3A: Structure and functions of the nervous and endocrine systems and ways in which these systems coordinate the organ systems Flashcards
Neurons
Highly specialized cells responsible for the conduction of impulses
How do neurons communicate?
Occur through electrical and chemical forms of communication
Electrical Communication
Occurs via ion exchange and generation of membrane potentials down the length of the axon
Electrical Communication
Occurs via ion exchange and generation of membrane potentials down the length of the axon
Chemical Communication
Occurs via neurotransmitter release from the presynaptic cell and the binding of these neurotransmitters to the postsynaptic cell
Chemical Communication
Occurs via neurotransmitter release from the presynaptic cell and the binding of these neurotransmitters to the postsynaptic cell
Dendrites
Appendages that receive signals from other cells
Dendrites
Appendages of the cell body that receive signals from other cells
Cell Body/Soma
Location of the nucleus and organelles such as ER and Ribosomes
Axon
Long appendage down which an AP travels
Axon Hillock
Where the cell body transitions to the axon and where AP are initiated
Axon Hillock
Where the cell body transitions to the axon and where AP are initiated
Nerve Terminal/Synaptic Bouton
The end of the axon from which neurotransmitters are released
Synapse
Consists of nerve terminal of the presynaptic neuron, the membrane of the postsynaptic cell and the space between the two known as the synaptic cleft
Synapse
Consists of nerve terminal of the presynaptic neuron, the membrane of the postsynaptic cell and the space between the two known as the synaptic cleft
Myelin
An insulating substance that prevents signal loss and dissipation of the impulse and crossing of neural impulses from adjacent neurons
Oligodendrocytes
Creates myelin in the CNS
Schwann Cells
Creates myelin in the PNS
Schwann Cells
Creates myelin in the PNS
Nerves or Tracts
Bundles of axons
Tracts
Carry only one type of information
Ganglia
Cell bodies of neurons of the same type within a nerve cluster in the PNS
Nuclei
Cell bodies of individual neurons with a tract cluster in the CNS
Nuclei
Cell bodies of individual neurons with a tract cluster in the CNS
Neuroglia/Glial Cells
Astrocytes
Ependymal Cells
Microglial Cells
Astrocytes
Nourish neurons and form the blood-brain barrier which controls the transmission of solutes from the bloodstream into nervous tissue
Ependymal Cells
Line the ventricles of the brain and produce CSF
CSF
Physically supports the brain and serves as a shock absorber
CSF
Physically supports the brain and serves as a shock absorber
Microglia
Phagocytic cells that ingest and break down waste products and pathogens in the CNS
Microglia
Phagocytic cells that ingest and break down waste products and pathogens in the CNS
Resting Membrane Potential
-70 mV
What maintains the resting membrane potential?
Sodium-Potassium ATPase
What maintains the resting membrane potential?
Sodium-Potassium ATPase
Excitatory Signals [EPSPs]
Cause depolarization; Glu, ACh
Inhibitory Signals [IPSPs]
Cause hyperpolarization; GABA
Ionotropic Receptors
Ligand gated, allow K and Cl to hyperpolarize the membrane
Metabotropic
Block Ca ions
Metabotropic
Block Ca ions
Threshold Potential
-55 mV
Threshold Potential/Voltage
-55 mV
Temporal Summation
Addition of multiple signals near each other in time
Spatial Summation
Addition of multiple signals near each other in space
What maintains the resting membrane potential?
