Integration of body systems Flashcards
(230 cards)
1
Q
What is system integration in biology?
A
System integration is the process by which different components of a biological system work together to perform complex functions. It involves the coordination of various parts to achieve a common goal, ensuring the efficient operation of the organism as a whole.
2
Q
Why is coordination necessary in living systems?
A
Coordination is essential in living systems because it allows the component parts to work together effectively. Without coordination, individual parts would function independently, leading to inefficiency and potentially harmful outcomes for the organism.
3
Q
Give an example of system integration in the human body.
A
The nervous system integrates with the muscular system to produce movement. The brain sends signals through neurons to muscles, coordinating their contraction and relaxation to achieve purposeful motion.
4
Q
How does the endocrine system demonstrate system integration?
A
The endocrine system integrates with various organs by releasing hormones into the bloodstream. These hormones coordinate responses across different body systems, such as regulating metabolism, growth, and reproduction.
5
Q
What role does feedback play in system integration?
A
Feedback mechanisms are crucial for system integration as they allow for self-regulation. Positive and negative feedback loops help maintain homeostasis by adjusting the output of various systems based on internal and external stimuli.
6
Q
How does the circulatory system contribute to system integration?
A
The circulatory system integrates various body systems by transporting hormones, nutrients, and waste products. It connects organs and tissues, allowing for coordinated responses and maintaining overall body function.
7
Q
What is the importance of cell signaling in system integration?
A
Cell signaling is vital for system integration as it allows cells to communicate and coordinate their activities. This process enables multicellular organisms to function as a cohesive unit, responding to changes in their internal and external environments.
8
Q
How does the immune system demonstrate system integration?
A
The immune system integrates various components, including white blood cells, antibodies, and the lymphatic system, to defend against pathogens. This coordinated response involves recognizing threats, mobilizing defenses, and remembering past infections.
9
Q
What role does the liver play in system integration?
A
The liver integrates multiple body systems by performing diverse functions such as detoxification, protein synthesis, and glucose regulation. It works in coordination with the digestive, circulatory, and endocrine systems to maintain overall body homeostasis.
10
Q
How does the concept of emergent properties relate to system integration?
A
Emergent properties are characteristics that arise from the interaction of system components, which are not present in the individual parts alone. System integration allows for the emergence of complex behaviors and functions that result from the coordinated activity of simpler components.
11
Q
What is the hierarchical organization of a multicellular organism?
A
The hierarchy in a multicellular organism, from smallest to largest, is: cells → tissues → organs → organ systems → organism. Each level builds upon the previous, creating more complex structures and functions.
12
Q
Define a tissue and give an example.
A
A tissue is a group of similar cells working together to perform a specific function. For example, epithelial tissue lines body surfaces and cavities, providing protection and facilitating absorption or secretion.
13
Q
What is an organ, and how does it relate to tissues?
A
An organ is a structure composed of multiple tissues working together for a common function. For instance, the heart contains cardiac muscle tissue, connective tissue, and nervous tissue, all cooperating to pump blood.
14
Q
Explain what an organ system is and provide an example.
A
An organ system is a group of organs working together to perform a larger function. The digestive system, for example, includes the mouth, esophagus, stomach, intestines, and accessory organs like the liver and pancreas, all collaborating to process food.
15
Q
What are emergent properties in the context of biological systems?
A
Emergent properties are characteristics or behaviors that arise from the interaction of components in a system, which are not present in the individual parts. For example, consciousness emerges from the integrated activity of neurons in the brain.
16
Q
How does the integration of body systems contribute to a cheetah’s predatory success?
A
The cheetah’s predatory success results from the integration of multiple systems: the muscular and skeletal systems provide speed and agility, the nervous system enables quick reflexes, the respiratory and circulatory systems support high-energy demands, and the sensory organs allow for precise targeting of prey.
17
Q
What is the relationship between structure and function in biological hierarchies?
A
Structure and function are closely related at all levels of biological organization. The specific structure of a cell, tissue, organ, or system is adapted to perform its particular function efficiently within the larger organism.
18
Q
How does the concept of specialization relate to the hierarchy of biological systems?
A
Specialization increases as we move up the biological hierarchy. While individual cells may be specialized, tissues and organs show even greater specialization. This allows for more complex functions to emerge at higher levels of organization.
19
Q
Explain how homeostasis is maintained through the integration of body systems.
A
Homeostasis is maintained through the coordinated efforts of multiple organ systems. For example, maintaining body temperature involves the integumentary system (skin), circulatory system (blood flow), muscular system (shivering), and nervous system (temperature sensing and regulation).
20
Q
How does the integration of subsystems contribute to an organism’s ability to respond to its environment?
A
The integration of subsystems allows an organism to respond to environmental changes more effectively. For instance, when a threat is perceived, the nervous system quickly coordinates with the endocrine, muscular, and cardiovascular systems to initiate a “fight or flight” response, enhancing the organism’s chances of survival.
21
Q
What are the two main systems responsible for integrating organs in animal bodies?
