Muscular tissue Questions in English

(B) Smooth muscles (non-striated muscles) are responsible for involuntary movements in the body,such as peristalsis,which is the rhythmic contraction and relaxation of muscles to move food through the alimentary canal.
These muscles are found in the walls of the oesophagus,stomach,and intestines,where they facilitate the peristaltic movement necessary for digestion.

(A) The correct pairing is as follows:
$1$. Iris - Involuntary smooth muscles (Correct).
$2$. Heart wall - Cardiac muscle (The heart wall consists of cardiac muscle,not unstriated muscle).
$3$. Biceps of upper arm - Skeletal muscle fibres (Biceps are voluntary muscles attached to bones,hence skeletal).
$4$. Muscles in abdominal wall - Skeletal muscles (These are primarily skeletal muscles involved in voluntary movement and posture).
Therefore,the correct option is $A$.

(B) Assertion is true because smooth muscle fibres are non-striated (lack cross-striations),fusiform (spindle-shaped,tapering at both ends),and uninucleate (contain a single,centrally located nucleus).
Reason is true because smooth muscles are involuntary,meaning their contraction is not under direct conscious control.
While both statements are correct,the involuntary nature of the muscle is a functional characteristic,whereas the structural description (unstriated,fusiform,uninucleate) is a morphological characteristic. Therefore,the Reason does not explain why the muscle has that specific structure.

(A) Cardiac muscles are specialized muscles found only in the heart.
They exhibit striations (bands) similar to skeletal muscles, which is why they are classified as striated.
However, unlike skeletal muscles, they are not under conscious control, meaning they are involuntary.
Therefore, cardiac muscles are $Striated$ and $Involuntary$.

(A) Striped muscles are also known as skeletal muscles or voluntary muscles.
These muscles are composed of a large number of muscle fibres.
Skeletal muscle fibres are multinucleated,meaning they contain many nuclei within a single cell membrane,a condition known as syncytial.
They are also characterized by the presence of striations and are not spindle-shaped (which is a characteristic of smooth muscles).

(C) During embryonic development,the three primary germ layers give rise to different tissues and organs in vertebrates:
$1$. Ectoderm: Forms the nervous system,epidermis of the skin,and associated structures.
$2$. Mesoderm: Forms the connective tissues,including bones,cartilage,blood,and all types of muscles (skeletal,smooth,and cardiac).
$3$. Endoderm: Forms the epithelial lining of the digestive tract,respiratory system,and associated organs like the liver and pancreas.
Therefore,skeletal muscles are derived from the mesoderm.

(C) The correct answer is $C$. Smooth muscles are involuntary muscles,meaning they are not under conscious control. They are found in the walls of internal organs like the stomach,intestine,and blood vessels. In contrast,skeletal muscles are voluntary muscles. Myosin is indeed a contractile protein,tendons are dense regular connective tissues,and red muscle fibers contain high amounts of myoglobin.

(A) Intercalated discs are found in cardiac muscle. They are irregular transverse thickenings of the sarcolemma that contain desmosomes,which hold cardiac muscle fibres together,and gap junctions,which aid in the conduction of muscle action potentials.

(D) The correct answer is $D$.
Tendon is a dense regular connective tissue that connects muscle to bone.
Smooth muscles are involuntary muscles found in the walls of internal organs.
Red muscles contain high amounts of myoglobin,which provides oxygen for aerobic respiration.
Troponin is a globular protein complex involved in muscle contraction,whereas tropomyosin is a fibrous protein that covers the active sites on actin filaments.

(B) Muscles are specialized tissues that are derived from the embryonic mesoderm layer.
During embryonic development,the three germ layers (ectoderm,mesoderm,and endoderm) give rise to different tissues and organs.
The mesoderm is responsible for the formation of muscles,bones,cartilage,the circulatory system,and the dermis of the skin.

(D) $Myocytes$: These are the specialized cells that make up the muscular tissue and are responsible for contraction.
$Osteoblast$: These are the cells responsible for bone formation.
$Osteocytes$: These are mature bone cells found within the bone matrix.
$Neuroblast$: These are embryonic cells that develop into nerve cells or neurons.

