homeostasis

What is the name given to the organs that secrete hormones

Endocrine system

What is meant by a target organ

How do hormones travel around the body

Blood plasma

Which 2 hormones are induced in regulating blood glucose levels ?

Glucagon, insulin

Which organs secrete …

Pancreas

What are the target organs of …

Liver

What is the name of the storage molecule that glucose is converted into

Glycogen

Define homeostasis

The maintenance of a constant internal environment

Define negative feedback

When the feedback causes the the corrective measures to be turned off, so returns to the normal level

What is a gland

Group of cells that are specialised to secrete a useful substance such as a hormone

What do homeostatic systems involve ?

Controls systems that keep the internal environment within narrow limits, keeping the environment in a state of dynamic equilibrium

What is a hormone ?

Chemical messengers that travel in the bloodstream

Why do body temperature and blood pH need to be controlled ?

To maintain optimum enzyme activity and to prevent enzymes denaturing.

Describe how an enzyme can become denatured at high temperatures

Heat energy increases the kinetic energy of the molecule, making the molecule vibrate more. The vibrations are strong enough to break the hydrogen and ionic bonds, holding the tertiary structure in place. This changes the shape of the active site.

How can the pH affect the rate of an enzyme- controlled reaction ?

Extreme changes in ph [lots of OH- and H+ groups] can disrupt the ionic bonds between the R- groups - this results in ionic bonds holding the tertiary structure in peace to break. This changes the shape of the ative site. This reduces the number of ES complexes formed as the substrate no longer fits in the active site this reducing rate of reaction.

What does the hypothalamus do in homeostasis?

It maintans body temperature at a constara level. it receives impuises from thermorecestors and then sends irapulses along motor neurons to the effectors.

What is vasodilation?

What is vasoconstriction

Give a physiological response to an increase in body temp

Give a physiological response to a decrease in body temperature

Give a behavioural response to a decrease in body temperature

Give a behavioural response to an increase in body temp

Why does blood glucose concentration need to be controlled

To maintain water potential of blood

What is positive feedback ?

A response that increases the stimulus, taking conditions further away from the optimum.

Why are positive feedback mechanism not a part of homeostasis ?

Positive feedback mechanisms take conditions further mechanisms not part of the optimum as negative feedback does. Negative feedback loops are a continuous cycle postive feedback is not.

Give an example of a positive feedback mechanism

The hormone oxytocin is released stimalating the feedback mechanism. contraction of the uterus during childbirth or blood clotting

How are hormones secreted ?

When a gland is stimulated. Glands can be stimulated by a specific substance or by electrical impulses.