Podcast
Questions and Answers
What is the outermost layer of the skin called?
What is the outermost layer of the skin called?
Epidermis
What is the deepest layer of the epidermis called?
What is the deepest layer of the epidermis called?
Stratum basale
What type of cells are primarily found in the stratum spinosum?
What type of cells are primarily found in the stratum spinosum?
Keratinocytes
What is the name of the layer of the epidermis that only appears in thick skin?
What is the name of the layer of the epidermis that only appears in thick skin?
Which of the following is NOT a function of the integumentary system?
Which of the following is NOT a function of the integumentary system?
What are the two main layers of the dermis?
What are the two main layers of the dermis?
What is the primary function of the subcutaneous layer?
What is the primary function of the subcutaneous layer?
Full-thickness burns affect only the epidermis.
Full-thickness burns affect only the epidermis.
What is the name of the cells that produce melanin, the pigment that gives skin its color?
What is the name of the cells that produce melanin, the pigment that gives skin its color?
What is the primary function of the nervous system?
What is the primary function of the nervous system?
What are the two main divisions of the nervous system?
What are the two main divisions of the nervous system?
What are the structural components of the peripheral nervous system?
What are the structural components of the peripheral nervous system?
Which of the following is NOT a function of the peripheral nervous system?
Which of the following is NOT a function of the peripheral nervous system?
What is the name of the space between the axon of one neuron and the dendrite of another neuron?
What is the name of the space between the axon of one neuron and the dendrite of another neuron?
What is the name of the neurotransmitter released at neuromuscular junctions?
What is the name of the neurotransmitter released at neuromuscular junctions?
What is the name of the specialized cell that provides support and insulation for neurons in the peripheral nervous system?
What is the name of the specialized cell that provides support and insulation for neurons in the peripheral nervous system?
The action potential is a brief, localized change in the membrane potential of a neuron.
The action potential is a brief, localized change in the membrane potential of a neuron.
What is the name of the period following an action potential when the neuron is less likely to fire another action potential?
What is the name of the period following an action potential when the neuron is less likely to fire another action potential?
Which type of conduction occurs in unmyelinated axons?
Which type of conduction occurs in unmyelinated axons?
What is the name of the specialized gap in the myelin sheath that allows for faster signal transmission in myelinated axons?
What is the name of the specialized gap in the myelin sheath that allows for faster signal transmission in myelinated axons?
Which of the following is NOT a classification of neurotransmitters based on their chemical structure?
Which of the following is NOT a classification of neurotransmitters based on their chemical structure?
What is the name of the neurotransmitter that is primarily involved in stimulating skeletal muscle contraction?
What is the name of the neurotransmitter that is primarily involved in stimulating skeletal muscle contraction?
What is the name of the type of neurotransmitter that directly binds to receptors to cause a rapid change in membrane potential?
What is the name of the type of neurotransmitter that directly binds to receptors to cause a rapid change in membrane potential?
Which of the following is a type of glial cell found in the CNS?
Which of the following is a type of glial cell found in the CNS?
Which glial cells are responsible for producing cerebrospinal fluid?
Which glial cells are responsible for producing cerebrospinal fluid?
What is the name of the glial cells that are responsible for myelinating axons in the central nervous system?
What is the name of the glial cells that are responsible for myelinating axons in the central nervous system?
Satellite cells are found in the CNS and help form blood-brain barrier
Satellite cells are found in the CNS and help form blood-brain barrier
Which of the following is NOT a function of glial cells?
Which of the following is NOT a function of glial cells?
What are the primary differences between the nervous system and the endocrine system?
What are the primary differences between the nervous system and the endocrine system?
What is the function of the myelin sheath in nerve transmission?
What is the function of the myelin sheath in nerve transmission?
What is found at the receiving end of a synapse?
What is found at the receiving end of a synapse?
Which part of the neuron transmits impulses away from the cell body?
Which part of the neuron transmits impulses away from the cell body?
What neurotransmitter is mentioned in the content that is found at neuromuscular junctions?
What neurotransmitter is mentioned in the content that is found at neuromuscular junctions?
What is the axon hillock's primary role in neuron function?
