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Three types of joints:
- Fibrous (synarthroses)
- Cartilagenous (amphiarthroses)
- Synovial (diarthroses)
Fibrous joints are also called what?
Cartilagenous joints are also called what?
Synovial joints are also called what?
Definition of fibrous joints:
Immovable joints, allow little or no movement between bones
Def of cartilagenous joint
Slightly movable joints
Def of synovial joint
Freely movable joint. Contain a synovial (joint) cavity.
What are the three types of fibrous/synarthrotic joints?
What are the two types of cartilagenous/amphiarthrotic joints?
What are the six types of synovial/diarthrotic joints?
Def of suture joint:
Type of fibrous joint. Bones held together by very short dense fibrous connective tissue fibers that penetrate into bones. Ossification occurs in adulthood, so become syntoses.
Def of syndesmosis joint:
Type of fibrous joint. Bones held together by a short ligament or sheet-like interosseous membrane.
Example of suture joint:
Fibrous joint, joint between cranial bones.
Example of syndesmosis joint:
Type of fibrous joint. Joint at distal end of tibia and fibula, and between radius and ulna.
Def of gomphosis:
Type of fibrous joint. Tooth anchored in socket by the periodontal ligament.
Def of symphysis joint
Type of cartilagenous joint. Broad, flat disc of fibrocartilage connected two bones.
Example of symphysis joint
Found between two pubic bones (pubic symphysis) and vertebral bodies (intervertebral disks)
Def of synchondrosis joint
Type of cartilagenous joint. Two bones united by a bridge or plate of hyaline cartilage.
Examples of synchondrosis joints
Between ribs and sternum (costal cartilage), and epiphyseal plates of long bones.
Def of plane/gliding joint
Type of synovial joint. Articular surfaces of bones are flat or slightly curved. Allows movement in one or two planes (back and forth or side to side).
Examples of plane/gliding joints:
Intercarpal and intertarsal joints, sternum and clavicle joint, scapula and clavicle joint, superior and inferior articular facets of vertebrae.
Def of hinge joints:
Type of synovial joint. A rounded or convext process of one bone fits into a concave surface or groove of another bone to allow movement in one plane, usually flexion and extension.
Example of hinge joints:
Elbow and knee joints
Def of pivot joints:
Type of synovial joint. Rounded or conical surface of one bone articulates with a shallow depression or foramen of another bone to allow movement in just one plane.
Examples of pivot joints
- Atlas and axis
- Radius and ulna
Def of ellipsoidal/condyloid joints
Type of synovial joint. Oval condyle of one bone fits into ellipsoidal depression in another bone. Allows bi-axial (two-way) movement (side to side and back and forth).
Examples of condyloid/ellipsoidal joints:
- Radius and carpals (wrist)
- Metacarpals and phalanges (knuckles)
- Occipital condyles and atlas
Def of saddle joint:
Type of synovial joint. Articulating surface of one bone is concave (saddle-shaped) and the reciprocal surface of the other bone is convex. Allows side to side and back and forth movement.
Example of saddle joint:
Metacarpal of thumb and trapezium
Def of ball-and-socket joints:
Type of synovial joint. Ball-shaped head of one bone fits into cup-like depression of another bone. Allows multi-axial movement (in all directions).
Examples of ball-and-socket joints:
Six important features of synovial joints:
- Joint/articular capsule
- Joint/synovial cavity
- Articular cartilage
Def of joint/articular capsule:
Encloses the joint/synovial cavity. Consists of 2 layers: fibrous capsule and synovial membrane.
Two layers of joint/articular capsule
- Fibrous capsule
- Synovial membrane
Def fibrous capsule:
Part of synovial joint. Layer of joint capsule. Outermost layer composed of dense, fibrous connection tissue. Encloses joint surfaces. Continuous with periosteum. May be reinforced by ligaments.
Def synovial membrane:
Part of synovial joint. Layer of joint capsule. Innermost layer, lies interior of joint capsule, except for articular surfaces. Comprised of loose connective tissue and produces synovial fluid.
Def synovial fluid:
Produced by synovial membrane in synovial joints. Acts as lubricant to reduce friction, provide nourishment, and contains phagocytic cells to remove microbes and debris.
Def joint/synovial cavity:
Fluid-filled cavity between articulating bones.
