Quiz 2 (Modules 6-10) Flashcards
Long bone parts
Diaphysis (shaft/body)
Epiphyses (ends)
Epiphyseal (growth) plate
Articular cartilage
Periosteum (surrounds bone surface)
Medullary cavity
Endosteum (lines the medullary cavity)
Sharpey’s (perforating) fibers
Thick bundles of collagen that extend from the periosteum into the bone extracellular matrix
Attaches periosteum to underlying bone
Hydroxyapatite
Crystals formed from calcium phosphate and calcium hydroxide in the bones
Calcification
Mineral salts are deposited in the framework formed by collagen in the extracellular matrix, where they crystallize and the tissue hardens Initiated by osteoblasts
Bone’s hardness depends on
crystallized inorganic mineral salts
Bone’s flexibility depends on
its collagen fibers
Tensile strength
Resistance to being stretched or pulled apart
4 types of cells present in bone tissue
Osteogenic cells
Osteoblasts
Osteocytes
Osteoclasts
Osteogenic cells
Unspecialized bone stem cells derived from mesenchyme
Only bone cells to undergo cell division
Found along the inner portion of the periosteum, in the endosteum, and in canals within bone that contain blood vessels
Osteoblasts
Bone-building cells
Synthesize and secrete collagen fibers and components for extracellular matrix of bone tissue
Initiate calcification
Turn into osteocytes
Osteocytes
Mature bone cells, main cells in bone tissue
Maintain daily metabolism, eg. exchange of nutrients and wastes with blood
Ostoclasts
“Carves out bone” - releases enzymes and acid that digest components of the extracellular bone matrix
Huge cells derived from fusion of monocytes
Concentrated in endosteum
Ruffled border on side of cell that faces bone surface
Resorption
Breakdown of bone extracellular matrix by osteoclasts
Helps regulate blood calcium level
Osteon (Haversian system)
Repeating structural units of compact bone tissue
Consists of concentric lamellae arranged around a small network of blood vessels, lymphatics, and nerves located in the central (haversian) canal
Lamellae
Circular plates of mineralized extracellular matrix
Lacunae
Located between the concentric lamellae
Small spaces which contain osteocytes
Canaliculi
Interconnecting channels that join lacunae with each other and to nearby blood vessels
Concentric vs. Interstitial lamellae
Concentric lamellae are found within osteons, interstitial lamellae are found between neighbouring osteons
Volkmann’s canals / Perforating canals
Transverse canals that allow blood vessels, lymphatic vessels, and nerves from the periosteum to penetrate the compact bone and connect with vessels and nerves of the medullary cavity, periosteum, and central canals
Function of compact bone tissue
Provides protection and support
Resists the stresses produced by weight and movement
80% of the skeleton, strongest form of bone tissue
Function of spongy bone tissue
Reduces overall weight of a bone
Support and protect bone marrow
20% of the skeleton, always covered by compact bone
4 situations in which bone formation occurs
Initial formation of bones in embryo and fetus
Growth of bones until adult sizes are reached
Remodeling of bone (replacement of old bone by new)
Repair of fractures
Where yellow bone marrow is contained
In the medullary cavity
2 methods of bone formation
Intramembranous ossification
Endochondral ossification
Steps in intramembranous ossification
- Mesenchymal cells cluster together and differentiate into osteogenic cells then osteoblasts. Osteoblasts secrete extracellular matrix of bone until they are surrounded by it
- Calcification
- Formation of trabeculae and development of the periosteum
Steps in endochondral ossification
- Mesenchymal cells crowd together and develop into chondroblasts, which produce hyaline cartilage covered by a perichondrium.
