Exam 3 terms Flashcards
myology
the study of muscles
striations
Cross-banded appearance of muscle tissue under the microscope, indicating the presence of sarcomeres.
Fascicle
a bundle of myofibers
sarcolemma
plasma membrane of a muscle cell
sarcoplasm
cytoplasm of muscle cells
sarcoplasmic reticulum (SR)
smooth endoplasmic reticulum (ER)of muscle cells. SR is well-developed in skeletal muscle myofibers and is wrapped in a highly organized pattern around myofibrils
terminal cisternae
Repeated expanded sections of the SR that lie adjacent to T-tubules
transverse tubules (T-tubules)
are narrow membranous tunnels formed from and continuouswith the sarcolemma. Functionis to transmit action potentialsfrom surface to interior of myofibers
triad
one T-tubule + two adjacent terminal cisterns of SR
myofibril
Myofibrils are elongated strands of protein complexes found inside myofibers.
sarcomere
Myofibrils are organized into longitudinally repeated subunits called “sarcomeres”, which are composed of alternating light and dark zones.
I-Band
Light zonesare called I-Bands containing only thin myofilaments (one of the components of a sarcomere).
A-Band
Dark zonesare called A-Bandscontainingthick myofilaments and overlapping thin myofilaments (one of the components of a sarcomere)
Z-Disk
a dense line composed of -actinin that attaches the thin myofilaments of adjacent sarcomeres.
titin
performs two functionsin sarcomeres: 1)It helps hold the thick filaments in proper alignment, and 2)its elasticity helps return a stretched sarcomere to its original resting length.
H-Zone
area within the A-band where only thick filaments exist
Bare zone
middle portion of H-zone lacking myosin heads
M-line
a dark line in the middle of the bare zone that contains proteins that are critical for organization and alignment of the thick filaments
thick myofilaments
contain myosin and titin; consist of approximately 2500 myosin moleculeswith their tails wound together and myosin heads projecting outward toward surrounding thin filaments.
thin myofilaments
are made of proteins: Nebulin, F-Actin, Tropomyosin, & Troponin.
nebulin
a structural protein that lies alongside thin filaments and attaches the thin myofilamentsto the Z-disks.
F-Actin (filamentous actin)
is a filamentous polymer consisting of G-actin (globular actin) subunits arranged in twoF-actin strands that twist together to form a helix.
G-Actin
The “pearl” on the thin filament; each on contains a myosin binding site.
Tropomyosin
filamentous protein that lies in the groove between the F-actin strands. Each tropomyosin molecule spans seven G-actin subunits.
Troponin
a Ca2+-binding protein that binds at regular intervals along tropomyosin molecules
Neuromuscular junction (NMJ)
is the synapse where the nervous system communicates with skeletal muscles
synaptic cleft
Space between the end of the synaptic bulb and the sarcolemma of the myofiber. 20 to 30 nm (10-9meters)
motor endplate
A specialized region of the sarcolemma of the myofiber where the synaptic bulb of the alpha-motor neuron sits. This region of the sarcolemma is made up of a series of membrane folds containing a high density of nicotinic cholinergic receptors.
nicotinic receptor
Nicotinic receptorson the myofibers are ligand-gated Na+,K+channels that open when ACh binds to them, allowing Na+to flow into the myofiber and K+to flow out.
Dihydropyridine (DHP) receptor
In the triads, the T-tubules contain voltage-sensing dihydropyridine (DHP) receptors that are mechanically linked to Ca+2-release channels called ryanodine receptors (RyR) in the adjacent sarcoplasmic reticulum (SR).
Ryanodine receptor (RyR)
In the triads, the T-tubules contain voltage-sensing dihydropyridine (DHP) receptorsthat are mechanically linked to Ca+2-release channels calledryanodine receptors(RyR)in the adjacent sarcoplasmic reticulum (SR).
Acetylcholinesterase
an enzyme found in synaptic cleft, rapidly degrades ACh
Motor unit
consists of an -motor neuron and all of the myofibers (muscle cells) that it stimulates.
Twitch contraction
A brief response of a single motor unit. A twitch contraction is the muscle movement generated in response to a single AP moving down an -motor neuron and stimulating its myofibers.
myoglobin
is an O2-storage protein found in muscle cells. This protein contains an iron-containing heme group which gives slow-twitch muscle its red appearance.
slow-twitch muscle fibers
Red muscle; have slow contraction and relaxation but are very resistant to fatigue and small diameter
fast twitch/glycolytic fibers
White muscle; have a fast contraction and relaxation time but fatigue quickly and large diameter.
fast twitch/oxidative fibers
Pink muscle; have fast contraction and relaxation with intermediate fatigue level and diameter.
summation
is the process of adding together individualtwitch contractions to increase the overall strengthof muscle contraction
Multiple motor unit summation (recruitment)
occurs when multiple
motor units are stimulated to contract simultaneously in a muscle, thus increasing the overall strength of a muscle contraction
Wave (frequency) summation
frequency of an individual motor unit is increased so that the overall tension is greater
tetany or tetanus
“steady state of muscle contraction” wave summation results in sustained contraction
tetanus “lock jaw”
is pathological condition caused by Clostridium
tetani toxin.
motor nucleus
A given skeletal muscle is served by a group of motor neurons, whose cell bodies are grouped together in the spinal
cord (or brainstem) to form a motor nucleus. Found in the ventral horn of gray matter.
