Test 2 Material Flashcards
Bone (Functions)
-Support
-Protection
-Movement
-Mineral Homeostasis
-Blood Cell Production (hemapoiesis/hematopoiesis)
-Storage
Structures in Bone
-Diaphysis
-Epiphyses
-Metaphyses
Diaphysis
-Long main portion of the bone
-a.k.a body, shaft
Epiphyses
-Ends of the bone
Metaphyses
-Regions between the diaphysis and the epiphyses
-Contains the epiphyseal growth plate/epiphyseal line
Epiphyseal Growth Plate
-Cartilagenous area within the metaphysis of a growing bone
-once growth stops, what remains is the epiphyseal line
Articular Cartilage
-Thin layer of hyaline cartilage covering the epiphyses
Perosteum
-Tough CT covering that surrounds bone
-Protects, nourishes, and heals bone
-Is an attachment for tendons & ligaments
-Outer layer is tough and supportive/protective
-Inner layer has bone forming cells
-Well vascularized and innervated *(Especially innervated for pain)
Medullary Cavity
-a.k.a marrow cavity
-Space within the diaphysis that contains:
1. Red Marrow (for blood cell formation)
2. Yellow Marrow (for fat storage)
Red Marrow
For blood cell formation
*(Pelvis, spine, ribs, sternum, scull, proximal ends of upper arm bone and thigh bones humorous & femur)
Yellow Marrow
For fat storage
*(everything else)
Bone is ______________.
CT
Bone Matrix
25% water, 25% collagen, 50% mineral salts
Bone Cells (In order)
- Osteoprogenitor Cells
- Osteoblasts
3.Osteocytes - Osteoclasts
Osteoprogenitor Cells
Active during normal growth, healing and cyclical bone replacement
Osteoblasts
Bone building cells
Osteocytes
Mature bone cells
Osteoclasts
Bone ‘eating’ cells
*Breaks down bone
Types of bone
- Compact
- Spongy
Compact
-a.k.a. cortical, dense
-external layer of all bones
-provides protection and support
Cortex is the __________ layer.
Outer Layer
Structures of Compact Bone
-Osteon
-Central Canal
-Concentric Lamellae
-Lacunae
-Canaliculi
-Volkmann’s Canals
Osteon is also known as _______________.
-a.k.a Haversian Systems
Central (a.k.a Haversian) Canal
-A hole through the centre of the osteon through which blood and lymphatic vessels run
Concentric Lamellae
-Rings of hard, calcified bone matrix around the central canal
Lacunae
-Spaces between the rings
-In the lacunae are osteocytes
Canaliculi
-Small channels sticking out (in all directions) from the lacunae
-Filled with extracellular fluid
-Allows osteocytes to communicate
Volkmann’s Canals
-a.k.a transverse perforating canals
-holes which run transversely to connect the inner and outer portions of the bone
Spongy Bone
-Trabeculae
-Trabeculae contain osteocytes in lacunae connected by canaliculi
-Lighter
-Spaces can contain red bone marrow
-Designed for lower stresses or stresses from different directions
Bone Blood Supply
-Well Vascularized
-Periosteal arteries enter the diaphysis at multiple points (Volkmann’s canals) to supply the periosteum and outer compact bone
-Nutrient arteries enter the diaphysis via the nutrient foramen to supply the inner compact bone, spongy bone & red bone marrow
-Metaphyseal arteries - supply the metaphysis
-Epiphyseal Arteries - supply the epiphysis
Metaphyseal arteries
Supply the metaphysis
Epiphyseal Arteries
Supply the epiphysis
Bone Growth/Aging
-Bone is in a constant state of remodelling
-From birth to adolescence, bone growth is greater than bone loss
-Long bones lengthen through growth at the epiphyseal growth plates and they get thicker by osteoblasts in the periosteum laying new bone at the periphery
-In young adults - bone growth is about equal to bone loss
-From middle ages - bone loss exceeds bone growth
From middle ages bone loss _____________ bone growth.
Exceeds
In young adults bone growth _______________ to bone loss.
Is about equal
From birth to adolescence, bone growth is _____________ than bone loss.