- Growth of the cartilage model
- Primary ossification
- Development of the medullary cavity
- Secondary ossification
- Formation of articulate cartilage and the epiphyseal (growth) plate
4 zones of the epiphyseal growth plate
Zone of resting cartilage
Zone of proliferating cartilage
Zone of hypertrophic cartilage
Zone of calcified cartilage
Appositional growth
Outward expansion - growth in thickness/diameter
Osteoblasts in periosteum form compact bone around external bone surface
Osteoclasts in the endosteum break down bone on the internal bone surface (around medullary cavity)
Wolff’s law
A bone grows or remodels in response to the forces or demands placed upon it
Bone remodeling
Balanced bone deposit and removal
Steps in fracture repair
Hematoma formation
Fibrocartilaginous callus formation
Bony callus formation
Bone remodelling
Why is the healing process of fractured bone slow?
Bone cell reproduction is normally a slow process
Blood supply has been interrupted
Compound fracture
Bone protrudes through the skin
Simple fracture
Bone does not protrude through the skin
Transverse fracture
Broken at right angles to the long axis of the bone
Comminuted fracture
Bone is crushed into small pieces
Bones in the axial skeleton
80 bones
Skull
Hyoid
Vertebral column
Sternum
Ribs
Bones in the appendicular skeleton
126 bones
Clavicle
Scapula
Upper and lower limbs
Pelvic girdle
Number of bones in the adult human body
206
5 main types of bones
Long
Short
Flat
Irregular
Sesamoid
Long bones
Long shaft
Composed mostly of compact bone with some spongy bone
Function in structural support for the limbs
Short bones
Roughly cube-shaped
Composed mostly of spongy bone
Flat bones
Thin and plate-like
A thin layer of compact bone surrounding a layer of spongy bone
Often curved
Eg. Skull, rubs, sternum
Irregular bones
Varied shapes that don’t fit into the other categories
Eg. Vertebrae, hip bones
Cranial bones
8
Frontal bone
2 parietal bones
2 temporal bones
Occipital bone
Sphenoid bone
Ethmoid bone
Facial bones
14
2 nasal bones
2 maxillae
2 zygomatic bones
Mandible
2 lacrimal bones
2 palatine bones
2 inferior nasal conchae
Comer
Hyaline cartilage
Composed of collagen fibers with a flexible matrix
Covers the ends of bones at joints
Fibrocartilage
Holds its shape under high compression
Found in between the vertebrae (vertebral discs)
Elastic cartilage
Stretchy
Provides support for flexible structures such as the external ear
26 vertebrae
7 cervical
12 thoracic
5 lumbar
1 sacrum
1 coccyx
Lordosis
Increase in the lumbar curve
Normal curvatures of the spine
Primary - thoracic and sacral curves; present before birth
Secondary - cervical and lumbar curves; develop after birth
Intervertebral discs - components
Outer fibrous ring - annulus fibrosis
Inner soft, pulpy elastic substance - nucleus pulposus
Parts of a vertebra
Vertebral body
Vertebral arch
2 transverse processes, 1 spinous process, 2 superior articular processes, 2 inferior articular processes
Parts of the sternum
Manubrium (superior)
Body
Xiphoid process (inferior)
Kyphosis
“Hunchback”
Increase in the thoracic curve
Components of the shoulder girdle
Clavicle and scapula
Glenohumeral joint
Where the scapula articulates with the humerus (shoulder joint)
Parts of the hip bones
Ilium
Pubis
Ischium
Acetabulum
The socket for the head of the femur
Where the three parts of the hip bone converge
Fibrous joints
No synovial cavity
Composed of dense irregular connective tissue
Allow very little movement
Eg. Skull sutures
Cartilaginous joints
No synovial cavity
Composed of cartilage
Allow very little or no movement
Difference between ligaments and tendons
Ligaments connect bone to bone
Tendons connect muscle to bone
Synarthrosis
Immovable joint
Amphiarthrosis
Slightly movable joint
Diarthrosis
Freely movable joint
All diarthroses are synovial joints
Synostosis
Bony joint
A joint in which there is a complete fusion of two separate bones into one
Gomphosis
Type of fibrous joint
Where a tooth fits into its socket
3 types of fibrous joints
Sutures
Syndesmoses
Interosseous membranes
Ligament
Parallel bundles of dense regular connective tissue in a fibrous membrane that are highly adapted for resisting strains
Connects bone to bone
6 categories of synovial joints based on movement
Plane
Hinge
Pivot
Condyloid
Saddle
Ball-and-socket
Type of joint between the wrist and the thumb
Saddle joint
Movements at synovial joints - 4 categories
Gliding
Angular movements
Rotation
Special movements
Functions of muscle
Producing body movements
Stabilizing body positions
Storing and moving substances within the body