What is the axon hillock's primary role in neuron function?
Which part of the nervous system is responsible for voluntary control of body movements?
Which part of the nervous system is responsible for voluntary control of body movements?
Which structure is primarily responsible for processing and evaluating sensory information?
Which structure is primarily responsible for processing and evaluating sensory information?
What is the role of effectors in the nervous system?
What is the role of effectors in the nervous system?
Which division of the nervous system consists of the brain and spinal cord?
Which division of the nervous system consists of the brain and spinal cord?
Visceral sensory responses are primarily associated with which component of the nervous system?
Visceral sensory responses are primarily associated with which component of the nervous system?
How does the peripheral nervous system function regarding the spinal cord?
How does the peripheral nervous system function regarding the spinal cord?
What process is initiated by the brain and spinal cord in response to sensory input?
What process is initiated by the brain and spinal cord in response to sensory input?
What type of signals do receptors detect in the context of the nervous system?
What type of signals do receptors detect in the context of the nervous system?
What is the primary function of ependymal cells?
What is the primary function of ependymal cells?
Which type of cell is responsible for myelination in the peripheral nervous system?
Which type of cell is responsible for myelination in the peripheral nervous system?
What role do microglia play in the central nervous system?
What role do microglia play in the central nervous system?
Which glial cells are involved in regulating nutrient and waste exchange in ganglia of the peripheral nervous system?
Which glial cells are involved in regulating nutrient and waste exchange in ganglia of the peripheral nervous system?
What is the primary function of oligodendrocytes in the central nervous system?
What is the primary function of oligodendrocytes in the central nervous system?
Which of the following correctly describes the role of ependymal cells?
Which of the following correctly describes the role of ependymal cells?
In addition to myelination, what is another function of Schwann cells?
In addition to myelination, what is another function of Schwann cells?
Which type of glial cell replicates during an infection within the CNS?
Which type of glial cell replicates during an infection within the CNS?
What is the primary cause of depolarization in an action potential?
What is the primary cause of depolarization in an action potential?
What occurs immediately after the Na+ channels close during an action potential?
What occurs immediately after the Na+ channels close during an action potential?
What happens to the membrane potential during hyperpolarization?
What happens to the membrane potential during hyperpolarization?
Which mechanism returns the membrane to its resting potential after an action potential?
Which mechanism returns the membrane to its resting potential after an action potential?
What role do voltage-gated Na+ channels play during action potentials?
What role do voltage-gated Na+ channels play during action potentials?
What is the result of K+ channels remaining open for a longer time during repolarization?
What is the result of K+ channels remaining open for a longer time during repolarization?
What occurs during the refractory period of an action potential?
What occurs during the refractory period of an action potential?
Why is the resting membrane potential (RMP) crucial for neuron function?
Why is the resting membrane potential (RMP) crucial for neuron function?
What is the main characteristic of the stratum lucidum?
What is the main characteristic of the stratum lucidum?
Which type of cells are predominantly found in the stratum corneum?
Which type of cells are predominantly found in the stratum corneum?
What is the primary purpose of collagen fibers in the dermis?
What is the primary purpose of collagen fibers in the dermis?
Why are incisions oriented along tension lines more likely to heal quickly?
Why are incisions oriented along tension lines more likely to heal quickly?
What role do sweat glands play in thermoregulation?
What role do sweat glands play in thermoregulation?
Which component is NOT found in the dermis?
Which component is NOT found in the dermis?
What is a potential consequence of skin stretching beyond collagen fiber capabilities?
What is a potential consequence of skin stretching beyond collagen fiber capabilities?
Which of the following is NOT a function of the dermis?
Which of the following is NOT a function of the dermis?
Which glands are responsible for secreting sebum?
Which glands are responsible for secreting sebum?
What type of connective tissue primarily makes up the subcutaneous layer?
What type of connective tissue primarily makes up the subcutaneous layer?
Which layer of skin is characterized by dead, interlocking cells?
Which layer of skin is characterized by dead, interlocking cells?
What are the primary cells found in the stratum lucidum filled with?
What are the primary cells found in the stratum lucidum filled with?
