Histology - June 19 block 2 Flashcards
Where are satellite cells located?
Satellite cells, which are located just outside the sarcolemma underneath the muscle basement membrane, control the repair of skeletal muscle. They become activated by cues induced by muscle injury or disease.
How do muscles get blood?
Generally, an artery and at least one vein accompany each nerve that penetrates the epimysium of a skeletal muscle. Branches of the nerve and blood vessels follow the connective tissue components of the muscle of a nerve cell and with one or more minute blood vessels called capillaries.
2 arteries, one vein and nerve through CT, with capillary system piercing each endomysium.
what does syncytial mean?
A multinucleate cell which can result from multiple cell fusions of uninuclear cells (i.e., cells with a single nucleus), in contrast to a coenocyte, which can result from multiple nuclear …
What proteins does the Z line contain?
desmin and alpha-actinin.
What does alpha-actinin do in skeletal muscles?
anchors the barbed end of actin filaments to the Z disk
Does smooth muscle have sarcomeres?
No.
At the top of a T tubule, what can be bound?
sodium???
What is the purpose of laminin?
A protein that shares several properties with fibronectin. … In the extracellular matrix, laminin can bind other laminin molecules as well as other proteins like collagen, which helps to reinforce the extracellular matrix structure
Dystrophin is a protein found in muscle cells. It is one of a group of proteins that work together to strengthen muscle fibers and protect them from injury as muscles contract and relax. It links muscles to the cytoskeleton and ECM. it links to Laminan 2 and others].
How do muscarinic vs. Nicotinic receptors differ?
G proteins vs. ligand gated
Muscarinic acetylcholine receptors belong to a class of metabotropic receptors that use G proteins as their signaling mechanism. … By contrast, nicotinic receptors use a ligand-gated ion channel mechanism for signaling.
What are subneural clefts? and what is their arrangement?
ACh gated channels at top
Voltage gated Na+ channels in bottom half
What are dense bars in the presynaptic terminal bulb?
Ca2+ channels are localized around linear structures on the pre-synaptic membrane called dense bars
Vesicles fuse with the membrane in the region of the dense bars.
How does end plate potential work?
ACh released into the neuromuscular junction binds to, and opens, nicotinic ACh receptor channels on the muscle fiber membranes (Na+, K+, Ca2+).
Opening of nACh receptor channels produces an end plate potential, which will normally initiate an AP if the local spread of current is sufficient to open voltage sodium channels.
What terminates the process?
Acetylcholinesterase
At the T-tubule triad, what are the two proteins of import?
Dihydrophyridine (voltage sensor) plucks RYANODINE out of the cisternae of the sarcoplamic reticulum.
How does this pump work? Ca2+ ATPase -
It gets CA back in sarcomeres - but I don’t know how.
Nuclear chain vs bag fiber?
A nuclear chain fiber is a specialized sensory organ contained within a muscle. Nuclear chain fibers are intrafusal fibers that, along with nuclear bag fibers, make up the muscle spindle responsible for the detection of changes in muscle length. … They are static, whereas the nuclear bag fibers are dynamic in comparison
A nuclear bag fiber is a type of intrafusal muscle fiber that lies in the center of a muscle spindle. Each has many nuclei concentrated in bags and they cause excitation of both the primary and secondary nerve fibers. There are two kinds of bag fibers based upon contraction speed and motor innervation.
What are muscle spindles and Golgi tendon organs?
Unlike muscle spindles (located in parallel with muscle fibres), Golgi tendon organs are located in tendons near the myotendinous junction and are in series, that is, attached end to end, with extrafusal muscle fibers. Golgi tendon organs are activated when the tendon attached to an active muscle is stretched.
What is a gamma motor neuron?
involved in reflexes and involved in adjusting muscle tension in spindles
What are motor neurons?
a nerve cell forming part of a pathway along which impulses pass from the brain or spinal cord to a muscle or gland.
What are intercalated discs?
Intercalated discs are part of the sarcolemma and contain two structures important in cardiac muscle contraction: gap junctions and desmosomes. A gap junction forms channels between adjacent cardiac muscle fibers that allow the depolarizing current produced by cations to flow from one cardiac muscle cell to the next.
