Homeostasis and Feedback Control (Lecture Notes)

Practice flashcards covering reflex arcs, sensors, integrating centers, effectors, temperature set points, hormonal regulation, feedback types, and key homeostatic examples from the notes.

What are the components and flow of the reflex arc?

Sensor detects a variable, the integrating center processes it (often the brain), the effector adjusts the variable, and the response loops back to the sensor.

What is a sensor in the reflex arc?

A sensor is a receptor sensitive to a specific variable.

What is the integrating center in reflex control?

The integrating center processes information and directs the reflex, often located in the brain.

What is an effector in reflex control?

An organ or tissue that can adjust a variable to counteract a change.

What is the normal set point temperature for the human body?

37 degrees Celsius.

In the brain, which structure acts as the temperature regulator?

The hypothalamus.

How does sweating help regulate body temperature?

Evaporation of sweat cools the body.

What is negative feedback?

A control mechanism where the response opposes the initial change, helping maintain homeostasis; negative feedback is common.

What is positive feedback?

A loop where the end product stimulates further production, amplifying the change; relatively rare in physiology.

What are antagonistic effectors?

Pairs of effectors that move conditions in opposite directions to maintain homeostasis (e.g., sweating vs. shivering).

Name some physiological variables maintained by homeostasis as mentioned.

Blood glucose levels, blood pH (around 7.4), and blood pressure.

What happens to blood glucose after eating?

Blood glucose increases after eating; insulin helps cells take up glucose.

Where is insulin produced and what does it do?

Insulin is produced by the pancreatic islets (beta cells) and promotes uptake of glucose by cells.

Where is glucagon produced and what does it do?

Glucagon is produced by pancreatic alpha cells and stimulates the liver to release glucose into the blood.

What is the brain's energy source and limitation?

The brain uses glucose and can only use glucose for energy.

What does hypoglycemia mean?

Low blood glucose.

How do the nervous and endocrine systems coordinate reflexes?

Reflexes involve both neural signaling (nerve fibers) and hormonal signaling (hormones in the blood to multiple targets).

What is a hormone?

A chemical signal transported in the blood to target organs.

What is dynamic constancy in homeostasis?

Maintaining conditions within a normal range around a set point, not a single fixed value.

What is the concept of feedback control of hormone secretions?

Hormone secretions are regulated by feedback mechanisms involving nervous and hormonal signals to maintain physiological balance.