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What is the primary function of the prickle cell layer in the epidermis?
What is the primary function of the prickle cell layer in the epidermis?
Which type of sweat gland is primarily responsible for thermoregulation?
Which type of sweat gland is primarily responsible for thermoregulation?
What is the function of keratin in the skin?
What is the function of keratin in the skin?
In which layer of the epidermis do keratinocytes undergo mitosis?
In which layer of the epidermis do keratinocytes undergo mitosis?
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What is the role of Langerhans cells in the epidermis?
What is the role of Langerhans cells in the epidermis?
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What is the main component of the sweat secreted by eccrine glands?
What is the main component of the sweat secreted by eccrine glands?
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What is the function of the granular layer in the epidermis?
What is the function of the granular layer in the epidermis?
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Where are melanocytes typically located in the skin?
Where are melanocytes typically located in the skin?
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What is the function of Merkel cells in the epidermis?
What is the function of Merkel cells in the epidermis?
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What type of junctions are found in the epidermis?
What type of junctions are found in the epidermis?
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What is the main function of sweat glands in the skin?
What is the main function of sweat glands in the skin?
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What is the composition of nails?
What is the composition of nails?
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What is the characteristic of third-degree burns?
What is the characteristic of third-degree burns?
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What is the function of the arrector pili muscle?
What is the function of the arrector pili muscle?
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What is the structure of the epidermis?
What is the structure of the epidermis?
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What is the function of keratinocytes in the epidermis?
What is the function of keratinocytes in the epidermis?
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What is the primary function of the skin?
What is the primary function of the skin?
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Which layer of the skin is derived from mesoderm?
Which layer of the skin is derived from mesoderm?
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What is the function of keratinocytes in the epidermis?
What is the function of keratinocytes in the epidermis?
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What is the main blood supply for the rest of the skin?
What is the main blood supply for the rest of the skin?
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What is the type of epithelium found in the epidermis?
What is the type of epithelium found in the epidermis?
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What is the function of Langerhans cells in the epidermis?
What is the function of Langerhans cells in the epidermis?
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What is the function of sweat glands in the skin?
What is the function of sweat glands in the skin?
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What is the name of the layer in the epidermis where keratinocytes lose organelles and produce keratin?
What is the name of the layer in the epidermis where keratinocytes lose organelles and produce keratin?
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What is the thinnest layer of a vein?
What is the thinnest layer of a vein?
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Which of the following features is characteristic of bronchioles?
Which of the following features is characteristic of bronchioles?
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What is the characteristic of bronchi?
What is the characteristic of bronchi?
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What is a feature of the alveolar duct?
What is a feature of the alveolar duct?
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What is the shape of the cartilage in the trachea?
What is the shape of the cartilage in the trachea?
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What is the function of the smooth muscle layer in the airway?
What is the function of the smooth muscle layer in the airway?
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Which of the following is NOT a feature of the trachea?
Which of the following is NOT a feature of the trachea?
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What is the characteristic of alveoli?
What is the characteristic of alveoli?
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What is the main characteristic of the dermis layer?
What is the main characteristic of the dermis layer?
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What is the function of chondrocytes in cartilage?
What is the function of chondrocytes in cartilage?
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What is the main characteristic of bone cells (osteocytes)?
What is the main characteristic of bone cells (osteocytes)?
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What is the function of the interstitial compartment (interstitum)?
What is the function of the interstitial compartment (interstitum)?
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What is the main characteristic of the respiratory epithelium?
What is the main characteristic of the respiratory epithelium?
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What is the main characteristic of the lamina propria?
What is the main characteristic of the lamina propria?
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What is the main characteristic of the fibroelastic tissue in the airways?
What is the main characteristic of the fibroelastic tissue in the airways?
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What is the main characteristic of exocrine glands in the digestive system?
What is the main characteristic of exocrine glands in the digestive system?
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What is the main component of the tunica adventitia/externa?
What is the main component of the tunica adventitia/externa?
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What is the characteristic of the tunica intima?
What is the characteristic of the tunica intima?
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What is the composition of capillaries?
What is the composition of capillaries?
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What is the function of the muscularis mucosae in the mucosa?
What is the function of the muscularis mucosae in the mucosa?
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What is the function of the submucosa?
What is the function of the submucosa?
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What is the function of the adventitia/serosa in the GI tube?
What is the function of the adventitia/serosa in the GI tube?
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What is the diameter of capillaries?
What is the diameter of capillaries?
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What is the function of the oesophagus?
What is the function of the oesophagus?
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Study Notes
Epidermis Layers
- Granular layer (stratum granulosum): Keratinocytes secrete waterproofing molecules for a protective barrier and moisture retention.
- Prickle cell layer (stratum spinosum): Keratinocytes are tightly joined by desmosomes, providing structural support.
- Basal layer (stratum basale/germinativum): Responsible for keratinocyte mitosis, the process of cell division.
- Horny layer (stratum corneum): Keratinocytes lose organelles and produce keratin.
Sweat Glands
- Apocrine gland: Large sweat gland leading to body odor, localized in axilla and groin.
