Plant Tropism and Growth Movements

• Plants utilize mechanisms enabling them to survive and respond to environmental changes through movement.
• Plant movements are often slow, making direct observation difficult, but their results are noticeable.
• Examples of movements include leaves turning towards the sun, flower opening/closing, stem twining, and bud unfolding.
• Stimuli for plant movements come from external sources and internal plant factors.

Plant Responses

• Tropism is plant growth toward or away from a directional stimulus, originating from one direction.
• Tropism is caused by differential growth, where one side elongates faster.
• The result of tropism is curving.

Types of Tropism as to Direction

• Positive tropism: growth towards a stimulus.
• Negative tropism: growth away from a stimulus.

Growth Movements

• These are responses to both external and internal stimuli and results in responses called tropisms.
• Plants react to a stimulus by growing toward or away from it.
• Growth movements occur when one part of a plant grows faster than others, causing bending.

Types of Tropisms

• Phototropism is growth response to light.
• Above-ground organs bend toward light, while aerial roots grow away.
• Positive phototropism: growth toward light.
• Negative phototropism: growth away from light.
• Geotropism is growth response to gravity.
• Roots growing towards the earth's center is an example.
• Positive geotropism: roots grow downward with gravity.
• Negative geotropism: stems and leaves grow upward against gravity.
• Thigmotropism is growth response to touch, resulting in curving towards or away from a solid object.
• Grape plants have thigmotropic stems that coil around supports.
• Hydrotropism is growth response to water/soil moisture, where roots move towards water.
• Chemotropism is growth response to a chemical stimulus.

Nastic Movements

• These are growth responses to environmental stimuli in different directions
• Nastic movements are independent to the direction of the stimulus

Types of Nastic Movements

• Epinasty is movements due to different growth rates, like flower buds opening in response to light.
• Seismonasty is movements due to mechanical stimulus (shaking), such as turgor movement in makahiya leaves.
• Nyctinasty is movements due to daily rhythms of light/day, such as the sleeping movement of legume leaves.

Photoperiodism

• Photoperiodism is the flowering response to the duration of continuous darkness.
• It causes different fruiting seasons.

Types of Plants as to Response to Photoperiod

• Day-neutral plants flower regardless of darkness duration, e.g., corn, roses, beans, sunflower, rice.
• Short-day plants flower when days are short, e.g., kataka-taka, poinsettia, strawberry, chrysanthemum.
• Long-day plants flower when days are long, e.g., cabbage, radish, wheat.

Turgor Movements

• Turgor Movements are responses of plant parts that are initiated largely by external stimuli.
• They are caused by differentiated changes in the water amount in the cells.
• Turgor movements are rapid, transient, and repeatable, unlike growth movements that are slow.
• Auxin appears to be a chief controlling agent in some cases.
• Opening and closing movements of guard cells in leaves/stems are significant turgor movements.
• Other turgor movements include contact movement in sensitive/carnivorous plants and sleep movements.

Types of Turgor Movement

• Guard cell movement: guard cells form the stomatal pore, which can open or close with changes in turgor.
• Turgor within the guard cells increases with additional water, causing them to swell and thin outer walls to curve out.
• Contact movement is a type of turgor movement brought about by contact stimuli.
• Sleep movement in plants is influenced by light intensity changes and is typical of legumes.
• Leaves assume specific positions during the night.
• Leaves are horizontal during the day and vertical (upright or hanging) during the night.

Integumentary System

• The integumentary system includes the integument and its derivatives/outgrowths.
• Dermatology is the study of vertebrate skin.
• The integument, commonly the skin, is the body’s largest organ which interfaces between the body and the environment.
• The skin of an average adult human covers about eighteen square feet and varies in thickness.
• The skin surface area is about 1.5 to 2 square meters in adults.
• The skin contains glands, hair, and nails, completely covering the body and continuing with membranes lining the body orifices.
• Skin protects from injury and microbes; contains nerve endings for pain, temperature, touch; regulates body temperature.

The Skin

• The integumentary system includes nails, hair, and skin to form the largest organ system.
• One of its main functions is waterproofing the body with the outer layer of dead, keratinized cells.

