Histology - June 19 block 2 Flashcards Preview

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Flashcards in Histology - June 19 block 2 Deck (217)
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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?



At the top of a T tubule, what can be bound?



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?


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 -

1. modulated by postganglionic Parasym neurons release ACH, which bind to muscainic or receptors.

2. postganglionic sympathetic neurons that release NE - binding to a1 and b2 adrenergic receptors.

3. hormones such as estrogen (CONTRACT), progesterone (RELAX) or Oxytocin generating IP3, IP3 opens gated ca2_ channels in cisternae