Detecting and regulating change Flashcards Preview

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Flashcards in Detecting and regulating change Deck (19)
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What are receptors?

- Detect changes in the bodies internal or external environment
- Some are simple nerve endings, while others are receptor cells grouped together to form sense organs EG. The eye


Types of receptors

- Thermoreceptors
- Osmoreceptors
- Chemoreceptors
- Touch receptors
- Pain receptors



respond to heat and cold



Are sensitive to osmotic pressure, which is the concentration of substances dissolved in the water of blood plasma. Located in the hypothalamus



stimulated by particular chemicals


Touch receptors

sensitive to very light touches. They are mainly found in the surface of the skin


Pain receptors

stimulated by damage to tissues. They are mainly found in skin and mucous. They warn us that damage to tissue is occurring and for this they don’t adapt


Protective reflexes

Present from birth


Acquired reflexes

Complex motor patterns that are learned


All reflexes...

- Require a stimulus
- Are involuntary
- Are rapid
- Are stereotyped (occur in the same way each time)


All reflexes consist of....

- A stimulus
- A receptor
- A sensory neuron
- At least one synapse
- A motor neuron
- An effector


What is homeostasis?

The process of keeping the environment inside the body fairly constant


What is the purpose of homeostasis

To help us stay independent of our external enviroment


It is important that the body regulates...

Core body temperature

pH and concentrations of dissolved

substances in the body fluids
concentration of glucose in the blood

concentration of oxygen and carbon dioxide in the blood and other body fluids

blood pressure

concentration of metabolic rates


What is a feedback system?

Circular system in which the body responds to a change with the response altering the original stimulus


Negative feedback system

The response causes the stimulus to change in a direction opposite to that of the original change


Common features of a negative feedback system

- The stimulus is the change in the environment that causes the system to operate
- The receptor detects this change
- The modulator is a control centre responsible for processing information received from the receptor and for sending information to the effector
- The effector carries out a response counteracting the effect of the stimulus
- Feedback is achieved because the original stimulus has been changed by the response


Positive feedback

When positive feedback occurs, the response to the stimulus reinforces and intensifies the stimulus
- This does not contribute to homeostasis


Example of positive feedback

An example is during child birth
- Labour is initiated by the secretion of oxytocin
- Causing contractions of the uterus
- The contractions push the baby’s head against the cervix, sending impulses to the brain
- The brain responds by instructing the pituitary to secrete more oxytocin
- Intensifying the uterus contractions