thermoregulation in humans
AS91604: Demonstrate Understanding of How an Animal
Maintains a Stable Internal Environment.
This assessment will be looking at how the humans body keeps remains at equilibrium despite normal but inconsistent environment in terms or physical exertion, being in an extreme environment, diet or even pregnancy. It is an open book assessment so it is very important that you understand this topic very well.
After you have gathered information and processed it YOU will do well to prove to yourself that you have SOUND UNDERSTANDING if you can explain it to another person without flicking through your referencing notes. (or just use them for support)
The following sentences must be understood before you walk into your test (:
BASIC PRINCIPLES OF HOMEOSTASIS
HOMEOSTASIS = maintenance of constancy of the INTERNAL ENVIRONMENT
Homeostasis is the physiological consistency of the body despite external fluctuations. All complex multicellular organisms maintain a stable internal environment using their organ systems. As you can see in the picture (click on it to see a bigger version) there are a lot of systems working together. Don't stress though as you assessment will only be looking at one of these.
In the case of glucose regulation an increase in the amount of glucose triggers a process to decrease it. Conversely, a decrease in the glucose level triggers a process to increase it. In both cases the result is a reasonably constant level of glucose. When a change in an entity brings about the OPPOSITE EFFECT this is known as a NEGATIVE FEEDBACK mechanism.
After you have gathered information and processed it YOU will do well to prove to yourself that you have SOUND UNDERSTANDING if you can explain it to another person without flicking through your referencing notes. (or just use them for support)
The following sentences must be understood before you walk into your test (:
- Explain in detail (organs, tissue, cells, hormones) of the homeostatic system that acts as the control system to keep glucose at the human body at 'set point'. Explain how and why the body system responds to the normal range of glucose fluctuations, (because glucose fluctuates in and around meals, exercise, and fasting within any given day) and the interactions between the parts of the system and how the interaction of the feedback mechanisms work? (I suggest you construct an annotated diagram that illustrates the system and use details worthy of a Year 13 please!!)
- What are the adaptive advantages of this homeostatic mechanisms for Humans.
- Explain how the pregnancy (disruption) interacts with the homeostatic mechanism of a pregnant human body. How is each component in the system working together to re-establish glucose balance with a baby on board. (I suggest another annotated diagrams and use details worthy of a Year 13 please!!)
- What are the adaptive advantage of this homeostatic mechanisms for reproductive Humans.
- Discuss how the demands of pregnancy can result in gestational diabetes for some people. Discuss how this causes a breakdown in the homeostatic system (organs, tissue, cells, hormones) which results in a condition called gestational diabetes. YUP (Use some great annotated diagrams and use details worthy of a Year 13 please!!)
- What are the implications of this compromised system on the mother and baby?
- Explain how gestational diabetes is treated (a treatment plan for these women) so that homeostasis is managed during or after the pregnancy.
BASIC PRINCIPLES OF HOMEOSTASIS
HOMEOSTASIS = maintenance of constancy of the INTERNAL ENVIRONMENT
Homeostasis is the physiological consistency of the body despite external fluctuations. All complex multicellular organisms maintain a stable internal environment using their organ systems. As you can see in the picture (click on it to see a bigger version) there are a lot of systems working together. Don't stress though as you assessment will only be looking at one of these.
In the case of glucose regulation an increase in the amount of glucose triggers a process to decrease it. Conversely, a decrease in the glucose level triggers a process to increase it. In both cases the result is a reasonably constant level of glucose. When a change in an entity brings about the OPPOSITE EFFECT this is known as a NEGATIVE FEEDBACK mechanism.
useful links
peter_shepherd-_homeostasis_slides_for_mwc_teacher_outreach_day_2012-1.pdf | |
File Size: | 5655 kb |
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tom_mulvey-_1_blood_pressure_homeostasis.pptx | |
File Size: | 3300 kb |
File Type: | pptx |
thermoregulation.pdf | |
File Size: | 3219 kb |
File Type: |
Glucose Homeostasis
One simple example of hormonal homeostatic control is the control of blood sugar level by insulin and glucagon produced by endocrine cells in the pancreas.
Insulin stimulaes uptake of glucose from the blood by tissues for use or storage. This lowers blood glucose concentration.
Glucagon stimulates the release of glucose from glycogen stored in the liver. This raises blood glucose concentration.
Why regulate it?
