10660932
Description
Flashcards by Brianne Schmiegelow, updated more than 1 year ago
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Created by Brianne Schmiegelow
over 6 years ago
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| Question | Answer |
| Primary function of circulatory system | Transport of O2/CO2 and nutrients/metabolic waste |
| Secondary functions of circulatory system | Thermoregulation and transport of immune cells/hormones |
| What is the blood vascular system? | Heart and blood vessels |
| What is the lymph vascular system? | Passive drainage system for returning extravascular fluid (called lymph) to blood vascular system Lymph catches high-protein plasma that leaks out of circulatory system |
| How does lymph move through body? | Lacks an intrinsic pump Therefore relies on muscle contraction and body movement |
| Open vs. Closed circulatory system | Closed: use blood vessels (i.e. us) Open: open cavity with fluid all over (hemolin) (i.e. many invertebrates) |
| What are the layers of the blood vessels? | Tunica intima Tunica media Tunica adventitia |
| What kind of cells make up tunics of BVs? | Intima: Simple squamous endothelial cells; Very thin, 1-2 cells thick Media: Smooth muscle cells and fibroblastic CT Adventitia: fibroblasts, collagen/elastic fibers, and smooth muscle cells |
| What are the characteristics of tunica intima? | Simple squamous endothelium Forms semi-permeable barrier supported by the basement membrane Have fascia occludens (discontinuous tight junctions) Have variable amounts of subendothelial CT |
| What is the internal elastic lamina? | Barrier composed of elastic fibers that separates the tunica intima and the tunica media Not always present/easy to see |
| What are the characteristics of tunica media? | Highly variable middle layer of tunic Made up of smooth muscle cells and fibroblastic CT In arteries, it is the thickest layer Can also contain reticulin (type III collagen) and elastic fibers |
| What is the external elastic lamina? | Barrier composed of elastic fibers between the tunica media and tunica adventitia Less organized than internal EL |
| What are the characteristics of tunica adventitia? | Outermost tunic layer Consists of loose fibroblastic CT (fibroblasts, collagen/elastic fibers, smooth muscle cells) Thinner in arteries, but thickest layer in veins Can contain vasa vasorum Contains autonomic nerves and nervi vasculares |
| What is the vasa vasorum? | Small blood vessels that supply tunica media and adventitia in large arteries and veins Necessary b/c larger walls means fewer nutrients getting in |
| What is the nervi vasculares? | Nerves found in tunica adventitia that control smooth muscle contraction in vessel walls (mainly in tunica media) autonomic vasoconstriction and vasodilation |
| What is vasoconstriction? What causes it? | Constriction of BVs due to action of sympathetic, post-ganglionic nerve fibers Act on smooth muscle of tunica media to cause vasoconstriction and decrease in lumen diameter |
| What is vasodilation? How does it occur in BVs? | Passive dilation of BVs that occurs in absence or inhibition of sympathetic stimulation Accomplished via INdirect parasympathetic innervation Acetylcholine causes endothelial cells to release nitrous oxide which then causes smooth muscle cells to relax ALSO, in response to low O2 tension, smooth muscle in walls of arterioles relax resulting in vasodilation and increased blood flow |
| What is a baroreceptor? Where are they located? | Specialized sensory receptors in BV walls that detect blood pressure (=> whether or not BV should dilate or constrict) Located in carotid sinus and aortic arch |
| What is a chemoreceptor? Where are they found? | Specialized sensory receptors in BV walls that detect changes in O2, CO2 tension, and pH Found at bifurcation of carotid artery and in the aortic bodies in the aortic arch |
| What is systole? | Contraction of ventricles that results in a pressure wave |
| What is diastole? | Relaxation of ventricles that results in a drop in pressure |
| What maintains blood pressure? How is it regulated? | Maintained by expansion and recoil of elastic arteries Regulation occurs via sympathetic control of smooth muscle in vessel walls (changes in diameter of BVs) |
| What is the diameter of elastic arteries? | >1 cm |
| Where do elastic arteries receive their blood from? | Directly from the heart I.e. aorta, common carotid, subclavian, pulmonary arteries |
