Non-striated or smooth muscles, Biology

NONSTRIATED (= SMOOTH) MUSCLES -

  1. Non-striated muscles are found in the posterior part of oesophagus, stomach, intestine, lungs, urinogenital tract, urinary bladder, blood vessels, iris of eye, dermis of skin and arrector pili muscle of hair. Smooth muscles never connect with skeleton.
  2. These muscle fibres or cells are elongated and spindle shaped.
  3. Each fibre contains a single oval nucleus surrounded by the cytoplasm (sarcoplasm). In the cytoplasm the myo- fibrils are arranged longitudinally.
  4. There is no sarcolemma, however, the fibre is enclosed by plasma membrane.

1574_non striated muscles.png

 

FUNCTION -

These muscles help in peristalsis which happens in tubular viscera.

Action of these muscles is controlled by autonomic nervous system and hence they are not under the control of the animal's will.

 

TYPES -

Functionally smooth muscles are of two types : single-unit smooth muscles and multi-unit smooth muscles.

(i)       Single-unit smooth muscles are composed of muscle fibres closely joined together. All the fibres of the single smooth muscle contract together as a single unit. These muscles are found in the walls of hollow visceral organs like gastrointestinal tract and urinary bladder.

(ii)      Multi-unit smooth muscles are composed of independent muscle fibres and are not closely joined together. Their fibres contract as separate units. Arrector pili muscles of skin dermis, ciliary and iris muscles in the eyes, and muscles of the walls of the large blood vessels are some examples of multi-unit smooth muscles.

Posted Date: 10/1/2012 3:57:49 AM | Location : United States







Related Discussions:- Non-striated or smooth muscles, Assignment Help, Ask Question on Non-striated or smooth muscles, Get Answer, Expert's Help, Non-striated or smooth muscles Discussions

Write discussion on Non-striated or smooth muscles
Your posts are moderated
Related Questions
Q. What are the kinds of fecundation that occur in arthropods? What is the predominant kind? In arthropods there are species having exterior fecundation and other species havin

Vitamins Animals cannot sustain a healthy life if they are fed on a diet having only carbohydrates, fats and proteins. They also require vitamins in small quantities in the r


Explain Stavudine It can be given either in initial combination therapy or after failure of regimens containing other NRTIs. Cross-resistance with zidovudine is frequent, ho

What are the antigens and the respective antibodies of the ABO blood group system? The ABO blood system contains the erythrocytic antigens A and B that can be attacked by the a

Social Determinants of Health - Unemployment That unemployment gives rise to social insecurity and psychological stress is well recognised. Fears and uncertainties are known t

Q. What is Echocardiography in pericardial diseases? Ans. One of the earliest clinical applications of echocardiography was in the detection of pericardial effusion and it rema

What are the main structures within the cell nucleus? Within the cell nucleus the major structures are: the nucleolus, an optically dense region, spherical shaped, where there

Which bone forms the non-moving muscle attachment in (a) the hip joint, (b) the shoulder joint, (c) the ankle joint?    (a) The pelvic girdle gives the non

Population Growth - Population Parameters and Regulation The size of a population depends upon the balance between natality and immigration through which individuals are added