Integumentary and Skeletal Systems PDF

# Integumentary System ## Points to be covered in this topic 1. Introduction 2. Structure of Skin 3. Functions of Skin 4. Regulation of Body Temperature ## Introduction - The integumentary system is the largest organ in the body. - It forms a protective covering for the body which is in contact wit...

# Integumentary System ## Points to be covered in this topic 1. Introduction 2. Structure of Skin 3. Functions of Skin 4. Regulation of Body Temperature ## Introduction - The integumentary system is the largest organ in the body. - It forms a protective covering for the body which is in contact with the external environment. - Skin plays an important role in the regulation of body temperature. - Skin consists of two layers - The outer layer is called epidermis - The inner layer is called dermis ## Structure of Skin ### Epidermis - It is the outer layer of the skin. - It is composed of stratified squamous epithelium. - Epidermis is divided into five layers, namely - Stratum corneum - Stratum lucidum - Stratum granulosum - Stratum spinosum - Stratum germinativum #### 1) Stratum Corneum - This is the most superficial layer - Keratin is present in the cells. - The nuclei are absent. #### 2) Stratum Lucidum - This is a thin, more or less transparent, glistening layer - The cell contains cytoplasm. #### 3) Stratum Granulosum - This layer contains spindle-shaped cells. - The cytoplasm and nucleus are present in these cells. #### 4) Stratum Spinosum - It contains polyhedral cells. #### 5) Stratum Germinativum - This layer is composed of single layer of columnar epithelium or cuboidal cells. - This layer is connected to the dermis - Melanin pigments are present in this layer ### Dermis - It is composed of connective tissue and is highly vascular. - It is made up of fibroelastic tissue which maintains the texture of the skin. #### Gland of the dermis 1. Sebaceous gland 2. Sweat gland 3. Ceruminous gland 4. Hair roots and erector pili muscles #### 1) Sebaceous Gland - They are flask shaped glands. - They secrete on oil like material called sebum - They have a duct which opens into a hair follicle . - It prevents excess evaporation of water from the skin and prevents drying of skin. - Sebaceous glands are present in the skin of many parts of the body except skin of palms of hands soles of feet. #### 2) Sweat Gland - There are two types of sweat glands Ecrine glands and Apocrine glands . - Ecrine glands are present all over the body. Apocrine glands are present in axilla, female genitalia and round the nipples, - Ecrine glands secrete watery sweat and apocrine glands secrete milky sweat. #### 3) Ceruminous Gland - They secrete wax in the external ear. #### 4) Hair Roots and Erector Pili Muscles - Contraction of these muscles produces straightening of the hair. ## Function of Skin 1. The skin protects the body against injury and bacterial invasion. 2. It regulates body temperature. 3. The skin serves as a medium for receiving the sensations like touch, pressure and temperature. 4. It excretes sodium chloride and metabolites like urea. 5. It maintains water and electrolyte balance. 6. The skin synthesizes vitamin D from ergosterol of skin by the action of ultraviolet rays of sunlight. 7. It synthesizes melanin from tyrosine. 8. It secretes sweat and sebum which keeps the skin soft. 9. It stores fat, water, chorides and sugar. ## Regulation of Body Temperature - The normal body temperature is 98.4°C (37°C). - The normal body temperature is maintained by a balance between heat production and heat loss. - Body temperature is controlled by Heat regulating centre present in the hypothalamus. ### Heat Production 1. During severe exercise, by the increased activity of muscles. 2. By the increased activity of liver and other glands in the body. 3. Increased intake of food (proteins). 