- Eccrine gland: Secretes odourless, clear substance primarily composed of water and sodium chloride, vital for thermoregulation.
Keratinocytes
- Produce keratin, a fibrous protein for skin strength, found in hair and nails.
- Undergo mitosis in the basal layer.
- Move up through the prickle cell layer, losing the ability to divide and their nuclei, forming the horny layer.
- The horny layer provides a hydrophobic skin barrier due to keratin.
Melanocytes
- Located in the basal layer of the epidermis.
- Synthesize melanin, a pigment that darkens skin and offers UV protection.
- Darker-skinned individuals have melanocytes that produce more melanin, not more melanocytes.
Langerhans Cells
- Antigen presenting cells.
- Circulate between the epidermis and local lymph nodes.
- Mediate immune responses.
Merkel Cells
- Connected to keratinocytes and sensory nerves.
- Receive the sensation of touch.
Cell Junctions in Epidermis
- Epidermis structure: Avascular and multilayered with a basement membrane at the bottom.
- Cell junctions in epidermis: Tight junctions, desmosomes, gap junctions, and hemidesmosomes.
Skin Appendages
- Hair: Used for thermal regulation and display.
- Arrector pili: Muscle that erects hair, trapping air for heat retention.
- Sebaceous glands: Associated with hair follicles, secrete sebum for waterproofing.
- Sweat glands: Eccrine and apocrine.
- Nails: Provide physical protection, composed of hard layers of keratin.
Burns
- First and second degree burns are also known as partial thickness because not all of the skin layers are destroyed.
- Third degree burns are full thickness, affecting all layers and some underlying tissues.
Skin Function
- The skin is the largest organ of the body.
- Acts as a physical barrier, protecting against infection, physical damage, and chemical damage.
- Provides touch, pressure, pain, and temperature regulation.
Skin Layers
- Epidermis: Derived from ectoderm, keratinized stratified squamous epithelium, contains keratinocytes and Langerhans cells.
- Dermis: Dense connective tissue, derived from mesoderm, contains fibroblasts, collagen, blood, mast cells, receptors, and nerves.
- Hypodermis (subcutaneous tissue): Main blood supply for the rest of the skin, provides insulation.
Airway Structure
- The smooth muscle layer controls airway diameter and resistance to airflow, and becomes more prominent in smaller airways.
- The submucosa layer is located under the smooth muscle layer and contains seromucous glands.
- Cartilage prevents collapsing and becomes less prominent as tubes get smaller.
Variations in Airway Structure
- Trachea: C-shaped cartilage, mucous glands
- Bronchi: discontinuous cartilage, more smooth muscle, mucous glands
- Bronchioles: no cartilage, no submucosal glands, no goblet cells
- Alveolar Duct: no cilia, no glands
- Alveoli: contain Type 1 & 2 Pneumocytes
Vein Structure
- Tunica Intima: thin layer with endothelial lining
- Tunica Media: smooth muscle + elastic fibers
- Tunica Adventitia/Externa: thickest layer with longitudinally arranged thick collagen fibers
Artery Structure
- Elastic Arteries: innermost to outermost structure
- Dermis: where fibers aren't organized
Cartilage Structure
- Chondrocytes embedded in an amphorous hydrated ground substance
- Chondrocytes: cells that secrete cartilage matrix and embed with the matrix
- Provides structural support, resistance to compression, poorly vascularized
Bone Structure
- Osteocytes: bone cells formed from an osteoblast
- Osteocytes embedded in a mineralized matrix, not hydrated
Interstitial Compartment
- A type of loose connective tissue that supports the bronchial tree, arterio-venous tree & continuous tubes in the digestive system
Airway Layers
- Respiratory Epithelium: ciliated cells, includes a basement membrane
- Lamina Propria: contains connective tissue, blood + lymph, fibroelastic tissue
- Tunica Intima: thin layer with an endothelial lining, contains little collagenous connective tissue
- Tunica Media: smooth muscle + elastic fibers
- Tunica Adventitia/Externa: almost as thick as the media, merges with surrounding tissue, composed of collagen
Capillary Structure
- Composed of a single layer of endothelium/endothelial cells
- Very small diameter, forcing red blood cells to fold to pass through
- Clefts or slits between endothelial cells allow for effective material exchange
Gut Tube Structure
- Mucosa: divided into three layers: epithelial lining, supporting connective tissue (lamina propria), and a thin layer of smooth muscle (muscularis mucosae)
- Submucosa: a layer of connective tissue that supports the mucosa, contains larger blood vessels, lymphatics, and nerves
- Muscularis Externa/Propria: consists of smooth muscle
- Adventitia/Serosa: conducts major blood vessels and nerves, part of the visceral peritoneum when GI tube is below the diaphragm
Oesophagus
- Conducts swallowed substances from pharynx to stomach (about 25 cm)
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Description
This quiz covers the different layers of the skin, including the granular layer, prickle cell layer, and basal layer, and their functions in providing a protective barrier and facilitating cell division.
