Obj 2.85

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

Stimulus: Hot flame

Receptor: Heat sensor in the skin
- The impulse travels to the spinal cord along the sensory neurone.
- In the spinal cord the impulse is passes on to the relay neurone.
- This passes the impulse on to the MOTOR NEURONE.

Effector: Arm muscles
The motor neuron carries the impulse to the muscle in the arm

Response: Muscles contract to remove the hand from the hot object.

Click4Biology p123 (image won't upload)

Extra notes from class:
After Sensory Neurone instead of taking the CNS it takes the short cut to the Relay Neurone and then passes the impulse down the motor Neurone to respond. Short cut to make the reaction faster. Called a Reflex

Obj 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

Your nervous system sends electrical messages along nerves to and from different parts of your body and they tell your body what to do.

Sense organs are our RECEPTORS (detect the change). They send messages to the central nervous system telling it what has happened. These messages are sent along sensory neurons.

Nerve cells are different from other cells. They do have a cell membrane; cytoplasm and nucleus by they are a different shape. Part of the cell is stretched out to form the AXON. The axon can be over a metre long.

The messages that nerves carry are called NERVE IMPLUSES.
They are electrical signals
They pass very quickly along the axon of the neuron.

Each impulse in separate from the next and they travel along one after another.

Some axons have a fatty sheath around them, which insulated the axon and make the impulse travel along faster.

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 main parts of the nervous system are the BRAIN and the SPINAL CORD. Together they are called the CENTRAL NERVOUS SYSTEM. They are both made of delicate NERVOUS TISSUE. The brain is protected inside the SKULL. The Spinal Cord is protected inside you BACKBONE.

The central nervous system is connected to difference parts of the body by nerves. Each nerve is made up of lots of nerve cells or neurons.

obj 2.82

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

The nervous system controls your actions. It coordinates different parts of you body so that they work together and are able to bring about the correct responses. It coordinates you muscles, similarly it also works things we don’t notice happening such as swallowing, blinking and breathing.

The hormonal system also coordinates the body. Hormones are chemicals produced by glands, which are carried around the body in the blood. They tell different parts of the body what to do.

The differences -
Nervous system:
- Information passes as electrical impulses alone neurons
- Effects are rapid and short-lived
- Affects particular organs
- Often involves reflexes

Hormonal System:
- Information passes as chemical messengers in the blood
- Effects are usually slow and longer lasting
- Affects the whole of the body
- Controls growth, development, metabolism and reproduction

2.77b - Thermoregulation

2.77b
Negative feedback loop – method of control and maintaining constant conditions (i.e humans = body temp 37/38 degrees)
Receptor – Hypothalamus (region of brain), responds to stimulus of temp of body (blood).
If body temp needs to be altered, this is done through the job of the Effector (i.e the skin – sweating)
The response is the increase of decrease of temp.

obj 2.77a Thermoregulation

2.77a
homeo – ‘same’
Stasis – ‘fixedpoint/conditions’
Homeostasis – The conditions kept the same/constant
Thermic –temperature (Homeothermic- same temp)
Organisms (i.e Mammals) , when the environment temp changes (increases or decreases) then their body tem stays constant. These are HOMEOTHERMIC ORGANISMS. They carry out a process called Thermoregulation
Other organisms have body temp that varies with the environment.

2.9
- The max rate of reacted is achieved at the optimum temperature for that enzyme
The opt temp for the enzyme is approximately the same as the temp at which the mammals maintain their body conditions

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Obj 2.76 Sensitivity

obj 2.76
Sensitivity – The characteristic in which organisms respond to changes in their environment.
Changes = Light, Temp, Pressure and Chemicals.
In order to be able to detect these changed in the environment, organisms require having receptors and in in order to respond to the changes in the environment they have effectors (like muscles and glands). It’s the response that insures the organisms in able to survive the changes in the environment