4. Increased metabolism, like oxidation of food stuffs and combustion of fat. 5. Endocrine secretions like adrenaline and noradrenaline. ### Heat Loss 1. Radiation, body heat (temperature) is lost to the surrounding air. 2. Conduction, body heat is lost through clothing, bedding etc. 3. Convection, the hot air around the body moves up and it is replaced by cool air, and thus body heat is lost. 4. Sweating, the skin becomes cool and this leads to heat loss. 5. Evaporation of water from the skin, mucous membranes and respiratory passages, the body heat is lost. # Joints ## Points to be covered in this topic 1. Introduction 2. Classification of Joints 3. Movement of Joints 4. Joints of the Upper Limb 5. Joints of the Lower Limb ## Introduction - A joint or articulation is the connection made between bones in the body which link the skeletal system into a functional whole. - They are constructed to allow for different degrees and types of movement. ## Classification of Joints and their Function ### 1. Fixed or fibrous joints - Synovial cavity and ligament absent, fixed by sutures - No movement occur (Immovable) - Eg. Bones of skull, Bones of pelvic girdle - **Functions** - Fibrous joints strongly unite adjacent bones and thus serve to provide protection for internal organs, strength to body regions, or weight-bearing stability. - Fixed joints permit stability to certain areas of the body, although they do not move. ### 2. Cartilagenous of slightly movable gland - Bones separated by cartilage, synovial cavity absent - Cartilagenous or imperfect joints - Allow little movements - Eg. Between center of 2 vertebra, ribs and sternum - **Function** - Cartilage is a tough, elastic connective tissue that helps to reduce friction between bones. ### 3. Freely movable or synovial joints - Perfect joints - Allow freely movements in one or more directions - **Freely movable or synovial joints are classified in six types** - **(a) Ball and socket joints** - A joint in which the rounded surface of a bone moves within a depression on another bone, allowing greater freedom of movement than any other kind of joint. - Eg. Hip joints - **(b) Gliding joints** - It is a common type of synovial joint built between bones that meet on flat or nearly flat articular surfaces - Eg. Between vertebra, wrest and ankle bones - **(c) Hinge joints** - A type of joint that functions much like the hinge on a door, allowing bones to move in one direction back and forth with limited motion along other planes. - Eg. Knee joint, elbow joints - **(d) Pivot joints** - Pivot joints are joints that permit rotatory movement of bones, around a single axis. Pivot joint is a synovial joint in which the ends of two bones connect. - Eg.between radius and ulna and atlas and axis vertebrae - **(e) Elliopsoid joint** - A synovial joint in which an oval-shaped process of one bone fits into an elongated or ellipsoidal cavity of the other, allowing movements such as flexion, extension, abduction and adduction - Eg. Wrist or radio carpal joints - **(f) Saddle joints** - A saddle joint is a type of synovial joint in which the opposing surfaces are reciprocally concave and convex. - Eg. Carpo metacarpal joints of human thumb ## Movements of joints 1. Flexion : Bending movement. Usually forward but occasionally backward. ex.: Knee joint. 2. Extension: Straightening or bending backwards. 3. Abduction: It is the movement away from the midline of the body. 4. Adduction: It is the movement towards the midline of the body. 5. Circumduction: It is the combination of flexion, extension, abduction and adduction. 6. Rotation: It is the movement round the long axis of a bone (a) Medial rotation.(b) Lateral rotation 7. Pronation : It means turning the palm of the hand down. 8. Supination: It means turning the palm of the hand up. 9. Inversion: It is turning the sole of the foot inwards. 10. Eversion: It is turning the sole of the foot outwards. ## Joints of the upper limb 1. Sterno-clavicular joints: It is a gliding joint between sternum and clavicle. A pad of cartilage is present in the joint cavity between the bones. 2. Acromio-clavicular joint: It is formed by outer end of clavicle articulating with acromion process of scapula. 3. Shoulder joint: It is a ball and socket type of joint. It occurs between. head of humerus and glenoid cavity of scapula. - Movements of the shoulder joint: All types of movements like flexion, extension, adduction, abduction, rotation and circumduction are possible at this joint 4. Elbow joint: It is a hinge joint. It is formed by humerus above and radius and ulna below. - Movements of the elbow joint: Flexion and extension. 5. Radio-ulnar joint: This is formed by the articulation of radius and ulna at their upper and lower extremities. - Movements of radio-ulnar joint : Pronation and supination. 