Overview of Basic Concepts Flashcards
skin is also called… and consists of….
cutaneous membrane; epidermis and dermis
epidermis
- outermost layer of skin
- consists of keratinized stratified squamous epithelial tissue
- no blood vessels here but relies on connective tissue underneath it for blood supply
- consists of 4 or 5 layers with extra layer being present in areas receiving a lot of wear & tear
- Stratum Corneum, Statum Lucidum, Statum Granulosum, Stratum Spinosum, Statum Basale (think…Come Let’s Get Sun Burned)
dermis
- largest part of skin
- connective tissue that contains blood vessels, nerves, glands and hair follicles
- consists of 2 layers: papillary and reticular layers
- Papillary Layer: connective tissue with collagen, elastic fibers and blood vessels; dermal papillae (superficial peglike projections)
- Reticular Layer: majority (~80%) of dermal thickness; dense fibrous connective tissue with elastic fibers (stretch-recoil properties) and collagen fibers (strength and resiliency)
papillary layer of dermis
connective tissue with collagen, elastic fibers and blood vessels; dermal papillae (superficial peglike projections)
reticular layer of dermis
- majority (~80%) of dermal thickness
- dense fibrous connective tissue with elastic fibers (stretch-recoil properties) and collagen fibers (strength and resiliency)
flexure lines
dermal folds at or near joints
- dermis tightly secured to deeper structures
- skin cannot slide easily for joint movement, causing deep creases
- visible on hands, wrists, fingers, toes, soles
cleavage/tension/langer’s lines
- lines of human body parallel to orientation of collagen fibers in and along muscle fibers
- ideal for skin incisions for minimal tension across the wound
osteogensis/ossification
process of bone formation
- at 6 wks, embryo is made from fibrous membrane and hyaline cartilage
- after 6 wks, bone begins to develop and eventually replacing most of existing fibrous or cartilage structures
intramembranous ossification
process of bone developing from fibrous membrane
endochondral ossification
process of bone formation that occurs by replacing hyaline cartilage
remodeling
bone absorption and deposition in response to stress and repair of bone
bone perform several important functions:
- support
- protection
- movement
- mineral storage
- blood cell formation
two types of bone tissue:
- Spongy/Trabecular/Cancellous Bone: found at end of long bones and in middle of other bones; always surrounded by compact bone
- Compact Bone: dense and solid; found at shaft of long bones and surrounding the spongy bone; contains medullary (marrow) cavity; provides strength for weight-bearing
Medullary Cavity
where bone marrow sits snd where blood cells and platelets are formed
bones are classified according to their shape:
- long bones = tubular structures; longer length than width
- short bones = cuboidal; found only in ankle and wrist
- flat bones = usually serve protective functions; ex - cranium, sternum, ribs
- irregular bones = various shapes other than long, short or flat; ex - facial bones, vertebrae
- sesamoid bones = protect tendons from excessive wear; ex - patella
osteoporosis
abnormal reduction in quantity of bone or atrophy of skeletal tissue
- decrease in organic and inorganic components of bone
- bones become brittle, lose their elasticity and fracture easily
Diaphysis
- long & tubular; shaft of the bone
- collar of compact bone surrounds a central medullary or marrow cavity
- in adults, cavity contains fat
- adults = more yellow bone marrow; children = more red bone marrow for blood cell formation
Epiphysis
- ends of the bone
- joint surface is covered with articular cartilage
- epiphyseal line separate diaphysis and epiphysis
Bone Membranes
- Periosteum: covers outer bone surface; contain nerve fibers, blood and lymph vessels secured by Sharpey’s fibers
- Endosteum: covers internal bone surfaces/lining the medullary cavity
functional classification of joints
- Synarthroses - immovable joints (think…syn→sin→bad→time out→ can’t move)
- Amphiarthroses - slightly movable joints
- Diarthroses - freely movable joints (think…di→die→spirit freely moves around)
structural classification of joints
- Fibrous Joints - united by fibrous tissue; generally immovable (synarthrotic); example - sutures of skull, dento-alveolar syndesmosis (gomphosis), syndesmosis (interosseous membrane)
- Cartilaginous Joints - united by hyaline cartilage or fibrocartilage; immovable or slightly moveable (amphiarthrotic); example - pubis symphysis (child birth), intervertebral discs
- Synovial Joints - most numerous in body; articulating bones are separated by a joint cavity which is filled with synovial fluid for lubrication and nourishment; freely moveable (diarthrotic)
fibrous joints
united by fibrous tissue; generally immovable (synarthrotic); example - sutures of skull, dento-alveolar syndesmosis (gomphosis), syndesmosis (interosseous membrane)
cartilaginous joints
united by hyaline cartilage or fibrocartilage; immovable or slightly moveable (amphiarthrotic); example - pubis symphysis (child birth), intervertebral discs
synovial joints