| Characteristics of elastic arteries | Largest arteries Have sheets of elastic tissue in tunica media which help maintain BP between systole and diastole Tunica media is the thickest layer Possess BOTH internal and external elastic laminae |
| What is the diameter of muscular arteries? | 2-10 mm |
| Characteristics of muscular arteries | Medium-sized arteries Have more smooth muscle and less elastin in tunica media than elastic arteries Tunica media is the thickest layer Have DISTINCT internal elastic lamina Larger ones may also have external elastic lamina |
| What is the diameter of arterioles? | 10-100 microns |
| Characteristics of arterioles | Terminal branches of arterial system that supply capillary beds Major sites of vasoconstriction and vasodilation that regulate distribution of blood to capillaries via pre-capillary sphincters Contain relatively little smooth muscle Tunica media is only 2-3 cells thick NO elastic laminae |
| What are pre-capillary sphincters? | Intermittent rings of smooth muscles found within walls of arterioleds Used to regulate distribution of blood to the capillaries |
| What are metarterioles? | Small-diameter arterioles that are intermediate in size between arterioles and capillaries Characterized by discontinuous layer of smooth muscle in the tunica media |
| What is the relationship b/w smooth muscle and CT with the diameter of blood vessels? | Smooth muscle INCREASES with INCREASED diameter of vessel As smooth muscle INCREASES, amount of CT DECREASES |
| What is microcirculation? | E |
| What is the diameter of a capillary? | 8-10 microns |
| What lines capillaries? | Thin, single layer of endothelial cells supported by basal lamina and a small number of pericytes |
| What are pericytes? | Cells derived from the same precursor cells as endothelial cells Can differentiate into endothelial cells or smooth muscle cells following injury |
| Characteristics of capillaries | Lack outer CT layer (NO tunica adventitia) Lack smooth muscle (NO tunica media) ONLY tunica intima Do not exhibit vasomotor activity themselves |
| How is vasomotor activity accomplished in the capillaries? | Vasodilation and vasoconstriction are accomplished via smooth muscle contraction in arterioles and pre-capillary sphincters Leads to PASSIVE change in capillary diameter |
| What are the types of capillaries? | CONTINUOUS - Endothelium forms continuous lining - Most common! - Muscle, lung, CNS FENESTRATED - Endothelial cells possess pores (aka fenestrae) WITHIN cells - Endocrine glands, GI tract DISCONTINUOUS - Basal lamina NOT continuous, so endothelial cells are separated by large gaps BETWEEN cells - May form sinusoids - Liver, spleen, bone marrow, lymphoid tissue |
| How can transport occur across capillaries? | Via fenestrae, transcytosis, or diapedesis |
| What are sinusoids? | Large-diameter (30-40 micron) capillaries that are formed from discontinuous capillaries |
| What is the function of the venous system? | Low-pressure collecting system for returning blood from capillary beds to the heart |
| Comparison of arteries and veins | Veins: - Thinner-walled vessels with larger relative luminal diameter than its corresponding artery - Fewer layers of smooth muscle in tunica media compared to similar-sized artery |
| What is the thickest tunic layer in veins? | Tunica adventitia |
| What is the function of valves in the veins? What happens if they fail? | Prevent backflow, especially in the limbs and thorax Failure => varicose veins |
| What are venules? | Small veins that lack elastic laminae Smaller venules may also lack tunica media |
| Types of venules (include size and characteristics) | Post-capillary: - 10-50 microns - Both tunica media and adventitia reduced or absent - Preferential site for diapedesis Collecting: - Where PC venules drain into Muscular: - Where collecting venules drain into - 50-100 microns - Have thin smooth muscle layer in the tunica media - Have thicker tunica adventitia |
| What acts on venules? What do they do? | Vasoactive substances (e.g. histamine, serotonin) Enlarge intercellular spaces and therefore increase the permeability of the vessel |
| What are muscular veins? | Large and medium-sized veins Small: may or may not contain internal elastic lamina Medium: contain internal elastic lamina only Large: contain internal and external elastic laminae |
| What does smooth muscle do in tunia media of muscular veins and venules? | Controls the luminal diameter |
| What are AV shunts? | Direct connections between the arterial and venous system that bypass capillary bed Type of anastomosis common in skin Function in thermoregulation |