Generating heat
4 special properties of muscular tissue
Electrical excitability
Contractility
Extensibility
Elasticity
Contractility
The ability of muscular tissue to contract forcefully when stimulated by an action potential
Extensibility
The ability of muscular tissue to stretch, within limits, without being damaged
3 layers of connective tissue in skeletal muscle
Epimysium (outermost, encircles the entire muscle)
Perimysium (surrounds fascicles)
Endomysium (inside of each fascicle, separates individual muscle fibers)
Fascicle
Bundles of 10-100+ muscle fibers
Tendon
Attaches a muscle to the periosteum of a bone
Somatic motor neurons
The neurons that stimulate skeletal muscle to contract
Axon typically branches many times
Sarcolemma
Plasma membrane of a muscle cell
Sarcoplasm
Cytoplasm of a muscle cell
Myoglobin
Protein, found only in muscle, that binds oxygen molecules that diffuse into muscle fibers from interstitial fluid
5 levels of organization within a skeletal muscle
Skeletal muscle
Fascicle
Muscle fiber (cell)
Myofibril
Filaments (myofilaments)
Transverse tubules (T tubules)
Invaginations of the sarcolemma
Sarcoplasmic reticulum (SR)
Fluid-filled system of membranous sacs encircling each myofibril In a relaxed muscle fiber, the SR stores calcium ions
Terminal cisterns
Dilated end sacs of the SR that are on either side of a transverse tubule
Releases calcium ions from the SR
Thin filaments
Composed mostly of actin
Directly involved in the contractile process
Thick filaments
Composed mostly of myosin
Directly involved in the contractile process
Sarcomere
Basic functional unit of a myofibril
Separated by Z-discs
Z disc
Narrow, plate-shapes regions of dense protein material
Separate one sarcomere from the next
A band
Portion of a sarcomere
Extends the entire length of the thick filaments
I band
Portion of a sarcomere
Lighter, less dense area
Contains thin filaments but no thick filaments
Z disc passes through the centre of the I band
H zone
Narrow area in the centre of each A band that contains thick but not thin filaments
M line
Middle of the sarcomere
Supporting proteins that hold thick filaments together at the centre of the H zone
3 kinds of proteins that make up myofibrils
Contractile proteins
Regulatory proteins
Structural proteins
2 contractile proteins in muscle
Myosin and actin
2 regulatory proteins in muscle
Tropomyosin and troponin
Sliding filament mechanism
Muscle contraction occurs because myosin heads attach to and “walk” along the thin filaments at both ends of a sarcomere, progressively pulling the thin filaments toward the M line
Result - each sarcomere is shortened, which leads to shortening of the entire muscle
Onset of contraction
SR releases calcium ions into the sarcoplasm, where they bind to troponin. Troponin moves tropomyosin away from the myosin-binding sites of actin. Then the contraction cycle can begin
Contraction cycle - 4 steps
ATP hydrolysis
Attachment of myosin to actin to form cross-bridges
Power stroke
Detachment of myosin from actin
Effect of calcium concentration on muscle contraction
Increase in Ca2+ starts muscle contraction
Decrease stops it
In the process of muscle contraction, calcium bonds to
Troponin
Isometric contraction
When the muscle contracts but does not shorten and does not produce movement
All-or-none principle of muscle contraction
Once a minimum threshold is reached the muscle fiber will contract fully
Origin of a muscle
The end that attaches to a stationary bone
Motor unit
A motor neuron and all the muscle fibers innervated by it
A motor neuron and all the muscle fibers innervated by it are called:
Motor unit
Muscle tone
Skeletal and smooth muscle remain in a state of continual, partial contraction
Insertion
Point of attachment to a moveable bone
Prime mover
Main muscle providing force for producing specific movement
During anaerobic respiration:
There is an absence of oxygen
Glucose is broken down producing lactic acid and 2 ATP molecules
Energy is provided for 30-40 seconds of strenuous muscle activity
Ganglia
Small masses of nervous tissue, consisting primarily of neuron cell bodies, that are located outside of the brain and spinal cord
Enteric plexuses
Extensive networks of neurons located in the walls of organs of the GI tract
Somatic nervous system (SNS)
Consists of sensory neurons that convey information from somatic receptors in the head, body wall, and limbs and from receptors for the special senses of vision, heating, taste and smell to the CNS, and motor neurons that conduct impulses from the CNS to skeletal muscles only.
