80 Questions
What is the primary function of mast cells and macrophages in the nervous system?
To kill any microorganism that enters the axons
What is the outermost covering of a spinal nerve?
Epineurium
What type of tissue is found in the epineurium?
Connective tissue
What is the characteristic shape of veins in the epineurium?
Flat
What is the functional classification of neurons based on?
Their structure and function
What is the purpose of capillaries in nerve fascicles?
To transport gases
What is the characteristic of the deeper region of the epineurium?
More loose and less dense
What is the organization of nerves classified into?
Cranial and spinal nerves, with a similar functional organization
What is the role of the receptor in the peripheral nervous system?
To receive the stimulus and trigger the formation of action potential
What type of axon extends from the receptor towards the cell body?
Peripheral afferent axon
What is the function of the interneurons?
To integrate afferent information and formulate an efferent response
What is the role of neurotransmitters in the transmission of signal from the axon terminal to the interneuron?
To bind to the receptors in the dendrites and cell body of the interneurons
What is the function of the efferent neurons?
To transmit signals from the CNS to effector organs
What happens when the neurotransmitters released by the axon terminal of the efferent neurons bind to the receptors in the dendrites and cell body of the efferent neurons?
Graded potentials are released in the dendrites and cell body of the efferent neurons
What is the role of the cell body of the afferent neurons?
To lack dendrites
What is the function of the axon hillock in the transmission of signal from the efferent neurons to the effector organs?
To allow the passive flow of current to the axon terminals
What is the primary mechanism of activation of β1 adrenergic receptor?
G-protein coupled mechanism
Which of the following regions of the CNS exerts control over skeletal muscle activity?
All of the above
What is the result of phosphorylation of sarcoplasmic reticulum in the heart?
Increased release of Ca2+ ions
What is the neurotransmitter released by motor neurons that stimulates muscle contraction?
Acetylcholine
What is the characteristic of the motor end plate?
Has no threshold potential
What is the primary function of nicotinic receptors in the autonomic ganglia?
To receive and integrate signals from preganglionic neurons
What is the result of increased Ca2+ ions in the heart?
Increased cardiac contractile force and velocity
What is the effect of muscarinic receptors on the heart?
Decreases the rate and force of contraction
What is the disease characterized by progressive degeneration of motor neurons?
Amyotrophic Lateral Sclerosis (ALS)
What is the mechanism of action of β adrenergic receptor in the heart?
Activation of adenylyl cyclase
What is the purpose of IP3 in the signaling pathway of alpha receptors?
To bind to a receptor in the sarcoplasmic reticulum and open the Ca2+ channel
What is the effect of blocking beta 1-adrenergic receptors with metoprolol?
Decreases heart rate and blood pressure
What is the primary function of phospholipase C in the signaling pathway of alpha receptors?
To cleave PIP2 into IP3 and diacylglycerol
What is the effect of salbutamol on the bronchioles?
Dilation of the bronchioles and increase in airflow
What is the purpose of diacylglycerol in the signaling pathway of alpha receptors?
To activate protein kinase and phosphorylate proteins
What is the effect of ACh on the heart rate when nicotinic receptors are blocked?
Increases the heart rate and contraction force
What is the third division of the efferent nervous system, aside from the somatic and autonomic nervous systems?
Enteric Nervous System
What type of neurons inform the CNS about conditions in both the external and internal environment?
Afferent neurons
What is the general effect of dual innervation of organs by both sympathetic and parasympathetic fibers?
It produces opposite effects on organ activity
Which of the following organs is only innervated by the sympathetic nervous system?
Sweat glands
What is the primary function of the sympathetic nervous system in emergency situations?
To inhibit actions that delay movement
What is the direction of travel of afferent fibers in relation to efferent fibers?
Opposite direction
What is the location of the enteric nervous system?
Entirely within the wall of the digestive tract
What is the primary function of the parasympathetic nervous system?
To promote digestion and relaxation
What is the primary mechanism of activation of β1 adrenergic receptor in the heart?
Binding of NE to β1 adrenergic receptor through a G-protein coupled mechanism
What is the role of motor neurons in the somatic nervous system?
To transmit signals from the CNS to skeletal muscles
What is the result of phosphorylation of sarcoplasmic reticulum in the heart?
Increase in Ca2+ ions in the heart
What is the neurotransmitter released by motor neurons that stimulates muscle contraction?
Acetylcholine
What is the characteristic of the motor end plate in the neuromuscular junction?
It has no threshold potential
What is the primary function of the postganglionic neuron in the autonomic nervous system?
To transmit signals from the CNS to the effector organ
What is the mechanism by which the preganglionic neuron influences the postganglionic neuron in the autonomic nervous system?
Through the release of neurotransmitters in the ganglion
What is the characteristic of the somatic nervous system in relation to muscle control?
It controls voluntary muscles, such as skeletal muscle
What is the role of the receptor in the neuromuscular junction?
To bind to neurotransmitters released by the motor neuron
What is the primary function of the motor neuron in the somatic nervous system?
To transmit signals from the CNS to the muscle fiber
What is the site of neurotransmitter release from the axon terminal of the efferent neurons that triggers the formation of graded potentials?
