A&P TEST 4 ESSAY QUESTIONS
Describe in detail the physiological changes within the body associated with a sympathetic response.
. The sympathetic response is concerned with preparing the body for exercise and emergencies and is considered the "fight or flight" division. It is characterized by increased alertness and metabolic activity. The overall effect on the cardiovascular system is to excite it (increases heart rate). The overall effect on the digestive system is to inhibit digestion. The overall effect of the respiratory system is to increase airflow to lungs. The overall effect on the urinary system is to prevent urination. The overall effect of the reproductive system involves changes that occur during an orgasm. The overall effect on the integumentary system is to stimulate effectors of the skin (cause goosebumps, sweating, and decrease blood flow to skin). The overall effect on the nervous system is to increase the amount of light entering the eye.
Describe in detail the path of a sound wave from the outside ear to the stimulation of CN VIII.
1) sound waves directed by the auricle into the external acoustic meatus, causing the tympanic membrane to vibrate2)tympanic membrane vibration moves auditory ossicles; sound waves are amplified3) the stapes at the oval window generates pressure waves in the perilymph w/in the scala vestibuli4)pressure waves cause the vestibular membrane to move, resulting in pressure wave formation in the endolymph w/in the cochlear duct and displacement of a specific region of the basilar membrane. hair cells in the spiral organ are distorted, initiating nerve signals in the cochlear branch of the vestibulocochlear nerve (CN III)
Describe the reflex arc in detail.
A reflex arc includes a sensory receptor, effector, & the neural wiring between the two. It always begins at a receptor in the peripheral nervous system, communicates with the CNS, & ends at a peripheral effector (muscle or gland). There are generally 5 steps involved in a reflex:First a stimulus, either external or internal, activates a sensory receptor. Next, the sensory neuron transmits a nerve signal to the CNS, either to the spinal cord or brain. After this, the information from the nerve signal is processed in the integration center by interneurons. If the reflex is more complex it involves interneurons while the simplest ones do not. Next, the motor neuron transmits a nerve signal from the CNS to an effector. Finally, the effector responds to the nerve signal from the motor neuron. This response is intended to counteract or remove the original stimulus.
Explain in detail how light is focused on the retina, be sure to include refraction, accommodation, convergence and the physiological/structural changes associated with each.
As light enters the eye, it is refracted, or bent, by the cornea and lens and is focused sharply on the retina. The image is projected upside down and reversed from left to right. The visual cortex somehow corrects this when it interprets the images.
Describe in detail the neurotransmitters used at the preganglionic and postganglionic axons of the sympathetic and parasympathetic nervous system and give examples of their effects.
Both preganglionic axons in parasympathetic and sympathetic divisions release the neurotransmitter acetylcholine. In both divisions, the acetylcholine binds to nicotine (cholinergic) receptors. Postganglionic axons of the sympathetic division release mainly norepinephrine. Postganglionic axons of the parasympathetic division release only acetylcholine which binds to muscarinic (cholinergic) receptors. Acetylcholine binding to nicotine receptors always initiates an excitatory response. Acetylcholine binding to muscarinic receptors may cause either an excitatory or inhibitory response. Norepinephrine binding with adrenergic receptors can initiate either an excitatory or inhibitory response.
Describe in detail the functional differences found between the spinal cord and brain.
Brain: controls all of the activities within the human body; it is responsible for controlling thought, memory, emotion, touch, motor function, breathing, temperature, and many other crucial functions.Spinal cord: acts as the pathway from the brain and the rest of the body; relays information from the brain to the body & vice versa.
Describe in detail the cardiovascular reflex.
Cardiac reflexes are fast-acting centrally mediated negative feedback mechanisms which maintain homeostatic control of cardiovascular variables. They sense changes in heart rate blood pressure and arterial oxygenation through peripheral receptors, and respond by altering myocardial function and peripheral vascular resistance.
List and describe in detail the functions of the receptors classified by the stimulus they perceive.
Chemoreceptors detect the presence of chemicals. Thermoreceptors detect changes in temperature. Mechanoreceptors detect mechanical forces. Photoreceptors detect light during vision. More specific examples of sensory receptors are baroreceptors, propioceptors, hygroreceptors, and osmoreceptors. Sensory receptors perform countless functions in our bodies mediating vision, hearing, taste, touch, and more.