Functions of the Integument

• Protection: Waterproof layer that protects deeper structures from microbes, chemicals, physical agents, and dehydration.
• Sensory nerve endings in the skin cause reflex actions to unpleasant/painful stimuli, protecting from injury.
• Regulation of body temperature: Body temperature remains fairly constant around 36.8°C (98.4°F).
• Metabolic rate is reduced if temperature is raised.
• These sensory receptors are stimulated by changes in the external environment and generate impulses to the cerebral cortex.
• Some areas e.g., lips, fingertips have more sensory receptors than others.
• Absorption: Limited to substances like some drugs in transdermal patches (e.g., hormones, nicotine).
• Excretion: Excretes substances including sodium chloride (in sweat), urea, and aromatic substances.
• Formation of Vitamin D: 7-dehydrocholesterol in skin converts to vitamin D upon exposure to sunlight.
• Vitamin D circulates in the blood, aiding calcium and phosphorus in bone formation and maintenance.
• Excess vitamin D is stored in the liver.

Structures of the Integument

• Two Main Parts: Epidermis and Dermis

Epidermis

• Epidermis: Most superficial layer, composed of stratified epithelium, varying in thickness.
• Thickest on palms/soles; lacks blood vessels/nerve endings; nourished by interstitial fluid from dermis.
• Several layers of cells extend from the deepest germinative layer to the stratum corneum.
• Basal cells innermost are polygonal with fibers linked by desmosomes.
• Surface cells are flat, thin, non-nucleated, dead, with cytoplasm replaced by keratin.
• Cells are rubbed off and replaced by cells from the germinative layer undergoing gradual change as they progress.
• Complete replacement takes about 40 days.
• The epidermis is a stratified squamous epithelial tissue layer 10 to 30 cells thick.

Five Layers of Epidermis

• Stratum Corneum: Thin, non-living layer composed of stratified, flat squamous epithelial cells; the most superficial layers are continually flaking off, a process called desquamation or exfoliation.
• Stratum Lucidum: Clear layer with three or four layers of translucent cells containing eleidin (precursor of keratin).
• Stratum Granulosum: Granular layer with two/three layers of cells containing dark-staining granules of keratohyalin (precursor of eleidin).
• Stratum Spinosum: Several layers of irregularly shaped cells displaying spine-like processes.
• Stratum Basale/Germinativum: Living and growing layer with a single layer of columnar cells that undergo mitosis.
• Maintenance of healthy epidermis depends upon three synchronized processes.
• Desquamation of keratinized cells from the surface.
• Effective keratinization as cells approach the surface.
• Continual cell division in deeper layers to push cells to the surface.
• The epidermis surface is ridged by the projection of cells in the dermis called the papillae.
• Papillae patterns are unique (fingerprint).
• Downward projections of the germinative layer between the papillae nourish epidermal cells and stabilize two layers.
• Blisters develop when trauma separates the dermis and epidermis, and serous fluid collects between the layers.

Epidermal cells

• keratinocytes - 90% of epidermal cells, produce keratin
• melanocytes - 8% of epidermal cells, produce melanin
• Langerhans cells - capable of trapping antigen in the skin
• Merkels cells - make contact with the ending of a sensory neuron

Dermis or Corium

• Dermis/Corium: Tough, elastic layer composed of collagen fibers inlaid with elastic fibers.
• Rupture of elastic fibers leads to stretch marks.
• Collagen fibers bind water, giving skin its strength; decline with age causes wrinkles.
• Areolar tissue and varying amounts of fat underlie the deepest layer.
• It is made up of fibrous connective tissue containing collagen and elastic fibers but it also contains muscles fibers, glands, pigment cells, blood vessels, and sensory nerves.
• 15x to 40x thicker than the epidermis; provides structural support and a matrix for nerves, muscles, and specialized cells.

Regions of the Dermis

• Papillary region consists of loose connective tissue, forms dermal papillae, some with tactile receptors (Meissner's corpuscles).
• Reticular region consists of dense, irregular connective tissue, attached to underlying organs.

