Students can go through AP Inter 2nd Year Zoology Notes Lesson 3(a) Musculo-Skeletal System will help students in revising the entire concepts quickly.
AP Inter 2nd Year Zoology Notes Lesson 3(a) Musculo-Skeletal System
→ Muscle is a mesodermal origin.
→ Muscles have special properties such as excitability, contractility and relaxation.
→ Skeletal muscles primarly involved in locomotor actions and bringing in changes in body postures.
→ Skeletal muscles are also called as voluntary muscles.
→ Skeletal muscles madeup of number of fascicles; these fascicles are held together by a connective tissue layer called fascia.
→ Each fascicle contains number of cylindrical muscle fibers.
→ Each muscle fiber is lined by plasma membrane called sarcolemma enclosing sarcoplasm.
→ Microfiber contains numbers of parallel filaments called myofibrils.
→ Each myofibril has alternative bands.
→ The light band contains actin proteins.
→ Anisotrpic band contains myosin.
→ Muscle contraction mchanism is best explained by Sliding filament theory proposed by Jean Hanson and Hugh Huxley.
→ Study of bones is called Osteology.
→ Skeletal system consist of frames work of bones, plays a significant role in maintaing posture and the movement of body parts.
→ Adult human skeletal system is made up of 206 bones and few cartilages.
→ Human skull is composed of 8 cranial bones and 14 facial bones.
→ Human vertebral column is formed by 26 serially arranged units called Vertebrae.
→ Rib cage is made up of 12 pairs of ribs to form a protective cage around the organs in the upper body.
→ Each forelimb is made up of 30 bones.
→ Femur bone is longest and strongest bone in the human body.
→ The junction between the ends of two bones is called a joint.
→ Joints are essential for all types of movements involving the body parts of the body.
→ Joints are classified into three forms namely fibrous joints, eartilagenous joints and synovial joints.
→ Inflamation of joints is called arthritis.
→ Inflamation of joints is due to accumulation of uric acid crystals.
→ Muscles are meant for movement.
→ The movements are
- internal (peristalsis)
- movements of various parts like head, eyes, hands
- Locomotory movements (one place to another like walking, running)
→ Skeleton gives ‘support and form’ to the body.
→ Each Skeletal muscle is madeup of muscle bundles (Fascicles).
→ The muscles are attached to skeleton by tendons.
→ Muscles classification based on location: Skeletal, Visceral, Cardiac.
→ Bones and muscles together form powerful locomotory organs.
→ Joints between bones facilitate free movement of different parts of the body.
→ T tubule and the two terminal cistemae at its sides form the triad system. [IPE]
→ Actin is a thin contractile protein where as Myosin is thick contractile protein. [IPE]
→ The ear ossicles are (i) Malleus (ii) Incus (iii) Stapes [IPE]
→ Synovial Joint is free moving joint. It prevents dislocation of joint. [IPE]
→ Synovial Joint acts a lubricant for free movement of joint [IPE]
→ Synovial joints: Ball & socket, Hinge joint, Pivot joint, glidingjoint, condyloid joint, saddle joint.
→ Accumulation of uric acid crystals in joints causes their inflammation, [NEET-2013]
→ Glidingjoint lies between carpals. [NEET-2014]
→ Stimulation of a muscle fiber by a motor neuron occurs at the neuromuscular junction. [NEET-2014]
→ Glenoid cavity articulates humerus with scapula. [NEET-2015]
→ Lack of relaxation between successive simuli in sustained muscle contraction is known as tetanus. [NEET-2016]
→ Osteoporosis, an age-related disease of skeletal system, may occur due to decreased level of estrogen. [NEET-2016]
→ The pivot joint between atlas and axis is a type of synovial joint. [NEET-2017]
→ The ciliated epithelial cells which move particles or mucous in a specific direction in humans are mainly present in Bronchioles and fallopian tubes. [NEET-2019]