25-26 NURS1604 - Structural organization of body, integumentary system

The Umbilical Region includes the Umbilicus (navel), parts of the small intestine, and duodenum.

The Hypogastric Region contains the Urinary Bladder, Sigmoid Colon, and Female Reproductive Organs.

The Left Lumbar region contains the left kidney, colon, and small intestine.

The Right Iliac region contains the Appendix and cecum (阑尾 and 盲肠).

The Left Iliac region includes the Descending Colon and Sigmoid Colon.

The integumentary system consists of:

• Skin
• Associated organs:
  • Hair
  • Sweat glands
  • Sebaceous glands
  • Arrector pili muscle

The primary cell types found in the epidermis include:

• Squamous cells
• Basal cells
• Melanocytes

Sensory acuity can be assessed by two-point discrimination, which measures the shortest distance at which two nearby stimuli can be distinguished as separate.

The main components include:

1. Cells - The basic unit of life.
2. Tissues - Groups of similar cells performing a specific function.
3. Organs - Structures composed of different tissues working together.
4. Organ Systems - Groups of organs that perform related functions.
5. Organism - The complete living entity made up of various systems.

Anatomical planes are important for:

• Describing locations: They provide a standard reference for locating structures.
• Facilitating communication: They help healthcare professionals communicate effectively about body parts.
• Guiding procedures: They assist in surgical and diagnostic procedures by defining approaches to the body.

The major body regions include:

The integumentary system consists of:

• Skin: The largest organ, providing protection and regulating temperature.
• Hair: Offers insulation and protection.
• Nails: Protects the tips of fingers and toes.
• Glands: Includes sweat and sebaceous glands that help with temperature regulation and skin lubrication.

Skin burns are classified into three types:

1. Chemical level: Atoms and molecules (e.g., DNA)
2. Cell level: Smooth muscle cell
3. Tissue level: Smooth muscle tissue
4. Organ level: Stomach (includes serous membrane, smooth muscle tissue layers, and epithelial tissue)
5. System level: Digestive system (includes esophagus, liver, stomach, pancreas, gallbladder, small intestine, and large intestine)
6. Organism level: Overall organism (e.g., a small child with the digestive system highlighted).

The Right Lumbar region contains the right kidney, colon, and small intestine.

The Sagittal plane divides the body into left and right halves, allowing for the examination of structures in a medial-lateral orientation.

The Frontal (coronal) plane divides the body into front (anterior) and back (posterior) halves, contrasting with the Sagittal plane which separates left and right.

The Transverse plane divides the body into upper (superior) and lower (inferior) halves, providing a cross-sectional view of the body.

The abdomen is inferior to the thorax.

The leg is distal to the thigh.

The nose is medial to the ears.

The appendicular region includes the upper limbs and lower limbs.

The axial region consists of the head, neck, thorax, abdomen, and pelvis.

The human body is divided into two main regions:

1. Axial region (body core): includes the head, neck, thorax, abdomen, and pelvis.
2. Appendicular region: includes the upper and lower limbs.

The Ulnar Nerve is located on the medial side of the hand, while the Median Nerve is positioned centrally. The Radial Nerve is found on the dorsal side of the hand.

The foot has a dorsal surface (top) and a plantar surface (bottom).

The key anatomical landmarks on the plantar view of the foot include:

The prefix 'epi-' means near to, or above. For example, 'epidermis' refers to a layer of cells near to the dermis.

The prefix 'hypo-' indicates inferior. An example is 'hypodermis', which refers to a layer of cells below the dermis.

The prefix 'supra-' signifies superior. For instance, 'supra-renal gland' refers to an endocrine gland that is superior to a kidney, also known as the adrenal gland.

The Right Hypochondriac region contains the Liver, gallbladder, right kidney, and small intestine.

The Epigastric Region contains the Stomach, liver, pancreas, duodenum, and adrenal glands.

The Left Hypochondriac region includes the Spleen, colon, stomach, left kidney, and pancreas.

The layers of the skin are:

1. Epidermis - the outermost layer
2. Dermis - the thicker layer beneath the epidermis
3. Subcutis - the innermost layer containing fat cells

The largest organ of the human body is the skin, which is composed of epithelium and connective tissues.

The skin covers an approximate surface area of 1.5 - 2 m² and weighs between 4 – 5 kg.

• Thin skin: approximately 1.5 mm thick
• Thick skin: approximately 4 mm thick (found in palms and soles)

1. Epidermis: Keratinized stratified epithelium
2. Dermis: Loose and dense connective tissue
3. Hypodermis: Subcutaneous layer consisting of adipose tissue, located beneath the dermis and next to muscle and bone.