Structures in the Dermis

• Blood Vessels: Arterioles form capillary networks to supply sweat glands, sebaceous glands, hair follicles, and the dermis.
• Epidermis has no blood supply; obtains nutrition/oxygen from interstitial fluid in papillae.
• Lymph Vessels: Form a network throughout the dermis and deeper layers of the epidermis.
• Sensory Nerve Endings: Nerve endings sensitive to touch, temperature change, pressure, and pain.
• Sensations are conveyed to the spinal cord and cerebrum.
• Sweat Glands: Widely distributed, numerous in palms, soles, axillae, and groins; coiled in subcutaneous tissue.
• Some open onto the skin surface at pores; others open into hair follicles.
• Glands opening into hair follicles activate at puberty and secrete odorless milky fluid whose surface microbes cause odor.
• Functions of this secretion are not known.
• Sweat glands are stimulated by sympathetic nerves in response to raised body temperature and fear.
• The most important function of sweat secreted by glands opening on to the surface is the regulation of body temperature.
• Evaporation of sweat on the surface takes heat from the body and the amount is produced is governed by the temperature-regulating center in the hypothalamus.
• Excessive sweating may lead to dehydration and serious depletion of body sodium chloride unless intake of water and salt is appropriately increased. After 7 to 10 days exposure to high environmental temperature, the amount of salt lost, is reduced but waterless remains high.
• Hairs: Formed by epidermal cell down-growth into dermis/subcutaneous tissue as hair follicles.
• At the follicle base is the bulb where cell multiplication forms the hair.
• Cells die and become keratinized when pushed upwards.
• Hair color depends on melanin; white hair results from replacing melanin with tiny air bubbles.
• Arrectores Pilgrim: Little bundles of involuntary muscle fibers attached to hair follicles.
• Contraction makes the hair stand erect and raises skin, causing "goose flesh."
• Muscle stimulated by sympathetic nerve fibers stimulated by fear and cold.
• Though small, contractions generate appreciable heat in response to fear and cold.
• Sebaceous Gland secretes oily sebum that keeps hair soft and pliable and also gives hair a shiny appearance.
• They are present in the skin of all parts of the body except the palms of the hands and the soles of the feet.
• Sebum is secreted into the hair follicles, keeping hair soft, pliable and present in the skin of all parts of the body except that the ones where there is no hair follicle.
• There are sebaceous glands thatare not associated with a type of skin that lacks hair folecules , secreting sebum directly in to the surface such as lips, eyelids, nipple, labia minora and glans penis.
• Sebum provides waterproofing and is a bacterial/fungicidal agent.
• It prevents drying and cracking of skin, especially on exposure to heat/sunshine.
• Glands increase at puberty and decrease at extremes of age, rendering infants/elderly prone to moisture effects (e.g., nappy rash).
• Nails: Equivalent to claws/horns of animals; derived from the same cells as epidermis and hair.
• They consist of hard, horny, and keratinized dead cells, and protect tips of fingers and toes.
• Fingernails grow more quickly than toenails, especially when environmental temperature is high.

Receptors

• Receptors place the body in sensitive touch with the outside world and is accomplished through external receptors or sensory nerve terminals.
• These receptors respond to pain, heat, cold, touch, and pressure.

Types of Receptors

• Pain Receptors or Nociceptors: Naked nerve filaments found throughout the skin and in several other areas.
• They are most numerous of all five kinds of receptors.
• Meissner's Corpuscles: Encapsulated receptors located in dermal papillae of fingers/toes, lips, mammary glands, and genitals.
• They are tuned to the sense of touch.
• Ruffini's Corpuscles: Branching nerve endings in the skin that are sensitive to heat.
• Pacini's Corpuscles: Receptors found in deeper parts of the skin covering hands/feet.
• Some occur throughout subcutaneous tissue in muscles, mesentery, and mesocolon.
• Krause's Corpuscles: Cold receptors (end bulbs of Krause) consisting of a spheroid capsule enclosing a granular mass and a terminal neuro fibril.
• They are located in the mucous membrane of the mouth, nose, eyes, and genitals.