Sodium-Potassium ATPase
K Leak Channels
Spatial Summation
Addition of multiple signals near each other in space
Action Potential Outline
Resting -> Depolarization -> Repolarization -> Hyperpolarization -> Refractory Period
Resting Stage
-70 mV maintained by ATPase and Leak Channels
Lots of sodium outside and lots of potassium inside
Depolarization
Voltage gated sodium channels open, sodium rushes in and membrane potential increases to +30 mV
Lots of sodium inside and lots of potassium inside
Depolarization
Voltage gated sodium channels open, sodium rushes in and membrane potential increases to +30 mV
Lots of sodium inside and lots of potassium inside
Repolarization
Potassium channels open and sodium channels inactivate, potassium rushes outside and membrane potential drops
Lots of sodium inside and lots of potassium outside
Repolarization
Potassium channels open and sodium channels inactivate, potassium rushes outside and membrane potential drops
Lots of sodium inside and lots of potassium outside
Hyperpolarization
Potassium channels close but due to the timing the membrane potential briefly drops below the resting potential to around -90 mV
Hyperpolarization
Potassium channels close but due to the timing the membrane potential briefly drops below the resting potential to around -90 mV
Refractory Period
Na/K ATPase works to reestablish the original resting state (more K inside and Na outside); neuron cannot general another action potential during this time
Absolute Refractory Period
Depolarization to original resting state
Relative Refractory Peroid
After hyperpolarization til the resting state; AP can fire if the stimuli is strong enough
Relative Refractory Peroid
After hyperpolarization til the resting state; AP can fire if the stimuli is strong enough
All-or-None Principle
The neuron will either respond completely or not at all to the stimuli
All-or-None Principle
The neuron will either respond completely or not at all to the stimuli
Neurotransmitter Breakdown
Done enzymatically or absorbed via reuptake channel or diffused out of the synaptic cleft
Types of Neurons
Motor (Efferent)
Interneurons
Sensory (Afferent)
CNS
Brain & Spinal Cord
White Matter
Consists of myelinated axons
Grey Matter
Consists of unmyelinated cell bodies and dendrites
Location of Matter in the Brain
White matter is deeper than grey matter
Location of Matter in the Spinal Cord
Grey matter is deeper than white matter
Location of Matter in the Spinal Cord
Grey matter is deeper than white matter
PNS Divisions
Somatic [Voluntary]
Autonomic [Involuntary]
Autonomic Nervous System
Parasympathetic [Rest & Digest]
Sympathetic [Fight-or-Flight]
Autonomic Nervous System
Parasympathetic [Rest & Digest]
Sympathetic [Fight-or-Flight]
Reflex Arcs
Use the ability of interneurons in the spinal cord to relay information to the source of stimuli while simultaneously routing it to the brain
Reflex Arcs
Use the ability of interneurons in the spinal cord to relay information to the source of stimuli while simultaneously routing it to the brain
Monosynaptic Reflex Arc
Presynaptic Sensory Neuron fires directly onto the Postsynaptic Motor Neuron
Polysynaptic Reflex Arc
Sensory neuron fires onto a motor neuron as well as interneurons that fire onto other motor neurons
Major Functions of Nervous System
High level control, integration of body systems, adaptive capability to external influences, integrative and cognitive abilities
Major Functions of Nervous System
High level control, integration of body systems, adaptive capability to external influences, integrative and cognitive abilities
CNS, Forebrain Structures
Telencephalon, Diencephalon
Telencephalon Structures
Cerebral Cortex, Basal Ganglia, Hippocampus, Amygdala
Diencephalon Structures
Thalamus, Hypothalamus
CNS, Midbrain Structures
Mesencephalon
Mesencephalon Structures
Tectum, Cerebellum
CNS, Hindbrain Structures
Metencephalon, Myelencephalon
Metencephalon Structures
Pons, Cerebellum
Myelencephalon Structures
Medulla
Myelencephalon Structures
Medulla
Sensory Neurons
Transmit sensory information, carries sensory input from the outside to the CNS
Effector Neurons
Cause an effect, transmit motor signals from CNS to an effector organic to respond to physiologically to external stimuli
Effector Neurons
Cause an effect, transmit motor signals from CNS to an effector organic to respond to physiologically to external stimuli
Antagonistic Control of SNS and PSNS
They have opposing effects on the internal organs they innervate
Sympathetic Function
Increases HR, BP Increase Blood Flow to Muscle Pupillary Dilation Decrease Blood Flow to Digestive System Increases Glycolysis and Glycogenolysis
Parasympathetic Function
Decreases HR, BP Decreases Blood Flow to Muscle Pupillary Constriction Increase Blood Flow to Digestive System Increases Glycogenesis
