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136 Cards in this Set
- Front
- Back
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The brain
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complex organ, primitive functions,
experience, people develop differently connections you make |
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the nervous system
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two parts
central nervous system peripheral nervous system |
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CNS
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In head, neck and trunk
skull and vertebrae house brain and spinal cord |
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PNS
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all other nervous tissue
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systems
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are made of tissue, cells
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abduct
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move away
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adduct
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move towards
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deep
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near the center of body
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efferent
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exit
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afferent
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towards
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CNS
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brain & spinal cord
oliogodendrocytes mylenate oligodendrocyte wraps around multiple axons can be damaged by MS tissue barrier: blood brain barrier complex functions |
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PNS
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everywhere else
Schwann cells myelinate Nodes of ranvier Schwann cells may ensheath MS tissue barrier: perineural sheath less complex functions sensory or motor neurons |
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lipid soluble molecules
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can cross the Blood brain barrier (BBB)
ex Lead |
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low lipid soluble
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molecules that cannot cross BBB
ex bones |
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epithelial tissue
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skin and mucous membranes
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fascia
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sheet-like membrane surrounding organs
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nervous tissue cell
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neurons
glial cells |
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cranial/ cephalad
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toward the head
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caudal/caudad
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towards the tail
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internal
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inner or medial
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transverse
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right angles to the long ais of a structure
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temporal
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lateral region of the head
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saggital
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parallel to the saggital suture
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coronal
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parallel to the saggital suture
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rostral
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towards the nose or brow
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frontal
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forehead
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basilar
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skull base
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saggital plane
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mid saggital plane divides right & left
nose (if straight) is in mid-saggital plane saggital plane can be off centre might separate an ear from head might separate arm from body |
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coronal (frontal) plane
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coronal plane divides front & back
also called frontal plane coronal plane might separate: nose from face, face from rest of skull |
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transverse plane
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transverse plane separates "upper body" from "lower body"
beltline would be in transverse plane transvers plane might separate: head from neck (or body) chest from abdomen, hips from legs |
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bones of the skull
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frontal bone
temporal bone parietal bone occipital bone |
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important sutures
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saggital
coronal lamdoid |
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spinal nerves
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are identified by the column from which they exit
are all very similar (unlike cranial nerves- which differ) |
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Blood brain barrier
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semi- permeable
capillaries are lined with endothelial cells endothelial tissues has small spaces between each individual cell so substances can move readily between the inside and the outside of the vessel in the brain the endothelia cells fit tightly together and substances Astrocytes form a layer around brain blood vessels and may be important in the development of the BBB. Astrocytes may be also be responsible for transporting ions from the brain to the blood. Circumventricular Organs: There are several areas of the brain where the BBB is weak. This allows substances to cross into the brain somewhat freely. These areas are known as "circumventricular organs |
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endothelial tissue
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has small spaces between each individual cell so substances can move readily between the inside and the outside of the vessel
fit tightly together and substances cannot pass out of the bloodstream |
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astrocytes
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form a layer around brain blood vessels and may be important in the development of the BBB. Astrocytes may be also be responsible for transporting ions from the brain to the blood.
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BBB functions
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Protects the brain from "foreign substances" in the blood that may injure the brain.
Protects the brain from hormones and neurotransmitters in the rest of the body. Maintains a constant environment for the brain. |
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The BBB can be broken down by:
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Hypertension (high blood pressure): high blood pressure opens the BBB.
