4.5 Homeostatis And Response Flashcards
(114 cards)
What is homeostasis?
Homeostasis is the regulation of the internal conditions of a cell or organism to maintain optimum conditions for function in response to internal and external changes
What for homeostasis do?
Maintains optimum conditions for enzyme action and all cell functions
What is controlled by homeostasis in the human body?
Blood glucose concentration
Body temperature
Water levels
What could automatic systems involve?
Nervous responses
Chemical responses
What do all control systems include?
Stimulus Cells called receptors Coordination centres Effectors Response
Why must the water content of the body be controlled?
High water concentration in the body leads to high blood pressure
We need water for transport between cells and within cells
Too little water means solutions will be too concentrated
How is the water content of the body controlled?
Kidneys filter excess water, and you store in the bladder and then you excrete it, through urine
Why must the ion content of the body be controlled?
Ions such as Na+, K+ and Cl- are in the blood
Too many ions make high blood pressure due to water in the blood through osmosis
How is the ion content of the body controlled?
Kidneys filter excess ions through urine
Why must the temperature of the body be controlled?
Enzymes in the human body only work well when at optimum temperature, 37 degrees
How is temperature controlled?
If you are too cold you shiver and also vasoconstriction occurs which keeps blood in core so you go pale
If you are too hot vasodilation occurs which lets blood into skin layers and you go red also you sweat
Why must blood sugar levels be controlled?
Affects osmotic relations of cells
When there is too little sugar, more water will enter cells via osmosis
When there is too much sugar more water will leave cells via osmosis
How are blood sugar levels controlled?
Insulin
Why must carbon dioxide concentration of the blood?
When CO2 is added to water it makes weak carbonic acid
pH will drop and enzymes work best at optimum pH
How is carbon dioxide concentration of the blood controlled?
Increase breathing rate and depth to get all the co2 out of the lungs.
What does the nervous system allow humans to do
React to their surroundings and to coordinate their behaviour
What wakes up the CNS
The brain
Spinal chord
What does the CNS do?
Coordinates the response of effectors which may be muscles contracting or glands secreting hormones
Complete this flow chart
Stimulus —>______—>_______—> ______ —> _____—>response
Stimulus Receptor Coordination centre Effector Response
What happens to the effector in the case of negative feedback?
In negative feedback the effector opposes the change and pushes the variable back to set point value
What does the peripheral nervous include?
All other nerves that radiate from the brain and spinal chord.
What are nerve fibres?
A bundle of nerve cells called neurones
How are nerve cells adapted?
Axon is long, allows electrical impulses to pass through the body
Dendrites allow them to connect with other nerve cells
Myelin sheath insulates cells. It’s made of fatty material so is a good insulator
What is a reflex action?
Quick automatic responses to stimuli, often designed to protect the body from harm