Supraspinal Circuits
Involves input from the brain or brainstem to process a stimuli, unlike most reflex arcs
Supraspinal Circuits
Involves input from the brain or brainstem to process a stimuli, unlike most reflex arcs
Voltage-Gated Channels
Group of transmembrane ion channel that open or close based on changes in the cells membrane potential; include sodium, calcium and potassium channels
Ligand-Gated Channels
Group of transmembrane ion channel proteins that open when a specific ligand molecule binds to the receptor protein; the binding causes a confirmational change
Receptor Enzymes
[Enzyme-Linked Receptors/Catalytic Receptors]
Extracellular ligand binds and activates intracellular enzymatic activity
Types of Receptor Enzymes
Receptor Serine-Threonine Kinases
Receptor Tyrosine Kinases
Tyrosine-Kinase Associated Receptors
Receptor Tyrosine Kinases
Kinase enzymes that specifically phosphorylate tyrosine amino acids; growth factor binds to the extracellular domain which eventually leads to the production of a second messenger cascade
G-Protein Coupled Receptors
Large integral membrane proteins; its ligand is usually cAMP, peptides or large proteins
G-Protein Coupled Receptors
Large integral membrane proteins; its ligand is usually cAMP, peptides or large proteins
GPCR Outline
Ligand binds to an active receptor causing conformational change that activates the protein, transmits the extracellular signal to inside of the cell
GPCR Outline
Ligand binds to an active receptor causing conformational change that activates the protein, transmits the extracellular signal to inside of the cell
G Protein On vs. Off State
GTP = active GDP = inactive
G Protein On vs. Off State
GTP = active GDP = inactive
GPCR Activity
GDP binds to the alpha subunit and the GP Complex binds to nearby GPCR,
GTP replaces GDP and activates the receptors and the subunits dissociate causing activity
GTP is hydrolyzed back to GDP when it’s no longer needed
GPCR Activity
GDP binds to the alpha subunit and the GP Complex binds to nearby GPCR,
GTP replaces GDP and activates the receptors and the subunits dissociate causing activity
GTP is hydrolyzed back to GDP when it’s no longer needed
Endocrine Signaling
Involves the secretion of hormones directly into the bloodstream; travel to distant target tissues where they bind to receptors and induce a change
Peptide Hormones
Composed of amino acids and are derived from large precursors that are cleaved during posttranslational modificaiton
Peptide Hormones
Composed of amino acids and are derived from large precursors that are cleaved during posttranslational modificaiton
Peptide Hormone Characteristics
Polar and cannot pass through the plasma membrane; bind to extracellular receptors where they trigger the transmission of a second messenger
Peptide Hormones
Composed of amino acids and are derived from large precursors that are cleaved during posttranslational modification; travel freely through the bloodstream
Peptide Hormone Characteristics
Polar and cannot pass through the plasma membrane; bind to extracellular receptors where they trigger the transmission of a second messenger; rapid onset but short-lived
Steroid Hormones
Derived from cholesterol, they are minimally polar and can pass through the plasma membrane; cannot dissolve in the blood stream and must be carried by specific proteins
Steroid Hormone Characteristics
Bind to intracellular or intranuclear receptors where they promote conformational change and bind to DNA, affecting the transcription of a particular gene; slow onset and are long-lived
Steroid Hormone Characteristics
Bind to intracellular or intranuclear receptors where they promote conformational change and bind to DNA, affecting the transcription of a particular gene; slow onset and are long-lived
Amino Acid-Derivative Hormones
Modified Amino Acids; share some features with peptide and steroid hormones; common examples are epinephrine, norepinephrine, T3 and T4
Amino Acid-Derivative Hormones
Modified Amino Acids; share some features with peptide and steroid hormones; common examples are epinephrine, norepinephrine, T3 and T4
Direct Hormones
Have effects on non-endocrine tissues
Tropic Hormones
Have effects on other endocrine tissues
Function of the Endocrine System
Regulate mood, growth, development, metabolism, sexual function and tissue function
Function of the Endocrine System
Regulate mood, growth, development, metabolism, sexual function and tissue function
Endocrine Glands
Hypothalamus, Pituitary Gland, Pineal Gland, Thyroid Gland, Parathyroid Gland, Adrenal Gland, Pancreas, Ovary, Testis
Hypothalamus
Releases hormones that stimulate the anterior pituitary gland through paracrine release of hormones through the hypophyseal portal system
Hypothalamic Hormones