Greater
Long bones lengthen through growth at the ___________________ and they get thicker by ___________ in the _______________ laying new bone at the ________________.
Epiphyseal growth plates, osteoblasts, periosteum, periphery
Nutrient arteries enter the ____________ via the ________________ to supply the inner compact bone, spongy bone & red bone marrow
Diaphysis, nutrient foramen,
Periosteal arteries enter the ______________ at multiple points (Volkmann’s canals) to supply the periosteum and outer compact bone
Diaphysis
Central Nervous System (CNS)
-Brain
-Spinal cord
Peripheral Nervous System (PNS)
-All of the nervous tissue outside of the CNS
Functions of the Nervous System
- Sensory
-detection & input - Integrative
-processing/storing/analyzing of sensory info
-decision making - Motor
-output
Sensory
Detection & input
Integrative
-Processing/storing/analyzing of sensory info
-Decision making
Motor
Output
Nervous Tissue
-Designed for communication
-2 types of cells
1.Neuroglia
2.Neurons
Neuroglia
-Support
-Nourish
-Protect
Neurons
-Nerve cells
-3 parts: dendrite, cell body, axon
Dendrite
Structure: multiple or single extensions off the cell body
Function: the input portion of the neuron
-Contain lots of receptor sites for receiving chemical messages from other cells
Dendrite (structure)
Structure: multiple or single extensions off the cell body
Dendrite (function)
Function: the input portion of the neuron
Cell Body (structure)
Structure: contains the nucleus and other organelles
Cell Body (function)
Function: cell processes
Axon
-This cylindrical process off the cell body
-Function: The output portion of neuron
-End of an axon divides into many fine processes called axon terminals
-Synaptic end bulb: swollen ends of some axon terminals
-Some axons are myelinated
-Myelin: Multilayered lipid and protein covering that speeds up signal (action potential) conduction (axons coated in myelinare called ‘myelinated’ axons)
*Conduction of action potential
Axon (Function)
Function: The output portion of neuron
Synaptic end bulb
Swollen ends of some axon terminals
*Myelin
Multilayered lipid and protein covering that speeds up signal (action potential) conduction (axons coated in myelinare called ‘myelinated’ axons)
*Conduction of action potential
Neurons
-Possess electrical excitability
-Can respond to a stimulus and convert it to action potential
-Stimulus: Any change in the environment (internal or external) that is strong enough to stimulate an action potential
-Action Potential: Electrical signal that travels along cell membrane of a neuron
-Can communicate over very small or very great distances
-Action Potentials travel at different speeds
Stimulus
Any change in the environment (internal or external) that is strong enough to stimulate an action potential
Action Potential
Electrical signal that travels along cell membrane of a neuron
Structural Classification of Neurons
-Neurons vary in size and shape
-Structurally, neurons are classified according to the number of processes extending from the cell body
What are the 3 Structural Classifications of Neurons?
1.Multipolar
2.Bipolar
3. Unipolar
Multipolar
-Several dendrites and one axon
-Most neurons in the brain and spinal cord and all motor neurons
Bipolar
-One main dendrite and one axon
*Not very common
Unipolar
Peripheral axon - has sensory receptors
Central axon - has axon terminals
Sensory neurons - in the PNS are unipolar
Functional Classification of Neurons
-Functionally, they are classified according to the direction in which the action potential is conducted with respect to the CNS
What are the 3 Functional Classifications of Neurons?
- Sensory Neurons
- Motor Neurons
- Interneurons
Sensory Neurons
-a.k.a Afferent neurons
-Most are unipolar
-Contain either sensory receptors at the dendritic cells or are located just after sensory receptors that are separate cells
-Once activated by a stimulus, action potential forms and propagates along the axon and is conveyed into the CNS (via sensory or afferent neurons)
-Sensory neurons travel together in spinal and cranial nerves
Motor Neurons
-a.k.a Efferent neurons
-Multipolar
-Action potential propagates away from the CNS to effectors (via motor or efferent neurons)
-Effectors: cells and organs
Effectors
Cells and Organs
Interneurons
-a.k.a association neurons
-Most are multipolar
-Primarily in the CNS between sensory and motor neurons
-Interneurons integrate/process info from sensory neurons
-If motor response is required, the specifics of the response are formulated and relevant. motor neurons are activated
Synapses
-Site of communication between two neurons or between a neuron and another type of cell
-2 types of synapses: electrical and chemical
What are the 2 types of synapses?
