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Which feature is not characteristic of epithelial tissue? (Select all that apply)
A __________ epithelium consists of a single layer of flattened cells attached directly to a basement membrane.
simple squamous
From deep to superficial, the order of the strata of the epidermis is __________.
Basale - spinosum - granulosum - lucidum - corneum
What is the function of melanin in the skin?
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Fine hair called __________, which is unpigmented or lightly pigmented, is the primary human hair and is found on the upper and lower limbs.
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The part of the hair that extends beyond the skin surface is called the __________.
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What structure is responsible for pulling on the follicle and causing 'goose bumps'?
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What is the function of cartilage located in the epiphyseal plates?
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As the bone matrix calcifies and the secreting cells become walled in, what happens?
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Interstitial growth of cartilage increases its __________ and occurs in the __________ region of the cartilage.
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Intramembranous ossification produces __________ and involves __________.
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Which is not a function of bone?
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The bones of the fingers and toes (phalanges) are categorized as __________ bones.
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Study Notes
Epithelial Tissue
- Epithelial tissues are composed of closely packed cells with little to no extracellular matrix.
- Epithelial tissue characteristics include:
- Polarity: Cells have distinct apical and basal surfaces.
- Cell junctions: Cells are connected by intercellular junctions, creating a barrier.
- High regeneration capacity: Epithelia readily divide and replace damaged cells.
- Attachment to basement membrane: A specialized extracellular layer providing structural support.
- Simple squamous epithelium consists of a single layer of flattened cells attached directly to a basement membrane.
- Simple cuboidal epithelium consists of a single layer of cube-shaped cells attached directly to a basement membrane.
- Simple columnar epithelium consists of a single layer of tall, column-shaped cells attached directly to a basement membrane.
- Stratified squamous epithelium consists of multiple layers of flattened cells, with the deepest layer attached to the basement membrane.
- Stratified cuboidal epithelium consists of multiple layers of cube-shaped cells, with the deepest layer attached to the basement membrane.
Integument
- The integument is the outer layer of the human body, commonly known as skin.
- The integumentary system performs many functions including:
- Protection: Barrier against external threats.
- Water loss prevention: Maintains hydration.
- Temperature regulation: Controls heat dissipation.
- Synthesis of vitamin D: Precursor produced in the skin.
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The epidermis is the outermost layer of the integument and consists of five strata (layers) from deepest to superficial:
- Basale: Stem cells dividing to produce new keratinocytes.
- Spinosum: Cells begin producing keratin and develop desmosomal connections.
- Granulosum: Keratinocytes accumulate keratin granules and flatten.
- Lucidum: Present only in thick skin, contains translucent keratinocytes.
- Corneum: Dead, keratinized cells providing a tough, protective layer.
- Melanin is a pigment produced by melanocytes in the epidermis, protecting against UV light damage.
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The dermis is the inner layer of the integument, comprised of two main layers:
- Papillary layer: Superficial layer with dermal papillae that interdigitate with epidermal ridges.
- Reticular layer: Deeper layer consisting primarily of dense irregular connective tissue.
- Subcutaneous layer (hypodermis) is not technically part of the integument, but provides insulation and anchors the skin.
- Blood capillaries in the dermal papillae supply nourishment to the epidermis.
Hair
- Vellus hair is fine, unpigmented or lightly pigmented hair found on the upper and lower limbs.
- Terminal hair is thicker, pigmented hair found on the scalp, eyebrows, eyelashes, and axillae.
- The shaft is the portion of the hair that extends beyond the skin surface.
- The hair follicle is the structure that surrounds the hair root and is responsible for hair growth.
- The arrector pili muscle is a smooth muscle attached to the hair follicle that causes hair to stand erect ("goosebumps") when it contracts.
- Sebaceous glands secrete sebum, which lubricates the skin and helps defend against bacteria.
Cartilage
- Cartilage is a specialized connective tissue found in the body, composed primarily of chondrocytes (cartilage cells).
- Epiphyseal plates are areas of hyaline cartilage located at the ends of long bones responsible for lengthwise bone growth.
- Hyaline cartilage is the most common type of cartilage and is found in the nose, trachea, and articular surfaces of joints.
- Elastic cartilage is more flexible than hyaline cartilage and is found in the ear and epiglottis.
- Fibrocartilage is the strongest type of cartilage and is found in the intervertebral discs and menisci of the knee.
Bones and Bone Tissue
- Bone tissue is a specialized connective tissue composed of a rigid extracellular matrix.
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Bone cells include:
- Osteoblasts: Produce and secrete bone matrix.
- Osteocytes: Mature bone cells located within the bone matrix.
- Osteoclasts: Break down and reabsorb bone matrix.
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Bone formation (ossification) can occur via two processes:
- Intramembranous ossification starts within a connective tissue membrane, forming flat bones.
- Endochondral ossification begins with a cartilaginous model, giving rise to long bones.
- Hemopoiesis is the process of blood cell formation, occurring within red bone marrow.
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Hematopoiesis occurs in:
- Red bone marrow: Found in spongy bone and some medullary cavities of long bones.
- Yellow bone marrow: Found in the medullary cavities of long bones, can be converted to red marrow.
- Endosteum: A layer of cells lining the medullary cavity.
- The epiphyseal line marks the location of the former epiphyseal plate.
- The nutrient foramina are small holes in the bone that allow blood vessels and nerves to enter.
- Bones can increase in length (interstitial growth) and thickness (appositional growth).
- Long bones are bones that are longer than they are wide, typically with a shaft (diaphysis) and two ends (epiphyses).
- The epiphyses are the knobby ends of long bones.
- The diaphysis is the shaft of a long bone.
- The medullary cavity is the hollow space inside the diaphysis that is filled with bone marrow
- The periosteum is a fibrous membrane that surrounds the outside of the bone.
- The articular cartilage is a thin layer of hyaline cartilage that covers the ends of bones in a joint.
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Types of bones:
- Long bones: longer than they are wide (e.g., femur, humerus)
- Short bones: cube-shaped (e.g., carpals, tarsals)
- Flat bones: thin and flattened (e.g., skull bones, ribs, scapula)
- Irregular bones: complex shapes (e.g., vertebrae, facial bones)
- Sesamoid bones: small, round bones embedded in tendons (e.g., patella)
Bone Function
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Bone function includes:
- Protection: Of vital organs.
- Mineral storage: Calcium, phosphorus, and other minerals.
- Body movement: Provides framework for muscles and joints.
- Hormone synthesis: Bone cells produce osteocalcin, influencing insulin sensitivity and glucose metabolism.
- Hemopoiesis: Blood cell formation in red bone marrow.
- Severe anemia can trigger the conversion of yellow marrow to red marrow to increase red blood cell production.
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Description
This quiz covers the characteristics and types of epithelial tissue. It discusses cell polarity, regeneration capacity, and various forms including simple squamous, cuboidal, and columnar epithelium. Test your understanding of these fundamental tissue types in biology!