Desmosome, Fascia Adherens, and gap:
TRANSVERSE component (right angles)- desmosome and fascia LONGITUDINAL (parallel) - gap.
In cardiac cells, does calcium trigger contraction?
Differences between atria and ventricles
The myocardium found in the ventricles is thick to allow forceful contractions, while the myocardium in the atria is much thinner. The individual myocytes that make up the myocardium also differ between cardiac chambers.
When does the heart become an endocrine organ?
When is ANP secreted by heart - which becomes an endocrine organ?
secreted from both right and left atria ANP is secreted in response to increased blood flow OR increased venous pressure.
Right (and left) atrial heart difference?
Yes, fewer ttubes, smaller, and special granules which act on kidneys to cause sodium and water loss - these OPPOSE aldosterone and antidiuertic hormone - whose effects on kidneys result in sodium and water conservation.
Main function of ANP?
The main function of ANP is causing a reduction in expanded extracellular fluid (ECF) volume by increasing renal sodium excretion.
What do diueretics do to your heart?
Diuretics, better known as “water pills,” help the kidneys get rid of unneeded water and salt. This makes it easier for your heart to pump. These medicines may be used to treat high blood pressure and ease the swelling and water buildup caused by many medical problems, including heart failure
Smooth muscles - characterisitcs?
no ttubes, caveloae near surface, leaky calcium channels, myofilaments form crisscross network; thin filaments have actin and tropomyosin - smooth muscle proteins (caldesmona and calponin) No troponin
In smooth muscles - where we also see thick filaments of myosin arranged in side polar design (striated bipolar). Sliding is similar to skeletal.
Calponin and caldesmon, constituents of smooth-muscle thin filaments, are considered to be potential modulators of smooth-muscle contraction. Both of them interact with actin and inhibit ATPase activity of smooth- and skeletal-muscle actomyosin.
What does calmodulin complex do in smooth muscles?
Activates myosin light chain kinase - the enzyme responsible for phophrylation of myosin. ?
Sex Hormones via cAMP is an example of non-neural control:
Estrogens increase cAMP and promote phosphorylations of myosin and CONTRACT of muscle -
Progesterone has opposite effect - decreases CAMP, promoting dephosphorylation of myosin, RELA
What are key filaments in smooth muscle?
Desmin and Viminetin
Dense bodies in smooth muscle?
They contain alpha-actinin and desmin - similar to Z lines of striated . Both thin and intermediate insert into dense bodies that transmit contractile force to adjacent muscles and the surrounding network
Visceral smooth muscles?
Single-unit smooth muscle, or visceral smooth muscle is a type of smooth muscle found in the uterus, gastro-intestinal tract, and the bladder. In SUVSM, a single smooth muscle cell in a bundle is innervated by an autonomic nerve fiber.
UNITLATERAL vs. Multiunit
Many smooth muscles are like this - large sheets such as found in walls of hollow viscera - intestines, uterus - with a lot of gap junctions, poor nerve supply.
Function in syncytial fashion as a single unit. vs. smooth muscles in eye which is a multiunit - with rich innervation that can produce precise and graded contractions
What can single unit smooth muscles generate?
Slow waves -
- modulated by postganglionic Parasym neurons release ACH, which bind to muscainic or receptors.
- postganglionic sympathetic neurons that release NE - binding to a1 and b2 adrenergic receptors.
- hormones such as estrogen (CONTRACT), progesterone (RELAX) or Oxytocin generating IP3, IP3 opens gated ca2_ channels in cisternae
How does nerve supply to smooth muscle differ from skeletal?
organs with smooth muscles generally have spontaneous activity - not looking for stimuli. The nerve supply modifies activity rather than initiating.
What stimulates the sympathetic nervous system?
Often called the emotional brain, the amygdala pings the hypothalamus in times of stress. The hypothalamus then relays the alert to the sympathetic nervous system and the signal continues on to the adrenal glands, which then produce epinephrine, and NE better known as adrenaline
In addition to contractile activity, what else can smooth muscles do?