| What are portal vessels? | veins or arteries that directly connect two capillary beds e.g. hepatic portal vein -Connects cap bed from small intestine to cap bed from liver to absorb nutrients directly |
| Characteristics of lymph vascular system | Structurally similar to veins but the endothelial cells are thinner and have greater permeability Lymph endothelial cells are highly active in phagocytosis Have very thin tunica media Valves present Basement membrane and pericytes may be present or absent |
| What is the function of the lymph vascular system? | Drain excess fluid (lymph) from the extracellular space and return it to the bloodstream |
| How is lymph formed? | High hydrostatic pressure in the arterioles exceeds colloidal oncotic pressure exerted by the plasma proteins This leads to leakage of water, electrolytes, and plasma proteins from the capillaries into the extracellular space |
| What happens if you can't move lymph? | Peripheral edema, swollen feet |
| Where does lymph return to the bloodstream? | Junction of L internal jugular vein and L subclavian vein |
| Where do lymphatic tubules converge? | Thoracic duct and R lymphatic duct Largest lymph vessels in the body Contain tunica media!!! |
| What are lymph nodes? What are their functions? | Nodes interspersed along the lymph vessels that contain lymphoid tissue Functions in antigenic sampling and recognition, activation of immune cells, and production of antibodies |
| What part of lymphatic system is important in tumor metastasis? | Asymmetrical lymph drainage from lymph nodes |
| Characteristics of lymph nodes | Thin-walled Lack blood Contain smooth, eosinophilic, proteinaceous fluid (lymph), and occasional WBCs Basement membrane rudimentary or absent May or may not have pericytes |
| What is elephantiasis? | Tropical disease caused by worms that colonize lymphatic systems and multiply enough to obstruct lymphatic flow which results in edema and limbs get huge |
| What is atherosclerosis? | Most commonly-acquired abnormality of blood vessels Thickening of tunica intima with lipid deposits and formation of foam cells Can be generalized or focal (plaque) Later accomp. by proliferation of smooth muscle cells and formation of fibrous CT capsule |
| What are foam cells? | Cells of tunica intima or macrophages that are filled with lipid Associated with atherosclerosis |
| What is the physiology of atherosclerosis? | As plaque enlarges (or if endothelium is damaged), it exposes underlying collagen which initiates clotting cascade resulting in thrombus formation If a piece of thrombus breaks off, it is called an embolus (=> thromboembolic disease) This embolus (if big enough) can get stuck somewhere and block bloodflow |
| What causes hypertension in atherosclerosis? | As cells within plaque dies, it leads to necrosis and secondary calcification (aka "hardening of the arteries") Hypertension (increase in systolic BP) is due to the decrease in the diameter of vessel lumen |
| What is stenosis? | Gradual narrowing |
| W | Occlusion of vessel |
| What causes an acute ischemic event? | Sudden occlusion by embolus that decreases O2 to heart muscle (anoxia) causing chest pain (angina) |
| What is the most common cause of ischemic heart disease? | Atherosclerosis Lumen of coronary artery may decrease by 90% |
| What is myocardial infarction? | Death of myocardium as a result of ischemia Caused by untreated atherosclerosis Since cardiac muscle cells are terminally differentiated, they are unable to regenerate and all healing occurs via fibrosis (makes CT "patch") Since CT is less contractile than muscle, you end up with a decrease or partial loss of function |
| What is endocarditis? | Inflammation and thickening of AV valves often associated with valvular incompetence i.e. vegetative endocarditis from thromboembolic disease Can have lesions that make embolus |
| What is a stroke? | Similar to myocardial infarction (death due to loss of O2), except affects the brain instead of heart Neurons also terminally differentiated, so it results in cerebral infarct with similar cell death and loss of function Location of clot determines the symptoms and severity |
| What is an aneurism? | Thin-walled, balloon-like regions of blood vessels caused by dilation Occasionally burst Common in aorta, brain |
| How much of body mass is skin? | 15-20% |
| What are the functions of skin? | - Protection - Sensation - Thermoregulation - Metabolic functions |
| What facilitates heat loss in the skin? | Sweat glands and dermal capillary network |