(D) Multiunit smooth muscle fibers: The smooth muscle cells in an organ behave independently,where each cell contracts and relaxes on its own.
Examples include the iris of the eye,the ciliary body,and the arrector pili muscles of the skin.
Single-unit (visceral) smooth muscle: Cells are interconnected by gap junctions,causing them to contract as a single unit.
Examples include the walls of the gastrointestinal tract,the uterus,and the urinogenital tract.
Therefore,the arrector pili muscle is a classic example of multiunit smooth muscle.

(C) Smooth muscles are non-striated,involuntary muscles found in the walls of internal organs such as blood vessels,the stomach,and the intestine.
Intercalated discs are specialized junctions found exclusively in cardiac muscles,which allow for rapid communication and synchronized contraction of the heart.
Therefore,the statement that communication among smooth muscle cells is performed by intercalated discs is incorrect.

(B) Based on the structural characteristics shown in the image:
$P$ represents Skeletal muscle,which is striated,multinucleated,and cylindrical.
$Q$ represents Smooth muscle,which is spindle-shaped,uninucleated,and non-striated.
$R$ represents Cardiac muscle,which is striated,branched,and contains intercalated discs.
Therefore,the correct sequence is $P$: Skeletal muscle,$Q$: Smooth muscle,$R$: Cardiac muscle. This corresponds to option $B$.

(A) The walls of blood vessels are lined with smooth muscle tissue.
Smooth muscles are involuntary in nature,meaning they are not under conscious control.
They are also known as non-striated or unstriped muscles.
Therefore,the correct answer is involuntary muscle.

(C) The muscles found in the walls of the intestine are smooth muscles (also known as visceral or involuntary muscles).
Smooth muscle fibers are fusiform (spindle-shaped) in structure,meaning they are thick in the middle and tapered at both ends.
Each smooth muscle fiber contains a single,centrally located nucleus (uninucleated).
Therefore,they are described as fusiform and uninucleated.

(C) Cardiac muscle tissue is a specialized type of muscle tissue that is found exclusively in the heart.
Unlike skeletal muscles (voluntary) which are attached to bones throughout the body,or smooth muscles (involuntary) which are found in the walls of various hollow organs like the stomach,intestines,and blood vessels,cardiac muscle is restricted to the heart wall (myocardium).
Therefore,it is unique to a single organ.

(B) Muscles are specialized tissues of mesodermal origin.
During embryonic development,the three primary germ layers are formed: the ectoderm,the mesoderm,and the endoderm.
The mesoderm gives rise to various structures including the muscular system,the skeletal system,the circulatory system,and the dermis of the skin.
Therefore,the correct answer is $B$ (Mesoderm).

(D) $1$. Voluntary muscles are those that are under the conscious control of the nervous system. Skeletal muscles are voluntary and are striated in appearance.
$2$. Involuntary muscles are those that are not under conscious control. These include smooth (non-striated) muscles and cardiac muscles.
$3$. Therefore,Voluntary muscles consist of striated muscles,while Involuntary muscles consist of non-striated (smooth) muscles and cardiac muscles.

(B) Visceral organs (such as the alimentary canal,reproductive tract,and blood vessels) contain smooth muscles.
These muscles are involuntary in nature and are also known as non-striated or unstriped muscles.
Striated muscles are primarily associated with the skeletal system,while cardiac muscles are exclusively found in the heart.

(D) The reproductive tract,like other visceral organs,is lined with smooth muscle tissue.
Smooth muscle cells are characterized by being fusiform (spindle-shaped) in structure.
They contain a single,centrally located nucleus,making them uninucleated.
Therefore,the correct description is fusiform and uninucleated.

(B) $1$. Skeletal muscle fibres are multinucleated (syncytial) and arranged in parallel bundles,not uninucleated.
$2$. Cardiac muscle cells are connected by intercalated discs,which function as communication junctions (gap junctions) allowing the cells to contract as a single unit.
$3$. The walls of blood vessels are primarily composed of smooth muscle tissue,not columnar epithelium.
$4$. Smooth muscles are uninucleated and involuntary,not multinucleated.

(A) The correct answer is option $(A)$.
Figure $(a)$ represents skeletal muscle fibres,which are striated and closely attached to skeletal bones. In a typical muscle such as the triceps,these fibres are bundled together in a parallel fashion.
Figure $(b)$ represents smooth muscle fibres,which are fusiform (spindle-shaped) and present in the walls of internal organs such as the stomach and intestine.
Figure $(c)$ represents cardiac muscle fibres,which are branched and exclusively present in the heart.