Describe in detail the functions associated with the cerebellum.
Coordinates & fine-tunes skeletal muscle movements that have already been initiated by the cerebrum, does this to ensure that skeletal muscle contractions follow the correct pattern for smooth, coordinated movement; adjusts skeletal muscle activity to maintain equilibrium & posture; receives proprioceptive information from the muscle & joints to help regulate body position; also involved in storing memories of movement patterns
What is dual innervation? Describe in detail an example of cooperative effects of dual innervation?
Dual innervation is the mechanism in which one organ can receive fibres (also known as receiving innervation) from both the parasympathetic and sympathetic systems. The target organ/structure generally experiences antagonistic effects from the two divisions of the autonomic nervous system.
Describe in detail the components (lobes) of the cerebrum and their function.
Frontal lobe: forms anterior portion of cerebral hemisphere; ends posteriorly at the central sulcus & inferiorly at the lateral sulcus; location of the precentral gyrus; primarily concerned with voluntary motor functions, concentration, verbal communication, decision making, planning, & personality.Parietal lobe: forms the superoposterior part of the cerebral hemispheres; ends anteriorly at the central sulcus, posteriorly at the parieto-occipital sulcus, & laterally at the lateral sulcus; location of the postcentral gyrus; primarily involved with general sensory input from both the skin & proprioceptors.Temporal lobe: internal to the temporal bone & inferior to the lateral sulcus; primarily involved in hearing & smell.Occipital lobe: forms the posterior region of the cerebral hemispheres; primarily involved in processing & storing visual information.Insula: found deep to the lateral sulcus, only visible when the temporal lobe is pushed aside; primarily believed to be involved in memory & processing taste information
Describe in detail the functions associated with each cerebral hemisphere.
Left hemisphere: Categorical hemisphere; typically the location of the Wernicke & Broca areas; specialized for language abilities & is important in performing sequential & analytical reasoning tasks; functions in categorization & identification.Right hemisphere: Representational hemisphere; concerned with visuospatial relationships & analyses; location of imagination & insight, musical & artistic skills, perception of patterns & spatial relationships, & comparison of sights, sounds, smells, & tastes
Describe in detail the functions and locations of the neurons in a motor pathway.
Motor pathways include the series of motor neurons that relay motor output from the brain to effectors, they are called descending pathways. The motor pathways for the muscles of the torso & limbs originate from either the cerebral cortex, cerebral nuclei, or brainstem. These pathways include at least two motor neurons to transmit signals from the brain to the body, these include the upper motor neuron & the lower motor neuron. The upper motor neuron is the first neuron in the chain. Its cell body is housed within the cerebral cortex, cerebral nuclei, or brainstem. Its axons synapse either directly onto the lower motor neuron or onto interneurons that will eventually synapse onto the lower motor neuron. The function of the upper motor neuron is to either excite or inhibit the activity of the lower motor neuron. The lower motor neuron is the last neuron in the chain. Its cell body is housed within the anterior horn of the spinal cord. The axons exit the spinal cord through the anterior root & project to & innervate a specific skeletal muscle. The function of the lower motor neuron is to always excite the skeletal muscle fibers to contract.
List the different classifications of reflexes and provide detailed examples of each.
Reflexes are classified in 5 different ways, depending on many different components.Some reflexes involve the spinal cord while others involve the brain. This classification includes spinal reflexes & cranial reflexes, depending on the specific area of the CNS that serves as the processing site.Some reflexes involve the skeletal muscle while others involve other muscle types or glands. This classification distinguishes between somatic reflexes & visceral reflexes, it is determined by the type of effector stimulated in the reflex. Somatic reflexes involve skeletal muscles & visceral reflexes involve glands & other muscles.Some reflexes are classified based on the amount of neurons that participate in the reflex. This classification includes monosynaptic reflexes and polysynaptic reflexes. Monosynaptic reflexes have only a sensory neuron & a motor neuron, they lack interneurons. Polysynaptic reflexes, on the other hand, have one or more interneurons involved.Other reflexes are classified based on whether it involves one side of the body. This classification distinguishes between ipsilateral & contralateral reflexes. Ipsilateral reflexes are reflexes in which both the receptor & effector organs are on the same side of the spinal cord while contralateral reflexes involve an effector on the opposite side of the body from the receptor that detected the stimulus.Some reflexes are classified based on whether you are born with it or not. This includes innate reflexes which individuals are born with and acquired reflexes that develop after birth.
