Homeostasis Flashcards
What are the roles of the endocrine and nervous systems in maintaining homeostasis?
Endocrine and nervous systems regulate physiological variables to maintain homeostasis
The endocrine system uses hormones, while the nervous system uses electrical signals.
Give an example of a disease caused by a disruption of homeostasis.
Diabetes mellitus
This condition is characterized by persistent high blood glucose levels.
Describe the homeostasis of blood glucose.
Blood glucose levels are regulated by insulin and glucagon to remain within a normal range (3.9 – 7.1 mMol/L)
Insulin lowers blood glucose, while glucagon raises it.
What are the components of a homeostatic control system?
Components include:
* Sensor
* Control Centre
* Effectors
* Set Point
These work together to maintain physiological variables.
True or False: All negative feedback systems are homeostatic.
False
Negative feedback alone does not ensure homeostatic function.
What is the function of insulin?
Stimulates uptake of glucose and storage as glycogen
Insulin is produced by beta cells in the pancreas.
Fill in the blank: Glucagon is produced by ______ cells in the pancreas.
alpha
Glucagon is released in response to low blood glucose levels.
What happens during hyperglycemia?
Glucose is taken up by liver and muscle cells and stored as glycogen
This occurs when blood glucose levels are high.
What is diabetes mellitus characterized by?
Persistent high blood glucose concentration (11-28 mMol/L)
It results from either lack of insulin or insulin resistance.
What are the long-term problems associated with diabetes mellitus?
Complications include:
* Dehydration
* Cardiovascular disease
* Kidney failure
* Glaucoma
* Retinal damage
* Peripheral nerve damage
These can lead to serious health issues.
What are the causes of obesity?
Multi-factorial causes include:
* Lifestyle
* Societal factors
* Genetic predisposition
* Environmental influences
* Physiological factors
Obesity is linked to excessive body weight and health risks.
What is the treatment for obesity?
Calorie-controlled diet and regular exercise
There is no evidence of a long-lasting ‘cure’ for obesity.
What is the classical approach to scientific understanding of disease?
Involves understanding normal physiological control systems and how they are disturbed in disease
Aims to develop therapies for recovery of normal homeostasis.
What is the normal range for blood glucose levels?
About 3.9 – 7.1 mMol/L
This range is crucial for metabolic functions.
What hormones are involved in blood glucose homeostasis?
Insulin and glucagon
These hormones work antagonistically to regulate blood sugar levels.
What role do glucose transporters play?
Carry glucose from extracellular fluid into the cell
They are stimulated by insulin.
What is the effect of glucagon on the liver?
Stimulates the liver to break down glycogen and release glucose into the bloodstream
This occurs during low blood glucose levels.
What is the primary energy substrate for cells?
Glucose
It is essential for ATP production in the Kreb’s cycle.
What is the definition of homeostasis?
- Maintenance of a relatively constant, stable internal environment
- Self regulatory process by which biological systems maintain stability while adjusting to environmental changes
What type of process is homeostasis?
Dynamic
What does homeostasis do to physiological variables?
Regulates them to remain relatively constant of time to prevent a potentially lethal change?
Examples of physiological variables regulated homeostatically?
Body temp
Body weight
Blood glucose levels
Blood gases
Levels of certain ions e.g. calcium, sodium, iron, K
Blood pressure
Blood Ph
What can the disruption of body temp cause?
Hypothermia
What can the disruption of body weight cause?
Obesity, anorexia
What can the disruption of blood glucose cause?
Diabetes
What can the disruption of blood gases cause?
Hypoxia
What can the disruption of blood pressure cause?
Hypertension
What can the disruption of Blood Ph cause?
Acidemia
What are environmental changes?
Anything that would lead to a change in internal conditions eg extreme low temps, low oxygen levels
What does the homeostatic regulatory system consist of?
1- sensor
2-set point
3- control centre
4- effector
5- response
What does the sensor do?
Measure the value of a physiological variable
What is the set point?
The normal range of values for physiological values
What does the control centre do?
Compares the measured value of the variable to the set point
What does the effector do?
Chnage the variable
What is the response?
Response of effectors to change the variable
Is the set point fixed?
No - set points can change. They can be reset either physiologically or as a result of a pathological change in the system
Is the change in the physiological variable a response of the effector?
No - the change in the physiological variable is a consequence of the effectors response
