Pyruvate to Acetyl-COA; Enzymatic step that prevents conversion of Lipid to CHO, but allows excess glucose to be converted and stored as lipid

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Lipogenesis

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Conversion of Amino Acids into triglycerides

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Coenzymes

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Organic molecules derived from vitamins

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Glucose-6-Phosphatase (G-6-Pase)

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Only found in the liver and allows for conversion of G-6-P back into blood glucose

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Endothelial Lipoprotein Lipase

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Stimulated by Apo C-II on both Chylomicrons and VLDLs and triggers uptake of fatty acids by adipocytes

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Insulin

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Increases the rate of facilitated diffusion of glucose into cells

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ATP Synthase

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Enzyme found in the hydrogen ion channels between the inner and outer mitochondrial membrane that allows for resynthesis of ATP at the end of the ETC

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Transcription

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Copy of genetic information on DNA to mRNA

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Buffering

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The deviation in CO2 production (VCO2) relative to O2 consumption (VO2) during intense exercise due to non-metabolic CO2

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Lipoprotein

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Combination of TG, phospholipid, cholesterol, and protein for lipid transport in the blood

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Krebs Cycle

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Occurs in the mitochondria; produces (per one pyruvate; two pyruvates per one glucose):
- 2 CO2
- 3 NADH,H+
- 1 FADH2
- 1 ATP

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Adenylate Kinase

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2 ADP --> ATP + AMP

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Creatine Kinase

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ADP + CP --> ATP + C

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Factors determining fate of Pyruvate

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1.) O2 availibility
2.) Energy demand of the cell
3.) Mitochondrial density

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Hexokinase

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Enzyme that traps glucose in the cell by phosphorylating it (requires ATP)

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Axoplasmic Flow

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Transport mechanism for neurotransmitter between cell body and synaptic end bulb

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CNS

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Central Nervous System; brain and spinal cord

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PNS

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Peripheral Nervous System; cranial and spinal nerves

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Somatic Nervous System (SNS)

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Voluntary, part of PNS; consists of afferent neurons that conduct impulses from cutaneous and special sense receptors to the CNS, and motor neurons that conduct impulses from the CNS to skeletal muscle tissue

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Autonomic Nervous System (ANS)

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Involuntary, part of PNS; contains sensory neurons from visceral organs and motor neurons that convey impulses from the CNS to smooth and cardiac muscle tissue and glands

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Neuroglia

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Specialized tissue cells that support neurons, attach neurons to blood vessels, produce myelin sheath and carry out phagocytosis

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Schwann Cells

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Type of neuroglia; Schwann cells myelinate only one axon which increases speed of conductance of an Action Potential

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Neurons

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Nerve cells, consist of a cell body (soma), many dendrites, and usually a single axon

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Dendrites

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Conducts impulses from receptors or other neurons to soma

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Axon

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Conducts nerve impulses from the neuron to dendrites or soma of another neuron or to an effector organ (muscle or gland)

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Leak Channels

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Always open; help regulate resting membrane potential by allowing movement of Na+, K+, and Cl-

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Gated Channels

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Not always open; regulated by change; voltage, ligand (chemical), mechanical, or light (in eyes); allows cell to depolarize or repolarize (hyperpolarize)

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Resting Membrane Potential (RMP)

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Membrane is positive outside and negative inside (usually -70mV) due in part to the relative permeabilities of the membrane to Na+ and K+ (50 to 100 times more permeable to K+); two dominant anions in cell are organic and amino acids in proteins (which are largely immobile contributing to negative value of the inside of the cell)

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Graded Potentials

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Changes in resting membrane potential caused by opening and closing of gated channels in response to neurotransmitters or physical changes

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Depolarization

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First phase of AP propagation; after cell reaches threshold Na+ channels open and allow influx of sodium; membrane potential goes from -70 to +30

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Repolarization

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Second phase of AP propagation; Na+ channels are closed and K+ channels are opened to allow eflux of potassium to reestablish resting membrane potential of -70mV

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Absolute Refractory Period

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A second AP cannot be generated at all; coincides with the period of Na+ channel activation and inactivation; absolute refractory ends once Na+ channels return to resting states

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Relative Refractory Period

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A second AP can only be generated by a suprathreshold stimulus; coincides with period when K+ channels are still open after inactivated Na+ channels have returned to their resting state

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Saltatory Conduction

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Conduction of AP that ocurrs along myelinated axons; AP jumps or leaps from neurofibril node to node

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Continuous Conduction

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Conduction of AP along unmyelinated axons; much slower than Saltatory

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All-or-None Principal

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A stronger stimulus will not generate a stronger AP; if RMP reaches threshold as a result of any strength of stimulus an AP of the same strength is propagated