Subcutaneous layer

• The subcutaneous layer composed of fat-rich cells, acts as shock absorbers and also provides insulation to conserve body heat.

Cutaneous or Dermal Glands

• Cutaneous/dermal glands originate from epidermal cells invaginating into the dermis.

Types as to methods of secretion

• merocrine glands - "true glands"; not destroyed during secretion; sweat glands
• apocrine glands - part of the cell is destroyed that go with the secretion
• holocrine glands the entire cell goes with the secretion but a new cell is produced to replace it; sebaceous or oil gland

Types as to secretory products

• serous glands - watery substances; sweat glands
• sebaceous glands - oily substance called sebum
• mucous glands - substance with mucin

Keratinized, non-living structures found on the outer layer of the epidermis

• Keratinized, non-living structures found on the outer layer of the epidermis includes
  • hair of mammals
  • feathers of birds
  • nails or claws
  • beak
  • scales of reptiles. -carapace/scutes of turtles
  • true horns (hollow)

Dermal derivatives

• false horns (solid)
• plates of turtles
• scales of fishes

Basal Cell Cancer

• Basal cell cancer is the most vast majority of all skin cancers, affecting the upper layer of the skin.
• Symptoms of basal cell cancer include skin growths and lesions varying in color from white to brown and maybe be raised or flat.

Alopecia Areata

• Alopecia Areata is a non-contagious autoimmune condition where your own immune system attacks the hair follicles.
• The disease results in hair loss in some or all regions of the body, especially the scalp, leading to baldness.
• This condition is also known as spot baldness, causing bald spots on the scalp in the initial stages
• This condition affects around 0.2% of people initially in earlier stages of development, however can really affect anybody.

Warts

• Warts are diseases of the integumentary system, characterized by tiny, round, rough tumors typically found on the hands and feet.
• Warts are caused by various types of human papillomavirus.
• Warts are contagious and spread through human contact.
• Warts resemble a cauliflower or solid blister on the skin.
• When situated on the feet they can be exacerbating and they can usually disappear after a few months, however, they can be safely removed as well.

Dermatitis

• Dermatitis is a general term used to describe inflammation of the skin.
• There are different types of dermatitis, including seborrheic dermatitis and atopic dermatitis (eczema).
• This disorder can have many causes presenting itchy rashes that spread to increased redness and swelling.
• This skin disorder is not life-threatening or contagious, but it can be uncomfortable and self-conscious.

Athletes foot

• Athletes foot (tinea pedis) a fungal infection of the skin that causes scaling, flaking and itchness of various areas of the skin.
• It is trasmitted mostly in most areas where people walk barefoot, example bathhouses, showers, etc.
• This condition typically affects the feet, but it can also spread to other areas such as the groin.
• To help prevent Athletes foot, maintain good hygiene.

Melasma

• Melasma is abnormal dark pigmentation on the face, especially around the upper cheeks, nose bridge, forehead, and upper lip; usually appears symmetrically.
• It can also appear on other parts of the body that are exposed to sunlight.
• Also known as Chloasma and is usually tan (muddy brown or dark gray).
• Melasma is common in women, resulting from hormonal changes in pregnancy (half of all pregnant women).
• Sometimes known as “the mask of pregnancy.”
• Melasma can also be caused by birth control pill and hormones.

Acne

• It is the rarest of all skin cancers but it is the rarest and most deadly.
• It spreads rapidly, attacking the cells that produce pigment, or skin coloring.
• The color melanoma in skin varies, and they often have irregular borders, change shape/size, and sometimes bleed.
• It is important to watch for changes in existing moles.

Tinea

• Tinea is a type of fungal infection caused by dermatophytes, which invade the keratin of nails, hair, and skin.
• These species belong to the genera Microsporum, Trichophyton, and Epidermophyton and can infect human beings.
• Tinea, also known as dermatophytosis, can spread the infection in three different ways.
• Antropophilic means that the infection can be spread from human to human.
• Zoophilic on the other hand pertains to the type of infection that can spread from animal to human.
• And lastly, geophilic means spreading of infection from soil to human.