•Some tissues can use a range of energy sources such as fats and even amino acids but several important tissues in the body can only really use glucose so these tissues have a need for a constant supply of glucose to function properly.
•These tissues includes red blood cells and immune cells
•Brain and the nervous system also rely on glucose which explains why when blood glucose levels fall below about 2.5 mM
that people get seizures and can go into a coma as the brain doesn’t function properly.
•Therefore maintaining a certain level of glucose is a matter of life and death.
Control of Blood Glucose ConcentrationThe Factors which Influence Blood Glucose Concentration
High Blood Glucose Concentration
Insulin stimulaes uptake of glucose from the blood by tissues for use or storage. This lowers blood glucose concentration.
Glucagon stimulates the release of glucose from glycogen stored in the liver. This raises blood glucose concentration.
Why regulate it?
•Some tissues can use a range of energy sources such as fats and even amino acids but several important tissues in the body can only really use glucose so these tissues have a need for a constant supply of glucose to function properly.
•These tissues includes red blood cells and immune cells
•Brain and the nervous system also rely on glucose which explains why when blood glucose levels fall below about 2.5 mM
that people get seizures and can go into a coma as the brain doesn’t function properly.
•Therefore maintaining a certain level of glucose is a matter of life and death.
Control of Blood Glucose ConcentrationThe Factors which Influence Blood Glucose Concentration
- Digestion of carbohydrates in diet
- Digestion → polysaccharide → glucose
- Fluctuation of glucose blood level depend on amount + type of carbohydrate eaten
- Breakdown of glycogen
- Excess glucose → glycogen → glucose
- Storage polysaccharide made from excess glucose by glycogenesis
- Glycogen is abundant in liver + muscles
- Conversion of non-carbohydrates to glucose by gluconeogenesis
- Oxidation of glucose by respiration
- Glucose → ATP → energy
- Rate of respiration varies for different activities
- This affects glucose uptake from blood into cells
- Brain is unable to store carbohydrates
- Lack of glucose in blood → no respiratory substrate → insufficient energy for brain
- Short period of time already causes brain to malfunction
- Normal glucose level in blood ≈90mg per 100cm²
- After a meal it rarely exceeds 150mg per 100cm²
- The Pancreas
- Endocrine role is to produce hormones
- Contains islets of Langerhans → sensitive to blood glucose conc
- Islet cells contain
- α-cells → secrete glucagon and β-cells → secrete insulin
- capillaries into which hormones are secreted
- delta cells → produce hormone somatostatin → inhibits secretion of glucagon
- Insulin mainly affects muscles, liver, adipose tissue
- Exocrine role is to produce digestive enzymes
- Active trypsin damages pancreas / digests proteins that make up pancreas / amylase leaks into blood from damaged tissues / amylase conc in blood higher
High Blood Glucose Concentration
- Detected by β-cells in islet of Langerhans (receptor) → secrete insulin
- Increase in insulin secretion (corrective mechanism → effectors bring about a return to norm)
- Speeds up rate of glucose uptake by cells from blood
- Glucose enters cells by facilitated diffusion via glucose carrier proteins
- Cells have vesicles with extra carrier molecules present in their cytoplasm
- Insulin binds to receptor in plasma membrane
- Chemical signal → vesicles move towards plasma membrane
- Vesicle fuses with membrane → increases glucose carrier proteins
- Activates enzymes / Converts glucose to glycogen / Promotes fat synthesis
- Speeds up rate of glucose uptake by cells from blood
- Low Blood Glucose Concentration
- Detected by α-cells in islets of Langerhans → secrete glucagon
- Increase in glucagon secretion
- Hormone activates enzymes in the liver → convert glycogen to glucose
- Stimulates formation of glucose form other substances such as amino acids
- Glucose passes out of cells into blood, raising blood glucose conc until norm is reached
- Diabetes and its Control with Insulin and Manipulation of Carbohydrate Intake
- Diabetes mellitus → inability of control of blood glucose level
- High levels of blood glucose because
- Pancreas becomes diseased → fails to secrete insulin
- Target cells lose responsiveness to insulin
- Kidney is unable to reabsorb back into blood all the glucose filtered into its tubules
- Glucose secreted into urine
- Craving for sweet food and persistent thirst
- DIAGNOSTIC: glucose tolerance test
- Patient swallows glucose solution
- Blood glucose level measured at regular intervals
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