Voluntary
Autonomic nervous system (ANS)
Consists of sensory neurons that convey information from autonomic sensory receptors to the CNS, and motor neurons that conduct nerve impulses from the CNS to smooth muscle, cardiac muscle, and glands
Involuntary
Two branches - sympathetic and parasympathetic
Sympathetic division of the autonomic nervous system
Generally helps support exercise of emergency actions
“Fight-or-flight”
Parasympathetic division of the autonomic nervous system
Generally takes care of “rest-and-digest” activities
Enteric nervous system
“Brain of the gut”
Involuntary
Muscles of GI tract
Functions of the nervous system
Sensory
Integrative (processing)
Motor
What organelles do neurons not have
centrioles (this is why neurons cannot replicate themselves; centrioles are needed for mitosis to take place)
Lipofuscin
A pigment that occurs as clumps of yellowish brown granules in the cytoplasm, present in aging neurons
Nerve fiber
General term for any neuronal extension that emerges from the cell body of a neuron (dendrites and axon)
Dendrites
The receiving or input portions of a neuron
Axon
Long, thin, cylindrical projection from the cell body
Propagates nerve impulses toward another neuron, a muscle fiber, or a gland cell
Neuroglia
Type of cell in nervous tissue
Smaller than neurons
Do not conduct nerve impulses
Support, nourish, and protect neurons
Capable of mitosis
Axon hillock
Cone-shaped elevation where the axon connects to the cell body of a neuron
Collaterals
Side branches of an axon
Multipolar neurons
Have several dendrites and one axon
All motor neurons
Bipolar neurons
One main dendrite and one axon
Unipolar neurons
Have dendrites and one axon that are fused together to form a continuous process that emerges from the cell body
Nissl bodies
Unique to neurons
Specialized layers of rough endoplasmic reticulum that synthesize neurofibrils and microtubules
Axon terminals (synaptic knobs)
Ends of the axon
Store neurotransmitters
Interneurons / Association neurons
Lie entirely within the central nervous system
Receive input from sensory (afferent) neurons and communicate with one another or with motor (efferent) neurons
The type of neuroglia responsible for generating the myelin sheath in the PNS is
Schwann cells
The type of neuroglia responsible for generating the myelin sheath in the CNS is
oligodendrocytes
Nodes of Ranvier
Gaps in the myelin sheath
Nerve
A bundle of nerve cell fibers (axons and dendrites) that follow the same path
Only found in the PNS
Tract
Bundle of nerve cell fibers
Found only in the CNS
Difference between tracts and nerves
Tracts are bundles of axons in the CNS, nerves are bundles of axons in the PNS
Ganglia
Clusters of neuron cell bodies
Found only in the PNS
Nuclei (nervous system)
Clusters of neuron cell bodies (one cluster is called a nucleus)
Found only in the CNS
Difference between ganglia and nuclei in the nervous system
Ganglia are clusters of neuron cell bodies in the PNS, nuclei are clusters of neuron cell bodies in the CNS
Blood-brain barrier
- Protective barrier that keeps harmful substances out of the brain
- Astrocytes form a wall around the outside of the blood vessels
- This astrocytic wall, plus the walls of the blood vessels, is collectively called the blood-brain barrier
Significance of the blood-brain barrier
Drugs (e.g., penicillin) that are needed to treat disorders in other parts of the body have no effect in the brain because they are not able to cross the blood-brain barrier
When the membrane is at the resting membrane potential
1) There is an unequal distribution of sodium ions at the inner and outer surface of the membrane
2) The membrane potential is approximately -70mV
3) The membrane is more permeable to the diffusion of potassium ions than sodium ions
4 types of ion channels in neurons
Leak channels
Ligand-gated channel
Mechanically gated channel
Voltage-gated channel