Motor end plate of the effector organs
What is the primary function of the interneurons in the central nervous system?
Integrating afferent information and formulating an efferent response
What is the direction of travel of the action potential in the peripheral afferent axon?
From the receptor to the cell body
What is the role of the axon terminal of the afferent neurons in the transmission of signal to the interneuron?
Releasing neurotransmitters to the receptors in the dendrites and cell body of the interneuron
What is the characteristic of the cell body of the afferent neurons?
It does not have dendrites
What is the primary mechanism by which β1 adrenergic receptors stimulate the heart rate?
Binding of G-protein to the receptor, leading to activation of adenylate cyclase
What is the primary function of the motor end plate in the neuromuscular junction?
To transmit the signal from the motor neuron to the muscle fiber
What is the primary function of the somatic nervous system in relation to motor control?
To control the contraction of skeletal muscle
What is the primary mechanism by which α1 adrenergic receptors stimulate smooth muscle contraction?
Activation of phospholipase C, leading to increased IP3
What is the primary function of motor neurons in the spinal cord?
To control the contraction of skeletal muscle
What is the primary function of β1 adrenergic receptors in the heart?
To increase the heart rate and contractility
What is the primary function of the motor end plate in the neuromuscular junction?
To receive neurotransmitters from the motor neuron
What is the primary function of the somatic nervous system?
To regulate voluntary actions such as movement and skeletal muscle contraction
What is the primary mechanism of activation of α receptors in smooth muscles?
Increase in IP3 and diacylglycerol levels
What is the primary function of motor neurons in the somatic nervous system?
To stimulate muscle contraction through neurotransmitter release
What is the effect of IP3 binding to its receptor in the sarcoplasmic reticulum?
Opening of the Ca2+ channel
What is the primary function of β2-adrenergic receptors in the bronchioles?
Dilation of bronchioles
What is the result of Metoprolol binding to β1-adrenergic receptors in the heart?
Decreased heart rate and contraction
What is the role of Phospholipase C in the signaling pathway of alpha receptors?
Cleavage of PIP2 into IP3 and diacylglycerol
What is the effect of ACh on the heart rate when nicotinic receptors are blocked?
Increased heart rate and contraction
What is the primary function of the endoneurium in the peripheral nervous system?
To maintain the blood-nerve barrier
What type of fibers are found in the endoneurium?
Reticular fibers
What is the function of ganglia in the peripheral nervous system?
To store cell bodies of neurons
What is the classification of nerves based on their origin?
Cranial and spinal
What is the function of myelin sheath in the peripheral nervous system?
To facilitate the transmission of nerve impulses
What is the role of the perineurium in the peripheral nervous system?
To maintain the blood-nerve barrier
What is the primary function of motor neurons in the somatic nervous system?
To stimulate muscle contraction
What is the role of the receptor in the neuromuscular junction?
To bind neurotransmitters
What is the characteristic of the motor end plate in the neuromuscular junction?
It is a type of synapse
What is the primary function of the autonomic nervous system in emergency situations?
To respond to stress
Study Notes
Organization of the Nervous System
- The nervous system consists of the Central Nervous System (CNS) and the Peripheral Nervous System (PNS)
- The PNS includes nerves, ganglia, and efferent and afferent neurons
Peripheral Nervous System
- The PNS is classified into two divisions: Somatic Nervous System (SNS) and Autonomic Nervous System (ANS)
- The SNS is responsible for voluntary control of skeletal muscles
- The ANS is responsible for involuntary control of smooth muscles, cardiac muscles, and glands
Nerve Structure
- Nerves are classified as cranial nerves (originating from the brain) or spinal nerves (originating from the spinal cord)
- Each nerve consists of:
- Epineurium: the outermost covering of the nerve containing blood vessels
- Perineurium: a layer of connective tissue surrounding groups of axons (fascicles)
- Endoneurium: a layer of connective tissue surrounding individual axons
- Axons: nerve fibers
Ganglia
- Ganglia are clusters of neuron cell bodies outside the CNS
- Types of ganglia:
- Terminal ganglia
- Collateral ganglia
- Ganglion chain
Afferent and Efferent Neurons
- Afferent neurons transmit signals from the periphery to the CNS
- Efferent neurons transmit signals from the CNS to the periphery
- Afferent fibers transmit sensory information, while efferent fibers transmit motor responses
Autonomic Nervous System
- The ANS is responsible for involuntary control of smooth muscles, cardiac muscles, and glands
- The ANS has two branches:
- Sympathetic Nervous System (SNS): promotes "fight-or-flight" responses
- Parasympathetic Nervous System (PNS): promotes "rest-and-digest" responses
Neurotransmitters and Receptors
- Acetylcholine (ACh) is a neurotransmitter that binds to nicotinic and muscarinic receptors
- Alpha receptors respond to norepinephrine (NE)
- Beta receptors respond to NE and epinephrine (E)
This quiz covers the organization of the vertebrate nervous system, including the peripheral nervous system, nerves, ganglia, and functional classification of neurons. It also touches on the role of mast cells and macrophages in immunity.
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