Seborrheic dermatitis

• Seborrheic dermatitis is a skin disorder affecting the scalp.
• It is also known as cradle cap when it occurs in infants.
• It can affect the scalp and cause stubborn dandruff, and it also affects the face, chest, back, and other areas that are oily, with or without red skin.
• Seborrheic dermatitis is not contagious, but it looks unattractive and may cause the person to feel uncomfortable, leading to secondary infections and people with low self-esteem.
• Often confused with other skin disorders, and it often takes a dermatologist to discern the difference and to prescribe an appropriate course of treatment.

Skin Cancer

• Psoriasis is a non-contagious skin disease that causes rapid reproduction of skin cells resulting in red, dry patches of skin.
• Psoriasis is commonly found in areas such as knees, elbows, and scalp.
• It causes dry, flaky skin scales.

Skin Cancer

• There are three separate forms of skin cancer that are recognized.
• Carcinoma
  • Comprises only sixteen percent of all skin cancers, and it attacks the mid layers of skin.
  • Presenting the same symptoms as basal cell cancer.

Skeletal System

• Humans have a great posture that are talking about covers in our discussion about skeletal system.
• The importance of skeletal should be more appreciated to more deeply know the use of each part of the skeleton.
• The word "skeleton" came from the Greek word meaning "dried up body".
• Osteology is the study of bone and bones, the hard supporting tissues of the body.
• Skeleton is a structural framework that supports the body against gravity and also provide beverage for the action of muscles and the movement of the body's part.

Functions of the Skeletal System

• Support the body
• Protection of internal organ
• Assists in movements
• Storage of minerals
• Production of blood cells
• Gives stability and shape to the body
• Storage of chemical energy

Types of Skeleton

• refers to the framework of the animal body, composed of cartilage, bone, or a combination of both.

As to Formation

• Membrane/dermal bone
• Formed by direct ossification in connective tissue without an intervening cartilage stage
• Endochondral/cartilage bone
• Formed by replacement of pre-existing cartilage

Kinds of Bone Tissue

• Spongy Bone Tissue
  • Located at the ends and interiors of long bones
  • also called bone marrow
  • composed of an open lattice of bone.
  • within this lattice framework, RBC are produced
• Compact bone tissue
  • surrounds the spongy bone tissue
  • also found at the core of bones
  • gives strength to withstand mechanical stress.

As to Location

• Exoskeleton or dermal skeleton
  • built up outside the body
  • muscles are attached to the inner surface
  • limits the size of animals formed
  • from a secretion called chitin which is made hard by the deposition of calcium salts
  • characteristics of arthropods
• Endoskeleton
  • built up inside the body
  • muscles are attached to the outer surface
  • characteristics of vertebrates
  • divided into axial and appendicular skeletons

Division of the Skeleton

• The axial skeleton, which includes the bony framework of the head and the trunk.
• The appendicular skeleton, which forms the framework for the extremities (Limbs) and for the shoulder and hips.

Axial Skeleton

• Axial skeleton forms the main axis of the body and is composed of the notochord, vertebral column, ribs, sternum, and skull.
• Notochord - the primitive axial skeleton is unsegmented and composed of dense fibrous connective tissue and the first skeletal element to appear in the embryo of chordates and is replaced by the vertebral column.
• Vertebral column - the main axial support of vertebrates is commonly called backbone and is also composed of segmentally arranged vertebrate from the base of the skull to the tip of the tail.
• The vertebral Column protects the spinal cord and provides rigidity to the body.
• The 26 vertebrae in man are divided into cervical, (7), thoracic (12), lumbar (5), sacral (1), and caudal vertebrae (1), the spine consist of 33 separate bones before birth but nine of these eventually fuse, vertebrae are named and numbered starting at the top.
• Regions of the vertebral column:
• In fishes - 2 regions, trunk and tail
• In frogs - 4 regions, no neck
• In salamanders, reptiles, birds, mammals - five regions, neck, thoracic, lumbar, sacral, tail
• Ribs are serires of cartilaginous or elongated bony structures attached to the vertebrae.
• Sternum - commonly called as the breast bone is an elongated structure lying in the mid-ventral region of the anterior trunk and articulates with pectoral girdles and strengthen the anterior part of the trunk.
• The skull is the framework of the head and is composed of cartilage and three parts of sense of capsule (cranium, dermatocranium, and splanchocranium).