Which type of tissue serves as the foundation of the dermis?
Which type of tissue serves as the foundation of the dermis?
What type of conduction is characterized by faster impulses jumping from node to node?
What type of conduction is characterized by faster impulses jumping from node to node?
Which neurotransmitter is synthesized from acetate and choline?
Which neurotransmitter is synthesized from acetate and choline?
Which classification of neurotransmitters includes glutamate and GABA?
Which classification of neurotransmitters includes glutamate and GABA?
What is the immediate effect of excitatory neurotransmitters on the postsynaptic membrane potential?
What is the immediate effect of excitatory neurotransmitters on the postsynaptic membrane potential?
What happens to acetylcholine after it is released into the synaptic cleft?
What happens to acetylcholine after it is released into the synaptic cleft?
Which type of neurotransmitter binds to receptors that involve G-proteins?
Which type of neurotransmitter binds to receptors that involve G-proteins?
Which of the following best describes the roles of neuropeptides?
Which of the following best describes the roles of neuropeptides?
What is the primary effect of GABA as a neurotransmitter?
What is the primary effect of GABA as a neurotransmitter?
Which chemical class of neurotransmitters is primarily formed from amino acids?
Which chemical class of neurotransmitters is primarily formed from amino acids?
What distinguishes direct transmitters from indirect transmitters?
What distinguishes direct transmitters from indirect transmitters?
Which of the following neurotransmitters can have varying effects depending on the receptor present?
Which of the following neurotransmitters can have varying effects depending on the receptor present?
What is the result of an impulse moving continuously along an unmyelinated axon?
What is the result of an impulse moving continuously along an unmyelinated axon?
What is the role of myelin in nerve conduction?
What is the role of myelin in nerve conduction?
What is one primary function of astrocytes in the central nervous system?
What is one primary function of astrocytes in the central nervous system?
Which function of astrocytes directly contributes to maintaining the chemical environment around neurons?
Which function of astrocytes directly contributes to maintaining the chemical environment around neurons?
In what way do astrocytes assist during neuronal development?
In what way do astrocytes assist during neuronal development?
What role do astrocytes play in the context of dying neurons?
What role do astrocytes play in the context of dying neurons?
What is NOT a function of astrocytes in the central nervous system?
What is NOT a function of astrocytes in the central nervous system?
What effect do excitatory neurotransmitters have on membrane potential?
What effect do excitatory neurotransmitters have on membrane potential?
What is the primary characteristic of direct neurotransmitters?
What is the primary characteristic of direct neurotransmitters?
How do indirect neurotransmitters differ from direct neurotransmitters?
How do indirect neurotransmitters differ from direct neurotransmitters?
What is the result of inhibitory neurotransmitters on postsynaptic neurons?
What is the result of inhibitory neurotransmitters on postsynaptic neurons?
Which of the following best describes the action of neurotransmitters classified as indirect?
Which of the following best describes the action of neurotransmitters classified as indirect?
What occurs during the depolarization phase of an action potential?
What occurs during the depolarization phase of an action potential?
What leads to hyperpolarization of the membrane during an action potential?
What leads to hyperpolarization of the membrane during an action potential?
What is the resting membrane potential of an unstimulated axon?
What is the resting membrane potential of an unstimulated axon?
Which of the following best describes the role of voltage-gated Na+ channels during repolarization?
Which of the following best describes the role of voltage-gated Na+ channels during repolarization?
What role do Na+/K+ pumps play after an action potential?
What role do Na+/K+ pumps play after an action potential?
What is the primary function of satellite cells in the peripheral nervous system?
What is the primary function of satellite cells in the peripheral nervous system?
What is the role of neurolemmocytes (Schwann cells) in the peripheral nervous system?
What is the role of neurolemmocytes (Schwann cells) in the peripheral nervous system?
Which of the following statements is true regarding the function of satellite cells?
Which of the following statements is true regarding the function of satellite cells?
What is a key feature of the myelination process performed by Schwann cells?
What is a key feature of the myelination process performed by Schwann cells?
In which part of the nervous system do satellite cells function?
In which part of the nervous system do satellite cells function?