Synthesize collagen, elastin and proteoglycans
What muscles do not have gap junctions?
Skeletal muscle cells lack gap junctions for the simple reason that they do not need them. Skeletal muscles are not single cells.
nor do multiunit smooth.
What are alpha 1 and alpha 2 receptors?
Alpha 1 receptors are the classic postsynaptic alpha receptors and are found on vascular smooth muscle. … Alpha 2 receptors are found both in the brain and in the periphery. In the brain stem, they modulate sympathetic outflow.
What receptor can only be excited?
Nicotinic receptors are all excitatory, but muscarinic receptors can be both excitatory and inhibitory depending on the subtype.
the parasympathetic effects (such as a slowed heart rate and increased activity of smooth muscle) produced by muscarine muscarinic receptors — compare nicotinic
Nicotinic receptors function within the central nervous system and at the neuromuscular junction. While muscarinic receptors function in both the peripheral and central nervous system, mediating innervation to visceral organs.
Where are nicotinic and muscarinic receptors located?
Muscarinic receptors predominate at higher levels of the central nervous system, while nicotinic receptors, which are much faster acting, are more prevalent at neurons of the spinal cord and at neuromuscular junctions in skeletal muscle.
Does skeletal muscle have muscarinic receptors?
Muscarinic receptors respond more slowly than nicotinic receptors. … Muscarinic receptors do not affect skeletal muscles, but do influence the exocrine glands as well as the inherent activity of smooth muscles and the cardiac conduction system.
Syncitia?
multinucleated cell that can not mitose
anisotropic vs isotropic?
diffusion varies vs is same -
When the properties of a material vary with different crystallographic orientations, the material is said to be anisotropic. Alternately, when the properties of a material are the same in all directions, the material is said to be isotropic.
What does high creatine kinase mean? (M Line)
CK stands for creatine kinase, an enzyme that leaks out of damaged muscle. When elevated CK levels are found in a blood sample, it usually means muscle is being destroyed by some abnormal process, such as a muscular dystrophy or inflammation.
Phospholamban?
is a 52-amino acid integral membrane protein that regulates the Calcium (Ca2+) pump in cardiac muscle cells.
Cardiac cells - run on fatty acids - where are they stored?
as triglicerides in lipid droplets seen in cardiac muscle cells. Glyogen also present for emergencies - stress
What acts against aldosterone and antidiuretic hormone (that in kidneys) conserves sodium and water?
ANP granules mostly in right atrium
LOWERS BLOOD PRESSURE
Secreted in response to increased venous pressure or increased blood volume
A LOT Of Dilute Urine. GETS RID of sodium….
and dilates blood vessels
reduce plasma volume by at least 3 mechanisms: increased renal excretion of salt and water, vasodilation, and increased vascular permeability. … Thus ANP-induced increases in endothelial permeability may be critical to the ability of ANP to lower arterial blood pressure.
Secreted in response to increased venous pressure or increased blood volume.
Getting sodium and water to LEAVE the body, thereby??? making the blood more fluid?
ANP functions include the following.
- ANP increases glomerular filtration pressure and glomerular filtration rate (via vasoconstriction of the efferent arteriole) and decreases Na+ resorption by the proximal convoluted tubule (PCT). These actions produce natriuresis (increased Na+ excretion) in a large volume of dilute urine.
- ANP inhibits secretion of antidiuretic hormone (ADH) from the neurohypophysis.
- ANP inhibits secretion of aldosterone from the adrenal cortex (zona glomerulosa).
- ANP inhibits secretion of renin from juxtaglomerular cells.
- ANP causes vasodilation of peripheral and renal blood vessels.
embryonic devel of skeletal vs cardiac?
splanchnic mesoderm
skeletal - fuse into syncytial cells -
Cardiac - align chainlike, and form complex junctions between their extended processes.