GnRH, GHRH, TRH, CRF, PIF/Dopamine
GnRH
Promotes release of FSH and LH
GHRH
Promotes release of GH
TRH
Promotes release of TSH
CRF
Promotes release of ACTH
PIF/Dopamine
Inhibits release of Prolactin
PIF/Dopamine
Inhibits release of Prolactin
Anterior Pituitary Hormones
FSH, LH, ACTH, TSH [Tropic] & Prolactin, Endorphins and GH [Direct]
FSH
Promotes development of ovarian follicles in females and spermatogenesis in males
LH
Promotes ovulation in females and testosterone production in males
ACTH
Promotes synthesis and release of glucocorticoids (cortisol) from the adrenal cortex
TSH
Promotes synthesis and release of T3 and T4
Prolactin
Promotes milk production (letdown)
Prolactin
Promotes milk production (letdown)
Endorphins
Decrease perception of pain and cause euphoria
Endorphins
Decrease perception of pain and cause euphoria
GH
Promotes growth of bone and muscle and shunts glucose to these tissues; raises blood glucose concentrations
GH
Promotes growth of bone and muscle and shunts glucose to these tissues; raises blood glucose concentrations
Posterior Pituitary Hormones
ADH/Vasopressin, Oxytocin
ADH/Vasopressin
Secreted in response to low blood volume or increased blood osmolarity and increases reabsorption of water in the collecting duct of the nephron, increase blood volume and decreasing blood osmolarity
ADH/Vasopressin
Secreted in response to low blood volume or increased blood osmolarity and increases reabsorption of water in the collecting duct of the nephron, increase blood volume and decreasing blood osmolarity
Oxytocin
Secreted during childbirth and promotes uterine contractions as well as milk letdown; regulated through positive feedback loop
Thyroid Hormones
T3 and T4, Calcitonin
T3 & T4
Produced by follicular cells and contain iodine; increase basal metabolic rate and alter the utilization of glucose and fatty acids
Calcitonin
Produced by parafollicular cells, decreases plasma calcium concentration by promoting calcium excretion in the kidneys, decreasing calcium absorption in the gut and promoting calcium storage in bone
Calcitonin
Produced by parafollicular cells, decreases plasma calcium concentration by promoting calcium excretion in the kidneys, decreasing calcium absorption in the gut and promoting calcium storage in bone
Parathyroid Gland Hormones
PTH
PTH
Increases blood calcium concentrations;
Decreases calcium by the kidneys;
Increase bone resorption directly to increase blood calcium concentrations
Activates vitamin D
Promotes resorption of phosphate from bone and reduces reabsorption
PTH
Increases blood calcium concentrations;
Decreases calcium by the kidneys;
Increase bone resorption directly to increase blood calcium concentrations
Activates vitamin D
Promotes resorption of phosphate from bone and reduces reabsorption
Adrenal Cortex Hormones
Glucocorticoids [Cortisol, Cortisone]
Mineralocorticoids [Aldosterone]
Cortical Sex Hormones [Androgens, Estrogens]
Adrenal Cortex Hormones
Glucocorticoids [Cortisol, Cortisone]
Mineralocorticoids [Aldosterone]
Cortical Sex Hormones [Androgens, Estrogens]
Cortisol/Cortisone
Increase blood glucose concentration, reduce protein synthesis, inhibit immune system, participate in the stress response; stimulated by ACTH
Aldosterone
Promote sodium reabsorption in the distal convoluted tubule and collecting duct thus increasing water reabsorption; increases potassium and hydrogen ion excretion; regulated by RAAS
Aldosterone
Promote sodium reabsorption in the distal convoluted tubule and collecting duct thus increasing water reabsorption; increases potassium and hydrogen ion excretion; regulated by RAAS
Adrenal Medulla Hormones
Catecholamines [Epinephrine, Norepinephrine]
Catecholamines
Promote glycogenolysis, increasing basal metabolic rate, heart rate, dilate bronchi and alter blood flow
Catecholamines
[Epi, Norepi]
Promote glycogenolysis, increasing basal metabolic rate, heart rate, dilate bronchi and alter blood flow
Catecholamines
[Epi, Norepi]
Promote glycogenolysis, increasing basal metabolic rate, heart rate, dilate bronchi and alter blood flow
Pancreatic Hormones
Glucagon
Insulin
Somatostatin
Pancreatic Hormones
Glucagon
Insulin
Somatostatin
Glucagon
[Alpha Cells]
Raises blood glucose levels by stimulating protein and fat degradation, glycogenolysis and gluconeogenesis
Insulin
[Beta Cells]
Lowers blood glucose levels by stimulating uptake by cells and anabolic processes like glycogenesis, fat and protein synthesis
Insulin
[Beta Cells]
Lowers blood glucose levels by stimulating uptake by cells and anabolic processes like glycogenesis, fat and protein synthesis
Somatostatin
[Delta Cells]
Inhibits insulin and glucagon secretion
Somatostatin
[Delta Cells]
Inhibits insulin and glucagon secretion
Pineal Gland Hormones
Melatonin
Melatonin
Regulates circadian rhythms