Which type of glial cell is responsible for producing cerebrospinal fluid?
Which type of glial cell is responsible for producing cerebrospinal fluid?
What is one of the functions of microglia in the central nervous system?
What is one of the functions of microglia in the central nervous system?
Which best describes the primary role of oligodendrocytes?
Which best describes the primary role of oligodendrocytes?
Which statement about astrocytes is incorrect?
Which statement about astrocytes is incorrect?
What is the primary connective tissue layer that encloses the entire nerve?
What is the primary connective tissue layer that encloses the entire nerve?
Which connective tissue wrapping specifically wraps individual axons?
Which connective tissue wrapping specifically wraps individual axons?
What is the composition of the perineurium's connective tissue?
What is the composition of the perineurium's connective tissue?
Which layer of connective tissue is crucial for electrically insulating each axon?
Which layer of connective tissue is crucial for electrically insulating each axon?
Which of the following correctly describes the epineurium?
Which of the following correctly describes the epineurium?
What is the primary function of the axon hillock in a neuron?
What is the primary function of the axon hillock in a neuron?
How does the myelin sheath affect the transmission of nerve impulses?
How does the myelin sheath affect the transmission of nerve impulses?
Which component of the neuron primarily receives sensory input?
Which component of the neuron primarily receives sensory input?
What role do Nodes of Ranvier play in the conduction of action potentials?
What role do Nodes of Ranvier play in the conduction of action potentials?
Which structure in the neuron is responsible for containing neurotransmitters?
Which structure in the neuron is responsible for containing neurotransmitters?
What is the primary role of keratinocytes in the stratum basale?
What is the primary role of keratinocytes in the stratum basale?
What characterizes the cells of the stratum granulosum?
What characterizes the cells of the stratum granulosum?
Which layer of the epidermis is only found in thick skin?
Which layer of the epidermis is only found in thick skin?
What major function do epidermal dendritic cells serve within the epidermis?
What major function do epidermal dendritic cells serve within the epidermis?
How are keratinocytes in the stratum spinosum primarily connected?
How are keratinocytes in the stratum spinosum primarily connected?
What is the main characteristic of cells in the stratum corneum?
What is the main characteristic of cells in the stratum corneum?
Which cell type in the epidermis is responsible for producing pigment to protect from UV radiation?
Which cell type in the epidermis is responsible for producing pigment to protect from UV radiation?
What occurs to the nucleus and organelles as keratinocytes transition through the stratum granulosum?
What occurs to the nucleus and organelles as keratinocytes transition through the stratum granulosum?
What is the structural arrangement of the cells in the stratum lucidium?
What is the structural arrangement of the cells in the stratum lucidium?
How does the integument contribute to temperature regulation?
How does the integument contribute to temperature regulation?
Which of the following accurately describes the skin's ability to absorb substances?
Which of the following accurately describes the skin's ability to absorb substances?
What role do dendritic cells play in the integumentary system?
What role do dendritic cells play in the integumentary system?
Which of the following statements about water retention in the epidermis is true?
Which of the following statements about water retention in the epidermis is true?
What is the proper formation of skin layers
What is the proper formation of skin layers
Flashcards
Integumentary System Functions
Integumentary System Functions
The integumentary system protects the body from injury, harmful substances, extreme temperatures, and UV radiation. It also regulates water balance, metabolism (e.g., vitamin D synthesis), and secretion/absorption. It plays a defensive role in immunity and regulates body temperature.
Epidermis Water Resistance
Epidermis Water Resistance
The epidermis acts as a water-resistant barrier, preventing excessive water loss but not completely waterproof.
Vitamin D Metabolism
Vitamin D Metabolism
The skin plays a crucial role in Vitamin D synthesis, a precursor for calcitriol, which regulates calcium and phosphorus levels in the body.