Fatigue
Decrease in work capacity of a muscle caused by work itself.
Rigor
is extreme fatigue that occurs when ATP is completely depleted in
a myofiber.
rigor mortis
Rigor mortis is the stiffening of a dead body that occurs a few hours after death of an animal. Body becomes stiff because ATP is not being produced by cells and Ca+2 leaks from SR
phasic smooth muscles
undergo periodic cycles of contraction and relaxation. So, the major function of phasic smooth muscle is to develop
force, shorten, and then relax similar to skeletal muscles
tonic smooth muscles
contract continuously (tonically) to maintain an organ’s dimensions against an imposed load or to keep a sphincter closed.
dense bodies
Actin myofilaments are attached to dense bodies, which serve a function
similar to Z-disks in skeletal muscles.
attachment plaques or membrane-dense areas
are dense bodies associated with inner surface of membranes of smooth muscle cells.
multi-unit smooth muscle
cells are NOT electrically connected by gap junctions. Each smooth muscle cell is individually stimulated at neuroeffector junctions by ANS motor neurons. (iris & ciliary body)
contact junctions
allow rapid and precise nervous system control of these smooth muscles. found in multi unit smooth muscle
single unit (unitary) smooth muscle
“Visceral type”- Found in walls of viscera (internal organs). 99% of all smooth muscle is this type.
diffuse junctions
(80 to 120 nm synaptic cleft). Diffuse junctions are slow to activate. found in unitary smooth muscles
calmodulin
a Ca2+ binding protein similar to troponin
myosin light chain kinase (MLCK)
Ca2+ calmodulin complex binds to and activates this that phosphorylates the myosin light chain called the regulatory chain, which is found associated with the myosin head.
macronutrient (fuel)
An organic compound (lipids, carbohydrates, and proteins) that can be broken down (degraded or catabolized) in the body to produce usable energy (e.g. ATP)
metabolism
the sum of all physical and chemical changes that take place within an organism
anabolism
(Biosynthesis) -all processes in which simpler substances are assembledinto more complex substances,usually requiring energy input
catabolism
(Degradation) -all processes in which complex substances are broken down into simpler substances, usually with the concomitant release of energy
Adenosine triphosphate (ATP)
ATP is “energy currency” ATP + H2O ADP + Pi+ ENERGY for work
ingestion
is to take into the body through the mouth.
digestion
Breakdown of food into smaller physical and chemical units that can be eventually be absorbed from the lumen of the GI tract into bloodstream.
mechanical digestion
Breakdown of food based on movements ofthe GI tract
chemical digestion
Breakdown of food based on enzyme-catalyzed hydrolysis reactions occurring in lumen of GI tract.
absorption
Passage of digested components of food from lumen of GI tract into the blood (or lymph)for distribution to all the cells of the body.
defecation
The elimination of indigestiblesubstances from the GI tract as feces
mastication
is the process of chewing
bolus
is a soft, flexible food mass that can be easily swallowed
salivary amylase (ptyalin)
begins breakdown of starches into maltose and dextrins; (limited in horses, and absent in ruminants and carnivores)
deglutition
“swallowing” is the process that movesthebolus of food from the mouth to the stomach
chyme
thin liquid layer formed by mixing the bolus with gastric juice.
peptic (chief or zymogenic) cells
secretes pepsinogen
zymogen
a pre-enzyme
pepsinogen
is a zymogen (an inactive precursor) of pepsin
pepsin
is a protease, which is an enzyme that digests proteins. Pepsin requires an acidic pH to catalyze the digestion of proteins
parietal (oxyntic) cells
secrete HCl & intrinsic factor
intrinsic factor
essential for Vitamin B12absorption
gastrin
a hormone secreted by G-cells Gastrin stimulates increased gastric motility and the secretion of gastric juice rich in HC
segmentation
is a process involving the alternating contraction and relaxation within a single segment of the GI tract. (for mixing)
acinar cells
constitute 99% of pancreatic cells and the exocrine portion of the pancreas. Acinar cells produce the secretions that form pancreatic juice.