| How is energy stored in skin? | primarily as triglycerides |
| What types of cells are in the epidermis? | Keratinized, stratified squamous epithelium Called keratinocytes |
| How thick is the epidermis? | <1mm ("thin") to >5 mm ("thick") |
| What is "thick skin"? | Epidermis with thick, highly keratinized layer Restricted to volar (soles) and palmar (palms) surfaces Lacks hair (glabrous) |
| Characteristics of epidermal vascularization | Lacks blood vessels (do not penetrate basement membrane) Supplied and nourished by blood vessels in underlying (subjacent) dermis |
| What makes up the dermis? | Dense, irregular, collagenous connective tissue (Type I collagen) Interspersed with elastic fibers Highly vascular, contains many sensory receptors |
| What causes skin "aging"? | Progressive damage to elastic fibers |
| What is the papillary layer? | Superficial thin layer of the dermis that interdigitates with the epidermis |
| What is the function of corrugations of dermis papillary layer? | Increase surface are for attachment Prevents shear and mechanical abrasion |
| What are rete ridges? | AKA epidermal ridges Epidermal projections into dermis |
| What are dermal papillae? | AKA dermal ridges Dermal projections into epidermis |
| What are dermatoglyphs? | AKA fingerprints Large dermal ridges in thick skin |
| What is the reticular layer? | Deep layer of the dermis that is thicker and less cellular than the papillary layer Contains hair follicles, sweat and sebaceous glands Interdigitates with underlying hypodermis (subcutis) Has Langer's lines |
| What are Langer's lines? | Lines of tension in reticular layer of dermis Formed by thick collagen bundles and elastin fibers Skin incisions parallel to these heal with less scarring |
| What is the hypodermis? | Layer of loose, irregular connective tissue and adipose tissue located below the dermis AKA subcutis, superficial fascia, or panniculus adiposus |
| What are the vascular plexi? | Vascular plexi in the skin Superficial subpapillary (junction of papillary and reticular layers), deep cutaneous (junction of reticular layer and hypodermis), and deeper subcutaneous (deep within hypodermis) |
| Which is the largest vascular plexus in the skin? | Subcutaneous plexus |
| What are glomus bodies? | Thickened regions of smooth muscle in wall of arterioles surrounded by connective tissue capsule Found in AV shunts in fingertips and ears Bypass capillary bed and re-route blood from arterial to venous circulation Act somewhat like sphincters Reason fingers/toes/etc. are most susceptible to frostbite |
| What is the function of vascular plexi in skin? | thermoregulation |
| What is the lifespan of skin cells? | ~25-50 days Travel from deep germinal layer, mature, and are sloughed from superficial epidermis |
| What is psoriasis? | Disease where keratinocyte maturation only takes ~1 week Absence of a granular layer Abnormal keratohyaline and tonofibrils |
| Layers of epidermis | Stratum basale (stratum germinativum) Stratum spinosum Stratum granulosum Stratum lucidum Stratum corneum |
| Characteristics of stratum spinosum | - Cells look spiny - Thickest layer in thin skin - Polyhedral cells with prominent intercellular bridges (desmosomes), numerous cytoplasmic processes, and lateral folding of cell membrane - Makes cytokeratin that forms tonofilaments (aggregate into tonofibrils and anchor onto desmosomes) |
| Characteristics of stratum basale | - Basal layer - Cuboidal cells bound to BM by hemidesmisomes - Attaches to underlying dermis via anchoring filaments and microfibrils |
| Characteristics of stratum granulosum | Granular cell layer Characterized by cells containing basophilic keratohyaline granules |
| What are keratohyaline granules? | Non-membrane bound, electron dense granules found in cells of the stratum granulosum of epidermis Interact with tonofibrils => keratinization |
| Process of keratinization | Initiated by release of lysosomal enzymes which rupture keratohyaline granules leading to polymerization of their contents and result in death of the cell Forms a matrix for tonofibrils of cytokeratin which leads to an amorphous mass of mature keratin As keratinocytes mature, they die and lose nuclei |
| What are keratinosomes? | Membrane-bound, lamellar structures in the cells of the granular layer of epidermis Contain glycolipids to provide waterproofing coat for skin cells |
| Characteristics of stratum lucidum | Layer of epidermis present ONLY in thick skin Homogenous, compact layer of enucleate cells between stratum granulosum and stratum corneum |