most numerous in body; articulating bones are separated by a joint cavity which is filled with synovial fluid for lubrication and nourishment; freely moveable (diarthrotic)
- – Plane Joint (Gliding Joints) - carpals
- – Hinge Joint - elbow, jaw, knee
- – Pivot Joint - neck
- – Condyloid Joint - knuckles
- – Saddle Joint - thumb
- – Ball-and-Socket Joint - shoulders, hips
types of muscle fibers
- Skeletal Striated Muscle - moves bones and other structures
- Cardiac Striated Muscle - forms most of the walls of heart and adjacent part of great vessels
- Smooth Muscle - forms part of the walls of most vessels and hollow organs, moves substances through viscera such as intestine, controls movement through blood vessels
skeletal muscle type
- location = skeleton
- function = movement, heat, posture
- appearance = striated, multi-nucleated (eccentric), fibers parallel
- control = voluntary
cardiac muscle type
- location = heart
- function = pump blood continuously
- appearance = striated, one central nucleus
- control = involuntary
visceral/smooth muscle type
- location = GI tract, uterus, eye, blood vessels
- function = peristalsis (movement of food), blood pressure, pupil size, erects hairs
- appearance = no striations, one central nucleus
- control = involuntary
skeletal muscle can undergo contraction in 3 ways:
- reflexive contraction
- tonic contraction
- phasic contraction
- – isometric contraction
- – isotonic contraction
reflexive contraction
skeletal muscle contraction; automatic and involuntary (reflexes, respiratory movements of diaphragm)
tonic contraction
skeletal muscle contraction; slight contraction (muscle tone) that does not produce movement or active resistance but gives muscle firmness, assisting the stability of joints and maintenance of posture
phasic contraction
skeletal muscle contraction
- Isometric Contraction - muscle contracts but length remains the same; no movement occurs but muscle tension is increased above tonic levels (holding a book out steady)
- Isotonic Contraction - muscle changes length to produce movement but tension is constant
- – Concentric = shortening a muscle (picking up a book)
- – Eccentric = lengthening a muscle; progressive relaxation of a contracted muscle (lowering a book)
isometric contraction
muscle contracts but length remains the same; no movement occurs but muscle tension is increased above tonic levels (holding a book out steady)
isotonic contraction
muscle changes length to produce movement but tension is constant
- – Concentric = shortening a muscle (picking up a book)
- — Eccentric = lengthening a muscle; progressive relaxation of a contracted muscle (lowering a book)
The structural unit of a muscle is a muscle fiber. Connective tissue wrapping the skeletal muscle include:
- Endomysium = around individual muscle fibers
- Perimysium = around a group of fibers/fiber bundles/fascicle
- Epimysium = surrounds the entire muscle
- Fascia = on outside of epimysium
The functional unit of a muscle is a motor unit (motor neuron and the muscle fibers it controls).
- When a motor neuron in spinal cord is stimulated, it initiates an impulse that causes all muscle fibers supplied by that motor unit to contract simultaneously.
- Neuromuscular Junctions - site of nerve and muscle association
Most muscles cross at least one joint and are attached at the articulating bones. When a muscle contracts, it draws one articulating bone toward the other. Origin? Insertion?
- Origin: attachment of the stationary bone
- Insertion: attachment to movable bone
Prime Mover/Agonist Muscle
main muscle responsible for producing a specific movement of body
Fixator Muscle
muscle that stabilizes proximal part of limb while movements occur on distal ends
Synergist Muscle
muscle that complements the action of prime movers
Antagonist Muscle
muscle that opposes the action of prime movers; as a prime mover contracts, the antagonist progressively relaxes, producing a smooth movement
characteristics of cardiac muscle
- Forms myocardium (muscular wall of heart)
- Has striations
- Involuntary; rhythmic contractions generated intrinsically by pacemaker nodes
- Usually has a single nucleus
- Joined to another muscle cell at an intercalated disc
characteristics of a smooth muscle
- Found in walls of hollow organs (blood vessels, digestive tract) and skin (arrector muscles associated with hair follicles)
- No striations
- Single nucleus
- Involuntary - no conscious control
Heart consists of two muscular pumps that act in a series diving the cardiovascular system in two circulations.
- Pulmonary Circulation = right heart propels low-oxygen blood returned to it into the lungs where carbon dioxide is exchanged for oxygen
- Systemic Circulation = oxygen-rich blood returned to the left heart is pumped to remainder of the body, exchanging oxygen and nutrients for carbon dioxide
different types of blood vessels
- Blood under high pressure leaves the heart and is distributed to body by a branching system of thicker-walled arteries. The final distributing vessels, arterioles, deliver oxygenated blood to capillaries.
- Numberous thin-walled capillaries form a capillary bed, where the interchange of oxygen, nutrients, waste products and other substances with the extracellular fluid occurs.
