Define a cell.
The basic unit of all living organisms.
Define a tissue.
An integrated group of similar cells performing a specific function.
Define an organ.
Composed of multiple tissues working together to perform a specific task.
Describe the relationship between the structural components (cells, organs, and tissues)
Cells → Tissues → Organs. The whole is greater than the sum of its parts.
What is the fundamental principle relating structure and function?
The structure-function principle: structure correlates with function.
What characterizes animals as an Open System?
The system exchanges mass and energy with the environment.
Define homeostasis.
A dynamic state of equilibrium in which internal conditions may vary, but always remain within relatively narrow limits.
List internal variables maintained by homeostasis.
Concentration of nutrients and wastes, O2 and CO2 levels, blood pressure, temperature, and pH.
What detects environmental change in a homeostatic mechanism?
The Sensor.
What processes information and sends a command?
The Control Center.
What carries out the command?
The Effector.
Define a Negative Feedback Loop.
A response that slows or reverses variation from normal.
Why is negative feedback important?
It is the most common mechanism for homeostatic control.
Give examples of negative feedback.
Thermostat, thyroid hormone regulation, breathing rate, blood pressure.
Define a Positive Feedback Loop.
A response that promotes continued change in the same direction.
Give examples of positive feedback.
Blood clotting, childbirth (Oxytocin release).
What is thermoregulation?
The mechanism that controls body temperature.
How does the body respond when temperature is above 37 °C (98.6 °F)?
Cooling mechanisms: blood vessels dilate and sweat is produced.
How does the body respond when temperature is below 37 °C (98.6 °F)?
Warming mechanisms: blood vessels constrict and shivering occurs.
What is osmoregulation?
Control of the gain or loss of water and solutes (like NaCl).
Why is glucose essential?
It is the main energy molecule; the brain is almost completely glucose-dependent.
Which organ regulates blood glucose?
The Pancreas.
What two hormones regulate glucose?
Insulin and Glucagon.
Stimulus: High blood glucose (Hyperglycemia). What happens?
Pancreas secretes Insulin.