A
The nervous system and the endocrine system are the primary systems responsible for integrating organs in animal bodies. They work together to coordinate various bodily functions and maintain homeostasis.
22
Q
How does the nervous system send messages in the body?
A
The nervous system sends messages through electrical impulses that travel along neurons. These signals are rapid and specific, allowing for quick responses to stimuli.
23
Q
How does the endocrine system communicate within the body?
A
The endocrine system communicates by releasing hormones into the bloodstream. These chemical messengers travel throughout the body to target specific organs or tissues, producing slower but longer-lasting effects.
24
Q
What is a key difference between nervous and hormonal signaling?
A
Nervous signaling is fast and localized, while hormonal signaling is slower but more widespread. Nervous signals travel along specific pathways, whereas hormones can affect multiple organs simultaneously.
25
How does the circulatory system contribute to organ integration?
The circulatory system transports hormones, nutrients, oxygen, and waste products between organs. It acts as a highway for communication and material exchange, supporting the integrated function of body systems
26
Give an example of how the blood system transports materials between organs.
The blood transports oxygen from the lungs to other organs and tissues. Red blood cells pick up oxygen in the lungs and deliver it to cells throughout the body, while also removing carbon dioxide for exhalation.
27
How does the digestive system interact with the circulatory system to integrate organ functions?
The digestive system breaks down food into nutrients, which are then absorbed into the bloodstream through capillaries in the small intestine. The circulatory system then distributes these nutrients to cells throughout the body.
28
What role does the liver play in the integration of organ systems through the blood?
The liver removes toxins from the blood and produces bile, which is essential for fat digestion. It also regulates blood sugar levels by storing excess glucose and releasing it when needed, demonstrating its integrative role in metabolism.
29
How does the kidney contribute to organ integration through the circulatory system?
The kidneys filter waste products and excess water from the blood, forming urine. They also play a crucial role in regulating blood pressure and producing hormones that stimulate red blood cell production, showcasing the integration of the urinary, circulatory, and endocrine systems.
30
Explain how the nervous and endocrine systems work together to regulate blood glucose levels.
The nervous system detects changes in blood glucose through specialized cells in the pancreas. In response, the endocrine system releases hormones like insulin or glucagon from the pancreas into the bloodstream. These hormones then act on various organs, such as the liver and muscles, to either store or release glucose, maintaining homeostasis.
31
What is the primary role of the brain in information processing?
The brain acts as the central information integration organ, receiving, processing, and coordinating information from various sensory inputs to generate appropriate responses.
32
How does the brain integrate multiple sensory inputs?
The brain processes and integrates multiscale inputs from different sensory systems, combining them into a meaningful whole. This integration occurs across various brain regions with different intrinsic neural timescales.
33
What are the key brain regions involved in learning and memory?
The amygdala, hippocampus, and prefrontal cortex (PFC) are pivotal for shaping memory and facilitating learning. The hippocampus is crucial for forming new memories, while the PFC is involved in memory consolidation and retrieval.
34
How does synaptic plasticity contribute to learning and memory?
Synaptic plasticity, including long-term potentiation (LTP) and long-term depression, is a key mechanism in memory formation and consolidation. It allows for changes in the strength of connections between neurons, enabling the brain to store and retrieve information.
35
What is the role of the limbic system in information processing?
The limbic system, which includes structures in the cerebrum, subcortex, and brainstem, controls emotions, olfaction, and homeostasis. It plays a crucial role in processing and integrating emotional and sensory information.
36
How does the brain handle multiple simultaneous tasks?
The conscious mind cannot effectively process multiple tasks simultaneously if they require the same brain regions. Instead, the brain rapidly switches between tasks, which can lead to reduced efficiency in processing each individual task.
37
What is the function of the cerebral cortex in information integration?
The cerebral cortex is divided into motor and sensory areas, with association areas responsible for complex cognitive processes such as perception, thought, and decision-making. These areas work together to integrate and process various types of information.
38
How do neurotransmitters contribute to learning and memory processes?
Neurotransmitters like glutamate, acetylcholine, dopamine, norepinephrine, and serotonin play crucial roles in synaptic plasticity, attention, memory consolidation, and modulation of cognitive processes related to learning and memory.
39
What is the role of the prefrontal cortex in information processing?
The prefrontal cortex, particularly the dorsolateral region, is involved in working memory and executive functions necessary for learning and memory processes. It also plays a role in attention, abstract thinking, and problem-solving.
40
How does the brain process information from multiple inputs during dual-task performance?
The brain employs both serial and parallel processing mechanisms. Some brain networks process information serially, while others work in parallel to handle multiple inputs simultaneously during complex cognitive tasks.
41
What is the role of the spinal cord in unconscious processes?
The spinal cord acts as an integrating center for unconscious processes, coordinating reflexes and automatic responses without direct input from the brain.
42
What is a spinal reflex?
A spinal reflex is an involuntary, automatic response to a stimulus that is processed entirely within the spinal cord, without conscious input from the brain.