Calcitriol
Calcitriol
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Skin Secretion/Absorption
Skin Secretion/Absorption
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Transdermal Drug Delivery
Transdermal Drug Delivery
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Immune Function of Skin
Immune Function of Skin
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Temperature Regulation
Temperature Regulation
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Sensory Reception of Skin
Sensory Reception of Skin
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Epidermis Layers
Epidermis Layers
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Stratum Basale
Stratum Basale
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Keratinocytes
Keratinocytes
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Melanocytes
Melanocytes
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Stratum Spinosum
Stratum Spinosum
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Stratum Granulosum
Stratum Granulosum
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Stratum Lucidum
Stratum Lucidum
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Stratum Corneum
Stratum Corneum
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Dermis
Dermis
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Papillary Layer
Papillary Layer
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Reticular Layer
Reticular Layer
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Lines of Cleavage
Lines of Cleavage
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Subcutaneous Layer
Subcutaneous Layer
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Full-Thickness Burn
Full-Thickness Burn
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Rule of Nines
Rule of Nines
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Synaptic Transmission
Synaptic Transmission
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Pre-synaptic neuron
Pre-synaptic neuron
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Post-synaptic neuron
Post-synaptic neuron
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Neurotransmitter
Neurotransmitter
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Synaptic Cleft
Synaptic Cleft
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Keratinized Cells
Keratinized Cells
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Areolar CT
Areolar CT
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Adipose CT
Adipose CT
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Sensory Reception
Sensory Reception
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Sweat Glands
Sweat Glands
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Sebaceous Glands
Sebaceous Glands
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Hair Follicles
Hair Follicles
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Arrector Pili Muscles
Arrector Pili Muscles
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What are glial cells?
What are glial cells?
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Ependymal cells
Ependymal cells
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Microglia
Microglia
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What do microglia do?
What do microglia do?
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Oligodendrocytes
Oligodendrocytes
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Myelin sheath function
Myelin sheath function
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Satellite cells
Satellite cells
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Schwann cells
Schwann cells
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What is the resting membrane potential?
What is the resting membrane potential?
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What is depolarization?
What is depolarization?
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What is repolarization?
What is repolarization?
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What is hyperpolarization?
What is hyperpolarization?
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What are voltage-gated channels?
What are voltage-gated channels?
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What is the sodium-potassium pump?
What is the sodium-potassium pump?
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What is the synaptic knob?
What is the synaptic knob?
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How does an action potential propagate?
How does an action potential propagate?
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Nervous System
Nervous System
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Central Nervous System (CNS)
Central Nervous System (CNS)
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Peripheral Nervous System (PNS)
Peripheral Nervous System (PNS)
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Somatic Nervous System
Somatic Nervous System
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Autonomic Nervous System
Autonomic Nervous System
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Sensory Input
Sensory Input
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Motor Output
Motor Output
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Neuron Structure
Neuron Structure
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Action Potential & Myelin
Action Potential & Myelin
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Saltatory Conduction
Saltatory Conduction
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Continuous Conduction
Continuous Conduction
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Neurotransmitter Classification
Neurotransmitter Classification
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Acetylcholine: Chemical Structure
Acetylcholine: Chemical Structure
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Biogenic Amines
Biogenic Amines
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Catecholamines
Catecholamines
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Indolamines
Indolamines
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Amino Acids as Transmitters
Amino Acids as Transmitters
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Neuropeptides
Neuropeptides
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Neurotransmitter Function
Neurotransmitter Function
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Excitatory Transmitters
Excitatory Transmitters
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Inhibitory Transmitters
Inhibitory Transmitters
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Neurotransmitter Action: Direct
Neurotransmitter Action: Direct
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Neurotransmitter Action: Indirect
Neurotransmitter Action: Indirect
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Astrocytes
Astrocytes
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Blood-Brain Barrier
Blood-Brain Barrier
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Astrocytes: Regulating Tissue Fluid
Astrocytes: Regulating Tissue Fluid
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Astrocytes: Structural Support
Astrocytes: Structural Support
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Astrocytes: Neuronal Development
Astrocytes: Neuronal Development
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Direct Transmitter
Direct Transmitter
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Indirect Transmitter
Indirect Transmitter
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What are the two ways to classify neurotransmitters by action?
What are the two ways to classify neurotransmitters by action?
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Resting Membrane Potential
Resting Membrane Potential
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Depolarization
Depolarization
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Repolarization
Repolarization
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Hyperpolarization
Hyperpolarization
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Action Potential Propagation
Action Potential Propagation
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What do glial cells do in the PNS?