Spontaneous rhythmic contraction - initiitated by Purkinje fibers in nodes. run by symp and parasym nerve fibers
mechanics of contraction in skeletal vs cardiac muscles?
skeletal - voltage activated calcium release
T tube has voltage gated sensor to DHP receptor
Ryan releases CA, proportional to membrane voltage
Cardiac - calcium activates calcium release
t tube has CA channel to DHP receptor
Ryan releases CA proportional to CA entry.??
What muscles have no CELL _ CELL junctions?
skeletal - they don’t need them, they are long.
Smooth muscles, tightly packed, narrow part lies with adjacent broad
scalloped border when contract, like a corkscrew
at poles of nucleus are mitochondria, polyribosomes, cisternae of rer, glycogen granules, and golgi. Pinocyctotic vesicles caveolae are frequent
NO T tubes
smooth muscle proteins?
caldesmon and calponin. Myosin arranged in side polar - contract w/ actin and myosin sliding similar to striated
Smooth muscle concentration?
influx of CA, myosin interacts with actin only when light chain is phsophorylated using calmodulin.
MLCK - light chain kinase
CA + Calnodullin - > myosin kinase-> light chain -> mysoin ATPase -> head attached with actin - contraction by sliding
How do smooth muscles relax?
Nitrous Oxide
neural crest cells?
dorsal root ganglia, sympathetic chain ganglia, all post ganglionic sym and parasym ganglia, pia, arachnoid, schwann and satellite.
if you see GFAP?
astrocyte (NOT neural crest - don’t know why I thought it was).
Are ependymal cells joined together my tight junctions?
No - that’s how the CSF gets thru.
What can pass thru the BBB?
Water, gases, small lips - glucose and amino acids via carrier mediated transport
Dysphagia?
is the medical term for swallowing difficulties. Some people with dysphagia have problems swallowing
HCO3? Are surface mucous cells attached to one another?
Bicarbonate. yes, via juxtaluminal tight junctions. They secrete mucous and HCO3
What cells do gastric glands consist of?
Stem cells (migrate upward and downward - every 4 - 7 days replacing cells)
muscous producting Mucous neck (mucus)
Parietal (HCL, HCO3 into blood stream (alkaline tide), Intrinsic factor (need for B12 absorption)
Chief cells (pepsinogen and lipase)
Enteroendocrine
G Cells - (gastrin in response to meal) ANTRUM - stim: HCI in parietal, histamine release in enterochromaffinlike ECL, if ULCERS - can take out Antrum to cut down on HCl
ECL cells - secrete serotonin and histamine (stim HCl)
D cells - SOMATOSTATIN - inhibits G cells and ECL cells
Antrum?
Lots of G cells (which secrete Gastrin which promote HCL in parietal - so if ulcers, take out antrum.
Zollinger Ellison syndrome?
excess gastrin secretion due to malignant tumor - too much HCL produced. Peptic ulcer can be this problem.
If HCL production is low, what may happen?
Gastrin will fire - upping HCl.
a condition in which a gastrin-secreting tumor or hyperplasia of the islet cells in the pancreas causes overproduction of gastric acid, resulting in recurrent peptic ulcers.
Arrangement of gastric pits?
These glands are narrow tubules composed of three major cell types: zymogenic, parietal, and mucous neck cells. At the base of the gland are the zymogenic (chief) cells, which are thought to produce the enzymes pepsin and rennin.
What stimulates parietal cells to produce HCI?
Gastrin, Histamine,
Parietal cells secrete acid in response to three types of stimuli: Histamine, stimulates H2 histamine receptors (most significant contribution). Acetylcholine, from parasympathetic activity via the vagus nerve and enteric nervous system, stimulating M3 receptors.
Small intestine inner luminal surface? layers?
plicae circulares (valves of kerckring0 , villi, microvilli,
Cells covering villi?
absorptive - enterocytes - possess microvilli - coated in glucocalyx w/ lots of enzymes - sucrase, lactase, enterokinase (converts inactive to active pancreatic enzyme typsinogen).
