Biology Flashcards
What is homeostasis?
Your body’s ability to regulate and maintain a stable condition inside your body, regardless of changes to the external environment.
What are some conditions in the body that need to be kept constant?
Blood glucose, temperature, systolic blood pressure, blood ph, oxygen levels, carbon dioxide levels, the amount of water inside your body
How does the body maintain homeostasis?
The stimulus response model…
- First there are receptors that detect change
- Then there is a processing centre to receive the information and coordinate the response
- Finally we need effectors to produce a response
Explain the role of the stimulus response model
- Stimulus: change in temp, light, loud noise
- Receptor or sense organs: detect signal or change
- CNS: interprets signal
- Effector organs: such as muscles glands
- Response: contrast muscle, release hormones
What is a negative feedback loop?
A negative feedback loop is a reaction that causes a decrease in function.
Eg
Glucagon Cycle
Blood glucose falls below normal– a change in the system.
Pancreas releases glucagon – another change, caused by the first one.
Target cells release glucose into the blood
Blood glucose rises back to normal– the second change brings the system back to its starting position.
Explain how blood glucose levels are regulated
Low Blood Sugar
Blood glucose falls below normal– a change in the system.
Pancreas releases glucagon – another change, caused by the first one.
Target cells release glucose into the blood
Blood glucose rises back to normal– the second change brings the system back to its starting position.
High Blood Sugar
Blood glucose rises above normal- a change in the system
Pancreas releases insulin- another change, caused by the first one
Target cells release insulin into the blood
Blood glucose drops back to normal- the second change brings the system back to its starting position.
What happens in diabetes?
- Stomach converts food to glucose
- Glucose enters bloodstream
- Pancreas produces insulin, but it is resist to effective use
- Glucose unable to enter body effectively
- Glucose levels increase
What is a positive feedback loop?
A positive feedback loop is a reaction that causes an increase in function.
Blood glucose rises above normal- a change in the system
Pancreas releases insulin- another change, caused by the first one
Target cells release insulin into the blood
Blood glucose drops back to normal- the second change brings the system back to its starting position.
What is the role of the endocrine system?
The endocrine system regulates, coordinates and controls growth, water balance, reproduction, metabolism, calcium and glucose levels, response to stress.
Name 3 areas that the endocrine system regulates
Thyroid, pancreas, adrenals
What is an endocrine gland? What does it secrete?
An endocrine gland is a gland that secretes hormones into the bloodstream for transport around the body
What is a hormone? How does it travel around the body?
Chemical messengers that are secreted from glands from glands into the bloodstream and affect cells in another part of the body.
How do hormones know which cells are their target cells?
The target cells have special receptors that recognise the hormones and allow them to influence the cell.
What is a target cell/organ? How does it respond to hormones?
A tissue or organ upon which a hormone exerts its action; generally, a tissue or organ with appropriate receptors for a hormone.
What controls the release of hormones? Give examples of different stimuli.
External stimuli: via nerves from the sensory organs in the nervous system.
e.g loud noise, a large dog runs at you and growls at you
Internal stimuli: via nerves and other hormones from inside the body
e.g you are sick and develop a fever, you have not eaten in 6 hours