Development: the BBB is not fully formed at birth. Hyperosmolitity: a high concentration of a substance in the blood can open the BBB. Microwaves: exposure to microwaves can open the BBB. Radiation: exposure to radiation can open the BBB. Infection: exposure to infectious agents can open the BBB. Trauma, Ischemia, Inflammation, Pressure: injury to the brain can open the BBB. |
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development of BBB
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the BBB is not fully formed at birth
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hypersmoliity
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a high concentration of a substance in the blood can open the BBB
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PNS
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any neural tissue outside the skull or spinal column
spinal nerves and cranial nerves (31,12) Mass of the PNS is 3/4 of CNS about 2.5 million fibres average diameter of a neuron- 0.5 mm to 5mm more sensory nerves than motor cranial nerves- sensory motor- 4:1 motor nerves- cell bodies within spinal cord or brainstem sensory nerves cell bodies are not |
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PNS has two divisions
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Somatic nervous system (SNS)
Autonomic nervous system (ANS) |
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Spinal nerves
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large role in ANS
31 pairs of spinal nerves emerges from vertebrae identified by column from which they exit for speech and language: thoracic nerves= respiration spinal nerves are very similar (unlike cranial nerves- which differ) have a dorsal and ventral root |
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Somatic Nervous System
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interacts with external environment
conducts signals to the CNS from sensory receptors conducts motor signals from the CNS to the skeletal muscles |
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Somatic sensory system
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deals with touch, pain, vibration, pressure, temperature, proprioception, hearing, balance and vision
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Somatic motor system
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deals with voluntary skeletal muscle contractions
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Gray vs White matter
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gray matter = cell bodies
white matter = transmission fibres in the spinal cord- gray matter = H dorsal root- afferent fibres- sensory (body to CNS) Ventral root- efferent fibres- motor axons that emerge (from CNS to the body) |
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autonomic nervous system
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Participates in the regulation of the bodies internal environment
Conducts signals from sensory receptors in the internal organs Conducts motor signals from the CNS back to the internal organs We are not aware/conscious of the activities of the ANS |
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visceral sensory system
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deals with stretching, pain, temperature, nausea, hunger, taste and smell
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visceral motor system
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deals with the involuntary contraction of smooth and cardiac muscle. this includes the sympathetic divisions (fight or flight) and parasympathetic division (rest and digest)
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Sympathetic (ANS)
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Motor signals from CNS to organs
Signals that organize and mobilize energy resources during periods of threat Leave the CNS at thoracic and lumbar regions Copes with emergency (activating internal environment) |
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Parasympathetic (ANS)
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Motor signals from CNS to organs
Signals that act to conserve energy Calms the viscera after an emergency has passed Leave the CNS from the brain and the sacral region of the spinal cord |
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Endocrine system
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Consists of glands that secrete products/hormones into the blood stream
Second route of internal communication Hormones act only on cells that have receptor molecules (molecules to which the hormone can bind) Pituitary gland (master gland) Hypothalamus Pineal gland Thyroid gland Parathyroid glands Pancreas Thymus gland Adrenal glands Gonads (reproductive gland) |
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hypothalamus
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in the brain
tip end attaches to the pituitary gland (the body's master gland) communicates with pituitary connected to endocrine and autonomic systems and is part of CNS-- it controls the internal environment of the organism so the organism responds appropriately to the outside world |
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cells of the nervous system
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2 types
neurons Glial cells astrocytes microglial cells oligodendrocytes schwann cells satelite cells |
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neurons
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smallest functional unit of the nervous system
communicate with other neurons through synapse neurotransmitter (chemicals) are released at synapse neurotransmitters may have inhibitory or excitatory action (increases or decreases the action potential) In the CNS and PNS involved in impulse formation, impulse conduction and information processing all or nothing |
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neurons cont'd
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researchers use microscopes to examine neurons
light microscopes to examine prepared slides fluorescent and confocal scanning laser microscope (to observe developmental changes and functions of living cells |
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types of neurons differ
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multipolar neurons with a long axon
multipolar neurons with a short axon pyramidal purkinjie pseudounipolar neuron |
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Glial cells
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surround neurons to provide structural and functional support
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Astrocytes
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CNS only
maintain a constant internal milieu contribute to the structural of the blood-brain barrier phagocytize dead synapse form scar tissue in the CNS |
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Microglial cells
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CNS only
have a role in phagocytosis |
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Oligodendrocytes
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CNS
myelin sheath formation |
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Schwann Cells
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PNS only
myelin sheath formation |
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satelite cells
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PNS only
modified schwann cells that surround the cell body of neurons protect and nourish |
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synaptic patterns
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axons can terminate at various sites on the target neurons and form synapses there
axodendritic axosomatic axoaxonal axodendritic |
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polarized neurons
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When a neuron is not stimulated — it's just sitting with no impulse to carry or transmit — its membrane is polarized.
Being polarized means that the electrical charge on the outside of the membrane is positive while the electrical charge on the inside of the membrane is negative. The outside of the cell contains excess sodium ions (Na+); the inside of the cell contains excess potassium ions (K+), and negatively charged protein and nucleic acid molecules. Ions are atoms of an element with a positive or negative charge. Na+ and K+ do, in fact, move back and forth across the membrane. However, there are Na+/K+ pumps on the membrane that pump the Na+ back outside and the K+ back inside. The charge of an ion inhibits membrane permeability (that is, makes it difficult for other things to cross the membrane). When the neuron is inactive and polarized, it's said to be at its resting potential. It remains this way until a stimulus comes along. |
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action potential
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When a stimulus reaches a resting neuron, the gated ion channels on the resting neuron's membrane open suddenly and allow the Na+ that was on the outside of the membrane to go rushing into the cell. As this happens, the neuron goes from being polarized to being depolarized.