6. Wrist joint: It is a condyloid joint. It is formed by the lower end of radius and three carpal bones - Movements of the wrist joint: Flexion, extension, adduction and abduction are the movements which occur at this joint 7. Metacarpo - phalangial joint: They occur between metacarpal and phalangial bones. The movements at these joints are flexion, extension, adduction and abduction. 8. Inter-phalangial joints: They occur between phalangial bones of the same finger. Flexion and extension are the movements possible at this joint. ## Joints of the lower limb 1. Hip joint - It is a ball and socket type of joint. It occurs between acetabulum of innominate bone and head of femur the joint capsule is strengthened by three ligaments. They are: - "Ilio-femoral ligament" in the front. - "Pubo-femoral ligament" below. - "Ischio-femoral ligament" at the back. - Movements of the hip joint: Flexion, extension, adduction, abduction, rotation and circumduction occur at this joint. 2. Knee joint - It is a hinge joint formed by - Two condyles of femur articulating with the condyles of tibia, and - Patella. - Movements of the knee joint: Flexion and extension. 3. Ankle joint - It is a hinge joint formed by: - Tibia and its medial malleolus. - Lateral malleolus of fibula. both from a socket - Talus below - Movements of the ankle joint - Dorsi flexion. - Plantar flexion 4. Joints of the foot They are: - Tarsal joints - Tarso-metatarsal joints - Metatarso-phalangial joints - Inter-phalangial joints # Skeletal System ## Points to be covered in this topic 1. Introduction 2. Functions of the Skeleton System 3. Divisions of Skeletal System 4. Disorders of the Skeletal System 5. Skeletal Muscle 6. Physiology of Muscle Contraction 7. Neuromuscular Junction ## Introduction - The skeletal system includes all of the bones and joints in the body. - Each bone is a complex living organ that is made up of many cells, protein fibers, and minerals. - The skeletal system supports and protects the body while giving it shape and form. - This system is composed of connective tissues including bone, cartilage, tendons and ligaments. ## Functions of the Skeleton System - **Support** - The skeleton serves as the structural framework of the body by supporting soft tissues and providing attachment points for the tendons of skeletal muscles - **Protection** - The skeleton protects the internal organs from injury. - **Assistance in movement** - Most skeletal muscles are attached to bones, when these muscles contract, they pull the attached bones to produce movement. - **Blood cell production** - Blood cells are produced in the bone marrow. - **Triglyceride storage** - Yellow bone marrow consists mainly of adipose cells, which store triglycerides. - **Mineral homeostasis** - Bone tissue stores several minerals, especially calcium and phosphorus, which contribute to the strength of bone. ## Divisions of Skeletal System - The skeleton is subdivided into two major divisions - Axial skeletal system - Appendicular skeletal system ### 1. Axial Skeleton #### 1. Skull - The skull is situated on the upper end of vertebral column and its bony structure is divided into two parts - Cranium - Face #### A. Cranium - It is formed by flat and irregular bones that provide a bony protection to the brain. - It has a base on which the brain rests and a vault that surrounds and covers it - In adults the sutures between the bones are immovable. - The cranium consist of - 1 Frontal bone - 2 Parietal bones - 2 Temporal bones - 1 Sphenoid bone - 1 Occipital bone - 1 Ethmoid bone #### B. Face - The face is formed by 13 bones in addition to the frontal bone. This includes: - 2 Cheek bones - 1 Maxilla - 2 Nasal bones - 2 Lacrimal bones - 1 Vomer - 2 Palatine bones - 2 Inferior conchae - 1 Mandible #### II Vertebral Column - It is composed of a series of bones called as vertebrae. - The vertebral column, the sternum, and the ribs form the skeleton of the trunk of the body - The vertebral column consists of spinal cord. - It supports the head and serves as a point of attachment for the ribs, pelvic girdleand muscles of the back and upper limbs - The adult vertebral column consists of 26 vertebrae - 7 cervical vertebrae: These are in the neck region. - 12 thoracic vertebrae: These are posterior