Locomotion And Movement

A. Fast muscle fibres ii. Lactic acid

The lactic acid is produced in the fast muscle fibres due to the larger exercise-induced loss of K⁺ ions as compared to slow muscle fibres.

B. Slow muscle fibres i. Myoglobin

Slow muscles fibres have a higher rate of myoglobin concentration as compared to the fast muscle fibres.

C. Actin filament iv. I-band

The I-band contains only thin (Actin) filaments in the myofilament.

D. Sarcomere iii. Contractile unit

A sarcomere is the functional contractile unit of a muscle fibre which contains two types of myofilaments myosin and actin.

The sternum is a flat bone which is located on the ventral midline of the thorax. There are 12 pair of ribs which are connected dorsally to the vertebral column and ventrally to the sternum. The ribs are connected to the sternum with the help of hyaline cartilage.

The type of movable joint present between the atlas and axis is known as the pivot joint. It is a synovial joint which is generally characterised by the presence of fluid filled in the synovial cavity between the articulating surfaces of the two bones. In humans, the pivot joint is present in the neck.

ATPase of the muscle is located in the Myosin. In the globular head of Myosin structure, the ATPase enzyme is found along with ATP-binding sites. Myosin is the thick filament contractile protein.

Intervertebral disc is found in the vertebral column of mammals which acts as a shock absorber and as a ligament which holds the vertebrae. It lies between adjacent vertebrae in the vertebral column.

In the vertebral column of human beings, cervical vertebrae are the vertebrae located in the neck region. The thoracic vertebrae are located in the chest region. The lumbar vertebrae is located in the lower abdomen. The sacral vertebrae are located in the hip region and the coccygeal is located at the end of the spinal cord region. It is a vestigial organ in the human body.

The incorrect pair is Hinge joint: between Humerus and Pectoral girdle because hinge joints are synovial joints which can move along a single axis to flex or extend. Examples of hinge joints includes the elbow, angle and the knee joints. The joint between Humerus and Pectoral girdle is ball and socket joint.

The hinge joint is a type of synovial joint which has synovial fluid in the synovial cavity between the articulating surfaces of the two bones. Knee and elbow joints are examples of hinge joints as they can move along a single axis to flex or extend.

Macrophages and leucocytes are specialized cells in the body, which helps in providing immunity. They exhibit amoeboid movement, which is effected by pseudopodia formed due to the presence of streaming protoplasm.

Atherosclerosis is not a disorder of the bone. It is a condition in which fats, cholesterol, and other substances get deposited in the walls of the artery, which can lead to clogging of arteries. While arthritis is the inflammation of the joints of bones. Osteoporosis is the disorder which leads to weak bones and reduced bone mass and Rickets is the softening and weakening of bones due to lack of vitamin D in the body.

The muscles located in the inner walls of the alimentary canal are non-striated and involuntary. These are smooth cells which are controlled without consciousness. These muscles couldn’t be controlled by the organism’s will. The other options are correct.

The glenoid cavity of the pectoral girdle has a depression which articulates with the head of the humerus bone. The glenoid cavity is a part of the shoulder. The other options are incorrect as femur is articulated by with the acetabulum by forming a ball and socket joint.

The muscles of the heart have striations, and they are involuntary. The muscles in the alimentary canal are smooth muscles, i.e., non-striated and involuntary. Muscles assisting locomotion are striated and voluntary while the muscles of the eyelids are involuntary and non-striated.

A. Sternum iv. Flat bones

Flat bones are the bones which are expanded into broad, flat plates. They are found in the sternum, hip bones, ribs, etc.

B. Glenoid Cavity iii. Pectoral girdle

The glenoid cavity is a depression which articulates with the head of the humerus bone along the pectoral girdle located in the shoulder.

C. Freely movable joint i. Synovial fluid

The freely movable joints have synovial fluid which is filled in the synovial cavity between the articulating surfaces of the freely movable joints. The synovial fluid reduces friction and shock between the joints and the joints function without any grinding noise or pain.

