Unit 5 Health And Physiology M2 Homeostasis
Anatomy and Physiology
P5/M2 - Homeostasis
Homeostasis is the need for an organism or a cell to regulate its internal environment (conditions within the fluid surrounding its body cells) by a system of feedback controls to stabilise health and functioning despite the outside changing conditions. This is important as this is what maintains and helps internal conditions (body temperature) to remain stable and constant.
In humans homeostasis happens when the body regulates its body temperature in an effort to maintain an internal temperature at around 37®C. For example, during the summer when the weather is very hot (outside condition) we sweat to cool ourselves down and in the winter when the weather is very cold (outside condition) we shiver …show more content…
to help our bodies to produce heat to keep ourselves warm.
Key facts
Homeostasis is the body 's attempt to maintain a constant and balanced internal environment, which requires persistent monitoring and adjustments as conditions change.
Homeostatic regulation is monitored and adjusted by the receptor, the command centre, and the effector.
The receptor receives information based on the internal environment; the command centre, receives and processes the information; and the effector responds to the command centre, opposing or enhancing the stimulus.
(Boundless, 2013)
Living cells can function only within a narrow range of such conditions as temperature, pH , ion concentrations, and nutrient availability, yet living organisms must survive in an environment where these and other conditions vary from hour to hour, day to day, and season to season. Organisms therefore require mechanisms for maintaining internal stability in spite of environmental change. American physiologist Walter Cannon (1871–1945) named this ability homeostasis ( homeo means "the same" and stasis means "standing or staying"). Homeostasis has become one of the most important concepts of physiology, physiological ecology, and medicine. Most bodily functions are aimed at maintaining homeostasis, and an inability to maintain it leads to disease and often death (Biologyreference, 2014.)
Temperature
The body’s main regulation of homeostasis is through the negative feedback system/loop. Body temperature is a physiological variable controlled by negative feedback. When body temperature falls below a stable, appropriate level specialised temperature sensitive nerve endings detect it and then send this information to groups of cells in the hypothalamus which is the control centre. The control centre then activates effectors, these raise body temperatures. For example, shivering – caused by stimulation of the skeletal muscles, narrowing of the blood flow to, and heat loss from, the peripheries and behaviour changes such as putting more/less clothes on. Once body temperature has reached the normal range again the temperature sensitive nerve endings no longer stimulate the cells of the control centre and the output from the centre ends. During homeostasis the nervous system controls and regulates other body parts. Not until body temperature drops below normal do receptors stimulate the regulating centre and effectors act to raise body temperature. Regulating centres are located in the central nervous system, consisting of the brain and the spinal cord. The hypothalamus is the part of the brain mainly involved in homeostasis - it influences the action of the medulla oblongata, a lower part of the brain, the autonomic nervous system, and the pituitary gland. Most of the homeostatic controls in the body use negative feedback systems/loops to stop any sudden and series changes in the internal environment.
During exercise the body experiences changes and responses especially in temperature, glucose control, heart rate and breathing rate.
Breathing rate and Heart Rate
Breathing rate is controlled by the autonomic nervous system, it has 2 branches: the sympathetic branch which accelerates the heart and the parasympathetic branch which slows it down. The ANS has the job to perceive the internal environment and - after processing the information in the Central Nervous System - regulating the functions of the internal environment (Breathing, 1997-2014). During exercise the sympathetic branch will be stimulated, increasing heart rate and breathing rate to also increase (breathing rate increasing during exercise is needed to allow breathing to happen properly i.e. let more oxygen in) and causing a number of physiological changes such as blood flow increases to muscles, lungs and brain but decreases to gut and kidney, sweat production increases, muscles of hairs contract, bladder and anal sphincters contract, glycogen converts into glucose in the liver and the iris in the eyes dilate. The nervous system helps keep homeostasis in breathing patterns because breathing is involuntary, the nervous system ensures that the body is getting much needed oxygen through breathing the appropriate amount of oxygen. This is done by the sympathetic response sending impulses to intercostal muscles and the diaphragm to expand and work harder. This system utilizes a negative feedback system meaning if the pH of the cerebral spinal fluid does not compare to the set level, then the receptor will send an error signal to the effectors and appropriate action may be executed. This is done by how I’ve mentioned about the negative feedback/system loops above.
