Anatomy & Physiology II Lecture (1) PDF

ANATOMY & PHYSIOLOGY II Lecture (1)  CORSE CONTENT Integumentary System Endocrine System Lymphatic System Digestive System Urinary System General Revission And Solved Questions INTEGUMENTARY SYSTEM INTEGUMENTARY SYSTEM Introduction: The integument...

ANATOMY & PHYSIOLOGY II Lecture (1)  CORSE CONTENT Integumentary System Endocrine System Lymphatic System Digestive System Urinary System General Revission And Solved Questions INTEGUMENTARY SYSTEM INTEGUMENTARY SYSTEM Introduction: The integumentary system is the largest body organ and is composed of the: ✓ Skin ✓ Hair ✓ Nails ✓ Glands STRUCTURE OF SKIN The skin is further divided into three layers: a) Epidermis b) Dermis c) Hypodermis (The Subcutaneous Layer)  EPIDERMIS The epidermis is the outermost layer of the skin. In some places, the epidermis becomes thick and hard like on the palms, soles, and especially on heels. It is devoid of blood vessels in all places. The epidermis prevents germs and bacteria from entering and causing infections inside our bodies. It forms new skin cells. It contains melanin which provides color to the skin.  EPIDERMIS LAYERS Epidermis is sub-divided into following layers: Stratum basale Stratum spinosum Stratum granulosum Stratum lucidum Stratum corneum  EPIDERMIS LAYERS Stratum Basale (pronounced stray-tum bay-say-lee): The stratum basale is in the deepest layer of your epidermis. New skin cells develop in this layer. It also contains the keratinocyte stem cells, which produce the protein keratin. Keratin helps form hair, nails and your skin’s outer layer, which protect you from the harsh environment. It also contains melanocytes , which are responsible for producing melanin, which provides the pigment of your epidermis.  EPIDERMIS LAYERS Stratum spinosum (pronounced stray-tum spin-o-sum): The stratum spinosum is between the stratum Basale and granulosum layers. This layer mostly consists of keratinocytes held together by sticky proteins called desmosomes (dez-mo-soam). The stratum spinosum helps make your skin flexible and strong.  EPIDERMIS LAYERS Stratum granulosum (pronounced stray-tum gran-yoo-lo- sum): The stratum granulosum is between the stratum spinosum layer and the stratum lucidum layer. Keratinocytes have granules within them, which are visible under a microscope in this layer. Stratum lucidum (pronounced stray-tum loo-sid-um): The stratum lucidum is between the stratum granulosum and the stratum corneum. It’s a thin, transparent layer of keratinocytes that are becoming less round and have a flatter shape.  EPIDERMIS LAYERS Stratum corneum (pronounced stray-tum corn-ee-um): The stratum corneum is the top layer of the epidermis. This is the layer you see. In the stratum corneum, keratinocytes become corneocytes (corn-ee-o-site). Corneocytes are strong, dead keratinocytes that protect you from harm, including abrasions, light, heat and pathogens. This layer also consists of fats that keep water from easily entering or leaving your body. The corneocytes eventually shed as new keratinocyte cells develop in the stratum basale layer and move through the other layers of skin.  EPIDERMIS CELLS The epidermis contains 3 different types of cells, including: Keratinocytes: Keratinocytes produce the protein keratin, which is the main component of the epidermis. Melanocytes: Melanocytes make your skin pigment, known as melanin. Langerhans cells: Langerhans cells prevent things from getting into your skin.  DERMIS The dermis is the connective tissue below the epidermis. Dermal thickness varies from 1 to 4 mm. The dermis is very vascular.  DERMIS The dermis is divided into two layers, an upper thin papillary layer and a deeper, thicker reticular layer. The papillary layer is folded into ridges which extend into the upper epidermal layer. These exposed surface ridges form congenital patterns called fingerprints and footprints.  HYPODERMIS (The Subcutaneous Layer) The hypodermis is the innermost layer of the skin located under the dermis (outer layer) and the epidermis (middle layer). The thickness of the hypodermis varies in different regions of the body and can vary considerably between different people. The hypodermis layer also provides shaping and contouring. For those assigned male at birth, the hypodermis is thickest in the abdomen and shoulders. Whereas the hypodermis for those assigned female at birth is generally thickest in the hips, thighs, and buttocks.  HYPODERMIS STRUCTURE The hypodermis is a complex structure composed of different cells, tissues, glands, and vessels that work together to protect the body and ensure that it functions normally. The components of the hypodermis include: 1. Fibroblasts: This is a type of cell that produces collagen, the primary building block of skin, muscles, bones, tendons, ligaments, cartilage, and hair. 2. Adipose tissue: Also known as body fat, these are fatty tissues found under the skin (subcutaneous fat), around organs (visceral fat), in the breasts, and between muscles. 3. Connective tissue: These are dense, fibrous tissues made up of collagen and elastin that supports, protects, and gives structure to other tissues and organs in the body.  