When more positive ions go charging inside the membrane, the inside becomes positive, as well; polarization is removed and the threshold is reached. Each neuron has a threshold level — the point at which there's no holding back (all or nothing). When the stimulus goes above the threshold level, more gated ion channels open and allow more Na+ inside the cell. This causes complete depolarization of the neuron and an action potential is created. |
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hyperpolarization
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When the K+ gates finally close, the neuron has slightly more K+ on the outside than it has Na+ on the inside.
This causes the membrane potential to drop slightly lower than the resting potential, and the membrane is said to be hyperpolarized because it has a greater potential. After the impulse has traveled through the neuron, the action potential is over, and the cell membrane returns to normal (that is, the resting potential). |
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refractory period
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Na+ and K+ are returned to their original sides: Na+ on the outside and K+ on the inside.
While the neuron is busy returning everything to normal, it doesn't respond to any incoming stimuli. After the Na+/K+ pumps return the ions to their rightful side of the neuron's cell membrane, the neuron is back to its normal polarized state and stays in the resting potential until another impulse comes along. |
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At synapse
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At the end of the axon from which the impulse is coming, the membrane depolarizes, gated ion channels open, and calcium ions (Ca2+) are allowed to enter the cell.
When the calcium ions rush in, a chemical called a neurotransmitter is released into the synapse (when synaptic vesicles bind to the membrane). The chemical that serves as the neurotransmitter moves across the synapse and binds to proteins on the neuron membrane that's about to receive the impulse. The proteins serve as the receptors, and different proteins serve as receptors for different neurotransmitters Excitation or inhibition depends on what chemical served as the neurotransmitter and the result that it had |
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development of nervous system
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develops for embryonic tissue called the ectoderm
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neural plate
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forms 18 days after conception, these are the cells for the nervous system
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neural groove
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forms a few days later (after neural plate)
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Neural tube
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is a fluid filled tube and is the deepened neural groove
(Cerebral spinal fluid) |
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neural crest
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cells on the edge of the neural plate that break away (PNS)
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Neural crest
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PNS
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neural plate & neural tube
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CNS
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proliferation
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new neurons are created by cell division in the region of the neural tube
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migration
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movement of cells
newly created neural cells migrate from the region of cell division to appropriate locations in the neural tube |
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aggregation
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similar cells
developing neurons align themselves to form specific structures of the brain |
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process growth and synapse formation
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cells
axons and dendrites grow and establish synaptic contacts |
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neuron death
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large numbers of neurons that have not established effective synaptic contacts die
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myelination
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axons become myelinated by the glial cells
not complete until after birth |
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forebrain divides into
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telencephalon & diencephalon
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midbrain divides into
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mesencephalon
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hindbrain divides into
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metencephalon & mylencephalon
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process growth
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neurons in correct location- nervous system 'wires up' ie axons and dendrites grow from neurons and establish synaptic connections
it is unknown how the growth cone finds its destination but there are two theories |
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chemoaffinity theory
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follow chemical signals
each target releases & specific chemical label |
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blueprint theory
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genetically predetermined
growing axons are programmed to follow specific traits |
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fassciculation
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the tendency of a bundle of axons to grow along the same path as their neighbors
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neurogenesis
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adult neurogenesis- growth of new neurons in adult brain
discovered in 1990's adult brains have a capacity for growth however- functions newly created neurons is unknown as to why this neurogenesis is limited to the hippocampi and the olfactory bulb (Alzheimers) |
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intramembranuous ossification
called Desmocranium |
ossification of connective tissue
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endochondral ossification
called chondocranium |
ossification of cartilage
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desmocranium
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nasal bone
lacrimal bone maxilla mandible zygomatic bone frontal bone parietal bone occipital bone (part) temporal bone (part) palantine (palate) vomer |
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chrondocramium
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ethmoid
sphenoid bone temporal (part) occipital bone (part) nasal concha (inferior) hyoid |
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paranasal sinuses
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frontal sinus
ethmoid cells sphenoid sinus maxilary sinus nasal cavity sinuses- spaces/ cavities filled with air, help with drainage, lined with hair that protect used for voice production |
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cleft palate
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the result of incorrect fusion of septum and either side of the palantine process (maxillary bone, vomer )
premaxilla fails to fuse- cleft lip |
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LaFort midfacial fractures