D. Cartilaginous joint ii. Vertebrae

Cartilaginous joints are flexible joints which allow more movement and they are found in the vertebral column. The ribs are connected to the sternum with the help of hyaline cartilage.

a. The cells/tissues in the human body which exhibits ameboid movement are the macrophage cells and leucocyte cells which are specialised cells of the body which helps in providing immunity. They exhibit amoeboid movement which is affected by pseudopodia formed due to the presence of streaming protoplasm.

b. The cells/tissues in the human body which exhibits ciliary movement are the tissues present in the fallopian tube, trachea, and bronchioles. These tissues have ciliated epithelium which facilitates ciliary movement.

Locomotion requires a perfect coordinated activity of muscular, Skeletal, Nervous systems.

Locomotion is a coordinated process which involves the skeletal system and nervous system along with the muscular system to achieve a voluntary and efficient locomotive process.

These names refer to the muscle cells or muscle fibres. They are lined by a plasma membrane, which is known as sarcolemma, which encloses the sarcoplasm. The sarcoplasmic reticulum refers to the endoplasmic reticulum of the muscle cells, which acts as a storehouse for calcium ions.

The various components of actin filament in the given diagram are:

• Troponin: It acts as a mask for active binding sites for myosin in the actin filament when it is in the resting state.

• Tropomyosin: It is a protein which is involved in the contraction of the skeletal muscles, and when required, it prevents myosin interaction.

The correct sequence of the three bones present in the middle ear are:

Malleus ---> Incus ---> Stapes.

• Malleus: It is the hammer-shaped component of the middle ear, which helps in transmitting the sound vibrations from the eardrum to the incus.

• Incus: It is an anvil-shaped component of the middle ear which receives vibrations from the malleus and helps in transmitting these vibrations to the stapes medially.

• Stapes: It is a stirrup-shaped component of the middle ear, which helps in the conduction of sound vibrations to the inner ear.

Myasthenia gravis is an autoimmune disease which affects the neuromuscular junction tissue, i.e., it interrupts the connection between nerves and muscles, causing paralysis, fatigue, and weakening of skeletal muscles.

The underlying cause of Myasthenia gravis (MG) is that the immune system starts to attack its own cells, causing transmission errors between the nerve impulses and skeletal muscles which disrupts the proper coordination in the body.

Our bone joints function without grinding noise and pain due to the presence of synovial fluid, which is filled in the synovial cavity between the articulating surfaces of two bones. The synovial fluid reduces friction and shock between the joints and the joints function without any grinding noise or pain.

The ball and socket joint is a joint in which a ball-shaped surface of a bone is fitted into a cup-like indentation of another bone. It can move in 360 degrees. It is found between:

• The humerus and Pectoral girdle (Shoulder Joint).

• Femur and Acetabulum of Pelvic girdle (Hip Joint).

There are four ball and socket joints present in the human body.

• Two shoulder joints and two hip joints.

Our forearms are made up of three different types of bones. Humerus, Radius, and Ulna.

•The humerus forms the joints at the shoulder and the elbow.

•Radius or radial bone extends from the other side of the elbow to the side of thumb of the wrist, and it runs parallel to the ulna.

•The ulna stretches from the elbow to the smallest finger.

a. Bicephalic ribs: It is called bicephalic because each of the two ribs has articulating surfaces on the dorsal end and each rib is flat and thin bone which is connected vertically to the sternum and dorsally to the vertebral column.

b. True ribs: The first seven ribs known as true ribs. Ventrally they are connected to the sternum with the help of hyaline cartilage, and it is dorsally attached to the thoracic vertebrae.

c. Floating ribs: These ribs are not connected to the sternum, and they are the last two ribs (11th and 12th ribs) of the rib cage.