List and describe in detail 4 visual disturbances or defects.
Refractive errors include myopia (near-sightedness), hyperopia (farsightedness), astigmatism (distorted vision at all distances), and presbyopia that occurs between age 40-50 years (loss of the ability to focus up close, inability to read letters of the phone book, need to hold newspaper farther away to see clearly) ...
Describe in detail the functions and locations of the neurons in a sensory pathway.
Sensory pathways include the sensory neurons that relay sensory input from the sensory receptors to the brain, these are called ascending pathways; The sensory input is detected by general sense receptors and relayed to the brain. Sensory pathways use a series of 2 or 3 neurons to transmit nerve signals from the sensory receptors to the brain. These include the primary neuron, secondary neuron, & tertiary neuron. The primary neuron is the first neuron in the chain, it extends from the sensory receptor to the CNS where it synapses with the secondary neuron. The secondary neuron is an interneuron that extends from the primary neuron to either the tertiary neuron or cerebellum. The tertiary neuron is another interneuron that extends from the secondary neuron to the cerebrum when present.
Describe in detail the similarities and differences between the somatic nervous system (SNS) and the autonomic nervous system (ANS).
Similarities: The sympathetic nervous system (part of the autonomic nervous system) and the somatic nervous system respond to external stimuli. The sympathetic nervous system responds to external stimuli by preparing the body for fight or flight and the somatic nervous system responds to external stimuli (by carrying information from sensory receptors to the spinal cord and brain). Differences: The autonomic nervous system consists of two sub-components, whereas the somatic nervous system only has one. The somatic nervous system has sensory and motor pathways, whereas the autonomic nervous system only has motor pathways. The autonomic nervous system controls internal organs and glands, while the somatic nervous system controls muscles and movement. The brain consists of multiple regions responsible for different functions, whereas the spinal cord has one main function.
Describe in detail the process of gustation and perception.
Taste perception or gustation is the sensory detection of food on the tongue. Taste is the sensation that occurs in the mouth when a substance reacts chemically with taste receptor cells located on taste buds or papillae (Figure 3.5. 3). Taste determines flavors of foods.
Name the 2 speech areas, their location (lobes) in the brain and explain in detail how they function.
The 2 speech areas within the brain are known as the Broca area & the Wernicke area; the Broca area is the motor speech area within the inferolateral portion of the left frontal lobe, it is responsible for controlling the muscular movements involved in vocalization; the Wernicke area is typically located within the temporal lobe of the left hemisphere, it is responsible for recognizing, understanding, & comprehending spoken or written language; both areas work together for fluent communication to occur; Wernicke area helps us comprehend words while Broca area helps us speak them.
Describe in detail the key structures of the brainstem and their function.
The brainstem connects the cerebrum, diencephalon, & cerebellum to the spinal cord; it is composed of the midbrain, pons, & medulla oblongata.Midbrain: superior portion of brainstem, composed of many different components that contribute to its numerous functions, responsible for relaying voluntary motor commands from the primary motor cortex, produces the neurotransmitter dopamine, houses nuclei of the oculomotor nerve & trochlear nerve which gives rise to its role in processing visual sensory information & relaying visual motor output.The pons: bulging region on the anterior portion of brainstem, houses the pontine respiratory center which regulates skeletal muscles of breathing, functions in coordinating facial movements as it houses many cranial nerves involved in movement of facial muscles.Medulla Oblongata: makes up the inferior portion of the brainstem that is continuous with the spinal cord, contains several autonomic nuclei that form centers which regulate many functions vital for life, these include the cardiovascular center, composed of both the cardiac & vasomotor center, & the medullary respiratory center, these centers give the medulla its role in helping to regulate breathing, HR, BP, & swallowing
Describe in detail the key structures of the diencephalon and their function.