What do glial cells do in the PNS?
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What's the difference between satellite cells and Schwann cells?
What's the difference between satellite cells and Schwann cells?
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Astrocytes Function
Astrocytes Function
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Microglia Function
Microglia Function
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Oligodendrocytes Function
Oligodendrocytes Function
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Nerve
Nerve
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Epineurium
Epineurium
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Perineurium
Perineurium
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Endoneurium
Endoneurium
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Fascicle
Fascicle
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Cell Body
Cell Body
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Dendrites
Dendrites
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Axon Hillock
Axon Hillock
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Myelin Sheath
Myelin Sheath
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What are the functions of the different layers of the epidermis?
What are the functions of the different layers of the epidermis?
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What happens to cells in the stratum corneum?
What happens to cells in the stratum corneum?
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Integument Protection
Integument Protection
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Skin Water Balance
Skin Water Balance
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Vitamin D Synthesis
Vitamin D Synthesis
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Skin: Immune Response
Skin: Immune Response
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Skin Temperature Regulation
Skin Temperature Regulation
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Study Notes
Integumentary System
- Protection: Protects body from injury, harmful substances, extreme temperatures, and radiation.
- Water Balance: Epidermis is water-resistant, not waterproof. Water loss occurs through sweat and transpiration.
- Metabolic Regulation: Vitamin D formation (a precursor to calcitriol) is crucial for calcium and phosphate absorption from the diet to regulate blood calcium levels.
- Secretion & Absorption: Skin absorbs some chemicals/drugs but blocks others. It releases waste products like those in sweat.
- Immune Function: Dendritic cells initiate immune responses in the epidermis and dermis.
- Temperature Regulation: Dermal blood vessels adjust, constricting to conserve heat and dilating to release heat.
- Sensory Reception: Extensive innervation detects stimuli.
Epidermis
- Structure: Keratinized, stratified squamous epithelium with layers (strata) from deep to superficial.
- Layers:
- Stratum Basale (deepest): Single layer of cuboidal to low columnar cells. Contains keratinocytes, melanocytes, tactile cells.
- Stratum Spinosum: Several layers of polygonal keratinocytes attached by desmosomes. Epidermal dendritic cells (Langerhans cells) are present.
- Stratum Granulosum: Flattened keratinocytes with granules. Keratinization (hardening of cells) occurs. Nucleus and organelles disintegrate.
- Stratum Lucidum (only in thick skin): Clear layer, densely packed, flat, translucent cells filled with keratin.
- Stratum Corneum: Outermost layer of many layers of dead, interlocking, keratinized cells. Protective layer against abrasion and infection.
- Location: Palms and soles have all 5 layers; other parts may not have the Stratum Lucidum layer.
Dermis
- Structure: Deep to epidermis, composed of connective tissue (CT). Contains blood vessels, sweat glands, sebaceous glands, hair follicles, nail roots, sensory nerve endings, and arrector pili muscles.
- Layers:
- Papillary layer
- Reticular layer
- Functions:
- Temperature Regulation: Dilating or constricting blood vessels to release or conserve heat, respectively.
- Secretion & Absorption: Sweat glands release fluids (sodium, water, urea) to cool the body and Sebaceous glands secrete sebum (oil).
- Sensory Reception: Variety of sensory receptors.
- Strength & Support: Collagen and elastic fibers resist stress and influence cleavage lines.
Subcutaneous Layer (Hypodermis)
- Structure: Not part of the integument; composed of areolar and adipose connective tissues.
- Functions: Protection, energy storage, insulation, and rapid drug absorption (extensive vascular network).
General Information
- Burns: First-degree, Second-degree, Third-degree burns. Full thickness burns may initially be painless due to nerve damage. Symptoms and treatment differ based on burn severity.
- Glandular, Nervous, & Vascular Tissue: Location and function in the dermis.
- Keratin & Melanocytes: Keratin waterproofs skin; melanocytes produce pigment for UV protection and skin color.
- Vitamin D & Calcium: Vitamin D aids in calcium absorption.