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fractures lines that may be the site of a fracture in a traumatic head injury or blast injuries
I- across maxilla above hard palate- separating maxilla from facial skeleton II- across nasal root, ethmoid bone, maxilla and zygomatic bone, pyramid fracture III- facial skeleton, separated from the base of theskull through orbits and may involve ethmoid, spheniod and zygomatic bones |
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development of the skull
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cranial bones grow as the brain expands
sutures remain open open areas are called fontanelles close at different times |
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scaphocephaly
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premature closure of saggital sutures
long narrow skull |
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oxycephaly
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premature closure of coronal suture
pointed skull |
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trigonocephaly
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premature closure of frontal suture
triangular skull |
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plagiocephaly
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asymmetrical suture closure
asymmetrical skull |
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hydrocephalus
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accumulation of cerebrospinal fluid before sutures ossify
expanded neurocranium (facial skeleton stayed the same) |
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microcephaly
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premature closure of sutures
small neurocranium w ith large orbits |
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bones of the cranial skeleton
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ethmoid
sphenoid frontal parietal temporal occipital |
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ethmoid
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complex delicate structure
holes for sinuses |
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spehnoid bone
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root of pharyngeal and nasal cavities
bat like shape greater wings lesser wings sphenoid sinus |
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bones of the face
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mandible (lower jaw- 1 bone)
maxillae (singular= maxilla, upper jaw) nasal bone (divide r & l top of the nose) palantine bone & nasal conchae vomer (nasal septum) zygomatic bone (cheek) vomer (nasal septum) lacrimal bone (behind nose) hyoid bone (suspends voicebox) |
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maxilla
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upper jaw
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vomer
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nasal septum
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lacrimal bone
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behind nose
small almost completely hidden |
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hyoid bone
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suspends voicebox, voice production not connected to any other bones
right above thyroid cartilage |
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jaw (mandible) lower jaw
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body
ramus angle coronoid process condylar process tempromandibular joint |
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maxilla (upper jaw)
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right and left
frontal processes zygomatic process alveolar process palantine |
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nasal bones
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form top of the face
rest of nose made up of cartilage |
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palantine bone & nasal conchae
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mucosal lining covers nasal conchae is thickest of nose and warms and humidifies air
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vomer
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unpaired midline bone
makes up nasal septum, the dividing plate between the two cavities |
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zygomatic bone
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cheekbones
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facial muscles
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since they attach to the skin (connective tissue) they can move it to wrinkle the skin and produce facial expression
protective function (eyes) active during eating ingestion (eating) chewing innervated by by the facial nerve (cranial nerve VII) |
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muscles of facial expression are important for
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speech articulation
emotion communication |
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muscles of mastication
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masseter- powerful
temporalis medial pterygoid lateral pterygoid primary function of these is to close the mouth |
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madibular movement in mastication (chewing)
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opening- requires little effort (gravity mainly and suprahyoid muscles)
closing the jaw needs powerful muscles capable more movement than needed for speech (for chewing, grinding and biting) hindging motion (biting and speech) glinding (for protrusion) translational movement (lateral) grinding at rest 2-4 mm space between teeth (this force is gravity and antigravity pull from muscles creating an upward force) |
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muscles of the mouth
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tongue
extrinsic muscles originate outside and insert into tongue intrinsic muscles originate in and insert into tongue |
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galea aponeurotica
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sheet like muscle over skull
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occipitofrontalis
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front belly- forehead
wrinkles forehead |
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temproparietal
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joins temporal and parietal
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orbicularis oculi
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eyes- around eye socket
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corrugator supercilli
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eyebrow muscle
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procerus
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bridge of nose
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nasalis
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nose
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levator labii superioris alaeque nasai
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elevates lips
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buccinator
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elevates lips and involved in chewing
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orbicularis oculi
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closes the eye- a protective function and prevents drying of eye
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orbicularis oris
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rounds lips
important in whistling and producing bilabial sounds also important in drinking (keeps liquid in mouth) |
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buccinator
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foundation of cheek
important in control of food when eating |
