Homeostasis (Biology) Assignment
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Added on 2020-10-05
Homeostasis (Biology) Assignment
Added on 2020-10-05
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Homeostasis (Biology)
TABLE OF CONTENTSINTRODUCTION...........................................................................................................................1TASK 1............................................................................................................................................1A. Homeostasis and role of thyroxine in regulating metabolic rate ...........................................1B. Structure and function neurons ..............................................................................................3C. Transmission and propagation of nerve impulses across synapse .........................................5TASK 2............................................................................................................................................7A. Endocrine system and principle secretions of glands ............................................................7B. Action of hormone on target cells ..........................................................................................8C. Positive and negative feedback systems .................................................................................9TASK 3..........................................................................................................................................10Glucose regulation ....................................................................................................................10CONCLUSION .............................................................................................................................12REFERENCES .............................................................................................................................13
INTRODUCTIONHomeostasis is defined as the process to maintain stability and equilibrium conditionagainst external changes (Waguespack and Chemaitilly, 2018). The report will discuss theHomeostasis process through endocrine and nervous system. It will also explain the role andfeedback systems related to endocrine system. TASK 1A. Homeostasis and role of thyroxine in regulating metabolic rate Homeostasis using temperature receptors: The internal balance or homeostasis of the body is regulated by hypothalamus which actsas a link or connection between nervous and endocrine system. It performs several functionssuch as regulation of body temperature, heart rate, blood pressure and glandular secretions ofintestine and stomach. The anterior hypothalamic nucleus is responsible for the thermoregulationin the body. Thermoregulation process allows the body to maintain the internal temperature sothat temperature changes does not affect the normal functioning and homeostasis is maintained.Anterior hypothalamus is provided with warmth and cold receptors (La Perle and Dintzis, 2018).When hypothalamus senses variations in the internal body temperature then it transmits signalsto nervous system and various muscles so that body can respond to make the body temperaturenormal. 1
(Source: Thermoregulation, 2019)Illustration: When there is rise in ambient temperature then, peripheral warm receptors arestimulated. On the other hand hypothalamic warm receptors are stimulated by increase in bloodtemperature. The efferent signals are then transmitted to posterior hypothalamus so that heatdissipation response such as sweating or vasodilatation can be performed. Similarly, when coldreceptors of anterior hypothalamus are stimulated then signals are transmitted to posteriorhypothalamus and heat producing mechanisms such as vasoconstriction and shivering areaccomplished (Manley and et.al., 2018). Thyroxine: Basal metabolic rate (BMR) is defined as the least number of calories required by anindividual for survival. Thyroxine hormone is the key hormone secreted by thyroid gland and isalso known as T4 or tetraiodothyronine. Usually the hormone is active in nature but is convertedinto active form called triiodothyronine. Thyroxine plays significant role in regulation ofmetabolic rate. For the proper metabolism every cell in the body depends upon Thyroxine andother thyroid hormones. The hormone consist of iodine and for controlling metabolism it helps inreleasing fat from fat cells (Furness, 2016). The lack of thyroxine hormone causes growth2Illustration 1: Homeostasis and temperature control
disorders while its excessive amount in the body make metabolism rate too low. As a result,extremes in the weight of body can be observed. Thus, the metabolic rate is controlled by thesecretion of thyroxine hormone (Peiris and Keating, 2018). B. Structure and function neurons There neurons are of three types and their function and structure is follows: Sensory neurons: These neurons convert external environment stimuli into internal stimuli. The sensoryinputs such as heat, light, sound, smell, taste and physical contact activate these neurons so thatthey can convey sensory information to spinal cord, brain and other elements of nervous system.The axon in most of the sensory neurons is branched into two extensions (Kleine andRossmanith, 2016). One extension is attached to dendrite for receiving information while theother extension sends information to spinal cord. Motor neurons:These neurons transmit information from spinal cord to smooth and skeletal muscles.Thus, motor neurons controls and regulate the voluntary and involuntary movement of muscles.This type of neurons are present in central nervous system (CNS). The axons of these musclesare projected outside CNS so that they can control the muscle actions. These neurons havemultipolar structure thus each cell has multiple dendrites and single axon. Relay Interneuron:Interneurons forms the connection between sensory and motor neurons. They are locatedwithin CNS and their axon is connected with the nearby neurons. Similar to motor neurons thestructure of relay neurons is also multipolar. The projection interneurons have long axons so thatthey can connect distant regions of brain as well (La Perle and Dintzis, 2018). On the other handthe local interneurons have short axons which forms small circuits between surrounding cells. 3
(Source: Neurones: Structures and Functions, 2019)Illustration:Motor neuron ad relay neuron have multipolar structure. In relay neurons the nerveimpulses have bidirectional transmission while in motor and sensory neuron transmission is inone direction only. Since relay neurons establishes connection between other two types ofneurons they do not have myelin sheath. Reflex arc action: Reflex is defined as the instantaneous and involuntary movement against any stimulus.The path used by nerve impulses in a reflex is called reflex arc. When any stimulus stimulatesensations like pain then, impulses are initiated in sensory neurons. Sensory neurons transmitthese impulses to relay neurons which are situated in spinal cord by means of synapse. The relayneuron then makes synapse with motor neurons so that impulse can be send to muscles andmovement like pulling away from the pain causing object can be accomplished. This entireaction is known as the reflex arc (Gordan, Gwathmey and Xie, 2015). Usually brain is notinvolved in reflexes but in certain cases it can prevent reflex action. Sensory neurons does notpass into brain while synapse does. This attribute makes reflex action to occur quickly by rapidactivation of motor neurons. Most of the reflex arcs involve multiple interneurons which aresituated between other two neuron types. 4Illustration 2: Structure of different types of neuron
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