Nervous System
- Functions: Monitors internal and external environments, processes and integrates sensory information, and initiates responses.
- Organization: Central Nervous System (CNS) - Brain and Spinal Cord; Peripheral Nervous System (PNS) - Nerves and Ganglia.
- General Function: Collect information, process and evaluate information (brain and spinal cord determine response), and initiate responses (brain and spinal cord send signals to effectors).
Neuron Structure
- Cell Body (Soma): Contains nucleus, plasma membrane encloses cytoplasm (perikaryon), initiates graded potentials, receives and conducts potentials to axons.
- Dendrites: Unmyelinated processes extending from cell body, receive input and transfer information to cell body.
- Axon Hillock: Transmit nerve impulse to axon terminal. (decision point if the axon will fire.)
- Axon: Transmit nerve impulse to axon terminal.
- Myelin Sheath: Increases speed of transmission.
- Schwann Cells: Maintenance and regeneration of axons.
- Nodes of Ranvier: Repeats of action potential along the axon.
Spinal & Cranial Nerves
- Classification: Structural (Cranial Nerves & Spinal Nerves), Functional (Sensory Nerves & Motor Nerves).
- Sensory Nerves: Contain sensory neurons that carry information to the CNS.
- Motor Nerves: Contain motor neurons that take information from the CNS to effectors.
- Mixed Nerves: Contain both sensory and motor neurons.
Nerves & Ganglia
- Nerves: Bundles of parallel axons, surrounded by connective tissue wrappings (epineurium, perineurium, and endoneurium). Nerves are vascularized.
- Ganglia: Clusters of neuron cell bodies located within the PNS.
- Nerve Branches: blood vessels that branch through the epineurium and perineurium into capillaries; allow for exchange between axon and blood.
Neurons at Rest
- Resting Membrane Potential (RMP): Typically -70 mV; negative inside compared to outside determined by concentration gradient and electrical potential of K+ and Na+.
- Factors Affecting RMP: K+ diffusion is the primary factor, while Na+ leakage also plays a role.
Overview of Events in Each Neuron Segment
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- EPSP (excitatory postsynaptic potential) and IPSP (inhibitory postsynaptic potential). Events associated with the neuron starting and stopping firing information. The process of the propagation of action potential from the axon hillock down the axon.
Glial Cells
- **Glial Cells (CNS & PNS):**Non-excitable cells that support and nourish neurons.
- Astrocytes: Most abundant, form blood-brain barrier.
- Ependymal Cells: Line cavities of the brain and spinal cord, produce cerebrospinal fluid (CSF).
- Microglia: Phagocytes of the immune system, respond to infection/injury.
- Oligodendrocytes: Myelinate neurons in the CNS.
- Satellite Cells: Surround neuron cell bodies in PNS, regulate nutrients, and waste exchange.
- Schwann Cells: Myelinate neurons in the PNS.
Action Potential: Depolarization & Repolarization
- Depolarization: Membrane potential becomes more positive due to Na+ influx.
- Repolarization: Membrane potential returns to negative due to K+ efflux.
Action Potential Steps
- Depolarization: At rest, voltage-gated channels are closed. When a threshold is reached, Na+ channels open rapidly, and Na+ rushes into the axon, causing depolarization.
- Repolarization: Na+ channels close and inactivate, and K+ channels open; K+ rushes out of the axon, causing repolarization.
- Hyperpolarization: K+ channels remain open longer than necessary to return to RMP, causing the membrane potential to become slightly more negative than RMP. Na+/K+ pumps return the membrane potential to RMP.
Action Potential Propagation
- Continuous vs Saltatory Conduction: Continuous conduction occurs on unmyelinated axons; the signal is propagated along the whole axon membrane. Saltatory conduction occurs on myelinated axons, the signal jumps from node to node; faster propagation.
Neurotransmitters
- Classification: Chemical classes (acetylcholine, biogenic amines, amino acids, neuropeptides) and by action (excitatory or inhibitory).
- Direct vs Indirect: Direct neurotransmitters bind to chemically gated channels, while indirect neurotransmitters bind to receptors that involve G-proteins and second messengers.
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