Appendicular Skelton

• Axial Appendicular skelton consists of the interior pectoral appendages and girdle and the posterior pelvic appendages and girdle.
• The bony framework of the head is called the skull.
• The frontal bone forms the forehead, the front of the skull's roof over the eyes and the nasal cavities. -The two parietal bones form most of the top and side of the walls of cranium.
• The two temporal bones form part of the sides and some of the base of the skull.
• The occipital bone forms the back and a part of the base of the skull. -The foramen magnum, located at the base of the occipital bone, is a large opening through which the spinal cord communicates with the brain.

Composition of the Appendicular Skeleton has four parts :

• Pectoral girdle - scapula (shoulder blade), coracoids, clavicle (collarbone).
• Forelimbs - humerus (upper arm), radius and ulna (forearm), carpals (wrists), metacarpals (palm), phalanges (fingers).
• Pelvic girdle (hip bones) – ilium, ischium, pubis.
• Hindlimbs - femur (thigh), tibia and fibula (shank), patella (knee cap), tarsals (ankle), metatarsals (sole), phalanges (toes).
• There are total of 206 bones in human adult, while the infant has 350 bones broken up by the follwing:
  • Skull (cranium + face):-22 (8+14)
  • Ears:-6
  • Hyoid: -1 -Vertebral column: -26 -Sternum: -1 -Ribs: -24 -Pectoral girdle: -64 -Pelvic girdle and hindlimbs: -62
• Every bone in the human body is a collection of several different combinations of the organic matrix laden with the calcium.
• Joints is the articulation between cartilages or bone and the study of joints is known as syndesmology.

Amount of Movement and Structural Composition

• Synarthroses - immovable joints, connected by fibrous tissue cartilage- like sutures, which are the lines of junction of the skull.
• Amphiarthroses - slightly movable joints; symphysis, a joint where two long bony surfaces are connected by a broad, flat disc of fibrocartilage.
• Diarthroses - freely movable joints, most common joint in the body.

Types of Diarthroses

• Gliding joint - gliding movement only; wrists, ankles, vertebrae.
• Ball and socket joint - permit full freedom movement.
• Pivot joint - movement in the long axis of a bone.
• Biaxial or saddle joint concave in one direction and convex in another metacarpal bone of the thumb.
• Hinge joint - angular movement in one direction.
• Condyloid joint - angular movement in all planes but no axial rotation. The wrist joint, between the radius and carpals, is a good example.
• Gait is the manner of walking of animal or the manner by which any part of the foot or hand in contact with ground when animal walks.

Types of Gait

• Plantigrade - entire sole of the foot touches the ground; man, apes, bears, raccoons.
• Digitigrade - which the digits are provided with pads touch the ground and the rest of the foot is elevated as in cat.
• Ungultigrade - tips of the digits (specialized into hoofs) touch the ground; ungulates or hoofed animals, cows, carabaos, pigs, horse, goats

Bone structure and formation

• Bone is a special form of cartilage in which the collagen are coated by calcium phosphate salt.
• Bone is formed in 2 stages:
• • Collagen is laid down in a matrix of fibrils along lines of stress.
• • Calcium containing minerals (hydroxyapatite) impregnate the fibril.
• Hydroxyapatite provides rigidity while collagen provides flexibility.
• Bone is laid down in concentric layers called lamellae.
• Lamellae are laid down as a series of tubes around narrow channels called haversian canals.
• Haversian canals are interconnected containing blood vessels and nerve cells. Disorders associated with skeletal system

Disorders associated with skeletal system with bone structure and formation

• Compound fracture of the tibia and fibula bones, breaking completely in several locations.
• Spiral fracture of the leg with a spiral fracture of the tibia.
• Dislocated shoulder - the humerus is dislocated anteriorly and medially.
• Whiplash of the head and neck movement and position of the head and spine when caught in whiplash, with the normal position of the head.