Def articular cartilage:
Contained in synovial joints. Composed of hyaline cartilage which covers articulating surfaces of bones forming the joint.
Some synovial joints. Fluid-filled sacs that cushion and reduce friction in areas where tendons, ligaments, or muscles cross bone. Walls of bursae composed of dense connective tissue and lined by synovial membrane.
Some synovial joints. Both intrinsic and extrinsic. May be present to reinforce the fibrous capsule.
Four properties of muscle:
Def exitability of muscle
The ability to receive and respond to a stimulus
Def contractility of muscle
Ability to shorten
Def extensibility of muscle
The ability to be stretched
Def elasticity of muscle
The ability to return to the original length after contraction or extension
Four functions of muscle
- Maintain posture
- Stabilize joints
- Heat production
Def muscle movement
Skeletal muscle contractions pull on tendons which then pull on bones
Def muscle maintain posture
Due to constant contraction of opposing pairs of muscles
Def muscle stabilizing joint
The tendons of many muscles extend over joints and contribute to their stability
Def muscle heat production
Muscle contraction generate heat and helps maintain body temperature. Approximately 85% of the heat produced by the body is from muscle contraction.
Functional contractile units of muscle
Muscle structure outline
Whole muscle -> fascicle -> muscle fiber/cell -> myofibril -> sarcomere -> myofilaments
Connective tissue sheath surrounding fascicle
Connective tissue sheath surrounding muscle fiber, outside of sarcolemma
cell membrace of muscle cell, surrounds muscle fiber and is covered by endomysium
As muscles are exercised, hypertrophy occurs. This is due to the increase in number of _____ and not the number of ________.
Type of thick filament in muscle
Def Sarcoplasmic reticulum
- specialized ER of skeletal and cardiac muscles consisting of lacy, sleeve-like network of tubules that surrounds each myofibril
- specialized structure called triad is located at Z-discs. Each triad consists of t-tubule flanked by terminal cisternae on each side
- t-tubule is invagination of sarcolemma
Fxn sarcoplasmic reticulum
Stores and, on demand, releases Ca+ ions. Ca+ ions control muscle reactions. It knows when to release when nerves send electricity down t-tubule as nerve impulse
Ach function in muscles
After release from the synaptic head via synaptic vesicles,Ach triggers depolarization of the sarcolemma when it binds to the receptors of the sarcolemma
Sliding Filament Mechanism Steps (12):
- 1) Ca+ ions are released from the SR
- 2) Ca+ binds to troponin
- 3) Troponin changes shape
- 4) Tropomyosin is moved into the groove between 2 actin strands, exposing the binding sites on actin
- 5) Myosin heads bind to the binding sites on actin = cross bridge attachment
- 6) Myosin heads change shape - from its high energy (upright) configuration to its low energy (bent) configuration. When the myosin head bends toward the center of the sarcomere, the attached thin filament also moves toward the center.
- 7) At the same time ADP + Pi from the previous cycle are released from the myosin head.
- 8) A new ATP immediately binds to the myosin head.
- 9) The binding of the ATP to the myosin head causes it to release the binding site on actin (cross bridge detachment).
- 10) ATP is hydrolyzed into ADP + Pi by myosin head ATPase enzyme.
- 11) Energy from ATP hydrolysis causes myosin head to become "cocked" in the high energy configuration once again.
- 12) The myosin head is now ready for a new cycle to begin again.
Muscle Fiber Characteristics
Def motor unit
Motor neuron + muscle fibers it innervates
How smooth muscle different from striated in organization:
- Smooth muscle contraction is involuntary.
- Smooth muscle lacks striations due to different proportion and organization of myofilaments
- Ratio of thick to thin is 1:13 instead of 1:2 in striated
- No troponin
- No sarcomeres, no interdigitating thick and thin filaments. Instead, small parallel group of thick and thin groups are arranged in spiral configuration
- Contain intermediate filaments attached to dense bodies
- Thin filaments are attached to dense bands, which are analagous to the Z discs of striated muscle
How smooth muscle is same as striated in contraction:
- Actin and myosin interact by sliding filament mechanism
- Ca+ triggers contraction
- ATP provides energy
Smooth muscle contraction steps(4)
- 1) Ca+ binds to calmodulin and activates it
- 2) Activated calmodulin activates myosin light chain kinase enzyme
- 3) Kinase enzyme catalyzes transfer of Pi from ATP to myosin, which allows it to interact with the thin filaments
- 4) Smooth muscle relaxes when Ca+ levels decrease
Smooth muscle is innervated by the ________ nervous system, whereas striated is innervated by the __________ nervous system.