HYPODERMIS STRUCTURE 4. Blood vessels: These are the arteries, capillaries, and veins that deliver blood and oxygen to vital organs and remove waste products. 5. Lymphatic vessels: These vessels help regulate fluid levels in the body, receive waste products from tissues, and transport a fluid called lymph that defends the body against infection. 6. Hair follicles: These tube-like structures house each hair strand and extend into the hypodermis where the hair root is located. 7. Sweat glands: These tiny organs secrete sweat to keep the body at a normal temperature (98.6 F) whenever it is overheated. 8. Nerves: Large nerves pass through the hypodermis to the surface of the skin, including sensory nerves that register pain, temperature, and pressure  HAIR Hair or pili grows on most of the body except for the lips, the palms of the hands, and the soles of the feet The color of the hair is a result of heredity and is determined by the type and amount of melanin in the hair shaft. Hair grows approximately 1 cm per month. On average 100 hairs are lost each day. When lost hair is not replaced, baldness results  STRUCTURE OF HAIR The shaft is the superficial portion of the hair, which projects above the surface of the skin. The root is the portion of the hair deep to the shaft that penetrates into the dermis, and sometimes into the subcutaneous layer. The shaft and root of the hair both consist of three concentric layers of cells: medulla, cortex, and cuticle of the hair. Cuticle of the hair, the outermost layer, consists of a single layer of thin, flat cells that are the most heavily keratinized  STRUCTURE OF HAIR Surrounding the root of the hair is the hair follicle, which is made up of an external root sheath and an internal root sheath, together referred to as an epithelial root sheath. The dense dermis surrounding the hair follicle is called the dermal root sheath. The base of each hair follicle and its surrounding dermal root sheath is an onion-shaped structure, the bulb  NAILS Nails are plates of tightly packed, hard, dead, keratinized epidermal cells that form a clear, solid covering over the dorsal surfaces of the distal portions of the digits. Each nail consists of a : i. Nail Body ii. Free Edge iii. Nail Root.  NAILS The nail body (plate) is the visible portion of the nail. The free edge is the part of the nail body that may extend past the distal end of the digit. The free edge is white because there are no underlying capillaries The nail root is the portion of the nail that is buried in a fold of skin. The whitish, crescent-shaped area of the proximal end of the nail body is called the lunula. The proximal portion of the epithelium deep to the nail root is the nail matrix, where cells divide by mitosis to produce growth  SKIN GLANDS Two types of Skin Glands are present: 1) Sebaceous (Oil) Glands 2) Sudoriferous (Sweat) Glands  SKIN GLANDS Sebaceous (Oil) Glands: Sebaceous glands or oil glands are simple, branched acinar glands. They are connected to hair follicles. The secreting portion of a sebaceous gland lies in the dermis and usually opens into the neck of a hair follicle. Sebaceous glands secrete an oily substance called sebum, a mixture of triglycerides, cholesterol, proteins, and inorganic salts. Sebum coats the surface of hairs and helps keep them from drying and becoming brittle. Sebum also prevents excessive evaporation of water from the skin, keeps the skin soft.  SKIN GLANDS Sudoriferous Glands: There are three to four million sweat glands, or sudoriferous glands. The cells of these glands release sweat, or perspiration, into hair follicles or onto the skin surface through pores. Sweat glands are divided into two main types, eccrine and apocrine, based on their structure, location, and type of secretion. Eccrine sweat glands , also known as merocrine sweat glands, are simple, coiled tubular glands that are much more common than apocrine sweat glands.  SKIN GLANDS Sudoriferous Glands: They are distributed throughout the skin of most regions of the body, especially in the skin of the forehead, palms, and soles. Eccrine sweat glands are not present, however, in the margins of the lips, nail beds of the fingers, toes and eardrums. The secretory portion of eccrine sweat glands is located mostly in the deep dermis (sometimes in the upper subcutaneous layer)  FUNCTIONS OF INTEGUMENTARY SYSTEM Regulates body temperature – regulates heat loss Helps regulate fluid balance – absorbs water – prevents excessive water & electrolyte loss. – Slow loss up to 600 ml daily by evaporation Immune Response Function  FUNCTIONS OF INTEGUMENTARY SYSTEM Vitamin production – exposure to UV light allows for the conversion of substances necessary for synthesizing vitamin D – Necessary to prevent osteoporosis, rickets Excretion: – Partial excretion of metabolic wastes occurs through the skin. Transmits sensation – nerve receptors allows for feelings of temperature, pain, light touch and pressure  FUNCTIONS OF HAIR Head: UV protection Cushion from trauma Insulation Nostrils, Ear canals, Eyelashes: Prevent entry of foreign material Body Hair: sensory detection