43
How does the spinal cord contribute to proprioception?
The spinal cord contains spinocerebellar tracts that conduct unconscious proprioceptive information from joints and muscles to the cerebellum.
44
What is the nociceptive flexion reflex?
The nociceptive flexion reflex, also known as the withdrawal reflex, is an automatic response to noxious stimuli that is processed in the spinal cord without conscious control.
45
How does the spinal cord process sensory information before it reaches the brain?
The spinal cord can process and integrate sensory information through interneurons, allowing for rapid responses to stimuli before the information reaches the brain.
46
What is primary afferent polarization (PAD)?
PAD is a mechanism where interneurons in the spinal cord, controlled by descending cortical inputs, modulate incoming sensory afferents, affecting reflexes and somatosensation.
47
How do central pattern generators in the spinal cord contribute to unconscious processes?
Central pattern generators in the spinal cord can produce rhythmic movement patterns, such as walking, without conscious input or sensory feedback.
48
What is the difference between the spinothalamic tract and the lemniscal pathway?
The spinothalamic tract and lemniscal pathway are two separate routes for sensory information to reach the brain, potentially affected differently by spinal cord injuries.
49
How does the spinal cord contribute to the "fight or flight" response?
The spinal cord contains sympathetic pathways that control the "fight or flight" response, regulating bodily functions automatically in response to danger.
50
What is the key difference between conscious and unconscious processes in the spinal cord?
Conscious processes involve higher brain centers and voluntary control, while unconscious processes in the spinal cord occur automatically without direct conscious awareness or control.
51
What is the primary function of sensory neurons?
Sensory neurons carry information about changes in external and internal environments to the central nervous system (CNS).
52
How are sensory neurons classified based on their direction of information flow?
Sensory neurons are classified as afferent, meaning they carry information to the CNS.
53
What are the two main categories of sensory neurons?
Sensory neurons can be categorized as peripheral (responding to external stimuli) or visceral (responding to internal stimuli).
54
Where are the cell bodies of primary sensory neurons that bring information to the spinal cord located?
The cell bodies of primary sensory neurons are located in the dorsal root ganglia
55
How does sensory information reach the cerebral cortex?
Sensory information travels through ascending neural tracts in the spinal cord, then through subcortical structures like the thalamus, before reaching the cerebral cortex.
56
What is the role of first-order neurons in sensory pathways?
First-order neurons are afferent, carrying sensory input from receptors through peripheral nerves to the spinal or dorsal root ganglion.
57
How do second-order neurons contribute to sensory pathways?
Second-order neurons receive input from first-order neurons in the spinal cord's posterior gray horn and ascend to subcortical structures like the thalamus.
58
What is the function of third-order neurons in sensory pathways?
Third-order neurons carry neural impulses from subcortical structures, such as the thalamus, to the cerebral cortex.
59
How do sensory neurons in the head connect to the CNS?
Sensory information from the head enters the CNS through cranial nerves.
60
What is the process of sensory transduction?
Sensory transduction is the process by which sensory neurons convert specific stimuli into action potentials or graded receptor potentials via their receptors.
61
What is the primary function of motor neurons?
Motor neurons carry signals from the central nervous system to muscles, stimulating them to contract.
62
How are motor neurons classified based on their direction of information flow?
Motor neurons are classified as efferent, meaning they carry information away from the central nervous system.
63
What are the two main types of motor neurons?
The two main types of motor neurons are upper motor neurons and lower motor neurons.
64
Where do upper motor neurons originate?
Upper motor neurons originate primarily in the cerebral cortex, specifically in the primary motor cortex.
65
What is the main neurotransmitter used by upper motor neurons?
Upper motor neurons primarily use glutamate as their neurotransmitter.
66
Where do lower motor neurons originate?
Lower motor neurons originate in the brainstem (cranial nerve nuclei) and the spinal cord (anterior horn).
67
What is the main neurotransmitter used by lower motor neurons?
Lower motor neurons primarily use acetylcholine as their neurotransmitter.
68
What is a motor unit?
A motor unit consists of a single motor neuron and all the muscle fibers it innervates.
69
How do motor neurons stimulate muscle contraction?
Motor neurons release neurotransmitters at neuromuscular junctions, which are received by motor end plates on muscle fibers, signaling the muscle to contract.
70
What is the corticospinal tract?
The corticospinal tract is a neural pathway that carries signals from the motor cortex to lower motor neurons in the ventral horn of the spinal cord, controlling fine voluntary motor movements of the limbs.
71
What is a nerve?
A nerve is a bundle of nerve fibers containing both sensory (afferent) and motor (efferent) neurons, wrapped in protective connective tissue sheaths.
72
What are the three main protective sheaths of a nerve, from outermost to innermost?
The three main protective sheaths of a nerve are the epineurium (outermost), perineurium, and endoneurium (innermost).
73
What is the function of the epineurium?
The epineurium is the outermost protective sheath that surrounds the entire nerve, bundling together multiple fascicles and providing mechanical resistance.
74
What is the perineurium?