Peripheral chemoreceptor’s (carotid and aortic bodies) and central chemoreceptor’s (medullar neurons) mainly function to regulate respiratory activity. This is an important system for maintaining arterial blood O2, CO2 and pH at an appropriate physiological level. For example, a fall in arterial pO2 or an increase in arterial pCO2 leads to an increase in the rate and depth of respiration through activation of the chemoreceptor reflex.
The carotid body is a small cluster of chemoreceptor’s and supporting cells located near the fork of the carotid artery which runs along both sides of the throat. The carotid body detects changes in the composition of arterial blood flowing through it, mainly the pressure of oxygen and carbon dioxide. It is, however, also sensitive to changes in pH and temperature.
Chemoreceptor activity also affects cardiovascular function either directly (by interacting with medullar vasomotor centres) or indirectly (through altered pulmonary stretch receptor activity). Respiratory arrest and circulatory shock (these conditions decrease arterial pO2 and pH, and increase arterial pCO2) dramatically increase chemoreceptor activity leading to enhanced sympathetic outflow to the heart and vasculature.
Temperature
Our core body temperature is the one concerned with operating enzymes and surface temperature can fluctuate rapidly.
We gain heat by the metabolism of food and by absorbing solar energy from objects, from the ground and connections with the ground. However we lose heat by evaporation (sweat), conduction (lost to the ground or by touching cooler objects), convection (heat lost upwards to the cooler air) and radiation (moved out from the body in all directions to the cooler air). Humans are warm blooded and derive most of their heat from metabolism, and loose heat through our respiratory surfaces, the gut and the skin. Although we can’t control if we lose heat via our respiratory surfaces or the gut, the skin is able to control its heat loss. The regulation of body temperature is the role of the hypothalamus. It sends nerve impulses to muscles, sweat glands and skin blood vessels to cause changes that counteract the external changes - the skin is the main organ of thermoregulation.
Our body also responds to temperature change (heat loss/gain). This is shown when we are cooling down as the metabolism speeds up, we shiver to produce heat and we experience vasoconstrictions which is the blood diverting through the lower skin levels to lessen the heat lost. It is also shown when we are warming up as the metabolism slows down, we sweat, we lose insulation by the relaxation of the hair erector lowering the hair meaning there is less of an insulating layer of warm air next to the skin and we experience vasodilatation which is when the blood comes to the surface and heat can be radiated
out.
Glucose Control
The control of glucose in the blood is referred to as blood sugar level. The cells use glucose for respiration, carbohydrate levels fluctuate and cells need a constant supply of glucose which is achieved by hormones interacting with glycogen stored in the liver.
Glucose is extremely important for cells as if glucose levels fall too low the cells are starved of energy and the cells of the brain are particularly vulnerable and a coma quickly results. However if the cells have too much glucose it affects the osmotic balance and water is lost from the cells. The normal glucose level in the blood is 3.5-7.5 mmol dm3 90mg glucose per 100 cm 3 blood.
Through the day our supply of carbohydrates fluctuate because we don’t keep eating but our cells need to maintain a constant supply of glucose in the blood so despite times in the day when there is a limited and intermittent supply of glucose from carbohydrates digested from the digestive system.
The pancreas secretes insulin and glucagon which are both hormones. Insulin lowers blood glucose if the level goes too high. Excess glucose is then converted to glucagon and stored in the liver. Glucagon raises blood glucose if the level goes too low. Glycogen in the liver is broken to glucose and released into the blood.
If glucose is not controlled properly then it can cause type 1 or type 2 diabetes. Type 1 occurs when the pancreas doesn’t function properly and doesn’t produce enough insulin to control blood glucose. People with this type of diabetes need to have regular injections of insulin. Type 2 occurs when insulin is produced by the pancreas but the receptors in the cells don’t recognise it as being there, people have to control the amount of sugar they eat in their diet as injections wouldn’t work. (NHS, 2012)
References
Boundless, 2013 - https://www.boundless.com/biology/the-animal-body-basic-form-and-function/homeostasis/homeostatic-process/
Biologyreference, 2014 - http://www.biologyreference.com/Ho-La/Homeostasis.html#b#ixzz2qTgZB3m#b
Breathing, 1997-2014 - http://www.breathing.com/articles/autonomic-nervous-system.htm
NHS, 2013 - http://www.nhs.uk/conditions/diabetes/pages/diabetes.aspx
P5/M2 - Homeostasis
Homeostasis is the need for an organism or a cell to regulate its internal environment (conditions within the fluid surrounding its body cells) by a system of feedback controls to stabilise health and functioning despite the outside changing conditions. This is important as this is what maintains and helps internal conditions (body temperature) to remain stable and constant.
