Homeostasis Flashcards
(20 cards)
Homeostasis
the ability of an organism to seek or maintain a stable environment, regardless of external changes
What is controlled by Homeostasis
Water, pH, glucose and temperature
What do control systems do?
Adjust to external and internal changes
Control Systems
- Stimuli receptors: gather information about the body and environment, there are two main receptors.
- Communication Systems: messages are sent throughout the body to respond.
- Control Centre: Receives information from the sensors.
4) Effectors: Body part that changes its activity.
Exteroreceptors
receives signals from the external environment
Interoreceptors
receives signals from within the body’s internal environment
The Principle of Feedback
feedback systems are the mechanisms that maintain homeostasis by returning an environment back its optimum or tolerance range
Stimulus Response Model
Stimulus : changes to the environment
Receptor : detects stimuli
Control Centre : processes information from the receptor and sends that message to the effector.
Effector : carries out the messages from control centre to stimulus
Response : returns organism to tolerance range.
Negative Feedback Loop
A process where your body reverses a change that is occuring
What does the Negative Feedback Loop do
- Regulates most of the body
- Works to switch off or change the stimuli
- Restores internal environment to a constant set of conditions
Thermoregulation
When there is a balance between heat loss and heat gain, the organism is said to be in heat balance, which is the purpose of thermoregulation
Positive Feedback Loops
A process where your body promotes and encourages change.
- Important when rapid change is needed
- Works to reinforce or increase stimuli
Normal Insulin Produciton
Cells need glucose, after meals glucose levels in blood will increase. But the channels that allow glucose into your cells are closed. Beta cells in your pancreas will respond by releasing insulin into your bloodstream, insulin causes the channels to open. Glucose is diffused into the cells, giving them nutrition. Blood glucose levels will remain back to normal.
When Blood Glucose levels are high
Insulin is released from the beta cells of the pancreas, insulin causes the channels to open allowing glucose to diffuse into the cells.
When Blood Glucose levels are low
The liver receives glucagon from the alpha cells of the pancreas, liver cells released stored glucose.
Malfunction of Glucose Regulation: Diabetes
After meals, glucose levels in the blood will increase. But the channels that allow glucose into the cells are closed. A damaged pancreas will often release too little insulin which causes only a few channels to open meaning that only little glucose is diffused into the cells.
The glucose levels in the blood never return to normal and glucose will remain in the bloodstream and not be taken up by cells. During your next meal, it adds even more glucose. Weirdly, cells will begin to starve even though glucose is there.
Hyperglycemia
When blood glucose levels remain above the normal range.
Hypoglycemia
when blood glucose levels are too low, below the normal range.
Stimulus Response for increase in Blood Glucose
Stimulus: increase in blood glucose levels
Receptor: detected by chemoreceptors in the beta cells of the pancreas.
Control Centre: Beta cells of the pancreas will release the hormone insulin
Effector: Skeletal muscle, adipose tissue, liver
Response: Glucose uptake by muscle and adipose tissue, glucose is converted into glycogen in a process called glycogenesis. This leads to a decrease in blood glucose.
Stimulus Response for decrease in Blood Glucose
Stimulus: Decrease in Blood glucose levels.
Receptor: detected by chemoreceptors in the alpha cells of the pancreas.
Control Centre: alpha cells of the pancreas will release the hormone glucagon
Effector: Liver cells, and body cells
Response: glycogen stored in the liver breaksdown to glucose in a process called glycogenolysis. Reduced use of glucose in most body cells. Leading to an increase of blood glucose levels.