The four layers (strata) of the epidermis are:

1. Stratum corneum (SC)
2. Stratum granulosum (SG)
3. Stratum spinosum (SS)
4. Stratum basale (SB)

The four cell types in the epidermis are:

• Keratinocytes
• Melanocytes
• Merkel cells
• Langerhan's cells

Keratinocytes are the predominant cell type in the epidermis, and their primary function is to form a waterproof barrier by being filled with keratin, a type of protein.

Melanocytes produce melanin, a pigment that is transferred to keratinocytes, contributing to skin color and protection against UV radiation.

Melanocytes produce melanin and transfer it to keratinocytes. This relationship helps in providing pigmentation to the skin and protecting it from UV damage.

Merkel disks are associated with sensory nerve endings, playing a crucial role in the sensation of touch.

Langerhans cells act as phagocytes that engulf cancer cells or pathogens, contributing to the skin's immune response.

The dermis consists of two layers:

1. Papillary layer:

   • Made of loose connective tissue.

2. Reticular layer:

   • Composed of dense connective tissue.

A dermal papilla is a dermal projection that extends into the epidermis, playing a role in the interface between the dermis and epidermis.

The papillary layer contains the papillary plexus (capillary network) and sensory receptors.

The reticular layer includes the following accessory organs:

1. Hair follicle
2. Sweat gland
3. Sebaceous gland
4. Cutaneous plexus
5. Arrector pili muscle
6. Nerve fibers & sensory receptors

Meissner's corpuscle is a tactile receptor located in the dermal papilla that is responsible for sensing fine touch and low frequency vibration.

Meissner's corpuscle is located in the dermal papilla of the skin.

A sensory unit contains a single sensory/afferent neuron and its receptor endings or associated receptor cells.

A receptive field is an area where all sensory receptors respond to a single neuron. Each sensory unit has its own size of the receptive field.

Each single sensory unit has its own size of the receptive field, indicating that the area of response can vary between different sensory units.

The smaller and higher number of receptive fields lead to greater acuity. For example, areas like the fingertip have high acuity due to their small and numerous receptive fields.

The two-point discrimination threshold for the fingertip is 0.25 cm, while for the lower back it is 2.5 cm. This indicates that the fingertip has a much higher sensitivity to touch compared to the lower back.

Pain and touch two-point discrimination thresholds vary significantly across body locations. For example, the fingertip has a low threshold for both pain and touch, while the lower back has a much higher threshold for both. This suggests that areas like the fingertip are more sensitive to tactile stimuli than areas like the lower back.

Receptive fields are crucial in touch sensation as they determine the area of skin that a sensory neuron responds to. Smaller receptive fields, like those at the fingertip, allow for finer discrimination of touch, while larger receptive fields, like those in the lower back, result in less precise touch perception.

Dermatomes are areas of the skin that are innervated by sensory neurons originating from specific levels of the spinal cord. Each dermatome corresponds to a particular spinal nerve, which provides sensory information from that skin area to the central nervous system.

A dermatome is an area of skin that is mainly supplied by a single spinal nerve. There are 31 spinal nerves: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal nerve, each relaying sensation from a specific skin region to the brain.

In the thorax and abdomen, dermatomes are arranged like a stack of disks forming the human body. In contrast, in the arms and legs, dermatomes run longitudinally along the limbs, showing a different pattern of innervation.

• Reason: Sunbath without the use of sunscreen
• Outcome: Mild edema followed by skin peeling
• Recovery: Within weeks, without scarring

• Reason: Exposure to hot objects or flame
• Outcome: Blisters due to escape of fluid from damaged capillaries
• Healing: Depends on whether accessory structures survive

A first degree burn involves limited damage to the epidermis. It typically results in redness, minor swelling, and pain, but does not cause blisters or affect deeper skin layers.

A second degree burn involves partial destruction of the dermis. It is characterized by redness, swelling, pain, and the presence of blisters. This type of burn affects both the epidermis and part of the dermis.

A third degree burn results in extensive destruction of the dermis and may also affect the hypodermis. It can appear white, charred, or leathery, and typically does not cause pain in the burned area due to nerve damage.

Causes: Prolonged exposure to hot objects, flames, or corrosive chemicals.

Outcomes: Skin turns white or charred (blackened) and is numb.

Causes: Skin burn destroys underlying fat and muscle.

Outcomes: Skin appears charred (blackened) and is numb.