In humans homeostasis happens when the body regulates its body temperature in an effort to maintain an internal temperature at around 37®C. For example, during the summer when the weather is very hot (outside condition) we sweat to cool ourselves down and in the winter when the weather is very cold (outside condition) we shiver …show more content…
to help our bodies to produce heat to keep ourselves warm.
Key facts
Homeostasis is the body 's attempt to maintain a constant and balanced internal environment, which requires persistent monitoring and adjustments as conditions change.
Homeostatic regulation is monitored and adjusted by the receptor, the command centre, and the effector.
The receptor receives information based on the internal environment; the command centre, receives and processes the information; and the effector responds to the command centre, opposing or enhancing the stimulus.
(Boundless, 2013)
Living cells can function only within a narrow range of such conditions as temperature, pH , ion concentrations, and nutrient availability, yet living organisms must survive in an environment where these and other conditions vary from hour to hour, day to day, and season to season. Organisms therefore require mechanisms for maintaining internal stability in spite of environmental change. American physiologist Walter Cannon (1871–1945) named this ability homeostasis ( homeo means "the same" and stasis means "standing or staying"). Homeostasis has become one of the most important concepts of physiology, physiological ecology, and medicine. Most bodily functions are aimed at maintaining homeostasis, and an inability to maintain it leads to disease and often death (Biologyreference, 2014.)
Temperature
The body’s main regulation of homeostasis is through the negative feedback system/loop. Body temperature is a physiological variable controlled by negative feedback. When body temperature falls below a stable, appropriate level specialised temperature sensitive nerve endings detect it and then send this information to groups of cells in the hypothalamus which is the control centre. The control centre then activates effectors, these raise body temperatures. For example, shivering – caused by stimulation of the skeletal muscles, narrowing of the blood flow to, and heat loss from, the peripheries and behaviour changes such as putting more/less clothes on. Once body temperature has reached the normal range again the temperature sensitive nerve endings no longer stimulate the cells of the control centre and the output from the centre ends. During homeostasis the nervous system controls and regulates other body parts. Not until body temperature drops below normal do receptors stimulate the regulating centre and effectors act to raise body temperature. Regulating centres are located in the central nervous system, consisting of the brain and the spinal cord. The hypothalamus is the part of the brain mainly involved in homeostasis - it influences the action of the medulla oblongata, a lower part of the brain, the autonomic nervous system, and the pituitary gland. Most of the homeostatic controls in the body use negative feedback systems/loops to stop any sudden and series changes in the internal environment.
During exercise the body experiences changes and responses especially in temperature, glucose control, heart rate and breathing rate.
Breathing rate and Heart Rate
Breathing rate is controlled by the autonomic nervous system, it has 2 branches: the sympathetic branch which accelerates the heart and the parasympathetic branch which slows it down. The ANS has the job to perceive the internal environment and - after processing the information in the Central Nervous System - regulating the functions of the internal environment (Breathing, 1997-2014). During exercise the sympathetic branch will be stimulated, increasing heart rate and breathing rate to also increase (breathing rate increasing during exercise is needed to allow breathing to happen properly i.e. let more oxygen in) and causing a number of physiological changes such as blood flow increases to muscles, lungs and brain but decreases to gut and kidney, sweat production increases, muscles of hairs contract, bladder and anal sphincters contract, glycogen converts into glucose in the liver and the iris in the eyes dilate. The nervous system helps keep homeostasis in breathing patterns because breathing is involuntary, the nervous system ensures that the body is getting much needed oxygen through breathing the appropriate amount of oxygen. This is done by the sympathetic response sending impulses to intercostal muscles and the diaphragm to expand and work harder. This system utilizes a negative feedback system meaning if the pH of the cerebral spinal fluid does not compare to the set level, then the receptor will send an error signal to the effectors and appropriate action may be executed. This is done by how I’ve mentioned about the negative feedback/system loops above.