Neuromuscular junction in smooth muscle are not highly structured:
- Varicosities instead of synaptic knobs
- Have diffuse junctions instead of synaptic clefts
- ANS releases other neurotransmitters in addition to Ach
- Neurotransmitters may be either excitatory or inhibitory
- Same neurotransmitter chemical may affect smooth muscle in different areas in different ways.
Isometric muscle contraction
- Muscle contraction in which length of muscle remains the same
- Ex. posture, flexing triceps and biceps at same time
Def isotonic muscle contraction
Muscle contraction that result in change of length of muscle
Types of isotonic contraction (2)
Def eccentric muscle contraction
Muscle lengthens as muscle develops force
Def concentric muscle contraction
Muscle shortens as muscle develops force
5 Types of glial cells
- 1) Astrocytes
- 2) Ependymal cells
- 3) Microglia
- 4) Oligodendrocytes
- 5) Schwann cells
Type of glial cell. Star-shaped cells with processes that wrap around capillaries and nerve cell processes. Form blood-brain barrier, regulate movement of substances from blood to brain
Type of glial cells. Line cavities and passages within the brain -- analagous to epithelial cells elsewhere in the body
Type of glial cell. Phagocytic cells of the brain.
Type of glial cell. Wrap around axons in CNS, forming myelin sheath.
Type of glial cell. Wrap around axons in PNS, forming myelin sheath.
2 Functions of Neurons
- 1) excitability
- 2) conductivity
Def Excitability in neurons
Ability to respond to a stimulus
Def Conductivity of neurons
Ability to transmit an impulse
Characteristics of Neurons
- 1) Extreme longevity
- 2) Amitotic - no division, can't be replaced
- 3) High metabolic rate - susceptible to lack of O2
3 Functional Components of Neurons
- 1) Receptive (input) region
- 2) Conducting region
- 3) Secretory (output) region
3 Anatomical Regions of Neuron
- 1) Cell Body
- 2) Dentrites
- 3) Axon
Cell bodies of neurons made up of:
- Nissl bodies (rough ER)
- Golgi apparatus
- Neurofibril (int. filament) - maintain shape
Features of dendrites of neurons
- Short processes
- Receptive/input region of neuron
- Contain many dendritic spines for more surface area for input
- Conduct graded potentials (short-distance messages) toward cell body
Features of Axons of Neurons
- Axon hillock
- Terminal branches (telodendria)
- Axon terminals (synaptic knob/bouton)
Types of cell bodies
- Nucleus = Cluster of nerve cell bodies in CNS
- Ganglion = Cluster of nerve cell bodies in PNS
Types of cell processes
- Tract = collection of axons in the CNS
- Nerve = collection of axons in the PNS
Measure of potential energy generated when two separate regions have a difference in electric charge
Def potential difference
Difference in voltage between two points
Movement or flow of electric charge between two points
Current is typically created by movement of _____ toward a positive charged region. In nerve cells, the flow of ______ constitutes the current
Material that permits the flow of electrons of ions through it
Hindrance to charge flow
Material that hinders the flow of electrons or ions through it
Equation that expresses the relationship between current, voltage, and resistance
Current (I) = Voltage (V)/Resistance (R)
Current and voltage are __________ proportional, which current and resistance are ___________ proportional.
Def Passive/leakage ion channel
Always open, allows ions to diffuse down their concentration gradient.
Two types of active/gated ion channels
- Chemically gated ion channels
- Voltage gated ion channels
Def Chemically gated ion channel
Opens in response to binding of a neurotransmitter molecule
Def Voltage gated ion channel
Opens in response to a change in voltage across the membrane
Def Resting membrane potential
Difference in charge across axolemma -- slightly positive on outside, slightly negative on inside.
Varies from -40 to -90 mV
Resting membrane potential is due to these two reasons:
Differences in permeability of membrane to