In old age, people often suffer from stiff and inflamed joints due to an autoimmune disease known as rheumatoid arthritis, which occurs due to the immune system attacking the cells of its own body. The cells lined in the synovial membrane of the synovial joints are attacked, which causes inflammation and stiffness in the joints.

•Thus, the reasons for these symptoms are the inflammation in the synovial joints due to the immune system attacking its own synovial cells.

•The trigger behind the immune system attacking itself is still unknown, but possible reasons are smoking, genetic factors, and vitamin D deficiency.

a. If more of Ca++ is in the extracellular fluid, then it will get accumulated into the bones under the influence of the hormone Thyrocalcitonin (TCT).

b. If very less amount of Ca++ is in the extracellular fluid thin bone resorption would occur due to the Parathyroid hormone.

The two hormones which results in the fluctuation of Ca++ levels are:

• Thyrocalcitonin (TCT): It lowers the levels of Ca++ and K+ in the blood and promotes the formation of bone in the body.

• Parathyroid hormone: When the Ca++ in our blood goes too low, the parathyroid glands make more parathyroid hormone (PTH). The Increased levels of Parathyroid hormone (PTH) cause the bones to release their Ca++ into the blood.

b. Rahul has gained weight due to increased muscle and less of fat.

Explanation: Regular exercise leads to an increase in the amount of sarcoplasm i.e., the thickness of myofibrils increases along with increase in protein synthesis and mitochondria, and the reduction of body fat content occurs with the increase in the muscle mass of the human body which leads to weight gain.

a. Due to strenuous exercise her muscles got fatigued as the accumulation of lactic acid in the muscles occurred because the muscles did not receive adequate oxygen during the exercise and by the anaerobic respiration pathway the glucose was broken down to lactic acid due to lack of oxygen.

b. The change in the breathing rate occurred because the body demands more oxygen during strenuous exercise for more ATP (i.e., Energy) production. Therefore, breathing rate increases to obtain more oxygen to produce more ATP by aerobic respiration.

•Gout is a form of arthritis which is caused by the accumulation of sodium urate crystal in the joints.

•Sodium urate is a metabolic waste which gets deposited in the joints when the kidneys couldn’t remove it due to its excessive presence in the bloodstream.

•Notable symptoms of gout are intensely painful joints, redness, and swollen joints.

•The symptoms of gout can be managed and reduced by Non-steroidal Anti-inflammatory drugs (NSAIDS).

The source of energy for muscle contraction is ATP (Adenine Triphosphate). An enzyme called myosin ATPase present on the head of myosin molecule breaks down into ADP and inorganic phosphate in the presence of magnesium and calcium ions and releases energy in the head of the myosin.

i.e., ATP -> ADP + Pi + Energy

This energy from the ATP causes the myosin to form a cross-bridge by binding to the actin filament. The movement along the cross-bridge causes the sliding of thin and thick myofilaments which initiates muscle contraction.

• The pectoral girdle has two bones called the clavicle and scapula which is articulated by a cavity called glenoid cavity with the head of the humerus by forming a ball and socket joint.

• The pelvic girdle has three bones Ilium, Ischium, and Pubis which is articulated by a cavity called the acetabulum with the femur by forming a ball and socket joint.

Yes, in certain cases calcium ion concentration in the blood leads to tetany. Calcium plays a significant role in muscle contraction.

• The parathyroid glands secretes parathyroid hormones, which increases the concentration of Ca2+ ions in the bloodstream.

• During the deficiency of the parathyroid hormone, the Ca2+ concentration would decline. The decrease in the Ca2+ levels would result in excitability in the muscles and nerves, which results in cramps and convulsions in the muscles.

Therefore, Calcium ion concentration in the blood affects muscle contraction. When these contractions are sustained due to low levels of parathyroid hormone, which causes a decrease in the Ca2+ concentration and affects the muscles of larynx, hands, feet, and face, this is known as parathyroid tetany. Thus, fluctuation in blood calcium concentration can lead to tetany.