The perineurium is a protective sheath that surrounds individual nerve fascicles, bundling together axons targeting the same anatomical location.
75
What is the endoneurium?
The endoneurium is the innermost delicate protective sheath that surrounds individual nerve fibers (axons) within a fascicle.
76
What are the two main types of nerve fibers visible in a transverse section of a nerve?
The two main types of nerve fibers visible in a transverse section are myelinated and unmyelinated nerve fibers.
77
How do myelinated nerve fibers appear in a transverse section?
Myelinated nerve fibers appear as nearly circular profiles surrounded by a spirally wound multilamellar sheath called myelin.
78
How do unmyelinated nerve fibers appear in a transverse section?
Unmyelinated nerve fibers appear as groups of small-diameter axons surrounded by thin sheets of Schwann cells.
79
What is the function of myelin in nerve fibers?
Myelin acts as an insulating layer around axons, greatly increasing the speed of nerve impulse transmission.
80
How do sensory and motor neurons differ in their direction of information flow?
Sensory (afferent) neurons carry information from sensory receptors to the central nervous system, while motor (efferent) neurons carry information from the central nervous system to muscles and glands.
81
What is a pain reflex arc?
A pain reflex arc is an involuntary response to a painful stimulus that involves skeletal muscle as the effector, bypassing conscious control from the brain.
82
What are the components of a simple pain reflex arc?
A simple pain reflex arc consists of a receptor, sensory neuron, interneuron in the spinal cord, motor neuron, and effector (skeletal muscle).
83
What type of receptor is involved in a pain reflex arc?
Free nerve endings act as pain receptors (nociceptors) in a pain reflex arc.
84
Where are free nerve endings typically located in the body?
Free nerve endings are most commonly found in the skin, penetrating the dermis and ending in the stratum granulosum.
85
What is the function of the interneuron in a pain reflex arc?
The interneuron in the grey matter of the spinal cord relays the signal from the sensory neuron to the motor neuron.
86
How does the effector respond in a pain reflex arc?
The effector, which is a skeletal muscle, contracts to withdraw the body part from the painful stimulus.
87
Why is a pain reflex arc considered an involuntary response?
A pain reflex arc is involuntary because it occurs automatically without conscious control from the brain.
88
What is the advantage of a reflex arc bypassing the brain?
Bypassing the brain allows for a faster response, which is crucial for protecting the body from harmful stimuli.
89
What types of nerve fibers are primarily involved in transmitting pain signals?
Pain signals are primarily transmitted by Aδ (A delta) fibers and C fibers.
90
What is the "double pain sensation" phenomenon?
The "double pain sensation" occurs when a sudden painful stimulus results in two sequential pain sensations: a fast, sharp pain transmitted by Aδ fibers, followed by a slower, duller pain transmitted by C fibers.
91
What is the primary function of the cerebellum in movement control?
The cerebellum primarily coordinates skeletal muscle contractions, maintains balance, and fine-tunes motor activities.
92
How does the cerebellum contribute to balance?
The cerebellum has special sensors that detect shifts in balance and sends signals for the body to adjust and move accordingly.
93
What role does the cerebellum play in coordinating movement?
The cerebellum times muscle actions so that the body can move smoothly, coordinating multiple muscle groups for complex movements.
94
How does the cerebellum contribute to motor learning?
The cerebellum helps the body learn movements that require practice and fine-tuning, such as riding a bicycle or playing a musical instrument.
95
What is the cerebellum's role in eye movements?
The cerebellum coordinates eye movements, which is crucial for maintaining visual focus during body movements.
96
How does the cerebellum process information for movement control?
The cerebellum uses feedforward processing, receiving input from sensory systems and other parts of the brain to fine-tune motor activity
97
What happens to movement control when the cerebellum is damaged?
Cerebellar damage doesn't cause paralysis but produces disorders in fine movement, equilibrium, posture, and motor learning.
98
How does the cerebellum contribute to posture maintenance?
The cerebellum makes postural adjustments to maintain balance by modulating commands to motor neurons based on input from vestibular receptors and proprioceptors.
99
What is the cerebellum's role in voluntary movements?
The cerebellum coordinates the timing and force of different muscle groups to produce fluid limb or body movements.
100
How does the cerebellum enhance proprioception during movement?
The cerebellum predicts body position and velocity from motor commands, enhancing proprioception specifically during active movements.
101
What is melatonin?
Melatonin is a hormone primarily produced by the pineal gland that plays a crucial role in regulating the sleep-wake cycle and circadian rhythms.
102
When does melatonin secretion peak?
Melatonin secretion peaks during the middle of the night, typically around 3 to 4 AM.
103
How does light affect melatonin production?
Light suppresses melatonin production. The pineal gland releases the highest levels of melatonin in darkness and decreases production when exposed to light.
104
What is the "sleep gate"?
The "sleep gate" opens when melatonin secretion rises, typically about 2 hours before a person's regular bedtime, increasing sleep propensity.
105
How does melatonin secretion vary throughout the day?