The components of the diencephalon include the epithalamus, thalamus, & hypothalamus.Epithalamus: forms part of the posterior roof of the diencephalon & covers the third ventricle, houses the pineal gland & habenular nuclei, functions in regulating individuals circadian rhythm through the pineal gland & relaying signals from the limbic system to the midbrain through the habenular nuclei.Thalamus: forms the superolateral walls of the third ventricle within the diencephalon, sensory nerve signals from all the conscious senses (except olfaction) converge here, it's the principal & final relay point for the incoming sensory information that is processed & then transmitted to the appropriate region of the cerebral cortex.Hypothalamus: anteroinferior portion of the diencephalon, attached to the pituitary gland via the infundibulum, functions as the master control of both the autonomic nervous system & endocrine system, responsible for regulating body temperature & circadian rhythms, controls food & water intake, & controls emotional behavior.
Describe in detail the gastrointestinal reflex.
The gastrocolic reflex is a physiological reflex that controls the motility of the lower gastrointestinal tract following a meal. As a result of the gastrocolic reflex, the colon has increased motility in response to the stretch of the stomach with the ingestion of food.
Describe in detail the functional differences of gray matter and white matter of the central nervous system.
The gray matter regions of the CNS, the brain and spinal cord, contrast with the white matter regions. The gray matter is the areas where the actual "processing" is done whereas the white matter provides the communication between different gray matter areas and between the gray matter and the rest of the body.The neurons in the gray matter consist of neuronal cell bodies and their dendrites. The dendrites are short protrusions that communicate with immediately neighboring neurons in the CNS. In contrast with the neurons of the white matter, gray matter neurons don't contain long axons that transmit the nerve impulses to more distant regions of the CNS. Gray Matter: derives its color from cell bodies & dendrites of neurons that compose it; often designates as a "cortex," usually indicating superficial areas, or "nucleus/center," indicating deep areas; the general function of gray matter is to serve as an integrating & processing area.White Matter: derives its color from the bundles of myelinated axons that compose it; these areas are called "tracts" and are located on or close to the surface or deep; the general function of white matter is to relay nerve signals, it provides the means for information to be transmitted between different regions of the brain & spinal cord & between the brain & the body.
Describe in detail the functions of the hypothalamus.
The hypothalamus is responsible for numerous functions within the body; it is the mater control of both the autonomic nervous system & endocrine system; It's a major autonomic integration center, it projects descending axons to autonomic nuclei in the brainstem that influence activities such as HR, BP, digestion, & respiration; its also secretes hormones that control secretory activities in many areas of the endocrine system; its also responsible for temperature regulation; functions in controlling food & water intake as its neurons are responsible for producing both the sensation of hunger & thirst; regulates the circadian rhythm because an area within the structure directs the pineal gland to secrete melatonin at certain times of the day; controls emotional behavior as its located at the center of the limbic system
Describe in detail the function of the limbic system and highlight at least 2 component parts.
The limbic system is composed of many structures within the cerebrum & diencephalon; these structures collectively process & express emotions; the components of the limbic system include the cingulate gyrus, parahippocampal gyrus, hippocampus, amygdaloid body, olfactory bulbs, tracts, & cortex, & the fornix; all of these structures are involved in either processing & expressing emotions or storing & forming memories; the Hippocampus is one of the structures within the cerebrum that is a part of the limbic system, it is essential in both storing & forming long-term memories; the amygdaloid body is found attached to the hippocampus, it is involved in several aspects of emotion, especially fear; the amygdaloid body also helps store & code memories based on how an individual emotionally perceived the memory
Describe in detail the micturition reflex.
The micturition reflex involves a coordinated and sustained contraction of the detrusor muscle (the detrusor reflex) along with simultaneous relaxation of the urethra. Moreover, depending on the size of the bladder, the micturition reflex may also result in urine storage.
Describe in detail the structural differences between the sympathetic and parasympathetic divisions of the autonomic nervous system. Be sure to include the following in your response: length of preganglionic and postganglionic axons, location of preganglionic neuron, and location of ganglia.