A slipped disc is a condition in which the intervertebral disc is displaced from its original position. The spine gets affected as the intervertebral disc is displaced due to wear and tear of the outer fibrous ring.

It affects our health in the following ways:

i) It causes muscle weakness.

ii) It can cause numbness of the body and pain in the muscles of arms, legs, and lower back.

iii) The activities like walking and standing would become painful.

iv) The affected area around the slipped disc would cause burning and tingling sense along with severe pain.

v) Permanent nerve damage and paralysis can occur if it is left untreated in severe cases.

The sliding filament theory states that contraction of a muscle fibre occurs through the sliding of the thin filaments over the thick filaments. The thin filament is known as actin, and the thick filament is known as myosin.

• The contraction of the muscle is initiated when a neural signal is sent to the neuromuscular junction by a motor neuron by the central nervous system (CNS).

• In the muscle fibre it has an alternate light and dark bands which has the specialised contractile protein filaments called actin and myosin.

• An elastic fibre called Z-line is present in the muscle fibre which bisects each of the I-bands.

• The actin filament gets anchored to the Z-line. The central part of the myosin is not overlapped by actin filament, and it is known as the H-zone.

• During the muscle contraction, the head of the myosin filament come in close contact with the actin filament. This results in the actin filament to be pulled or slide towards the middle of the sarcomere.

• The Z-line which is attached to the actin filaments which leads to the shortening of the sarcomere.

• Thus, the length of the A-band would remain constant while the I-band shortens in length, and the H-zone gets reduced and ultimately disappears.

This mechanism occurs in all the sarcomeres results in the shortening of the myofibrils and thus causes muscle contraction.

The above diagram shows the contraction of a muscle fibre according to the sliding filament theory by the sliding of the thin filaments over the thick filaments.

The muscle shortens during its contraction and returns to its original form during relaxation by the following steps:

i) The neurotransmitter acetylcholine is released when a neural signal reaches the neuromuscular junction and acetylcholine creates an action potential in the sarcolemma.

ii) A release of calcium ions occurs due to the action potential, which is spread through the muscle fibres.

iii) The increase in the calcium ion concentration causes the binding of the calcium ion to a sub-unit of troponin on the actin filaments. This causes the removal of active sites in myosin.

iv) The myosin head binds with the exposed active sites of actin and forms a cross-bridge.

v) This causes the attached actin filaments to move towards the centre of A-band.

vi) The Z-line also moves inwards, and a contraction of the sarcomere occurs in the muscles.

vii) During the muscle contraction, the I-band gets reduced while the A-band retains its original length.

viii) Breaking of cross-bridge occurs when the ADP and Pi releasing myosin goes back to its relaxed state and another new ATP binds which breaks the cross-bridge.

ix) Further sliding occurs when the ATP is hydrolysed again by myosin head, and repetition of cross-bridge formation and breakage occurs.

x) This process continues as the calcium ion concentration causes the formation of an action potential.

The above diagram represents the various stages involved in the cross bridge formation, sliding of filaments and breaking of the cross bridge. These processes occur during muscle shortening during its contraction and returning to its original state during relaxation.

The role of Ca2+ ions in muscle contraction are :

i) Stored calcium ions are released by the sarcoplasmic reticulum which binds into the specific sites of the troponin component of the thin filament.

ii) This binding causes a change in conformation of the troponin molecule and the active sites which are present on the F-actin molecules become exposed.

iii) The active sites of F-actin are specific to myosin head which have ATPase activity dependent on Mg2+ .

iv) Ca2+ is pumped back to the sarcoplasmic reticulum during the relaxation of the muscles.

v) This causes the masking of active sites of myosin head by the troponin component.

vi) The muscles get relaxed due to the breaking of cross-bridge and thin filaments occupying their normal position.

The above figure represents the role of calcium ions in the process of muscle contraction and muscle relaxation.

The difference between Pectoral and Pelvic girdle are :