to the thoracic cavity. - 5 lumbar vertebrae: It supports the lower back. - 1 sacrum: It consists of five bones fused with sacral vertebrae. - 1 coccyx: It consists of four fused coccygeal vertebrae. ### Functions of Vertebral Column - It provides a strong bony protection for the spinal cord. - The pedicles of adjacent vertebrae form intervertebral for amina providing access the spinal cord for spinal nerves, blood vessels and lymph vessels. - It supports the skull. - The intervertebral discs act as shock absorbers, protecting the brain. - It forms the axis of the trunk, giving attachment to the ribs, shoulder girdle, upper limbs, the pelvic girdle and lower limbs. #### Parts of a typical vertebra - Body - Vertebral arch - Vertebral foramen - Pedicles - Processes - Atlas vertebrae - Axia vertebrae #### Cervical Vertebrae - The body of the cervical vertebrae is smaller and the vertebral arches are larger. - The cervical vertebrae have three foramina one vertebral foramen and transverse foramina - The vertebral foramen is the largest in the spinal column - Processes are split into two parts. Each cervical transverse process contains a transverse foramen through which the vertebral artery, vertebral vein and nerve fibers pass #### Lumbar Vertebrae - The lumbar vertebra is the largest and strongest vertebrae of the vertebral column. - The projections are short and thick. - The superior articular processes are directed medially instead of superiorly and the inferior articular processes are directed laterally instead of inferiorly. - The spinous processes are quadrilateral in shape, thick and broad and project straight #### Thoracic Vertebrae - These are larger and stronger than cervical vertebrae. - The spinous processes are long and flattened. - Thoracic vertebrae have longer and larger transverse processes. - The bodies of thoracic vertebrae have facets for articulation with the head of the ribs. #### Sacrum - It consists of five vertebrae fused to form a triangular bone. - The upper part of sacrum articulates with the 5th lumbar vertebra. - On each side it articulates with the ilium to form a sacroiliac joint, and at its inferior tip it articulates with the coccyx. #### Coccyx - It consists of four terminal vertebrae fused to form a small triangular bone, the broad base of which articulates with the tip of the sacrum. #### Thoracic cage - The bones of thoracic cage are divided in to - 1 sternum - 12 pairs of ribs - 12 thoracic vertebrae ### 2. Appendicular Skeleton - Human body has two pectoral girdles that The appendicular skeleton consists of the pectoral girdle with the upper limbs and the pelvic girdle with the lower limbs. #### Pectoral (Shoulder girdle) - pectoral girThe attach the bones of the upper limbs to the axial skeleton. - The dles consists of - 1 Clavicle - 1 Scapula #### Clavicle (Collar bone) - The clavicle is located between the ribcage (sternum) and the shoulder blade (scapula). - It is the bone that connects the arm to the body. - The clavicle lies above several important nerves and blood vessels. #### Scapula - Scapula, also called shoulder blade, either of two large bones of the shoulder girdle in vertebrates. - In humans they are triangular and lie on the upper back between the levels of the second and eighth ribs. #### Upper limbs (upper extremity) - The upper extremity or arm is a functional unit of the upper body. - It consists of three sections, the upper arm, forearm, and hand. - It extends from the shoulder joint to the fingers and contains 30 bones. #### Humerus - The humerus is the bone in your upper arm that's located between your elbow and your shoulder. - Its main function is to provide support for your shoulder and a wide variety of movements for your arm. #### Ulna - The ulna is one of two bones that make up the forearm, the other being the radius. - It forms the elbow joint with the humerus and also articulates with the radius both proximally and distally. - The main function of the ulna, along with the radius, is to assist with rotation. #### Radius - The radius, also known as the radial bone, is one of the two forearm bones in the human body, with the other one being the ulna. - It is instrumental in the shaping and use of hands #### Carpals - The carpal bones are bones of the wrist that connect the distal aspects of the