| Characteristics of stratum corneum | AKA cornified layer Most superficial layer of epidermis Thickest layer of epidermis in thick skin Contains flattened, enucleate, dead cell remnants called squames Continuously exfoliated (desquamation) Composed primarily of soft keratin that acts as a hydrophobic barrier and prevents desiccation |
| What are squames? | Flattened, enucleate, dead cell remnants found in the stratum corneum layer of epidermis |
| What is examined in a Pap smear? | Exfoliated cervical epithelial cells from stratum corneum layer |
| Which skin tumors are derived from epithelial cells? | Squamous cell carcinoma Basal cell carcinoma |
| Which skin tumor is derived from melanocytes? | Melanoma |
| What is the process of first intention healing? | From a clean (surgical), approximated incision 1. Incision immediately fills with blood and clots 2. Within 3-24 hrs, neutrophils infiltrate clot (acute phase) 3. Epithelial cells of stratum basale begin mitosis and epithelial closure (reapproximation) occurs within 24-48 hours 4. Day 3-7 neutrophils begin to be replaced by macrophages (subacute phase) 5. Day 5 incision is filled with granulation tissue 6. Week 2 is continued fibroplasia and collagen accumulation to make mature granulation tissue; progressive decrease in inflammation 7. Month 2, CT scar is covered by intact epithelium |
| What is granulation tissue? | Tissue that fills incision Process: 1. Neovascularization 2. Fibroplasia (fibroblasts elaborate collagen) 3. Re-epithelialization (epithelial proliferation) leads to production of granulation tissue |
| Why does a wound itch while healing? | Presence of inflammatory cells and inflammatory cell products |
| What occurs in wound repair in case of vitamin C deficiency? | Collagen breaks down and old scars can re-open and bleed |
| What is a keloid? | A raised, thickened CT scar caused by excess fibroplasia |
| What is second intention healing? | Occurs with more extensive loss of tissue where wound edges do not approximate |
| Process of second intention healing | 1. Following initial clot formation, epithelial cells of stratum basale migrate from edges of wound at ~0.5 mm/day 2. Takes ~3 weeks to fill a 1 cm-wide cut 3. In haired skin, migration of ells from external root sheath of hair follicles augments re-epithelialization 4. Simultaneous proliferation/maturation of keratinocytes behind migrating front slowly restores multilayered stratified epidermis 5. ~25 days, cells mature from stratum basale to stratum corneum (keratinization) 6. ~3 weeks, lifting of scab and desquamation 7. Wound contraction due to myofibroblasts |
| What is full thickness abrasion? | Third degree burns Grafting of skin generally necessary |
| What are melanocytes? | Neuroectodermal (i.e. of neural crest origin) dendritic cells present in epidermis Usually restricted to basal layer Have extensive cytoplasmic processes that may extend into the stratum spinosum |
| What are melanosomes? | Organelles in melanocytes that contain melanin Released and taken up by surrounding epidermal cells |
| Types of melanin | Eumelanin (dark haired ppl) Pheomelanin (red/blond haired ppl) |
| What causes differences in skin color? | Equal number of melanocytes, but variable rates of melanin production and degradation by lysosomal enzymes Ligher skinned people produce less pigment and/or digest pigment faster |
| What is vitiligo? | Autoimmune disease Causes destruction of melanocytes and therefore depigmentation |
| What controls melanin synthesis? | Melanocyte stimulating hormone Produced by pituitary gland |
| Production of melanin | Tyrosine precursor oxidized to DOPA (3,4- dihydroxyphenylalanine) by tyrosinase in premelanosome organelles DOPA is converted to melanin in melanosomes |
| What causes albinism? | Lack of tyrosinase enzyme DOPA and melanin NOT formed Premalanosomes form, but don't mature |
| How is tyrosinase used as a marker? | Differentiates melanocytes from keratinocytes containing phagocytosed melanin Useful in distinguishing tumor types (e.g. melanoma vs. squamous cell carcinoma) |
| Why make melanin? | DNA subject to damage by UV; melanin functions as shield to protect nucleus (inhibits mutagenesis) Exposure to UV stimulates melanin synthesis (results in tanning) Also necessary for normal neural development |
| What are Langerhans cells? | Fixed-tissue macrophages in stratum spinosum of epidermis Phagocytic, antigen-presenting cells Contain Birbeck granules and abundant cytoplasmic extensions Involved in contact allergic dermatitis |
