Detecting and regulating change Flashcards
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
Thermoreceptors
respond to heat and cold
Osmoreceptors
Are sensitive to osmotic pressure, which is the concentration of substances dissolved in the water of blood plasma. Located in the hypothalamus
Chemoreceptors
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