- Electrical
- Chemical
Electrical Synapses
-Action potentials conduct directly between the plasma membranes of adjacent cells through gap junctions
-Faster (than chemical)
-Allow for synchronization of function
Pre-Synaptic neuron
Neuron sending the signal
Post-Synaptic Neuron
Neuron receiving the signal
Synaptic Cleft
Space between the communicating neurons
Neurotransmitter
Chemical released by the pre-synaptic neuron to affect (excite or inhibit) the post-synaptic neuron(s) or effector (muscle/gland)
Neurotransmitters are specific to the _________________?
Neurotransmitters released (think lock and key)
Chemical Synapse Processes
-When action potential reaches the end of the pre-synaptic neuron, it causes release of a neurotransmitter that diffuses across the synaptic cleft, binds to the post-synaptic neuron
-If neurotransmitter is excitatory - continuation of action potential is more likely
-If neurotransmitter is inhibitory - continuation of the action potential is less likely
-Chemical synapses are slower (than electrical)
If neurotransmitter is excitatory?
Continuation of action potential is more likely
If neurotransmitter is inhibitory?
Continuation of the action potential is less likely
What are 4 common neurotransmitters?
- Acetylcholine
- Gamma-Aminobutyric Acid
- Dopamine
- Seratonin
Acetylcholine (ACh)
PNS/CNS, excitatory at NMJ
Gamma-Aminobutyric Acid (GABA)
CNS, inhibitory
Dopamine
Excitatory or inhibitory (depending on the receptor), emotional responses, addictive behaviours, skeletal muscle tone
Seratonin
excitatory or inhibitory (depending on the receptor), sensory perception, temperature regulation, mood, sleep, appetite
Neuroglia
-Support, nourish, and protect neurons
-With injury and/or disease, neuroglia multiply to fill the spaces formerly occipied by neurons
What are the 4 types neuroglia of the CNS?
- Astrocytes
- Oligodendrocytes
- Microglia
- Ependymal cells
Astrocytes
-Help form blood-brain barrier (BBB)
-Provide nutrients to neurons
Oligodendrocytes
-Form/maintain the myelin sheath of CNS neurons
Microglia
-Phagocytotic (similar to tissue macrophages)
-Remove debris, phagocytize microbes
Ependymal cells
-Line the cavities of the brain and spinal cord
-Produce and assist in circulation of cerebrospinal fluid (CSF) clear, colourless fluid that circulates around brain and spinal cord (protects brain and spinal cord from injury)
Blood-Brain Barrier (BBB)
-Specialized barrier prevents passage of materials from the blood and the brain (and its surrounding fluid)
-Protects brain from harmful substances
-Thick basement membrane, tight junctions
What is Neuroglia of the PNS?
Schwann Cells
Schwann Cells
-Cells that encircle axons in the PNS
-Form myelin sheath of PNS axons
-Involved in regeneration of PNS axons
Central Nervous System (CNS) includes?