Resting membrane potential of a neuron
-70 mV
3 major factors that cause resting membrane potential
Unequal distribution of ions in the ECF and cytosol
Inability of most anions to leave the cell
Electrogenic nature of the Na+/K+ ATPases
Graded potential
Small deviation from the membrane potential
Occurs when a stimulus causes gated channels to open or close in an excitable cell’s plasma membrane
Disperses over a short distance
Occur mostly in the dendrites and cell body of a neuron
Decremental conduction
Mode of travel by which graded potentials die out as they spread along the membrane
Summation
The process by which graded potentials add together
Action potential
A rapid change in the membrane potential along a nerve fiber
Depolarizing phase
Negative membrane potential becomes less negative, reaches zero, then becomes positive
Repolarizing phase
Membrane potential is restored to the resting state of -70mV
After-hyperpolarizing phase
Memrane potential temporarily becomes more negative than the resting level
Absolute refractory period
Even a very strong stimulus cannot initiate a second action potential
Relative refractory period
Period of time during which a second action potential can be initiated but only by a larger-than-normal stimulus
Continuous conduction
Involves step-by-step depolarization and repolarization of each adjacent segment of the plasma membrane
Occurs in unmyelinated axons and muscle fibers
Saltatory conduction
Occurs along myelinated axons
Action potential appears to “leap” from node to node
Much faster and energy-efficient (less ATP used)
Factors that affect the speed of propagation of action potentials
- Amount of myelination
- Axon diameter (larger diameter -> faster)
- Temperature (lower temp -> slower)
Axodendritic synapse
From axon to dendrite
Axosomatic synapse
From axon to cell body
Axoaxonic synapse
From axon to axon
Electrical synapse
Action potentials conduct directly between the plasma membranes of adjacent neurons through structures called gap junctions
Advantages of electrical synapses
Faster communication Synchronization
Acetylcholine (ACh)
The only neurotransmitter that is released at the synapses between neurons and skeletal muscle cells (i.e., at the neuromuscular junction– NMJ)
Meninges
3 protective connective tissue coverings that encircle the spinal cord and brain Dura mater Arachnoid mater Pia mater
Epidural space
A space between the dura mater and the wall of the vertebral canal Contains a fat and connective tissue that protect the spinal cord
Subdural space
Between the dura mater and the arachnoid mater Contains interstitial fluid
Denticulate ligaments
Extensions of the pia mater that suspend the spinal cord in the middle of its dural sheath Protect the spinal cord against sudden displacement
Subarachnoid space
Between the arachnoid mater and the pia mater Contains CSF
Endoneurium
Innermost layer of connective tissue that wraps around individual axons (and their myelin sheaths if present) in a nerve
Perineurium
Layer of connective tissue surrounding a fascicle (bundle of axons)
Epineurium
Outermost covering over the entire nerve
The innermost meninx adhering to the brain and spinal cord
Pia mater
4 main regions of the brain
Cerebrum, diencephalon, brain stem, cerebellum
Frontal lobes
• Movements of voluntary skeletal muscles • Higher intellectual processes such as concentration, planning, and problem solving
Parietal lobes
• Sensations of temperature, touch, pressure, and pain • Understanding speech and using words
Temporal lobes
• Hearing and smelling • Memory of scenes and music
Occipital lobes
• Vision • Combining
Corpus colossum
connects the two hemispheres and provides the communication pathway between the two halves
4 ventricles of the brain
fluid-filled cavities - two lateral ventricles, the third ventricle, and the fourth ventricle
Cerebrospinal fluid is produced by the
Choroid plexus
