2.85

2.85 describe the structure and functioning of a simple reflex arc illustrated by the withdrawalof a finger from a hot object

Only the spinal chord is used to product a reflex. This is so that time is reduced for the response and the persons finger won't be damaged as much.

Reflexes are always the same.
Reflexes can't be controlled but responses can.

The receptors are stimulated by the heat, electrical impulses sent to the spinal chord, The relay nerve directly connects the impulses to the motor nerve which creates the response to withdraw the hand.

2.84

2.84 understand that stimulation of receptors in the sense organs sends electrical impulses along nerves into and out of the central nervous system, resulting in rapid responses

- The receptors in the sense organs, when stimulated create electric impulses along the nerves.

- This moves into the nervous system and out to create a rapid response.
 e.g. Light enters the eyes, this creates an electrical impulse along the nerves. They move in and out of the nervous system, to the effector and create a response such as blinking.

2.83

2.83 recall that the central nervous system consists of the brain and spinal cord and is linked to sense organs by nerves


- The Central Nervous system consists of two parts; the brain, and the spinal cord.

- Receptors send electrical signals to the effectors using these nerves.

2.82

2.82 describe how responses can be controlled by nervous or by hormonal communication and understand the differences between the two systems

Differences:

-Hormones act much slower and have a longer effect
-Hormones are transported via the blood stream and bind to receptors on the outside of cells
-Hormone molecules can cause chain reactions
-Nerves communicate through electrical impulses
-They both use they same transmitters, but use them in different way.

2.77b Thermoregulation

- The Negative feedback loop is a method of control and retaining constant conditions.

- The average body temperature of a human is 37/38 degrees centigrade. 

- The hypothalamus responds to a stimulus which is the temperature of the body or blood. 

- Body temperature feeds into the brain and is compared to the theoretical level of control.

- If the body temperature needs to be increased of decreased then it is brought about through the action of the effector such as the skin.

2.77a Thermoregulation

- Homeothermic: Same Temperature.

- Homeostasis: Conditions are kept the same or are constant.

- If the environmental temperature increases or decreases a mouse's body temperature remains constant.

- Homeothermic carries out a process called Thermoregulation.

- Mammals remain the same body temperature.

2.76 Sensitivity

- Sensitivity is the characteristic of the organisms respond to changes in their environment.


- These changes in the environment include: Temperature, Light, Pressure and Chemical.

- Organisms are required to have receptors and effectors such as muscles and glands.

- Response is used to survive the changes in the environment.