Melatonin levels are low during daylight hours, begin to rise in the evening, peak at night, and decrease as dawn approaches.
106
What is the role of the suprachiasmatic nucleus (SCN) in melatonin secretion?
The SCN, located in the hypothalamus, controls circadian rhythms and regulates melatonin secretion based on light information from the retina.
107
How does melatonin help establish the sleep-wake cycle?
Melatonin prepares the body for rest and sleep by shifting it into "sleep mode" as light decreases in the evening.
108
What is the typical timing of melatonin secretion for a person with normal circadian regulation?
Melatonin levels typically rise around 9 PM, peak between 2 and 4 AM, and then decrease, with minimal presence during the day.
109
How does melatonin secretion differ between day and night?
Melatonin secretion is highest during the night and lowest during daylight hours, following a robust circadian rhythm.
110
What factors can affect melatonin secretion and circadian rhythms?
Factors such as light exposure, blindness, and certain medical conditions can affect melatonin secretion and disrupt circadian rhythms.
111
Where is epinephrine produced in the body?
Epinephrine is primarily produced in the adrenal medulla of the adrenal glands.
112
What triggers epinephrine release?
Epinephrine release is triggered by stress, fear, emotional stress, pain, cold, hypotension, hypoglycemia, and other stressful situations.
113
How does epinephrine affect the heart?
Epinephrine increases heart rate, contractility, and conduction across the AV node, leading to increased cardiac output.
114
What effect does epinephrine have on the lungs?
Epinephrine causes bronchodilation and increases respiratory rate, improving breathing during intense activity.
115
How does epinephrine impact blood glucose levels?
Epinephrine stimulates glycogenolysis in the liver and muscles, raising blood glucose levels to provide energy for vigorous activity.
116
What is the effect of epinephrine on skeletal muscles?
Epinephrine has a positive inotropic effect on fast-contracting skeletal muscles, enhancing muscle contraction.
117
How does epinephrine affect blood vessels?
Epinephrine causes vasoconstriction in many blood vessels but dilates blood vessels in skeletal muscles and the liver, redirecting blood flow to these areas during intense activity.
118
What is the impact of epinephrine on fat metabolism?
Epinephrine triggers lipolysis, increasing the level of circulating free fatty acids that can be used as fuel during vigorous activity.
119
How does epinephrine prepare the body for the "fight-or-flight" response?
Epinephrine increases heart rate, blood flow, breathing rate, blood sugar levels, and muscle strength while reducing pain perception, preparing the body for intense physical activity
120
What is the effect of epinephrine on mental state during vigorous activity?
Epinephrine increases attention, alertness, vigilance, and cognition, enhancing mental focus during intense physical activity.
121
What is the primary role of the hypothalamus in the endocrine system?
The hypothalamus acts as the main link between the endocrine system and nervous system, controlling hormone release and maintaining homeostasis
122
How does the hypothalamus communicate with the pituitary gland?
The hypothalamus communicates with the pituitary gland through a stalk of blood vessels and nerves, sending hormones and nerve impulses.
123
What are releasing hormones?
Releasing hormones are produced by the hypothalamus to stimulate the pituitary gland to release specific hormones.
124
How does the pituitary gland influence other endocrine glands?
The pituitary gland secretes hormones that regulate the activity of other hormone-secreting glands throughout the body.
125
What is the function of corticotropin-releasing hormone (CRH)?
CRH is part of the hormone system regulating carbohydrate, protein, and fat metabolism, as well as sodium and water balance in the body.
126
How does feedback regulation work in the endocrine system?
Feedback regulation involves hormones or their effects feeding back to the original signal to control further hormone release, helping maintain hormone levels at the right level.
127
What are some key hormones produced by the pituitary gland?
The pituitary gland produces hormones such as growth hormone, thyroid-stimulating hormone, adrenocorticotropic hormone, and gonadotropins.
128
How does the hypothalamus maintain homeostasis?
The hypothalamus maintains homeostasis by influencing the autonomic nervous system and managing hormone release in response to internal and external signals.
129
What is the role of neurotransmitters in hypothalamic function?
Neurotransmitters regulate the production and release of hormones from the hypothalamus, conveying information about the internal environment.
130
How does the hypothalamus-pituitary complex function?
The hypothalamus-pituitary complex serves as the brain's central command center, controlling vital bodily functions through hormone release and nervous system regulation.
131
Where are baroreceptors located?
Baroreceptors are primarily located in the aortic arch and carotid sinus.
132
What do baroreceptors monitor?
Baroreceptors monitor blood pressure.
133
Where are peripheral chemoreceptors located?
Peripheral chemoreceptors are located in the aortic body and carotid body.
134
Where are central chemoreceptors located?
Central chemoreceptors are located on the ventrolateral medullary surface in the central nervous system.
135
What do chemoreceptors monitor?
Chemoreceptors monitor blood pH and concentrations of oxygen and carbon dioxide.
136
How do central chemoreceptors detect changes in CO2?