The parasympathetic nervous system (PNS) controls homeostasis and the body at rest and is responsible for the body's "rest and digest" function. The sympathetic nervous system (SNS) controls the body's responses to a perceived threat and is responsible for the "fight or flight" response. The PNS and SNS are part of the ANS, or autonomic nervous system which is responsible for the involuntary functions of the human body. They both use a preganglionic and postganglionic neuron to innervate cardiac muscle, smooth muscle, or glands. Parasympathetic preganglionic cell bodies are in either the brainstem or the lateral gray matter of the s2-s4 spinal cord segments (craniosacral). Sympathetic preganglionic neuron cell bodies are in the lateral horns of T1- L2 spinal cord segments (thoracolumbar). Parasympathetic division has longer preganglionic axons and shorter postganglionic axons. The sympathetic division has shorter preganglionic axons and longer postganglionic axons. The parasympathetic division tends to have fewer preganglionic axon branches, while sympathetic division has many preganglionic axon branches. Parasympathetic autonomic ganglia are either close to or within the effector. Sympathetic autonomic ganglia are relatively close to the spinal cord.
Describe in detail the physiological changes within the body associated with a parasympathetic response.
The parasympathetic system is active when we are maintaining homeostasis and is considered the "rest and digest" division. It is characterized by energy conservation and nutrient replenishment. It has the opposite physiological changes as the sympathetic division. The effect on the cardiovascular system is to decrease heart rate. The effect on the respiratory system is to decrease airflow into lungs. The effect on the digestive system is to increase digestion. The effect on the urinary system is to facilitate urination. It causes vasodilation in blood vessels, which in the reproductive system can cause erection of structures. The effect on the nervous system is to decrease the amount of light entering the eye.
Describe in detail the process of olfaction and perception.
The perception of odors begins in sensory neurons residing in the olfactory epithelium that express G protein-coupled receptors, the so-called olfactory receptors. The binding of odor molecules to olfactory receptors initiates a signal transduction cascade that converts olfactory stimuli into electrical signals.
Describe in detail how a stroke at the precentral gyrus of the right cerebral hemisphere would affect the individual.
The primary motor cortex is located within the precentral gyrus. Neurons within this region control voluntary skeletal muscle activity. The axons here project contralaterally, meaning that the right primary motor cortex controls the skeletal muscle of the left side of the body & vice versa.So if an individual were to have a stroke within the precentral gyrus of the right hemisphere, they would experience deficits in the voluntary skeletal muscle movement on the left side of the body.
Describe in detail the organization (components) and functions of the spinal cord and nerves including their protective coverings.
The spinal cord is a roughly cylindrical structure that extends through the vertebral column, to the inferior border of L1 vertebrae. It has two longitudinal depressions that extend its full length, the posterior median sulcus & anterior median fissure. The spinal cord is subdivided into 4 continuous parts. The cervical part, continuous with the medulla oblongata, the thoracic part, lumbar part, & sacral part. The spinal cord is covered by three spinal cord meninges. These include the pia mater, which adheres directly to the spinal cord, the arachnoid mater, external to the pia mater, & the dura mater which is the outermost layer. The spinal cord has 31 pairs of spinal nerves extending from its periphery. These spinal nerves are composed of bundles of axons enclosed within three layers of connective tissue coverings. These coverings include the epineurium that ensheathes the entire nerve, the perineurium that encloses each fascicle, & the endoneurium that insulates each axon. There are 8 pairs of cervical nerves, 12 pairs of thoracic nerves, 5 pairs of lumbar nerves, 5 pairs of sacral nerves, & 1 pair of coccygeal nerves. Each nerve is anchored to the spinal cord by two roots, a posterior root & anterior root.The spinal cord & nerves have two important functions. The first function is to provide an essential structural & functional link between the brain & the torso & limbs. Sensory input & output are relayed along neuron pathways within the spinal cord & nerves. The second function is their role in spinal reflexes. These involve nervous system responses that do not require the involvement of the brain, instead have the spinal cord as the integration center. They initiate our quickest reactions to a stimulus & its through these that the spinal cord exhibits some functional independence from the brain.
Describe in detail the functions of the thalamus.
The thalamus is the principal & final relay point for incoming sensory information; the information is processed & then sent to the appropriate region of the cerebral cortex; it also helps the cerebrum determine where specific sensory information is coming from.
Describe in detail the visual pathway from cornea to the occipital lobe.
starts by going through the cornea, pupil, lens, then focus' on the retina (fovea), rods/cones see them; they stimulate ganglion cells, then they merge to form the optic nerve,then the info goes to optic chiasma, to the tectal system, goes to the thalamus, then goes to the occipital lobe of the brain (that's when we process that we're seeing stuff)then goes to visual cortex of occipital lobe