Anatomy Final Exam 2 Review

Epinephrine, also known as adrenaline, is the transmitter most closely associated with the sympathetic ANS. The sympathetic ANS is responsible for the "fight or flight" response, which prepares the body for intense physical activity or stress. Epinephrine is released by the adrenal glands in response to stress or danger, and it increases heart rate, blood pressure, and blood sugar levels. This helps to provide the body with the energy and resources it needs to respond to a perceived threat.

The opening of sodium channels in the membrane of a resting neuron results in depolarization. This is because sodium ions rush into the neuron, causing the inside of the membrane to become less negative and more positive. Depolarization is an important step in the generation of an action potential, which allows the neuron to transmit signals.

The choroid plexus is the site for cerebrospinal fluid (CSF) production. CSF is a clear fluid that surrounds and protects the brain and spinal cord. The choroid plexus is located in the ventricles of the brain and consists of a network of blood vessels covered by a layer of specialized cells called ependymal cells. These cells produce CSF by filtering blood plasma and secreting it into the ventricles. CSF then circulates through the brain and spinal cord, providing nutrients, removing waste products, and cushioning the central nervous system.

During the standard action potential, sodium (Na) ions enter the cell, causing depolarization and the initiation of the action potential. This is followed by potassium (K) ions leaving the cell, leading to repolarization and the restoration of the resting membrane potential. Therefore, the correct answer is Na; K.

Cholinergic nerve fibers secrete acetylcholine as the neurotransmitter. Acetylcholine is a neurotransmitter that plays a crucial role in the transmission of signals between nerve cells. It is involved in various physiological processes such as muscle contraction, memory, and attention. Cholinergic nerve fibers are found in the autonomic nervous system and the neuromuscular junction, where they transmit signals to activate muscle contraction. Acetylcholine is also involved in the parasympathetic nervous system, which controls rest and digestion.

The correct answer is the build-up of cerebral spinal fluid in the brain. Hydroencephaly, also known as hydrocephalus, is a condition characterized by an excessive accumulation of cerebrospinal fluid (CSF) within the brain. This build-up of CSF can lead to increased pressure on the brain, causing various symptoms such as headaches, cognitive impairments, and neurological deficits. It is often caused by an imbalance between the production and absorption of CSF or a blockage in its flow, leading to the accumulation of fluid in the ventricles of the brain.

The sarcomere is the correct answer because it is the functional unit of skeletal muscle. It is the segment of a muscle fiber that lies between two Z lines and contains the contractile proteins actin and myosin. When a muscle contracts, the sarcomeres shorten, causing the muscle to generate force and produce movement. The sarcomere is responsible for the striated appearance of skeletal muscle and plays a crucial role in muscle contraction and function.

The correct order of the layers of meninges, from superficial to deep, is dura mater (5), subdural space (4), arachnoid (3), subarachnoid space (1), and pia mater (2).

The major centers concerned with autonomic control of breathing, blood pressure, heart rate, and digestive activities are located in the Medulla Oblongata. The medulla oblongata is a part of the brainstem and plays a crucial role in regulating vital functions such as respiration, cardiovascular activity, and digestion. It contains various nuclei that control the autonomic functions of the body, including the respiratory center, which regulates breathing, and the cardiovascular center, which controls blood pressure and heart rate. Additionally, the medulla oblongata also influences digestive activities through its connections with the gastrointestinal system.

Smooth muscle is characterized by automaticity, which means that it can contract without external stimulation. Unlike skeletal muscle, which requires nerve signals to initiate contraction, smooth muscle can generate its own electrical signals and contract spontaneously. This allows smooth muscle to perform involuntary movements and maintain continuous contractions, such as those in the digestive system or blood vessels. The other options listed (actin and myosin myofilaments arranged into sarcomeres, strong contraction speeds, and striated) are characteristics of skeletal muscle, not smooth muscle.