Health Sciences Discussion of Disorders

• Discussion of disorders with discussion of disorders:
  • Arthritis: Arthritis is an inflammatory condition of one or more joints, accompanied by pain and often by changes in bone position.
  • Gout: Gout includes an increase of uric acid in the bloodstream, Uric and Crystals are deposited in joint cavities and kidneys. -Rickets - usually found in children and caused by a lack of vitamin D. Bones become soft, due to lack of calcification, causing such deformities.
  • Whiplash injury- Trauma to the cervical vertebra, usually the result of an automobile accident. The force generated by the strain on the cervical spine and neck muscles.

Abnormal Curvatures of the Spine

• Kyphosis - (Hunchback) is a humped curvature in the thoracic area of the spine.
• Lordosis - (Swayback) is an exaggerated inward curvature in the lumbar region of the spine just above the sacrum.
• Scoliosis – is a side-to-side or "lateral curvature" of the spine.
• Osteoporosis - lose in bone mass leaves the bone thinner, porous, and susceptible to fracture.
• Osteomyelitis: An infection, which may involve all parts of the bone, may result from injury and occurs in children 5-14 years. -Osteosarcoma: Bone cancer may occur in younger people and occurs just above the knee.

Muscular System

• The muscular system includes the organ, which by their contraction and relaxation facilitate movement of the body and the muscle cell is the structural unit, which is long and provided with myofibrils that enable them to shorten or contract.
• In man, the great bulk of the body consists of muscles. It is attached to the skeletal system and they give the body a graceful symmetry.
• Muscles are contractile. They are irritable.
• They are elastic and flexible so they can return to original position. They are covered by sarclolemma and they all have blood vessles and nerves.

Functions of Muscles

• Motion - move the body and its appendages;
• Contraction of skeletal muscle is equally important in breathing and in moving body fluids.
• Heat production- Muscles constitute nearly one half of the body weight and are in the continuous state of fiber activity and are very important in the production of heat.
• Posture and body support- Muscles maintain posture and support around the flexible joints.
• Elasticity- Muscle tissue has an innate tension that causes it to assume a desired shape and tightness.

Muscles can perform functions in three ways.

• Voluntary function =
• • maintain posture
• • accomplish movements
• Involuntary Function =
• • propulsion of substances through body passage
• • regulation size of opening
• -regulation of diameter of tubes

Types of Muscles

• Striated Voluntary Muscle Tissue - designed primarily to give movement to the skeletal framework through gross of action directed by higher centers of the brain
• Smooth Involuntary Muscle Tissue - also called visceral muscle and is composed of elongated, spindle-shaped cells with large elongated nuclei. It is involuntary and contains homogenous or clear sarcoplasm and centrally located nucleus.
• Striated Involuntary Mucle Tissue - also called cardiac muscle - muscle tissue that composes most of the wall of the heart.
• It is involuntary, has the ability to contract/respond, and is found in the walls of the heart causing involutary contraction.

Classification of muscles

• Agonist or prime mover: Each muscle bears the responsibility for a specific process.
• Antagonist: the muscle produces the opposite action.
• Synergist: The muscle helps to stabilize the action of one joint so that the force can be applied at the desired point.
• Fixator: The muscle fixes the position of a limb when movement is occurring in the distal pint.

As to Specific Function

1. Flexors

• draw one segment toward another. -Extensors: - straighten segments of part ex: limbs @ vertebral column for a joint.

2. Adductors: to draw a part toward the ventral surface. -Abductors cause displacement away from ventral surface.
3. Protractors:

• cause a part to be moved forward, outward. -Retractors - pull a part backward/ inward.

4. Elevators/levators

• raise a part. -Depressors: lower a part.

