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Questions and Answers
Which type of muscle is characterized by being elongated, branched, and having intercalated disks?
Which type of muscle is characterized by being elongated, branched, and having intercalated disks?
Which type of muscle is characterized by being fusiform, having no striations, and having a central nucleus?
Which type of muscle is characterized by being fusiform, having no striations, and having a central nucleus?
Which type of muscle is characterized by being quick, forceful, and involved in the sliding of thin actin and thick myosin filaments?
Which type of muscle is characterized by being quick, forceful, and involved in the sliding of thin actin and thick myosin filaments?
What is the function of contracting muscle cells in the body?
What is the function of contracting muscle cells in the body?
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What is the term used to refer to the plasma membrane of a muscle cell?
What is the term used to refer to the plasma membrane of a muscle cell?
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What is the term used to refer to the cytoplasm of a muscle cell, excluding myofibrils?
What is the term used to refer to the cytoplasm of a muscle cell, excluding myofibrils?
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Which structure is responsible for the production of sebum?
Which structure is responsible for the production of sebum?
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What is the function of sebum?
What is the function of sebum?
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Where are sweat glands most numerous?
Where are sweat glands most numerous?
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What is the function of sweat?
What is the function of sweat?
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What happens when sweat accumulates on the skin surface?
What happens when sweat accumulates on the skin surface?
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Where are nails formed?
Where are nails formed?
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Which type of gland is innervated by adrenergic nerves?
Which type of gland is innervated by adrenergic nerves?
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Which type of gland begins to function at puberty?
Which type of gland begins to function at puberty?
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What is the mode of secretion for both eccrine and apocrine glands?
What is the mode of secretion for both eccrine and apocrine glands?
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Where is the rete subpapillary located?
Where is the rete subpapillary located?
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What role do arteriovenous anastomoses play in thermoregulation?
What role do arteriovenous anastomoses play in thermoregulation?
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Where do the lymphatic capillaries in the skin join a deeper network of lymphatics?
Where do the lymphatic capillaries in the skin join a deeper network of lymphatics?
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Which connective tissue layer surrounds the entire muscle?
Which connective tissue layer surrounds the entire muscle?
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What is the function of collagen in connective tissues?
What is the function of collagen in connective tissues?
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Which connective tissue layer immediately surrounds each bundle of muscle fibers or fascicle?
Which connective tissue layer immediately surrounds each bundle of muscle fibers or fascicle?
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What type of connective tissue forms the external sheath of the muscle?
What type of connective tissue forms the external sheath of the muscle?
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What is the function of the endomysium?
What is the function of the endomysium?
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What penetrates the perimysium to supply each fascicle?
What penetrates the perimysium to supply each fascicle?
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Which part of the hair is responsible for hair growth?
Which part of the hair is responsible for hair growth?
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Which part of the hair provides most of its weight?
Which part of the hair provides most of its weight?
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Which part of the hair covers the hair shaft like shingles on a roof?
Which part of the hair covers the hair shaft like shingles on a roof?
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What is the function of the medulla in the hair?
What is the function of the medulla in the hair?
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What is the significance of vestigial hairs in humans?
What is the significance of vestigial hairs in humans?
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Study Notes
Here are the study notes in detailed bullet points:
Muscles
- Muscles are differentiated cells containing contractile proteins, generating forces for cellular contraction and movement
- Originated from mesodermal or mesenchymal cells and make up a significant part of the body
- Function: regulate the position and movements of body parts with respect to each other
- Types of muscle cells:
- Skeletal muscles: voluntary, striated, multinucleated, and have peripheral nuclei
- Smooth muscles: involuntary, non-striated, single nucleus, and central nucleus
- Cardiac muscles: involuntary, striated, branched, and intercalated disks
Skeletal Muscles
- Originated from mesenchymal myoblasts
- Formed by fusion of myoblasts, leading to myotubes with many nuclei
- Myotubes synthesize proteins, differentiate to form striated muscle fibers, and exhibit striations
- Structure:
- Composed of cylindrical bundles of muscle fibers (10-30 cm long)
- Muscle fibers have diameter range of 10-100 μm and are multinucleated
- Fibers are aggregated in bundles called fascicles
- Arrangement of fascicles varies in different muscles (e.g., parallel, oblique, or radiating)
Nerves
- Two categories of sensory nerve endings:
- Free nerve endings (pain receptors or thermoreceptors)
- Encapsulated nerve endings (mechanoreceptors, responding to slight deformation of the skin)
- Examples of encapsulated nerve endings:
- Pacinian corpuscles
- Meissner's corpuscles
- Ruffini corpuscles
- Merkel endings
Hair and Scalp
- Hair varies in length and diameter across different body regions
- Hair growth rate: approximately 1 mm per week
- Hair structure:
- Cuticle: transparent, protects hair shaft from chemicals and moisture loss