radial and ulna bones of the forearm to the bases of the five metacarpal bones of the hand. - It consist of - Proximal row - Distal row #### Metacarpus (palm) - It consists of five bones called metacarpals - It consists of - Proximal base - Intermediated shaft - Distal head #### Phalanges (finger bones) - The phalanges are the bones that make up the fingers of the hand and the toes of the foot. - There are 56 phalanges in the human body, with fourteen on each hand and foot. - Three phalanges are present on each finger, and toe #### Pelvic - The pelvis is the area of the body below the abdomen that is located between the hip bones and contains the bladder and rectum. - In females, it also contains the vagina, cervix, uterus, fallopian tubes, and ovaries. - It consist of three bones - Ilium - Pubis - Ischium #### Lower limb (lower xtremity) - Each lower limb consists of 30 bones in four locations. - They consist of - Femur in the thigh - Patella (knee cap) - Tibia and fibula in the leg - 7 tarsals in the tarsus (ankle) - 5 metatarsals in the metatarsus - 14 phalanges (bones of the digits) in the foot #### Femur - The femur is the largest and strongest bone in the human body. - It is commonly known as the thigh bone and reaches from the hip to the knee - The main function of the femur is weight bearing and stability of gait An essential component of the lower kinetic chain. #### Patella (knee cap) - The patella is a small bone located in front of the knee joint where the thighbone (femur) and shinbone (tibia) meet. - It protects the knee and connects the muscles in the front of the thigh to the tibia. #### Tibia and fibula - Tibia and fibula are the two long bones located in the lower leg. - The tibia is a larger bone on the inside, and the fibula is a smaller bone on the outside. - The tibia is much thicker than the fibula. #### Tarsals - The tarsal bones consist of seven short bones located at the proximal region of the foot. - They are arranged in proximal and distal rows. - 1. Calcaneus bone: The largest tarsal bone that projects posteriorly as the heel. #### Metatarsals - The metatarsal bones, or metatarsus, are a group of five long bones in the foot, located between the tarsal bone of the hind- and mid-foot and the phalanges of the toes #### Phalangs - The 14 bones that are found in the fingers of each hand and also in the toes of each foot. ## Disorders of the Skeletal System 1. Herniated (Slipped) disc - If the anterior and posterior ligaments of the discs become injured, the pressure developed in the nucleus pulposus may be great enough to rupture the surrounding fibrocartilage. 2. Abnormal Curves of the Vertebral Column - Various conditions may exaggerate the normal curves of the vertebral column, or the column may acquire a lateral bend, resulting in abnormal curves of the vertebral column. 3. Scoliosis - It is a lateral bending of the vertebral column, usually seen in the thoracic region. 4. Kyphosis - It is an increase in the thoracic curve of the vertebral column. 5. Lordosis - It is an increase in the lumbar curve of the vertebral column. 6. Spina Bifida - It is a congenital defect of the vertebral column in which laminae of L5 and/or $1 .fail to develop normally and unite at the midline. # Skeletal Muscle - A muscle which is connected to the skeleton to form part of the mechanical system which moves the limbs and other parts of the body. - They play an essential role in respiratory mechanics and help in maintaining posture and balance. - They also protect the vital organs in the body. ## Structure of Muscle - Each skeletal muscle is an organ that consists of various integrated tissues. - These tissues include the skeletal muscle fibers, blood vessels, nerve fibers, and. connective tissue - Each muscle is wrapped in a a sheath of dense, irregular connective tissue called the epimysium, which allows a muscle to contract and move powerfully while maintaining its structural integrity. - Inside each skeletal muscle, muscle fibers are organized into bundles, called fascicles, surrounded by a middle layer of connective tissue called the perimysium. - Inside each fascicle, each muscle fiber is encased in a thin connective tissue layer of collagen and reticular fibers called the endomysium. - The endomysium surrounds the extracellular matrix of the cells