Summary Notes for Communication and Homeostasis

Communication

Communication is needed in order to detect and respond to changes in the internal and external environments. This is monitored by the endocrine and nervous systems.

Cell signalling is communication between cells by using electrical signals travelling along neurones and are aided by hormones.

Nervous system- Rapid, Localised, short-lived

Endocrine system- Slow, wide-spread, long lasting

Hormones travel into the blood to target organs where they perform a function.

Homeostasis

Homeostasis is the maintenance of the constant internal environment such as temperature, water potential, PH and blood glucose levels despite changes in the external environment.

Negative feedback- Counteracts any change in internal conditions by returning value to optimum.

Key features of negative feedback:

  1. Sensory receptors e.g thermoreceptors detect changes in internal conditions

  2. Effectors e.g muscles or glands provide a response

  3. When a change is detected it goes through the nervous or endocrine system to bring about a response to restore optimum conditions.

Positive feedback- It increases the original change in the conditions e.g dilation of the cervix or release of oxytocin during pregnancy.

Thermoregulation

Ectotherm- Regulates its body temperatures using external stimuli and cannot using internal environment therefore they rely on their environment to obtain energy.

Lower temp- Panting, sweating, going into shade, decreasing their surface area

Raise temp- going into sunlight, shivering, increasing their surface area

Endotherms- Able to maintain a constant temperature using internal environment. Thermoreceptors are found in skin and hypothalamus which detect a change in core temperature which causes the endotherm to coordinate a response to the change using behavioural and physiological changes.

To Increase body temp- Vasoconstriction, Shivering, sweat glands closed, hairs on skin contract to trap moisture.

To decrease body temp- Vasodilation, sweating, hair on skin relax to reduce moisture intake