B9. Coordination and Response

(0654) Coordinated Science 

Subheadings and key concepts covered

B9.1. Nervous control in humans: CNS and PNS, types of neurons, the Reflex Arc

B9.2. Sense organs: the eye, the Pupil Reflex, fine-focussing = accommodation

B9.3. Hormones: adrenaline from adrenal glands, insulin from the pancreas

B9.4. Homeostasis: negative feedback, controlling blood glucose, body temperature, the skin

B9.5. Tropic responses: phototropism, gravitropism, plant hormone: auxin

09. Coordination and Response pdf

#96 Summary of coordination and response

All organisms are able to sense changes in their environment, called stimuli, and respond to them. The part of the body that senses the stimulus is a receptor, and the part that responds is an effector.

#95 Control of plant growth by auxins, weedkillers

Auxins are plant growth substances, produced by the shoot and root tips of growing plants.

- Auxins in the shoot → stimulate cell growth, by the absorption of water.

- Auxins in the root → slow down the cell growth.

#94 Coordination in plants – tropism

Tropism are responses by part of a plant toward of away from a stimulus coming from one direction.

The movement is always a growth movement. 

#93 Voluntary and involuntary actions

Knee jerk is an involuntary reflex. 

Two types of action controlled by the human nervous system are: voluntary and involuntary actions. The peripheral nerves transmit both of them.  

#92 Use of hormones in food production

 Farmer sometimes use hormones to make their animals grow faster, or to produce more of a particular product. One hormone used in this way is called bovine somatotropin, or BST.

#91 Hormones, role of adrenaline

Credit:biologie.uni-hamburg.de

Hormone is a chemical substance, secreted by endocrine gland, carried by the blood, which alters the activity of one or more  specific  target organs and is then destroyed by the liver.

# 90 Accommodation - focusing on objects far and near

The amount of focusing needed by the lens depends on the distance of the object being viewed – light from near objects requires a more convex lens than light from a distant objects. 

#89 Structure and function of the eye, rods and cones

You need to be able to label parts of the eye on diagrams. 

#88 Effectors, biceps and triceps

Effectors are muscles or glands which respond when they receive impulses from motor neurones. Examples of effectors are the biceps and triceps muscles in the arm. 

#87 Simple reflex arc

A reflex action is an automatic response to a stimulus. 

A reflex arc describes the pathway of an electrical impulse in response to a stimulus.

# 86 The human nervous system

The human nervous system is made up of two parts: 

• Central nervous system (CNS) - brain and spinal cord: role of coordination
• Peripheral nervous system - nerves: connect all parts of the body to the CNS. 

Together, they coordinate and regulate body functions.