Central chemoreceptors detect changes in CSF pH caused by CO2 diffusing across the blood-brain barrier.
137
What is the role of the medulla in heart rate control?
The medulla coordinates responses from baroreceptors and chemoreceptors, sending nerve impulses to the heart to change stroke volume and heart rate.
138
How do baroreceptors respond to increased blood pressure?
When blood pressure increases, baroreceptors increase vagal nerve activity and inhibit sympathetic outflow, leading to decreased heart rate and blood pressure.
139
How do chemoreceptors respond to decreased blood pH?
When blood pH decreases, chemoreceptors stimulate increased respiratory drive and heart rate to improve CO2 clearance.
140
What is the difference in response time between peripheral and central chemoreceptors?
Peripheral chemoreceptors respond within seconds to CO2 changes, while central chemoreceptors respond within minutes.
141
Where are central chemoreceptors located?
Central chemoreceptors are primarily located on the ventral surface of the medulla in the brainstem.
142
What do central chemoreceptors monitor?
Central chemoreceptors monitor changes in blood pH and CO2 levels in the cerebrospinal fluid.
143
How do changes in blood CO2 levels affect pH?
Increased blood CO2 levels lead to decreased pH (more acidic), while decreased CO2 levels lead to increased pH (more alkaline)
144
How do central chemoreceptors respond to increased CO2 levels?
When CO2 levels increase, central chemoreceptors detect the resulting decrease in pH and stimulate an increase in ventilation rate.
145
What is the primary goal of chemoreceptor regulation of breathing?
The primary goal is to maintain blood pH within a normal range through negative feedback control of ventilation.
146
How does the respiratory control center respond to chemoreceptor input?
The respiratory control center in the medulla adjusts the rate and depth of breathing by sending signals to the diaphragm and intercostal muscle.
147
What happens to ventilation when blood pH decreases?
When blood pH decreases, chemoreceptors stimulate an increase in ventilation rate to expel more CO2 and restore normal pH
148
How does increased ventilation help restore normal blood pH?
Increased ventilation expels more CO2 from the body, reducing carbonic acid formation in the blood and raising pH back to normal levels.
149
What is the role of the diaphragm in adjusting ventilation rate?
The diaphragm contracts and relaxes in response to signals from the respiratory control center, changing the volume of the thoracic cavity and adjusting ventilation rate.
150
How do intercostal muscles contribute to changes in ventilation rate?
Intercostal muscles contract and relax to move the rib cage, altering lung volume and contributing to changes in ventilation rate in response to chemoreceptor signals.
151
What controls the initiation of swallowing?
The central nervous system (CNS) controls the initiation of swallowing, which is a voluntary action.
152
Which system controls the egestion of feces?
The central nervous system (CNS) controls the egestion of feces, which is a voluntary action.
153
What controls peristalsis between swallowing and egestion?
The enteric nervous system (ENS) controls peristalsis between swallowing and egestion, which is an involuntary action.
154
What is peristalsis?
Peristalsis is the involuntary contraction and relaxation of longitudinal and circular muscles throughout the digestive tract, propelling contents from the pharynx to the anus.
155
How does the ENS ensure coordinated passage of material through the gut?
The ENS coordinates gut functions such as motility and peristalsis through a complete sensorimotor reflex circuit consisting of intrinsic primary afferent neurons, interneurons, and motor neurons within the gut wall.
156
Where is the enteric nervous system located?
The enteric nervous system is located in the walls of the gastrointestinal tract, consisting of the myenteric plexus and the submucosal plexus.
157
How does the CNS interact with the ENS in digestive control?
The CNS, particularly the dorsal vagal complex, permissively governs the largely autonomous control by the ENS of functions such as motility.
158
What is the role of the myenteric plexus in peristalsis?
The myenteric plexus, located between the longitudinal and circular muscles of the GI tract, contains pacemaker cells and mediates the process of peristalsis
159
How does the peristaltic reflex work?
The peristaltic reflex involves sensory neurons detecting stretch, which activates neurons in the myenteric plexus to cause contraction behind the food bolus and relaxation ahead of it.
160
Why is the ENS sometimes called the "second brain"?
The ENS is sometimes called the "second brain" due to its complexity, containing 200-600 million neurons and the ability to function independently of the CNS.
161
What are tropic responses in seedlings?
Tropic responses are growth movements of plants in response to environmental stimuli, such as light (phototropism) or gravity (gravitropism).
162
How can qualitative data be gathered for tropic responses?
Qualitative data can be gathered by creating detailed diagrams or sketches of seedlings, illustrating their growth direction and curvature in response to stimuli.
163
What quantitative measurement can be taken to study tropic responses?
The angle of curvature of seedlings can be measured as a quantitative data point to study tropic responses.
164
What is the difference between qualitative and quantitative observations?
Qualitative observations describe qualities or characteristics without numerical measurements, while quantitative observations involve precise numerical measurements.
165
What factors can limit the precision of measurements in tropism experiments?
Factors limiting precision may include the resolution of measuring tools, human error in reading measurements, and natural variations in plant growth.