Peripheral chemoreceptor’s (carotid and aortic bodies) and central chemoreceptor’s (medullar neurons) mainly function to regulate respiratory activity. This is an important system for maintaining arterial blood O2, CO2 and pH at an appropriate physiological level. For example, a fall in arterial pO2 or an increase in arterial pCO2 leads to an increase in the rate and depth of respiration through activation of the chemoreceptor reflex.
The carotid body is a small cluster of chemoreceptor’s and supporting cells located near the fork of the carotid artery which runs along both sides of the throat. The carotid body detects changes in the composition of arterial blood flowing through it, mainly the pressure of oxygen and carbon dioxide. It is, however, also sensitive to changes in pH and temperature.
Chemoreceptor activity also affects cardiovascular function either directly (by interacting with medullar vasomotor centres) or indirectly (through altered pulmonary stretch receptor activity). Respiratory arrest and circulatory shock (these conditions decrease arterial pO2 and pH, and increase arterial pCO2) dramatically increase chemoreceptor activity leading to enhanced sympathetic outflow to the heart and vasculature.
Temperature
Our core body temperature is the one concerned with operating enzymes and surface temperature can fluctuate rapidly.
We gain heat by the metabolism of food and by absorbing solar energy from objects, from the ground and connections with the ground. However we lose heat by evaporation (sweat), conduction (lost to the ground or by touching cooler objects), convection (heat lost upwards to the cooler air) and radiation (moved out from the body in all directions to the cooler air). Humans are warm blooded and derive most of their heat from metabolism, and loose heat through our respiratory surfaces, the gut and the skin. Although we can’t control if we lose heat via our respiratory surfaces or the gut, the skin is able to control its heat loss. The regulation of body temperature is the role of the hypothalamus. It sends nerve impulses to muscles, sweat glands and skin blood vessels to cause changes that counteract the external changes - the skin is the main organ of thermoregulation.
Our body also responds to temperature change (heat loss/gain). This is shown when we are cooling down as the metabolism speeds up, we shiver to produce heat and we experience vasoconstrictions which is the blood diverting through the lower skin levels to lessen the heat lost. It is also shown when we are warming up as the metabolism slows down, we sweat, we lose insulation by the relaxation of the hair erector lowering the hair meaning there is less of an insulating layer of warm air next to the skin and we experience vasodilatation which is when the blood comes to the surface and heat can be radiated
out.
Glucose Control
The control of glucose in the blood is referred to as blood sugar level. The cells use glucose for respiration, carbohydrate levels fluctuate and cells need a constant supply of glucose which is achieved by hormones interacting with glycogen stored in the liver.
Glucose is extremely important for cells as if glucose levels fall too low the cells are starved of energy and the cells of the brain are particularly vulnerable and a coma quickly results. However if the cells have too much glucose it affects the osmotic balance and water is lost from the cells. The normal glucose level in the blood is 3.5-7.5 mmol dm3 90mg glucose per 100 cm 3 blood.
Through the day our supply of carbohydrates fluctuate because we don’t keep eating but our cells need to maintain a constant supply of glucose in the blood so despite times in the day when there is a limited and intermittent supply of glucose from carbohydrates digested from the digestive system.
The pancreas secretes insulin and glucagon which are both hormones. Insulin lowers blood glucose if the level goes too high. Excess glucose is then converted to glucagon and stored in the liver. Glucagon raises blood glucose if the level goes too low. Glycogen in the liver is broken to glucose and released into the blood.
If glucose is not controlled properly then it can cause type 1 or type 2 diabetes. Type 1 occurs when the pancreas doesn’t function properly and doesn’t produce enough insulin to control blood glucose. People with this type of diabetes need to have regular injections of insulin. Type 2 occurs when insulin is produced by the pancreas but the receptors in the cells don’t recognise it as being there, people have to control the amount of sugar they eat in their diet as injections wouldn’t work. (NHS, 2012)
References
Boundless, 2013 - https://www.boundless.com/biology/the-animal-body-basic-form-and-function/homeostasis/homeostatic-process/
Biologyreference, 2014 - http://www.biologyreference.com/Ho-La/Homeostasis.html#b#ixzz2qTgZB3m#b
Breathing, 1997-2014 - http://www.breathing.com/articles/autonomic-nervous-system.htm
NHS, 2013 - http://www.nhs.uk/conditions/diabetes/pages/diabetes.aspx