Year 9 biology topic 2

What is homeostasis?

The maintenance of a relatively stable internal environment within a narrow range.

What are the five key features of a stimulus-response model?

Stimulus, receptor, control center, effector, and response.

What factors need to be kept within a certain range for homeostasis?

Temperature, pH, concentrations of ions, glucose, water, oxygen, and carbon dioxide.

What systems are involved in the stimulus-response model?

The nervous system and the endocrine system.

What are stimuli?

Changes in the internal environment that need to be detected for homeostasis.

What are the types of receptors involved in detecting stimuli?

Photoreceptors, mechanoreceptors, chemoreceptors, thermoreceptors, osmoreceptors, and nociceptors.

What is the role of the control center in the stimulus-response model?

To process the stimulus and determine an appropriate response.

What are effectors?

Muscles or organs/glands that respond to messages from the control center.

What is negative feedback?

A counteractive response to a stimulus that returns the stimulus back to the normal range.

How does negative feedback function in temperature regulation?

If blood temperature is too high, the response is to lower it; if too low, the response is to increase it.

What is the nervous system's primary function in homeostasis?

To transmit electrical impulses to and from the central nervous system (CNS).

What are the three main types of neurons?

Sensory neurons, interneurons, and motor neurons.

What is the structure of a typical neuron?

It includes a cell body, dendrites, an axon, a myelin sheath, and axon terminals.

What is the function of the myelin sheath?

To protect the axon and speed up the electrical impulse.

What is a synapse?

The tiny gap between nerve cells where electrical impulses are converted into chemical messages.

What are neurotransmitters?

Chemical messages that transmit signals across synapses between neurons or to effectors.

What is the difference between a conscious response and a reflex action?

A conscious response involves thinking and decision-making, while a reflex action is a quick, automatic response.

How do sensory neurons contribute to homeostasis?

They detect stimuli and send messages to the CNS for processing.

What happens when a stimulus is detected?

A message in the form of a nerve impulse or hormone travels to the control center.

What is the role of the endocrine system in homeostasis?

To control body functions through hormones released by various glands.

What is the primary function of motor neurons?

To carry messages from the CNS to effectors to trigger a response.

What is the significance of the axon terminals?

They send the message to another neuron or an effector.

What is the role of interneurons?

To process information within the CNS.

What is the importance of maintaining homeostasis?

It ensures that the internal environment remains stable for optimal cell function.

How do changes in the internal environment affect homeostasis?

They create stimuli that must be detected and responded to for balance.

What is the relationship between the nervous system and the endocrine system in homeostasis?

They work together to maintain a stable internal environment through electrical impulses and hormones.

What are reflex actions?

Reflex actions are involuntary responses that may involve only a few neurons and travel to and from the spinal cord.

What is the role of the endocrine system?

The endocrine system coordinates homeostasis using chemical messages called hormones.

What are hormones?

Hormones are chemical messengers produced by endocrine glands that travel through the bloodstream to target tissues.

What is a reflex arc?

A reflex arc is the neural pathway involved in a reflex action, which typically bypasses the brain.

What is the function of the hypothalamus?

The hypothalamus acts as the control center for many bodily processes, linking the nervous and endocrine systems.

What is the 'master gland' of the endocrine system?

The pituitary gland is known as the 'master gland' because it controls many other endocrine glands.

What is thermoregulation?

Thermoregulation is the process of maintaining the body's core temperature around 37.5°C.

How does the body respond when temperature increases?

The body decreases thyroxine and adrenaline, produces sweat, and dilates blood vessels to cool down.

What happens when body temperature decreases?

The body increases thyroxine and adrenaline, causes shivering, and constricts blood vessels to retain heat.

What is the role of insulin in blood glucose control?

Insulin helps lower blood glucose levels by promoting the conversion of glucose to glycogen in the liver.

What does glucagon do?

Glucagon raises blood glucose levels by signaling the liver to convert glycogen back into glucose.

What are the major endocrine glands?

The major endocrine glands include the hypothalamus, pituitary gland, pineal gland, thyroid gland, adrenal glands, pancreas, ovaries, and testes.

What is the difference between the nervous and endocrine systems?

The nervous system uses electrical signals for rapid responses, while the endocrine system uses hormones for slower, longer-lasting effects.

What are thermoreceptors?

Thermoreceptors are sensory receptors that detect changes in temperature.

What is the role of the pancreas in blood glucose regulation?

The pancreas monitors blood glucose levels and releases insulin or glucagon as needed.

What is the function of the adrenal glands?

The adrenal glands produce hormones such as adrenaline that help the body respond to stress.

What is the significance of specific hormone receptors?

Only cells with specific receptors for each hormone will respond to that hormone.

What is the relationship between the hypothalamus and the pituitary gland?

The hypothalamus sends messages to the pituitary gland to regulate various bodily functions.

What physiological responses are involved in thermoregulation?

Responses include blood vessel dilation or constriction, sweating, shivering, and changes in metabolic rate.

What are the three types of neurons?

The three types of neurons are sensory neurons, interneurons, and motor neurons.

What is the function of myelin?

Myelin insulates axons and speeds up the transmission of nerve impulses.

What is the central nervous system (CNS)?

The central nervous system consists of the brain and spinal cord, controlling most functions of the body and mind.

What is the peripheral nervous system (PNS)?

The peripheral nervous system includes all the nerves outside the CNS, connecting it to the rest of the body.