Brain and Spinal Cord
Peripheral Nervous System (PNS)
-Cranial nerves and their branches
-Spinal nerves and their branches
-Ganglia
-Enteric plexuses
-Sensory receptors
Nucleus
Cluster of neuronal cell bodies in the CNS (plural: nuclei)
Ganglion
Cluster of neuronal cell bodies in the PNS (plural: ganglia)
Tract
Bundle of axons in CNS
-Tracts interconnect neurons in the spinal cord and brain
Nerve
Bundle of axons in PNS
-Spinal Nerves: connect the spinal cord to the periphery
-Cranial Nerves: connect the brain to the periphery
Spinal Nerves
Connect the spinal cord to the periphery
Cranial Nerves
Connect the brain to the periphery
Grey Matter
Collections of cell bodies and unmyelinated nerve fibres in the CNS
White Matter
Collections of myelinated axons in the CNS
Spinal Cord
-Encased in vertebrae (bones of the spine)
-Extends from the bottom part of the brain stem to the 2nd lumbar vertebra (L2)
-At L2, it tapers into a structure called the conus medullaris
-Cauda Equina: the roots of the spinal nerves below the conus medullaris
*Spinal cord ends at L2
Cauda Equina
The roots of the spinal nerves below the conus medullaris
Neck/Cervical
C1-C7
Thoracic
T1-T12
Lumbar
L1-L5
Sacrum
S1-S5
Structure around Spinal Cord
-White matter surrounding an inner core of grey matter
-Anterior median fissure and posterior median sulcus: 2 grooves that divide the white matter into right and left sides
-Central canal: small tube in the centre if the SC that contains CSF
Anterior median fissure and posterior median sulcus
2 grooves that divide the white matter into right and left sides
Central canal
Small tube in the centre if the SC that contains CSF
Grey Matter
-Each side is divided into regions called horns
-Posterior Horn (a.k.a dorsal): axons of incoming sensory neurons and interneurons
-Anterior Horn (a.k.a ventral): motor nuclei
-Lateral Horn: Present in thoracic, upper lumbar, sacral portions, they contain the sympathetic nuclei
Posterior Horn (a.k.a dorsal)
Axons of incoming sensory neurons and interneurons
Anterior Horn (a.k.a ventral)
Motor nuclei
Lateral Horn
Present in thoracic, upper lumbar, sacral portions, they contain the sympathetic nuclei
What are the 3 horns in grey matter?
- Posterior Horn (a.k.a dorsal)
- Anterior Horn (a.k.a ventral)
- Lateral Horn
White Matter
-Each side is divided into regions called columns
3 Regions: anterior columns (a.k.a ventral), posterior columns (a.k.a dorsal), lateral columns
-Each column contains bundles of axons (tracts) that have a common origin or destination
-Sensory Tracts (a.k.a ascending): consist on axons that conduct action potentials toward the brain
-Motor Tracts (a.k.a descending): consist of axons that conduct action potentials away from the brain
What are the 3 regions of white matter?
- Anterior columns (a.k.a ventral)
- Posterior columns (a.k.a dorsal)
- Lateral columns
Sensory Tracts (a.k.a ascending)
Consist on axons that conduct action potentials toward the brain
Motor Tracts (a.k.a descending)
Consist of axons that conduct action potentials away from the brain
Brain Structure
- Brain stem
- Cerebellum
- Diencephalon
- Cerebrum
Brain Stem
-Continuous with spinal cord (SC, it is the part between the SC and the diencephalon
-3 Regions: medulla oblongata, pons, midbrain
-These regions also contain nuclei of specific cranial nerves
-The net-like reticular formation extends through the brainstem
3 Regions of Brain Stem?
- Medulla oblongata
- Pons
- Midbrain
Medulla Oblongata
-Contains centres (nuclei) for the control of the heart rate, blood pressure, breathing, swallowing, and vomiting
Pons
-Contains centres for the control of breathing
Midbrain
-Contain centres for reflex visual activities (e.g. tracking moving objects, scanning stationary objects), hearing
-Contains nuclei called the substantia nigra - Neurons that make dopamine extend from it
Neurons that make dopamine extend from _____________________.
substantia nigra (nuclei)
Reticular Formation
-Net-like formation of neural tissue that spreads throughout the brain stem
-Contains the reticular activating system (RAS) which helps:
-Consciousness
-Maintain Attention
-Prevent sensory overload by filtering out insignificant info
-*Regulate muscle tone
Reticular Activating System (RAS) helps?