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Synapse

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Functional junction between one neuron and another or an effector such as a muscle or gland

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Excitatory Postsynaptic Potential (EPSP)

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A depolarizing postsynaptic potential caused by a neurotransmitter that brings the membrane closer to threshold; usually results from opening of Na+, Ca2+, or K+ channels

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Inhibitory Postsynaptic Potential (IPSP)

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Caused by a neurotransmitter that hyperpolarizes the postsynaptic membrane and moves the membrane farther from threshold; often result from opening of Cl- or K+ channels

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Spatial Summation

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Summation that results from buildup of neurotransmitter released simultaneously by several presynaptic end bulbs

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Temporal Summation

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Summation that results from buildup of neurotransmitter released by a single presynaptic end bulb two or more times in rapid succession

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Fates of Neurotransmitter

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Can be cleared from synaptic cleft through diffusion, enzymatic degredation, and uptake into cells.

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Pericardium

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The heart is enclosed and held in place by the pericardium

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Epicardium

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Outermost layer of heart wall made up primarily of connective tissue

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Myocardium

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Makes up the majority of the heart wall; cardiac muscle tissue

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Endocardium

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Inner layer of heart wall made up primary of endothelium

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Systemic Circulation

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Once blood has been oxygenated in the lungs it passes through a series of channels via the heart and body before returning to the heart

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Pulmonary Circulation

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Deoxygenated blood containing high levels of CO2 from tissues returned to the right heart and to the lungs

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Sinoatrial (SA) Node

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Located in right atrial wall. Cells in SA Node spontaneously depolarize to threshold; the spontaneous depolarization is a pacemaker potential. When it reaches threshold it triggers an AP that propagates throughout the heart

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Atrioventricular (AV) Node

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AP reaches AV node located in the septum between the two atria

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Atrioventricular (AV) Bundle

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Also known as the bundle of His. Connected to AV node; it is the only place where AP can conduct from the atria to the ventricles

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Right and Left Bundle Branches

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Conduct AP through septum towards apex of heart

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Purkinje fibers

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Conduct AP from the base of the heart upward to the remainder of the ventricular myocardium. The ventricles then contract, pushing the blood upward toward the semilunar valves

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Tricuspid Valve

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Right Atrioventricular Valve

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Bicuspid Valve

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Left Atrioventricular Valve

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Chordae Tendineae

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Tendon-like cords attached to cusps of bi/tricuspid valves; they are slack when valves are opened and taut when valves are closed

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Semilunar Valves

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Both the aortic and pulmonary valves are semilunar; they allow ejection of blood from the heart into arteries but prevent backflow of blood into the ventricles

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Cardiac Contractile Fibers

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Have a stable RMP that is close to -90mV unlike the autorhythmic fibers which do not have a stable RMP

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Cardiac Depolarization

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When a contractile fiber is brought to threshold its voltage gated fast Na+ channels open resulting in a rapid depolarization

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Cardiac Plateau

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Period of maintained depolarization due in part to opening of voltage-gated slow Ca2+ channels allowing an influx of Ca2+ and the opening of K+ channels so that Ca2+ influx balances K+ eflux; lasts .25 secs

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Cardiac Repolarization

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More K+ channels open allowing eflux of K+ and Ca2+ channels close

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P-wave

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First wave on an EKG; Represents atrial depolarization, which spreads from the SA node through contractile fibers in both atria

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QRS Complex

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Second wave on an EKG; represents rapid ventricular depolarization

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T-wave

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Third wave on an EKG; indicates ventricular repolarization and occurs just as the ventricles are starting to relax

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P-Q interval

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Time from beginning of P-wave to the beginning of the QRS complex; represents the conduction time from the beginning of atrial excitation to the beginning of ventricular excitation; a lenghtened P-Q interval indicates scar tissue in the heart

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S-T segment

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Begins at the end of the S wave and ends at the beginning of the T wave; represents the time when the ventricular contractile fibers are depolarized during the plateau phase of the action potential

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Q-T interval

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Extends from the start of the QRS complex to the end of the T wave; it is the time from the beginning of ventricular depolarization to the end of ventricular repolarization

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Atrial Systole

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Atria are contracting while the ventricles are relaxed; contributes a last 25mL to each ventricle; the end of atrial systole is the end of ventricular diastole; lasts about .1sec

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End-Diastolic Volume (EDV)

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Blood volume in ventricles at the end of atrial systole/ventricular diastole (about 130 mL); this volume is greater in athletes

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Ventricular Systole

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Ventricles are contracting, forcing blood out of the heart; atria are relaxed (atrial diastole); about 70 mL is ejected into both aorta and pulmonary trunk leaving about 60mL in each ventricle