- Cortex: provides weight, contains melanin (color), stores oils, and adds flexibility and elasticity
- Medulla: inner hollow core (in some hair types)
- Hair follicle parts:
- Bulb: base of the follicle, surrounded by a loop of capillaries
- Hair papilla: underside of the bulb, provides nourishment to hair
- Hair matrix: epithelial cells covering the papilla, responsible for hair growth
Nails
- Fingernails and toenails: hard keratin structures protecting the ends of fingers and toes
- Nail root or germinal matrix: responsible for nail growth (approximately 1 mm per week)
- Nail plate or body of the nail has grooves that anchor it
- Cuticle or eponychium: fuses nail plate and skin of the finger together
- Hyponychium: under the free edge of the nail, creating a waterproof barrier
Glands
- Sebaceous glands:
- Oil glands located in the dermis, associated with hair follicles
- Secrete sebum, a complex mixture of lipids
- Function: lubricate hair and skin, maintain stratum corneum, and exert weak antibacterial and antifungal properties
- Sweat glands:
- Sudoriferous glands distributed over the body surface
- Produce sweat or perspiration, which evaporates and cools the body
- Also eliminate waste through skin pores
- Two types: eccrine glands (found on palms, soles, forehead, and underarms) and apocrine glands (found on lips, areola, and labia)
Blood and Lymph Vessels
- Rete cutaneum: plexus of small arteries, capillaries, and venules in the dermis
- Rete subpapillary: second plexus formed by small ascending arteries and capillaries
- Arteriovenous anastomoses: shunt blood directly from arteries to veins without an intervening capillary bed, important for thermoregulationHere are the study notes based on the provided text:
Integumentary System
- The skin has a rich blood supply and lymphatic drainage
- Rete cutaneum: a plexus of blood vessels parallel to the skin surface at the boundary between the dermis and hypodermis
- Rete subpapillary: a second plexus formed from the ramification of small ascending arteries, located at the boundary between the reticular and papillary layers of the dermis
- Each hair follicle receives blood from two sources
- Arteriovenous anastomoses: shunt blood directly from arteries to veins without an intervening capillary bed, playing an important role in thermoregulation
- Lymphatic drainage: begins in blind-ended lymphatic capillaries in the dermal papillae, joining an extensive network underlying the dermoepidermal junction
Nerves
- Two broad categories of sensory nerve-endings:
- Free nerve endings
- Encapsulated nerve endings
- Free nerve endings:
- Lack morphologically recognizable receptor specializations at their ends
- Most common in the epidermis
- Function: pain receptors or thermoreceptors
- Encapsulated nerve endings:
- Cellular and extracellular components organized to convey a mechanical stimulus to an axon in their interior
- Types: Pacinian corpuscles, Meissner's corpuscles, Kraus' end bulbs, Ruffini corpuscles
Muscles
- Different types of muscles:
- Skeletal muscles
- Cardiac muscles
- Smooth muscles
- Skeletal muscles:
- Originated from mesenchymal myoblasts
- Mesenchymal myoblasts fuse, forming myotubes with many nuclei
- Myotubes then further differentiate to form striated muscle fibers
- Cardiac muscles:
- Elongated, branched, and multinucleated
- Striated
- Function: involuntary, vigorous, and rhythmic
- Smooth muscles:
- Fusiform
- No striations
- Function: involuntary
Hair and Nails
- Hair:
- Composed of medulla, cortex, and cuticle
- Medulla: inner hollow core that runs the length of the shaft
- Cortex: provides most of the hair's weight
- Cuticle: transparent and covers the hair shaft like shingles on a roof
- Nails:
- Formed by proliferation and keratinization of epithelial cells in a nail matrix
- Nail root and its matrix are located under a fold of skin called the proximal nail fold
- Cuticle or eponychium: fuses the nail plate and the skin of the finger together to form a waterproof barrier
Sweat Glands
- Eccrine glands: found in the dermis of the entire integument, except on the palms and soles
- Apocrine glands: found in the axillae and areola of the nipples
- Sweat glands produce a watery secretion that helps regulate body temperature
Sebaceous Glands
-
Oil glands that secrete sebum
-
Found in the dermis of the entire integument, except on the palms and soles
-
Produce sebum, a complex mixture of lipids that helps maintain the stratum corneum and hair shafts
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Have a lobular structure consisting of elongated acini that open into a short duct### Organization of Skeletal Muscle
-
Skeletal muscle fibers are composed of a linear array of sarcomeres.
-
Fibers are aggregated in bundles called fascicles, with varying arrangements from muscle to muscle.
Arrangement of Fascicles
- In short muscles, fascicles are oriented parallel to the direction of pull and may continue without interruption throughout the muscle's length.
- In long muscles, fibers are shorter than the muscle and are connected to one or more transverse bands of connective tissue spaced at intervals along the muscle's length.
- Unipinnate muscles have fasciculi oriented obliquely with respect to a longitudinal band of connective tissue along one side of the muscle.
- Bipinnate muscles have oblique fascicles that radiate from a connective tissue core in the muscle, resulting in a pattern resembling that of the barbs extending obliquely from the axial core of a feather.
- Multipinnate muscles have oblique fascicles radiating from several longitudinal connective tissue strands within the muscle and converge on the tendon.
Function of Connective Tissues
- Collagen in connective tissue layers serves to transmit mechanical forces generated by muscle cells/fibers.
- Blood vessels and lymphatics penetrate the muscle within connective tissue.
Types of Connective Tissues
- Epimysium: a dense irregular connective tissue layer that surrounds the entire muscle, with septa extending inward to accommodate larger nerves, blood vessels, and lymphatics of the muscle.
- Perimysium: a thin connective tissue layer that immediately surrounds each bundle of muscle fibers or fascicle, penetrated by nerves, blood vessels, and lymphatics to supply each fascicle.
- Endomysium: a delicate layer of reticular and scattered fibroblasts that surrounds the external lamina of individual muscle fibers, featuring a rich network of capillaries that bring oxygen to the muscle fibers.
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Test your knowledge on the differences between eccrine and apocrine glands! Learn about their functions, secretions, innervation, and more. Perfect for students studying anatomy or anyone interested in the human body.