5. Rotators to cause a rotation of a part on its axis -Supinators rotate & turn part ex: Palm upward. -Pronators rotate palm / make it Prone -Tensors can cause a part ( eardrum) to be made taut.
6. Constrictors: compress internal parts: -Sphincters make opening smaller. -Dilators make an opening bigger
7. Skeletal muscles are further classified into:

• -Axial muscles – attached to the skull, vertebral column, ribs, and sternum.
• -Appendicular muscles – attached to appendiculars (bones in limbs, pectoral & pelvic).
• -Branchiometric muscles – viseral skeleton.
• -Integumentary muscles – skeletal on skin.

Structure of the Skeletal Muscle

• The entire muscle is surrounded by an external connective tissue wrapping called the epimysium.
• -Skeletal muscle is made up of fascicles, which are bundles of individual muscle cells called muscle fibers.
• Each fascicle is surrounded by connective tissue layer called the perimysium.
• Within the fascicle, the third connective tissue layer, the endomysium separates and electrically insulates the muscle fibers from each other.
• All (3) connective tissue layers bind the muscle cells together providing strength & support the the muscle.
• *Each muscle fiber is subdivided by the sarcoplasmic reticulum into smaller cylinders called myofibrils.
• The myofibril is composed of sacromeres, attached end to end.
• Within each sacromere are alternating thin & thick myofliaments (actin, mysoin proties).
• Arrangement (thin/thick) w/ alternating bands (Light (l band ) - Dark (A)) w/ striations along myofibris.

Muscle Proteins

• Myosin- make the the thick myofilaments.
• Actin- - compose the thin myofilaments.
• Troponin: subcomponenet
• Tropomyosin"
• Muscle Metabolism
• Energy (Muscle) =ATP; synthesis (muscle cells);
• 2Types Muscle Cells

1. White :ATP synthesis-> Glycolysis (rapid- powerful, fatigued.)
2. Red: -""-Kreb - high endurance."

• Motor unit = Neuron +muscles.
• Stimulus ( Unit #) = the degree of stimulus ( # increases),
• Small Motor Unit =few unit(precise, need)
• Bigger "-" ( larger "#"-gross, needs)
• Composition;

Structure of Myofilaments

• 1 (think mysoin): Tail +2heads. [H hasability to Move, move stroke] & ATP.
• Tail allows movement. 2-thin fill: Actin (twisted heflical, chained to myosin.)
• Tropormyosin -cover-cross bind side
• Tropanin- (attaches, spaved period)

Calcium los

After + potential Calcium is released & bond causes exchange -dregs bond site, Muscle contractions produce Force through the process of contraction and may change its shape, but its volume remains the same.

Types=

• 1- lsotiomic, shortened ( biceps brachi)
• 2-lsiometric tension " the muscle does NOT Shorten;

Stimulation Contraction:

• Potential at Axxon * changed U & opens V channels:

1. causes CA * enters push veside.
2. acH releases. Synapit cleft, & binds site;
3. -ACH removed & enzymes ac.cholinesteredose:

• Influx Na, K Causes local depolar
• Depolar initact POTENTIAL
• Potential causes influx CA * triggers contract.

Contraction Myofliaments"

Theory - Explain gliding + A F Hurley, & AE Hurley +mole+ CA Steps Contract

• (influx Ca*) bino sites
• Binding My+Ac expense ALOP
• Power stroke mysim sliolin
• Bind ATP to crass bridle
• Hydrolysis of ATP * CA is over

Disorders And Disases (Muscle System)

• Rbeunatizm: general use but obsolete: pain, sore, stiff @ Joints -muscles Ex:" " gout, Fever, osteo, Mysositis, Brusitis, & Rhumotoiol Arthilis
• Gout: Complex cause, over prod. / brk dwn Proteln. (high levels.
• DIET high malt)
• Arthis: (One Of many- over loO"s) pain, stiffm joints swell Degrader Joint Dicas -seriou / most painful :due Auto Innue/ Can occur -sides bod; Hands, -anktes, or Feet.
• The Joint System has A Synovital tissue & inflammation.
• Can lead- Severe damage & the patieris mobility Joints MAY Erode & Bone Will dislocate/ freeze in position