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End-Systolic Volume (ESV)

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Blood volume in ventricles at the end of ventricular systole (about 60 mL); no change in athletes

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Isovolumetric Contraction

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The point at which the ventricles have just started contracting and ventricular pressure is not yet greater than aortic pressure

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Stroke Volume

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Volume ejected per beat from each ventricle; SV = EDV - ESV

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Dicrotic Notch

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Caused by rebound of blood off the closed cusps of the aortic valve increasing aortic pressure briefly

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3 Factors That Regulate Stroke Volume

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1.) Preload
2.) Contractility
3.) Afterload

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Preload

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Degree of stretch on the heart before it contracts; more stretch = more overlap of Myosin-Actin filaments = more force production (Frank-Starling law of the heart)

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Contractility

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Forcefulness of contraction of individual ventricular muscle fibers

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Afterload

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Pressure that must be exceeded before ejection of blood from the ventricles can occur

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Venous Return

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Volume of blood returning to the right ventricle; one of the two determining factors of EDV

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Positive Inotropic Agents

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Substance that increases contractility; eg stimulation of sympathetic division of ANS, hormones such as epinephrine and norepinephrine, increased Ca2+ level in interstitial fluid

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Negative Inotropic Agents

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Substances that decrease contractility; eg clcium channel blockers (drugs)

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Cardiovascular Center

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Located in Medula; includes cardiac accelerator nerves and Vagus nerves alter heart rate by changing properties of leak channels

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Heart Rate Reserve (HRR)

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HRR = HRmax - RHR

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Factors that impact heart rate

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1.) Nervous system (i.e. cardiovascular center)
2.) Chemicals
3.) Age, fitness, body temp

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Arteries

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Carry blood away from the heart to the tissues

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Artery Wall

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Consists of tunica interna, tunica media (containing smooth muscle which maintains elasticity and contractility), and tunica externa

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Arterioles

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Very small, almost microscopic, arteries that deliver blood to capillaries

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Capillaries

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Microscopic blood vessels through which materials are exchanged between blood and tissue cells; usually connect arterioles and venules; capillary walls are composed of only a single layer of cells (endothelium) and a basement membrane

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Precapillary Sphincters

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Rings of smooth muscle fibers that regulate blood flow through capillaries

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Venules

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Small vessels that are formed from the union of several capillaries and drain blood from capillaries to veins

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Veins

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Have 3 layers but less elastic tissue and smooth muscle fiber and are therefore thinner-walled than arteries. They contain valves to prevent backflow of blood. They are the major reservoir of blood under resting conditions.

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Capillary Exchange

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Substances enter and leave capillaries by diffusion, vesicular transport (endocytosis and exocytosis) and bulk flow (filtration and absorption). The movement of water and dissolved substances (except proteins) through capillaries is dependent on hydrostatic and osmotic pressures.

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Velocity of blood flow

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Inversely related to cross-sectional area of blood vessels; blood flows most slowly when x-sectional area is greatest (e.g. capillary level)

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Blood Pressure

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Pressure exerted on the walls of arteries

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Factors that affect Blood Pressure

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CO, blood volume, viscocity, resistance, and elasticity of arteries

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Resistance

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Refers to the opposition to flow as a result of friction between blood and walls of blood vessels. Total peripehral resistance due to small diameters of vessels.

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Baroreceptors

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Important pressure-sensitive sensory neurons that monitor stretching of blood vessel walls and the atria

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Chemoreceptors

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Monitor blood levels of O2, CO2, and H+ ion cencentration

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Tachycardia

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Rapid pulse (>100bpm)

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Bradycardia

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Slow pulse (<60bpm)

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Systolic BP

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Force recorded during ventricular contraction

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Diastolic BP

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Force recorded during ventricular relaxation

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Pulse Pressure (PP)

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The difference between systolic and diastolic BP and provides info on condition of arteries

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Mean Arterial BP (MABP)

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MABP = DBP + 1/3 PP

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Vasoconstriction

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Contraction of smooth muscle lining arterioles; causes increase in BP

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Vasodilation

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Relaxation of smooth muscle lining arterioles stimulated by the presence of metabolytes; causes a decrease in BP

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Continuous Capillaries

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Plasma membranes of endothelial cells form a continuous tube that is interrupted only by intercellular clefts, which are gaps between neighboring endothelial cells

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Fenestrated Capillaries

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Plasma membranes of the endothelial cells have many fenestrations, which are pores for passage of slightly larger molecules

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Sinusoids

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Wider and more winding than other capillaries their endothelial cells have large fenestrations; also, they have an incomplete or absent basement membrane and very large intercellular clefts