-Consciousness
-Maintain Attention
-Prevent sensory overload by filtering out insignificant info
-*Regulate muscle tone
Cerebellum
-Posterior to brain stem
-Smoothes and coordinates skeletal muscle contraction
-Regulates posture and balance
3 Parts of the Diencephalon?
- Hypothalamus
- Thalamus
- Epithalamus
Hypothalamus
-Major regulator of homeostasis
-Controls and integrates the autonomic nervous system
-Hormone production
-Emotion and behaviour (with limbic system)
-Eating, drinking
-Body temperature
-Circadian rhythm (a 24hr cycle in the biochemical, physiological and/or behavioural processes of living things)
Circadian rhythm
24hr cycle in the biochemical, physiological and/or behavioural processes of living things
Thalamus
-Major relay station for most sensory input to the cerebral cortex
Epithalamus
-Contains the pineal gland
-Involved in smelling (especially emotional responses to smells)
Cerebrum
-2 halves or hemispheres (right & left)
-Consist of:
-Outer rim of grey matter (cerebral cortex;
-Inner region of white matter (association areas); and
-Grey matter nuclei deep within white (basal ganglia)
Outer rim of Grey Matter
Cerebral Cortex
Inner region of White Matter
Association Areas
Grey Matter Nuclei deep within White
Basal Ganglia
Cerebral Cortex
-Contains sensory areas involved in perception
-Contains motor areas involved in the execution of voluntary movements
Association Areas (White Matter)
-Contain areas that deal with more complex functions like memory, emotions, reasoning, will, judgment, personality traits, intelligence
Basal Ganglia
-a.k.a basal nuclei
-Helps regulate the starting and stopping of movements
-Helps control subconscious contraction of skeletal muscles
-Helps suppress unwanted movement
-Helps to set resting muscle tone
-Functionally, basal ganglia are linked to substantia nigra
Limbic System
-Involved in emotion, smelling, and memory
-Includes parts of the hypothalamus, hippocampus, amygdala, and other nearby structures
Hippocampus
-Functions in memory (encoding, consolidation, and retrieval)
-Very important in converting short term memory into long term memory
Amygdala
Important in emotional function (esp. fear)
Meninges
-3 protective layers of connective tissue (CT) that encircle the brain and spinal cord (SC)
-They cover the Brain/SC up to the point where the nerves exit the spinal cord
What are the 3 protective layers (meninges) of connective tissue (CT) that encircle the brain and spinal cord (SC)?
- Dura Mater
- Arachnoid Membrane
- Pia Mater
Dura Mater
Tough outer layer
Arachnoid Membrane
Middle layer
Pia Mater
Inner layer
Epidural Space
Adipose and CT- filled space between the wall of vertebral canal and dura mater (no epidural space in brain)
Subdural Space
Interstitial fluid-filled space between the dura mater and arachnoid membrane
Subarachnoid Space
CSF filled space between arachnoid membrane and the pia mater
Peripheral Nervous System (PNS)
All of the nervous tissue outside the CNS including:
-Cranial Nerves
-Spinal Nerves
-Ganglia
-Sensory Receptors
Cranial Nerves
-Paths of communication between brain and periphery
-12 pairs of nerves that exit from base of brain
Spinal Nerves
-Paths of communication between SC and the periphery
-31 pairs of spinal nerves
-Parallel bundles of axons (& their associated neurological cells) wrapped in several layers of CT
-Spinal nerves connect the SC to receptors, muscles, glands in all body parts of the body
-31 pairs numbered according to region and level of vertebral column from which they emerge
-1st pair of cervical nerves emerge from spinal cord between base of the scull and 1st cervical vertebra
-C1-C7 exit the spine above their corresponding vertebra
-C8 exits between C7 and T1 Vertebra
-Not all are aligne with their corresponding vertebrae - lumbar, sacral and coccygeal nerves descend from ~ L2 to their respective levels
What are 4 Spinal nerves ?
- Nerve root
- Anterior Root (ventral)
- Posterior Root (dorsal)
- Posterior/Dorsal Root Ganglion
Nerve Root
two bundles of axons that connect the spinal nerve to the SC
Anterior Root (ventral)
Bundle of motor axons
Posterior Root (dorsal)
Bundle of sensory axons
Posterior/Dorsal Root Ganglion
Swelling in the posterior root containing cell bodies of sensory (a.k.a. unipolar, primary afferent) neurons of the PNS
What are the 3 Connective tissues of a Spinal Nerve?