and plays a role in transferring force produced by the muscle fibers to the tendons. - In skeletal muscles that work with tendons to pull on bones, the collagen in the three connective tissue layers intertwines with the collagen of a tendon. ## Function of muscle - Move the skeleton - Maintain body posture - Support soft tissues. - Guard body entrances/exits. - Maintain body temperature. - Store nutrients. ## Structure of Human Muscle - Nucleus - Sarcolemma - Myofibril - Muscle belly - Perimysium ## Physiology of Muscle Contraction ### Step 1: Motor Neuron Sends Message to Muscle to Contract - The motor neuron sends an impulse in the form of a neurotransmitter to the muscle to contract. - The neurotransmitter involved is acetylcholine which floats between an area of the neuron and muscle called as synapti cleft. ### Step 2: Muscle Depolarizes - Acetylcholine present in the synaptic cleft floats across to the motor end plate. - It then attaches to the receptors on transport proteins on the motor end plate. - When acetylcholine attaches to the transport proteins, it responds by opening and letting sodium into the cell. - The rushing of sodium inside the cell changes its potential as sodium is positively charged. - The cell potential changes and become less negative. ### Step 3: Release of Calcium by the Sarcoplasmic Reticulum - The sarcolemma contains tube like structures called T-tubules. - Inside the sarcoplasmic reticulum the calcium concentration is very high almost 2000 times greater than inside the muscle cell. - When the cell depolarizes the sarcoplasmic reticulum responds by opening the calcium channels in the terminal cisternae of the sarcoplasmic reticulum - The opening of calcium channels results in rushing of calcium into the sarcoplasm of the muscle cell. - This process is known as excitation-contraction coupling. ### Step 4: Calcium Binds to the Troponin on the Actin - Calcium present in the sarcoplasm of the muscle cell attaches to the troponin on the troponin-tropomyosin complex wrapped around the actin. - This changes the position of the troponin that exposes the myosin binding site on the actin. - The myosin can now bind with actin and forms what is known as a cross-bridge. ### Step 5: Myosin Pulls Actin Along - Myosin can now move at its hinge region and subsequently move the actin along. It causes actin and myosin to slide past each other. - The cycle of movement ends when the myosin releases from actin and return to its original position. - The energy required for one cross-bridge cycle is one ATP molecule. - ATP binds with the myosin head that has ATPase activity. - The ATP decomposes into ADP and a phosphate. - Calcium binds to troponin and exposes the binding site of the myosin which binds to actin and releases phosphate while extracting energy from the phosphate bond. - When myosin pulls actin along, ADP is released from the myosin head. - ATP binds with myosin head and breaks it into ADP and phosphate which remain on the myosin head. - Now the myosin head releases from the actin and regains its resting position with ADP and phosphate still on it. - The energy released from the ATP is now stored in the myosin head. - In resting muscles energy from ATP is stored in the myosin heads while they wait for another contraction. - Muscle contraction usually stops when signaling from the motor neuron ends, which repolarizes the sarcolemma and Ttubules, and closes the voltage-gated calcium channels in the SR. - Ca++ ions are then pumped back into the SR, which causes the tropomyosin to reshield the binding sites on the actin strands. - A muscle also can stop contracting when it runs out of ATP and becomes fatigued. # Neuromuscular Junction - Neuromuscular junction is a junction between a nerve ending and the skeletal muscle. - At this site, the nerve loses its myelin sheath and gets expanded to nerve endings. - These nerve endings pierce the sarcolemma and come in contact with the sarcoplasm of the muscle cell. - Acetyl choline is produced and stored in some vesicles present in this expanded portion. - Motor end plate is the part of the muscle facing the expanded nerve terminal. - The surface of motor end plate is convoluted and it has the enzyme Acetylcholinesterase. - Acetylcholine is inactivated by this enzyme, if it is produced in excess.