sphincter of Oddi
is a valve around the hepatopancreatic ampulla that controls the flow of pancreatic juice and bile into the duodenum
Enterokinase (enteropeptidase)
enzyme produced by the duodenal mucosa. converts trypsinogen to trypsin
pancreatic amylase
hydrolyzes starches into maltose, maltotriose, and dextrins
pancreatic lipase
is the principal triglyceride-digesting enzyme in an animal; Triglyceride →2 fatty acids+ monoglyceride
ribonuclease (RNase)
hydrolyzes RNA
deoxyribonuclease (DNase)
hydrolyzes DNA
secretin
Stimulates sodium bicarbonate secretion by acinar cells.
cholecystokinin (CCK)
stimulates secretion of pancreatic juices, also stimulates opening of sphincter of Oddi.
intestinal brush border enzymes
are enzymes produced by the absorptive SI epithelial cells and associated with the microvilli (brush border)of these cells.
endopeptidase
enzymes that hydrolyze internal peptide bonds within proteins thus breaking proteins into smaller peptides
exopeptidase
enzymes that hydrolyze the peptide bonds that attachthe C-or N-terminal amino acids to a proteinor peptide thus releasing individual amino acids
trypsin
Pancreatic endopeptidase that hydrolyzes proteins into peptides.
chymotrypsin
Pancreatic endopeptidase that hydrolyzes proteins into peptides.
carboxypeptidase
Pancreatic exopeptidase that hydrolyzes peptide bond that attaches the carboxyl-terminal amino acid to the peptide
aminopeptidase
exopeptidase that hydrolyzes peptide bonds that attach amino-terminal amino acids to peptides
dipeptidase
splits dipeptides into amino acids.
Alpha-dextrinase
A brush border enzyme that clips of one glucose unit at a time from smaller fragments of starch and alpha-dextrins.
maltase
A brush border enzyme that splits maltose and maltotriose into two or three molecules of glucose
sucrase
A brush border enzyme that splits sucrose (common table sugar) into glucose and fructose
lactase
A brush border enzyme that hydrolyzes lactose (milk sugar) into glucose and galactose
micelle
a way to transport fats; soap bubbles are a form of micelles; After forming micelles with bile salts, long-chain fatty acids and monoglycerides are absorbed into intestinal epithelial cells by simple diffusion..
chylomicrons
Once inside intestinal epithelial cells, fatty acids and monoglycerides are resynthesized into triglycerides. These triglycerides, along with cholesterol,are then incorporated into protein-coated spherical masses called chylomicrons.
lipoprotein lipase
(an enzyme found on the endothelial cells lining these tissues) catalyzes breakdown of triglycerides into fatty acids (FA) and glycerol
feces
consists of water, inorganic salts, sloughed-off epithelial cells, bacteria, products of bacterial decomposition, and undigested components of food
Haustral churning
(haustrum = pouch of colon) involvesa haustrum relaxingand filling up until it becomes distended. Once it distends to a certain point, the walls contract and squeeze the contents into the next haustrum
ruminants
are animals that regurgitate and remasticate their food.
Rumination
Process of bringing food material from the forestomach back to mouth for further mastication
Regurgitation
Bolusof foodis brought back to the mouth from the reticulum and rumen
Remastication
Bolus (cud) is re-chewed 100 times or more.
Reinsalivation
Saliva is added to regurgitated bolus.
Redeglutition
Bolus is swallowed after remastication.
Fermentation
The anaerobic breakdown of organic substances (primarily plants materials) in foods by bacteria and other microorganisms.
Cellulose
Only digestible by microbes (estimated to represent more than 50% of all chemical energy in plants) hemicellulose, pectins, and fructosans.
Volatile fatty acids (VFAs)
short chain fatty acids that are products of bacterial fermentation
eructation
“belch without the noise”. During rumination, cattle produce 30-50 liters of gas per hour and sheep produce about 5 liters/hour. occurs once per minute
Rumen(paunch)
Primary functions of the rumen are mixing, soaking, fermentation of ingested foods, and absorption of volatile fatty acids (VFA)
Reticulum(honeycomb)
When feed, water,and saliva enter the reticulorumen through esophageal opening, heavy objects (grain, rocks, nails) fall into reticulum, while lighter material (grass, hay) enters the rumen
hardware disease
Sharp objects like nails or wire that collect in the reticulum can cause this the can puncture the reticulum, diaphram, and pericardium of heart.
omasum (Bookstomach, many plies)
Omasum is a site of: 1)continued fermentation, and 2)absorption of VFAsand bicarbonate before digesta enters abomasum.
abomasum(true stomach)
Performs glandular stomach functions
forestomach
Higher part of the GI tract; reticulum and rumen
Intercalated discs
Area where each cardiac muscle cell physically contacts neighboring muscle cells; contain gap junctions and desmosomes
autorhythmic cells
The heart’s AP conduction system consists of weakly contractile cardiac muscle that are specialized for generation and distribution of AP throughout the myocardium.