| What are Birbeck granules? | Look like tennis-rackets Found in Langerhans cells in skin Visible on EM, but we don't know what they do |
| What happens when you get a tattoo? | Have to put pigment in the dermis (why it bleeds) Once you do, Langerhans cells phagocytose it but can't digest so it just holds on to it When it dies, pigment is released and re-phagocytosed Over time, some colors can be digested (why they fade) Blur because macrophages migrate around with the pigment |
| What are skin appendages? | Embryological outgrowths of the epidermis Includes hair, nails, sebaceous & sweat glands, horns, etc. |
| What is terminal hair? | Coarse hair on scalp, axillae, and pubis Replaces vellus hair @ puberty |
| Characteristics of hair shaft | Consists of outer cortex and inner medulla Covered by thin cuticle of overlapping keratin plates that prevent matting Produced by hair follicles |
| What are hair follicles? | Cylindrical downgrowths of epithelium surrounded by collagen sheaths Produce hair shaft |
| What is the hair bulb? | AKA hair root Where hair growth occurs Deep terminal expansion of the hair follicle Lined by actively dividing epithelial cells homologous to stratum basale Dermal papilla at the base |
| What is the dermal papilla? | Vascular core, finger-like invagination of dermis containing blood vessels Found at base of hair bulb |
| What happens to epithelial cells lining hair bulb? | As the mature, they fill with hard keratin filaments arranged in parallel bundles |
| What causes hair color? | Melanocytes adjacent to hair follicle produce melanin that become incorporated into the cortex of hair shaft |
| What are the internal and external root sheaths? | Surround and protect developing hair Line hair follicle |
| What is the glassy membrane? | Modified basement membrane that separates hair bulb from the surrounding dermis |
| What is piloerection? | Raised hair Caused by sympathetic stimulation due to cold/fear/aggression |
| What are the arrector pili muscles? | Bundles of smooth muscle cells that attach to hair follicle sheath and insert on the epidermal ridges Contraction raises hair ("goosebumps") |
| Hair growth process | Growth phase - ANAGEN Involuting phase (loss of blood supply) - CATAGEN Inactive resting phase - TELOGEN Shedding of old hair shaft - EXOGEN |
| What is vellus hair? | Fine body hair in children and women |
| What is androgenic alopecia? | Most common form of hair loss (affects 30-40% of adults) Genetic and androgen-dependent Affected individuals have high levels of 5-alpha-reductase which leads to follicular atrophy |
| What is 5-alpha-reductase? | Enzyme that converts testosterone to dihydroxytesterone |
| What is the nail bed? | Stratified squamous epithelium where flattened nail plate rests |
| What is the nail root? | Proximal end of the nail that extends into the dermis and attaches to the periosteum of the distal phalanx |
| How does nail growth occur? | Occurs by proliferation and differentiation of epithelium at nail root in the germinative zone of the nail matrix |
| What is the eponychium? | AKA superficial cuticle |
| What is the lunula? | White crescent at base of the nail |
| What is the nail plate? | Consists of densely-packed, parallel, hard keratin filaments embedded in amorphous matrix Formed as epithelial cells mature, fill with keratin, and die Slides over underlying nail bed epithelium as it grows |
| How long does it take for nails to grow? | Longer for toenails Replace fingernails in ~3 months and toenails in ~9 months |
| What are sebaceous glands | Alveolar, holocrine glands consisting of branched acini One or more associated with each hair follicle |
| How do sebaceous glands develop? | As outgrowths of the external root sheath of hair follicle |
| What is the pilosebaceous canal? | Canal that secretes sebum from sebaceous glands |
| What is sebum? | Oily substance secreted by sebaceous glands High in lipid content and cell debris Used for waterproofing and moisturizing skin and hair Also secreted directly onto skin surface of non-haired transitional skin |
| What is seborrhea? | Excessive secretion of sebum |
| What is a pilosebaceous unit? | Each hair follicle and associated arrector pili muscles and sebaceous gland |
| What are sweat glands? Types? | Simple, coiled, tubular glands surrounded by myoepithelial cells that assist in secretion Merocrine/eccrine and apocrine |