The somatic nervous system is responsible for voluntary control of skeletal muscles. This system is part of the peripheral nervous system and consists of motor neurons that transmit signals from the central nervous system to skeletal muscles, allowing conscious control over movement. The somatic nervous system is involved in activities such as walking, talking, and writing. It is distinct from the autonomic nervous system, which controls involuntary functions such as heart rate and digestion. The parasympathetic and sympathetic nervous systems are two divisions of the autonomic nervous system, while the afferent nervous system refers to sensory neurons that transmit signals towards the central nervous system.

The hypothalamus is the structure that has overall control of the ANS (Autonomic Nervous System). It plays a crucial role in regulating and maintaining various bodily functions such as heart rate, blood pressure, body temperature, and hormone release. The hypothalamus receives information from different parts of the body and sends signals to the ANS to adjust and balance these functions. This control is essential for maintaining homeostasis and ensuring the body functions properly.

Calcium ions are required for the release of acetylcholine into the synaptic cleft. When an action potential reaches the presynaptic terminal, it causes voltage-gated calcium channels to open, allowing calcium ions to enter the terminal. The influx of calcium ions triggers the fusion of synaptic vesicles containing acetylcholine with the presynaptic membrane, leading to the release of acetylcholine into the synaptic cleft. This process is essential for the transmission of signals between neurons at the synapse.

Leak channels are non-gated membrane channels that are responsible for the permeability of the membrane at rest. Unlike other types of channels, leak channels are always open, allowing ions to passively move across the membrane according to their concentration gradient. This continuous leakage of ions helps maintain the resting membrane potential and is essential for various cellular processes. The Na/K ion pump, ligand-gated ion channels, and voltage-gated ion channels are not responsible for the permeability of the membrane at rest.

The action potential is a rapid change in membrane potential that occurs in neurons and muscle cells. It is regenerative because it can propagate along the entire length of the axon. It has a threshold, which is the minimum depolarization required to trigger an action potential. It has a refractory period, which is a brief period of time after an action potential where the membrane cannot be stimulated to generate another action potential. It is all-or-none amplitude, meaning that once the threshold is reached, the action potential will occur with a consistent amplitude. However, it does not jump from one location to another. Instead, it propagates along the axon in a continuous manner.

Creatine phosphate acts as an energy reserve in muscle tissue. It is a high-energy molecule that can quickly donate its phosphate group to ADP, converting it back into ATP, which is the primary source of energy for muscle contractions. This allows muscles to sustain high-intensity activities for short periods of time. Creatine phosphate is replenished during rest and is an important component of the phosphagen system, which provides immediate energy for muscle contraction.

The "cross bridge" between the actin and myosin myofilaments is formed by the myosin head. The myosin head attaches to the actin filament during muscle contraction and undergoes a conformational change, pulling the actin filament towards the center of the sarcomere. This interaction between the myosin head and actin is essential for muscle contraction and the generation of force.

The parasympathetic division of the autonomic nervous system is responsible for promoting rest and digestion. When activated, it increases digestive functions such as the secretion of digestive enzymes and the movement of food through the digestive tract. This is achieved by stimulating the release of acetylcholine, which enhances the activity of the gastrointestinal system. Therefore, the correct answer is increased digestive functions.

The stretch receptors, which detect changes in muscle length, are located in the muscles themselves. However, the soma, or cell bodies, of these stretch receptors are contained in the dorsal root ganglia. The dorsal root ganglia are located just outside the spinal cord and contain the cell bodies of sensory neurons. These sensory neurons receive information from the stretch receptors and transmit it to the spinal cord for processing. Therefore, the correct answer is dorsal root ganglia.

Smooth muscles are involuntary muscles, meaning that they are not under conscious control. Neurons that innervate smooth muscles are controlled by the autonomic nervous system, which operates without conscious effort. Therefore, the statement that neurons that innervate smooth muscles are under voluntary control is not characteristic of smooth muscle.

Complete tetanus refers to a sustained and maximal contraction of a muscle. This is achieved by generating action potentials (APs) at high rates from essentially all motor neurons that innervate the muscle. By activating a large number of motor neurons and causing them to fire APs rapidly, the muscle fibers are stimulated continuously, leading to a sustained contraction. This is in contrast to generating APs at low rates or from only a few motor neurons, which would not be sufficient to achieve complete tetanus.