What do enterocytes do?
absorb carbs, protein, lipids, vitamins, CA2, and FE2 (iron) from lumen and transport to blood or LYMPH
Enterocytes and everything but fat?
absorbs carbs, proteins, water soluable vitamins, CA2 and Fe2 - via various mechanisms. How they enter and exit to blood varies.
ie - carbs, glucose enters via NA+ dependent glucose transporter, but fructose via diffusion using GLUT5 trasnporter -
Proteins - broken into Amino acids - enter enterocytes via secondary active transport -
Vitamins thru diffusion, B12 absorbed in ILEUM, need intrinsic factor
CA2 - requires Vitamin D produced in Kidneys
FE
goblet cells in small intestine?
Lots - synthesize mucinogen which is stored as granules.
Fat cells and enterocytes ?
Long fatty chain - delivered to lacteals lymph
Short - to portal blood
Fat cells and enterocytes ?
Long fatty chain and fat soluble Vitamins - ADEK enter via micelle packaging w/ fatty acid-binding proteins - resynthesized into triglycerides?? eventually all
delivered to lymph via lacteals
Short - enter directly through diffusion, and exist same - to portal blood
How is fat broken down in GI system?
Bile salts.
Crypts of Lieberkuhn
stem cells - replacing enteroctyes every 3 - 6 days
Paneth Cells -BACTERIA fighters - base of intestinal glands, secrete Lysozyme, TNF, and DEFENSINS (increases membrane permeability of bacteria by forming ion channles)
Enteroendocrine cells
I cells - CCK
S cells Secretin (fireman)
K cells - GIP
L cells GLP
Mo cells - motilin
CCK?
stimulates PANCREAS (acinar cells)
BILE release (contraction) and oddi relax
decrease HCl secretion and gastric emptying,
increases pepsingogen secretion
secretin?
nature’s antacid - response to H+ (protons) and fatty acids in gut.
Stim release of Bicarb (HCO3 from Pancreas and Liver biliary tract
K cells - GIP?
stim insulin from islets - in response to oral admin glucose
L cells? GLP-1?
stim insulin when hyperglycemia, inhibits postprandial glucagon form islets
GALT (gut associated lympathtic tissue ) Peyer patches? M cell related
antigen transporting cells -
M cells endocytose antigens into vesicles - IGA related immunoglobulin A
Peyer’s patches are groupings of lymphoid follicles in the mucus membrane that lines your small intestine. Lymphoid follicles are small organs in your lymphatic system that are similar to lymph nodes. … Peyer’s patches play an important role in immune surveillance of materials within your digestive system
GALT (gut associated lympathtic tissue ) Peyer patches? M cell related
ILEUM
immune surveillance of materials within your digestive system
Monitoring intestinal bacteria populations and preventing the growth of pathogenic bacteria in the intestines.
antigen transporting cells -
M cells endocytose antigens into vesicles - IGA related immunoglobulin A
Peyer’s patches are groupings of lymphoid follicles in the mucus membrane that lines your small intestine. Lymphoid follicles are small organs in your lymphatic system that are similar to lymph nodes. … Peyer’s patches play an important role in immune surveillance of materials within your digestive system
Celiac Disease?
chronic diarrhea, weight loss, gas - can’t absorb gluten - destroys villi and other structures.
Crohn, chronic inflamation
genetic? linear ulcers,
cholera?
bacteria via contaminated food and water,
lactose intolerance
can be acquired later in life. all children ~5 - 7 have tolerance.
2 types of people, lactase persistent, lactase nonpersistent
icteric?
jaundiced
mallory bodies in liver?
keratin intermediate filaments. Hepatic stellate cells secrete collagen in cirrhosis. Liver is from epitheleal cells - hence keratin! and not desmin, vimenten, etc.
Desmin (w/ muscle
Desmin is a myofibrillar protein that is the chief intermediate filament of skeletal and cardiac muscle [40]. It maintains the structural and functional integrity of the myofibrils and functions as a cytoskeletal protein linking Z bands to the plasma membrane.)
Vimenten (mesenchymal cells_ bones, fat, muscle
kuppfer cells?
macrophages of liver
resting parietal cell?
H+, K+, ATPase is sequestered in tubulovesicles. Sounds like this thing is underneath the stomach, and comes out when stretch or stimulated?