- Endoneurium
- Perineurium
- Epineurium
Endoneurium
Innermost, covers the axon (whether it’s myelinated or not)
Perineurium
Middle layer, covers fascicles (bundles of axons)*Perineurium & epineurium are highly vascularized
Epineurium
Outermost layer, covers spinal nerve
*Perineurium & epineurium are highly vascularized
3 Subdivisions of the PNS?
- Somatic NS (SNS)
- Autonomic NS (ANS)
- Enteric NS (ENS)
*Somatic Nervous System (SNS)
-‘Voluntary nervous system’
-Sensor neurons (a.k.a. 1st order neurons) convey info to the CNS (e.g. temp, pressure, pain …)
-Motor neurons conduct impulses (signals from the CNS to skeletal muscles only
Autonomic Nervous System (ANS)
Monitors (sensory) and controls (motor) body activities (cardiac, smooth muscle, glands) automatically
2 divisions: sympathetic nervous system (SyNS) and parasympathetic system (PaNS)
What are 2 divisions of Autonomic Nervous System (ANS)?
- Sympathetic nervous system (SyNS)
- Parasympathetic system (PaNS)
Sympathetic nervous system (SyNS)
-Fight or flight
-High sympathetic activity comes from being excited, scared, threatened
Responses of Sympathetic nervous system (SyNS)?
-Pupil dialation
-Increased Heart Rate, blood pressure
-Airway dilation
-Vasodilation of skeletal and cardiac mm.
-Glucose release
-Vasoconstriction in kidneys and the digestive tract
Parasympathetic system (PaNS)
-Rest and digest
-Conserve and restore energy systems
-Increased digestive and urinary functions
Autonomic Tone
-Balance between sympathetic and parasympathetic activity
-Regulated by hypothalamus
-Most organs have dual innervation (PaNS & SyNS)
-Few structures receive only sympathetic innervation (sweat glands, arrector pilli, kidneys, most BVs, adrenal medullae) - function is determined by increasing or decreasing sympathetic stimulation
-For normal functioning there needs to be a balance between sympathetic and parasympathetic activity
-Effects of sympathetic stimulation last longer and are more widespread than effects of parasympathetic stimulation
Autonomic Control
Major control and integration centre for the ANS is the hypothalamus
Enteric Nervous System (ENS)
-Sensory neurons that monitor chemical changes within the gastrointestinal (GI) tract and stretching of its walls
-Motor neurons control contraction of GI tract smooth muscle and secretions of GI organs (e.g. acid secretions by stomach)
Sensory Input
-Peripheral sensory receptor (e.g. unipolar neuron) detects stimulus
-Sensory input (in form of AP) travels along the axon to cell body in the dorsal rood ganglion (DRG); from DRG, the sensory axon may proceed in 3 ways:
1. Axon extends into white matter an travels up to brain as part of sensory tract (ascending)
2. Axon enters the dorsal horn and synapses with an interneuron - it’s axon crosses over into white matter of opposite side and travels up to brain as part of a sensory tract
3. Axon enters dorsal horn and synapses with and interneuron which in turn synapses with a somatic motor neuron in the ventral horn as part of spinal reflex pathway
Motor Output occurs via 2 ways?
- Somatic
- Autonomic
Somatic
Axons from motor tract (descending) synapse with the somatic motor neurons in the ventral horn on the contralateral side - these axons extend through ventral root then spinal nerve to innervate skeletal muscles
Autonomic
Autonomic motor neurons in the lateral horn send output along axons which sequentially pass through the lateral grey horn, the anterior grey horn and the anterior root to enter spinal nerve. From spinal nerve, the axons of autonomic motor neurons synapse with another group of autonomic motor neurons which will innervate cardiac muscles, smooth muscles or glands
Metabolic Requirements of Nervous Tissue
-High metabolic rate
-Glucose is primary energy substrate for the nervous system but neurons have no glycogen stores (get it from blood or neuroglial cells)
Regeneration & Repair of Nervous TIssues
-Although nervous tissue can readily adapt, it has limited ability to regenerate
-In the PNS: damage to dendrites and myelinated axons can be repaired if the cell body is intact and schwann cells are active
-In the CNS: little or no repair of damaged neurons occurs
