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

11 Homeostasis and Drugs pdf

# 105 Summary of homeostasis, excretion, drugs

Homeostasis is the maintenance of a constant internal environment. It is achieved using negative feedback.

#104 Drugs: antibiotics, heroin, alcohol

Drug is any substance taken into the body that modifies or affects chemical reactions in the body. Drug used in medical care, or to relieve mild pain, are very helpful to us. However, some people misuse drugs, so that they cause harm to themselves and to others around them. 

#103 Negative feed back in homeostasis

Temperature and glucose blood levels regulation involve negative feedback: 

- a change from normal conditions (body temperature, blood glucose levels…) 

- triggers a sensor, 

- stimulates a response in an effector.

#102 Control of blood glucose content

The control of glucose concentration in the blood is a very important part of homeostasis. 

Two hormones insulin and glucagon control blood glucose levels. 

Both hormones are secreted by the pancreas and are transported to the liver in the bloodstream.

#101 Homeostasis

Homeostasis is the maintenance of a constant internal environment, which is vital for an organism to stay healthy. Fluctuations in temperature, water levels and nutrient concentrations … could lead to death.