- Blood from capillary bed passes into venules. Venules drain into small veins that open into larger veins. The largest veins, superior vena cava and inferior vena cava, return poorly oxygenated blood to the heart.
most blood vessels have three tunics or coats:
- Tunica Intima - innermost layer & exposed to blood; consists of simple squamous epithelium called endothelium (smooth and keeps blood flowing freely without sticking to vessel wall)
- Tunica Media - middle layer & thickest; composed of smooth muscle and elastic tissue; allows blood vessel to change diameter (for blood flow and blood pressure control)
- – Vasoconstriction = constriction of blood vessels; increases blood pressure
- – Vasodilation = dilation of blood vessels; decreases blood pressure
- Tunica Externa/Adventitia - outer layer & strongest; connective tissue coat; supports & protects blood vessel
three types of arteries:
- Conducting/Large Eslatic Arteries - expand when ventricles of heart contract and returns to normal between cardiac contractions when ventricles relax; examples - aorta, common carotid, subclavian
- Distributing/Medium Muscular Arteries - carry blood to specific organs/areas; decrease their diameter to regulate blood flow to different parts of body as required; examples - brachial, femoral, renal
- Arterioles/Small Arteries - narrow lumina and thick muscular walls; smooth muscles in walls allow them to resist blood flow; helps regulate blood pressure
veins
- thinner walls, larger lumen and lower pressure than arteries; formed when venules converge
- called capacitance vessels (blood reservoirs) - contain up to 65% of blood supply
- adaptations ensure return of blood to heart despite low pressure:
- – Large-diameter lumen offer little resistance
- – Venous valves prevent backflow of blood (most abundant in veins of limbs)
- – Musculovenous pumps - outward expansion of bellies of contracting skeletal muscles compresses the veins, “milking” blood superiorly toward the heart
varicose veins
- abnormally swollen, twisted veins
- walls of veins lose elasticity or deep fascia becomes incompetent in sustaining musculovenous pump → veins become weak and dilate under pressure of supporting a column of blood against gravity → varicose veins
- valve cusps do not meet or are destroyed by inflammation
capillaries
- Walls of just a thin tunica intima/endothelium
- Function = exchange of gases, nutrients, wastes, hormones, etc. between blood and interstitial fluid
- Arteriovenous Anastomoses (AV shunts): allow blood to pass directly from artertial to venous side of circulation without passing through capillaries; numerous in skin where they conserve body heat
lymphatic system
- Consists of lymphatic vessels, lymph (fluid within vessels), lymphatic tissue and lymphatic organs (tonsils, lymph nodes, thymus, bone marrow and spleen)
- Functions = maintain fluid balance, absorption of fats, immunity (filter lymph to remove foreign particles)
lymphatic vessels
have thin walls and valves to prevent backflow so lymph moves away from tissue and toward the heart
lymph nodes
small masses of lymphatic tissue through which lymph is filtered on its way to venous system
lymphatic ducts
- Right Lymphatic Duct: drains lymph from body’s right upper quadrant (right side of head, neck, thorax and entire right upper limb); ends in angular junction of subclavian and internal jugular veins (right venous angle)
- Thoracic Duct: drains lymph from rest of body; begins in abdomen and ascends through thorax and into internal jugular and left subclavian veins
The efferent nerve diners of Autonomic Nervous System (ANS) are organized into two divisions:
- Sympathetic = catabolic; preparing body for “flight or fight”
- Parasympathetic = anabolic; promoting normal function and conserving energy
types of neurons (nerve cells)
- Sensory/Afferent Neurons: conduct impulses to spinal cord and brain
- Motor/Efferent Neurons: conduct impulses away from brain and spinal cord to muscles and glands
- Interneurons/Central or Connecting Neurons: conduct impulses from sensory neurons to motor neurons
neuroglia (support cells)
- do not transmit impulses but holds functioning neurons together and protect them
- common types of brain tumor called glioma develop from glial cells
oliodendrocytes
neuroglia in CNS
form myelin sheaths around large nerve fibers in CNS
astrocytes
neuroglia in CNS
form blood-brain barrier
microglial cells
neuroglia in CNS
eat debris
ependymal cells
neuroglia in CNS
play role in cerebral spinal fluid (CSF)
satellite cells
neuroglia in PNS
surround neuron cell bodies
schwann cells
neuroglia in PNS
form myelin sheaths around larger nerve fibers in PNS
myelin
white, fatty substance segmented wrapping which surrounds an axon
— formed by Oligodendrocytes in CNS and Schwann cells in PNS
information flow through neurons
dendrites collect electrical signals → cell body integrates incoming signals and generates outgoing signal to axon → axon passes electrical signals to dendrites of another cell or to an effector cell
Multiple Sclerosis
myelin loss in central nerve fibers resulting in conduction impairment; destroyed myelin is replaced by hard, plaque-like lesions
- – Affects both sexes & all age groups but more common in 20-40 yr old women
- – Related to autoimmune or viral infections
Tumors/Neuroma
- Most are gliomas (glial tumors)
- Multiple Neurofibromatosis (numerous benign tumors of Schwann cells in nerves of skin)