The Na/K ion pump is responsible for maintaining the Na and K gradients by pumping out 3 Na ions for every 2 K ions that it takes in. This ensures that there is a higher concentration of Na ions outside the cell and a higher concentration of K ions inside the cell, which is necessary for various cellular processes such as nerve impulse transmission and muscle contraction.

The medulla is responsible for integrating conscious and unconscious sensory and motor pathways. It acts as a switching and relay center, allowing communication between different parts of the brain and spinal cord. It plays a crucial role in regulating vital functions such as breathing, heart rate, and blood pressure. Additionally, the medulla is involved in coordinating reflexes and maintaining balance and posture.

The left hemisphere of the cerebral cortex is normally associated with the ability to produce speech. This is because the left hemisphere contains the language centers, such as Broca's area and Wernicke's area, which are responsible for speech production and comprehension. Studies have shown that damage to the left hemisphere can result in speech difficulties, known as aphasia.

White muscle fibers are characterized by fast contraction times compared to red muscle fibers. This means that white muscle fibers are able to contract and relax more quickly, allowing for rapid movements and actions. This characteristic is important for activities that require quick bursts of strength and speed, such as sprinting or weightlifting. In contrast, red muscle fibers are more aerobic, have greater resistance to fatigue, and contain more myoglobin and mitochondria, which support endurance activities.

All the given options - volition, creativity, imagination, and emotion (such as love) - can be theoretically explained through future neuro-physiological research studies. This implies that scientific research has the potential to uncover the underlying neural mechanisms and processes associated with these cognitive and emotional functions. Therefore, none of the options are exempt from being explained through future neuro-physiological research studies.

When you move your light pencil smoothly over a paper to sign your name, you generate action potentials (APs) at high rates from relatively few motor neurons. This is because the movement requires precise control and fine motor skills, which are achieved by activating a specific group of motor neurons to control the muscles involved in the movement. The high rate of APs is necessary to ensure smooth and continuous movement of the pencil.

The preganglionic neuron refers to a neuron that originates in the central nervous system (CNS) and extends to the autonomic ganglion. This type of neuron is responsible for transmitting signals from the CNS to the autonomic ganglion, which then relays the signals to the postganglionic neuron. The postganglionic neuron, on the other hand, extends from the autonomic ganglion to the target organ or tissue. Therefore, the correct answer is preganglionic.

When a skeletal muscle is partially contracted, the H band (also known as the H zone) represents the region within the A band where there are no overlapping thin filaments. As the muscle is fully stretched out, the sarcomeres within the muscle lengthen, causing the H band to increase in size. This occurs because the thin filaments slide past the thick filaments, resulting in a greater distance between the ends of the thick filaments and therefore elongating the H band.

When calcium binds to troponin, it causes a conformational change in the troponin-tropomyosin complex. This change exposes the active sites on actin, allowing myosin to bind to actin and initiate muscle contraction. Therefore, calcium binding to troponin is a crucial step in the regulation of muscle contraction.

Calcium ions cause tropomyosin to move and thereby expose active sites on F-actin.

Myasthenia gravis is caused by an autoimmune response that attacks ACh receptors. In this condition, the body's immune system mistakenly targets and destroys the acetylcholine receptors at the neuromuscular junction, which are responsible for transmitting signals from nerves to muscles. As a result, the communication between nerves and muscles is disrupted, leading to muscle weakness and fatigue.

When a nerve is cut through, axons, which are responsible for transmitting signals in the nervous system, are often severed. Axons have limited ability to repair themselves or regenerate, which means that once they are damaged, they are unlikely to be able to reconnect with their target cells. This can lead to misdirection of axons, preventing them from properly transmitting signals and resulting in permanent paralysis. The death of soma, the cell bodies of neurons, may also occur as a result of the injury, further contributing to the loss of function. Schwann cells, which wrap around axons, play a role in supporting their regeneration, but this process is often insufficient to restore normal function.