slow response APs
used in autorhythmic(pacemaker) cells of the sinoatrial (SA) node, internodal pathway, atrioventricular (AV) node, bundle of His, and bundle branches
fast response APs
are used in the normal contractile cardiac muscle cellsand Purkinje fibers of the heart
Sinoatrial (SA) node
contains autorhythmic cells called pacemaker cells that spontaneously initiate slow response action potentials at a rate of ≈100 times/min does not require excitation by nervous system
pacemaker cells
autorhythmic cells in SA node
myogenic pacemaker
is made of muscles cells; creates slow response APs
I_f-channels
Slow response APs are created in pacemaker cells by these “funny channels”. leak Na+ until Vm = (-50mv)
T-type voltage-gated Ca2+ channels
(T stands for transient). Ca+2 will flow through these channels eventually bringing the cell to threshold(≈-40 mV).
L-type voltage-gated Ca2+ channels
(Lstands for Long-lasting) when Vm reaches threshold open leading to the rapid depolarization of these cells as Ca+2 flows into the cells and depolarizes their membrane
Systole
=contraction
Diastole
=relaxation (dilate)
internodal pathway
To excite ventricular muscle cells, AP from SA node travels through this
Atrioventricular (AV) node
is the only electrical connection between atria and ventricles. also has pacemaker (depolarizes 40-60/min)
Atriaventricular bundle (bundle of His)
From the AV node, slow response APs move here
Bundle branches
Action potential spreads from AV bundle into the right and left bundle branches, which run through interventricular septum, to apex of the heart and up both sides of the heart
Purkinje fibers
branch off of the bundle branches and conduct fast response AP (described below)into the contractile muscle cellsof the ventricular myocardium and papillary muscles
Ca2+ induced Ca2+ release
Ca+2 flows into the cell from the ECF and stimulates opening of ryanodine receptor channels in the SR causing flow of Ca+2 out of the SR, creating Ca+2 sparks.
electrocardiogram (ECG or EKG)
The EKG is a composite of action potentials produced by all the heart muscle fibers during each heartbeat
P wave
= Atrial depolarization, which is spread of AP over atria
QRS complex
=Ventricular depolarization, which is the spread of AP over the ventricles (Atrial repolarization is hidden within the large QRS complex. )
T wave
=Ventricular repolarization,which occurs just before ventricles start to relax.
hemodynamics
are the principles that describe the movement of blood in the circulatory system.
resistance
primarily due to the friction between flowing blood and the walls of blood vessels (influenced by; Length of the tube (l), Viscosity of the fluid (n), & Radius of the tube (r)
laminar flow
When blood flows in a long smooth vessel it streamlines into layers with the contents of each layer staying the same distance from the vessel wall.
velocity of flow
is the distance that a fixed volume of blood travels in a given period of time (cm/sec or cm/min) v=Q/A
mean arterial pressure
is blood pressurein thelarge arteries averaged over time
diastolic blood pressure
When turbulence subsides (Korotkoff sounds no longer heard) ( when ventricles relax)
systolic blood pressure
turbulent blood flow is heard when cuff pressure falls below the maximum
Sphygmomanometer
Used to measure blood pressure
Total peripheral resistance (TPR)
= Rarteries+ Rarterioles+ Rcapillaries+ Rvenules+ Rveins
cardiac output (CO)
The amount of blood ejected by the left (or right) ventricle into the aorta (or pulmonary trunk) per minute.
Stroke volume (SV)
(volume per beat) ×Heart Rate (HR; beats/min)
heart rate (HR)
beats/min
Frank-Starling law
The volume of blood ejected by the ventricle (SV) depends on the volume present in the ventricle at the end of ventricular diastole
End diastolic volume (EDV)
Same as the Frank-Starling Law
Preload
same as end diastolic volume and Frank-Starling law
skeletal muscle pumping (milking)
Contraction of skeletal muscles pumps blood in the veins back to the heart. Valves in the veins keep the blood moving toward the heart.
Respiratory pump
caused by movements of the diaphragm during breathing.
Cardiovascular center (CVC)
ANS control of CO comes primarily from here (CVC) located in medulla oblongata (and pons) of the brainstem.
Cardiac accelerator nerves
Sympathetic neurons extend from the CVC down the spinal cord and emerge out of sympathetic trunk ganglia) as the cardiac accelerator nerves that innervate the SA and AV nodes, and most portions of the ventricular myocardium
baroreceptors
pressure receptors in the aorta and carotid arteries
chemoreceptors
in the aorta and carotid arteries monitor chemical changes in blood (pH, CO2, O2) and under certain conditions can initiate neural reflex pathways that control HR