| What are merocrine sweat glands? | AKA eccrine Secrete only product Distributed over most of body surface except lips and genitalia Unbranched, coiled, tubular glands with 1-2 layers of cuboidal/columnar epithelium with excretory ducts Secrete sweat onto skin surface via sweat pore on epidermal ridge Important in thermoregulation for evaporative cooling |
| What causes acne? | Most commonly blockage of sweat glands |
| How much merocrine sweat does the body lose each day? | ~600 ml/day due to evaporation from lungs, skin, and mucous membranes |
| What is merocrine sweat made up of? | Hypotonic solution of salts, ammonia, urea, and uric acid |
| What causes merocrine sweating? | Thermoregulatory sweating is CHOLINERGIC (parasymp.) - First in axillae, forehead, scalp - last on hands/feet Emotional sweating is ADRENERGIC (symp) - Begins on palms/soles Alternative explanation: innervated by sympathetic, but cholinergic nerves (don't use adrenaline) |
| What are demodex? | Follicle mites found on skin Help keep sebaceous glands clear |
| What are apocrine sweat glands? | Sweat glands that secrete product along with some cytoplasm Coiled, tubular glands with large dilated lumina Located in axillae, groin (develop @ puberty) Lumen lined with secretory, cuboidal epithelium that is 2-3 cell layers thick |
| What do apocrine sweat glands secrete? | Thick, viscid secretions into hair follicle that contain proteins, carbohydrates, ammonia, lipids, and organic products Odorless when secreted, but bacterial breakdown leads to odor In mammals, serves as sexual attractant/pheromone used in scent marking and territoriality |
| What causes apocrine sweat secretion? | Adrenergic innervation |
| What are ceruminous glands? | Wax glands in external auditory meatus (ear canal) Modified apocrine glands! Produce cerumen (ear wax) |
| What are mammary glands? How do they develop? | Highly-modified apocrine sweat glands Along paired epidermal ridges (called mammary ridges or milk lines) that extend from axillae to groin (in humans, only first pair of glands along milk line develops) In female, develop under influence of pituitary and ovarian hormones then atrophy and involute at menopause |
| What composes INACTIVE mammary glands? | Mainly dense, irregular, collagenous CT interspersed with adipose tissue and occasional smooth muscle Tubulo-acinar glands organized into secretory lobules |
| What is the organization of ducts in mammary glands? | Tubuloacinar glands organized into secretory lobules --> terminal ducts --> lactiferous ducts --> lactiferous sinus in nipple |
| What is the areola? | Pigmented region of epidermis surrounding nipple Consists of stratified squamous epithelium with deep dermal ridges Contains numerous areolar glands, including merocrine sweat and sebaceous glands |
| Process of lactation | Mammary glands enlarge due to hypertrophy of secretory cells and accumulation of secretory product First few days after birth secrete colostrum then milk |
| What is colostrum? | An alkaline, yellowish secretion with high protein and salt content & low lipid and carbohydrate content Produced by mammary glands the first few days after birth Contains large amounts of antibodies to transfer passive immunity to offspring |
| Milk production | Both merocrine (protein) and apocrine (lipid) |
| What are Meissner's corpuscles? | Mechanoreceptors/touch receptors in dermal ridges of papillary layer of epidermis Especially prominent in hands, feet, lips, genitalia ~150 micron long cylindrical structures Consist of AFFERENT nerve fibers associated with minimally-modified Schwann cells |
| What are Pacinian corpuscles? | Mechanoreceptors located in dermis and hypodermis that detect mechanical and vibratory pressure Large, ovoid structures greater than 1 mm Prominent in fingertips and around joints Consist of AFFERENT nerve fibers surrounded by highly modified Schwann cells Form concentric lamellae separated by fluid-filled spaces |
| What are Ruffini corpuscles? | Small dermal mechanoreceptors Especially common in soles of feet |
| What are "free" nerve endings? | Most numerous sensory receptor in skin Present in epidermis and papillary dermis (surround most hair follicles) Lack CT capsule and associated Schwann cells Serve multiple sensory modalities (heat/cold, touch, pain, movement) |
| What are Merkel cells? | Epidermal cells derived from neural crest that look like melanocytes Pressure-sensitive mechanoreceptors that are assoc. with free afferent nerve endings Located in stratum basale Contain dense core granule |
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