166
How can the accuracy of measurements be improved in tropism experiments?
Accuracy can be improved by using more precise measuring tools, standardizing measurement techniques, and increasing the number of samples or repetitions.
167
What strategies can increase the reliability of measurements in tropism experiments?
Strategies include using multiple observers, repeating experiments under identical conditions, and using control groups to account for variables.
168
Why is it important to use both qualitative and quantitative data in tropism studies?
Using both types of data provides a more comprehensive understanding, with qualitative observations offering context and quantitative data allowing for statistical analysis.
169
How can time-lapse photography be used in studying tropic responses?
Time-lapse photography can capture the gradual movement of seedlings over time, providing both qualitative visual data and quantitative data on growth rates and angles.
170
What role does experimental design play in tropism studies?
Good experimental design, including proper controls and standardized conditions, is crucial for obtaining reliable and comparable results in tropism studies.
171
What is phototropism?
Phototropism is a directional growth response of plants to light.
172
What is positive phototropism?
Positive phototropism is the growth of plant shoots towards a light source.
173
How do plant shoots respond to lateral light?
Plant shoots grow towards the source of lateral light, exhibiting positive phototropism.
174
What hormone is primarily responsible for phototropic responses?
Auxin, particularly indole-3-acetic acid (IAA), is the primary hormone responsible for phototropic responses.
175
How does auxin distribution change in response to lateral light?
Auxin accumulates on the shaded side of the stem, causing cells there to elongate more than on the lit side, resulting in bending towards light.
176
What is the adaptive advantage of positive phototropism in shoots?
Positive phototropism allows plants to maximize light exposure for photosynthesis, enhancing growth and survival.
177
How quickly can phototropic responses occur?
Phototropic responses can begin within minutes of exposure to lateral light, though visible bending may take hours.
178
What part of the plant is most sensitive to light for phototropic responses?
The tip of the shoot, particularly the coleoptile in grass seedlings, is most sensitive to light for initiating phototropic responses.
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How does the intensity of light affect phototropic response?
Generally, stronger light intensities produce more pronounced phototropic responses, up to a certain threshold.
180
Can artificial light sources induce phototropic responses?
Yes, artificial light sources can induce phototropic responses, which is important in controlled experiments and indoor plant cultivation.
181
What are phytohormones?
Phytohormones are plant hormones that act as signalling chemicals, controlling growth, development, and responses to stimuli in plants.
182
How do phytohormones function in plants?
Phytohormones act as chemical messengers, produced in tiny amounts throughout the plant, influencing processes from seed germination to stem growth, flowering, and fruit production.
183
Name five major types of phytohormones.
The five major phytohormones are auxins, gibberellins, cytokinins, ethylene, and abscisic acid.
184
What is the role of auxins in plants?
Auxins control cell elongation, apical dominance, adventitious root formation, and plant tropisms.
185
How do gibberellins affect plant growth?
Gibberellins stimulate internode elongation, influence flower sexuality, and promote seed growth and germination.
186
What functions do cytokinins serve in plants?
Cytokinins promote morphogenesis of stems and roots, chloroplast maturation, and cell division.
187
How does abscisic acid (ABA) influence plant processes?
ABA regulates growth, induces stomatal closure, and helps plants respond to stress.
188
What is the primary function of ethylene in plants?
Ethylene primarily promotes fruit ripening and can act as both a growth promoter and inhibitor.
189
Where are phytohormones produced in plants?
Unlike animals, each plant cell is capable of producing hormones, though some tissues may specialize in producing certain types.
190
How do brassinosteroids contribute to plant growth?
Brassinosteroids control cell elongation and division, gravitropism, stress resistance, and xylem differentiation.
191
What are auxin efflux carriers?
Auxin efflux carriers are proteins in plant cell membranes that actively transport auxin out of cells.
192
How does auxin enter plant cells?
Auxin can freely diffuse into plant cells due to its lipophilic nature when in its protonated form.
193
Why can't auxin easily exit plant cells without efflux carriers?
Inside the cell, auxin becomes ionized due to the higher pH, making it unable to pass through the cell membrane without active transport.
194
How do auxin efflux carriers create concentration gradients?
By positioning efflux carriers on one side of the cell, auxin is actively transported in a specific direction, creating concentration gradients across tissues.
195
What is polar auxin transport?
Polar auxin transport is the directional movement of auxin through plant tissues, facilitated by the coordinated positioning of auxin efflux carriers.
196
How do plant cells coordinate the positioning of auxin efflux carriers?
Plant cells coordinate to concentrate auxin efflux carriers on the same side, allowing for directional transport through the tissue.
197
What is the significance of auxin concentration gradients in plants?
Auxin concentration gradients are crucial for various developmental processes, including organ formation, tropisms, and vascular tissue development.
198
Name an important family of auxin efflux carriers in plants.
The PIN-FORMED (PIN) protein family is a crucial group of auxin efflux carriers in plants.
199
How does the positioning of auxin efflux carriers affect plant growth?
The positioning of efflux carriers determines the direction of auxin flow, which influences cell elongation and division, thus affecting overall plant growth and development.
200
What role do auxin efflux carriers play in phototropism?
During phototropism, auxin efflux carriers redistribute to the shaded side of the stem, causing auxin accumulation there and resulting in differential growth towards light.
201
How does auxin promote cell growth?
Auxin promotes cell growth by stimulating hydrogen ion secretion into the apoplast, which acidifies the cell wall.
202
What effect does cell wall acidification have on cellulose?
Cell wall acidification loosens cross-links between cellulose molecules, facilitating cell elongation.
203
How does auxin activate proton pumps?
Auxin activates plasma membrane H+-ATPases, which pump protons into the cell wall space.
204
What is the "acid growth hypothesis"?
The acid growth hypothesis states that auxin induces proton extrusion into the apoplast, decreasing pH and promoting cell elongation.
205
How do auxin concentration gradients affect plant growth?
Auxin concentration gradients cause differences in growth rates, leading to directional growth responses like phototropism.
206
What role do auxin efflux carriers play in creating concentration gradients?
Auxin efflux carriers, such as PIN proteins, can be positioned on one side of cells to create directional auxin flow and concentration gradients.
207
How does auxin distribution change during phototropism?
During phototropism, auxin is transported from the illuminated side to the shaded side of the stem, creating a concentration gradient.
208
What effect does a higher auxin concentration have on cell elongation in shoots?
In shoots, a higher auxin concentration causes an increase in the rate of cell elongation.
209
How does auxin affect gene expression related to cell wall modification?
Auxin activates the expression of cell wall-related genes, including those for expansins, xyloglucan endotransglucosylase/hydrolases, and pectin methylesterases.
210
What is the role of expansins in auxin-induced cell growth?
Expansins are pH-dependent proteins activated by cell wall acidification, which break down hydrogen bonds in the cell wall to allow expansion.
211
Where is cytokinin primarily produced in plants?
Cytokinin is primarily produced in root tips.
212
Where is auxin primarily produced in plants?
Auxin is primarily produced in shoot tips.
213
How is cytokinin transported in plants?
Cytokinin is transported from root tips to shoots through the xylem.
214
How is auxin transported in plants?
Auxin is transported from shoot tips to roots through the phloem.
215
What is the general effect of auxin on root growth?
High auxin concentrations typically inhibit root growth but promote lateral root formation.
216
What is the general effect of cytokinin on shoot growth?
Cytokinin promotes shoot growth and branching.
217
How do auxin and cytokinin interact to regulate shoot branching?
Auxin inhibits lateral bud growth (apical dominance), while cytokinin promotes it. The balance between these hormones determines the degree of branching.
218
How do auxin and cytokinin interact to regulate root development?
The auxin-to-cytokinin ratio influences root development. A high ratio promotes root growth, while a low ratio inhibits it.
219
What role do auxin-cytokinin interactions play in plant tissue culture?
The ratio of auxin to cytokinin in growth media can determine whether cultured plant cells form roots, shoots, or undifferentiated callus tissue.
220
How do auxin-cytokinin interactions contribute to the integration of root and shoot growth?
The reciprocal transport and interactions of auxin and cytokinin help coordinate root and shoot growth, ensuring balanced development of the whole plant in response to environmental conditions.
221
What is the role of ethylene in fruit ripening?
Ethylene stimulates the changes in fruits that occur during ripening, such as softening, color change, and flavor development.
222
What is the IUPAC name for ethylene?
The IUPAC name for ethylene is ethene.
223
How does fruit ripening affect ethylene production?
As fruits ripen, they produce more ethylene, creating a positive feedback loop.
224
What is a positive feedback loop in fruit ripening?
A positive feedback loop occurs when ethylene stimulates ripening, which in turn stimulates more ethylene production, accelerating the ripening process.
225
Why is the positive feedback mechanism beneficial for fruit ripening?
The positive feedback mechanism ensures that fruit ripening is rapid and synchronized across the fruit or among fruits on the same plant.
226
How does ethylene trigger ripening in climacteric fruits?
In climacteric fruits, ethylene triggers a surge in respiration and a burst of ethylene production, initiating the ripening process.
227
What are some examples of climacteric fruits?
Examples of climacteric fruits include apples, bananas, pears, and tomatoes.
228
How can the ethylene-induced ripening process be manipulated commercially?
Commercially, ethylene gas can be used to artificially ripen fruits, or ethylene inhibitors can be used to delay ripening during storage and transport.
229
What are some physiological changes induced by ethylene during fruit ripening?
Ethylene induces changes such as increased respiration, chlorophyll breakdown, carotenoid synthesis, cell wall softening, and conversion of starches to sugars.
230
How does the positive feedback loop in fruit ripening benefit seed dispersal?
The rapid and synchronized ripening ensured by the positive feedback loop helps attract seed dispersers when fruits are at peak ripeness, enhancing the chances of successful seed dispersal.
