1. What is the difference between homeostasis and allostasis? Explain with examples.

- Homeostasis is the maintenance of a relatively constant internal environment despite changes in the external

environment. Allostasis is the process of achieving stability through change, by adapting to stressors and

restoring homeostasis. Examples of homeostasis are the regulation of body temperature, blood pressure,

and blood glucose. Examples of allostasis are the activation of the sympathetic nervous system, the

hypothalamic-pituitary-adrenal axis, and the immune system in response to stress.

2. What are the four primary tissue types in the human body? Describe their main functions and locations.

- The four primary tissue types are epithelial, connective, muscle, and nervous. Epithelial tissue covers body

surfaces, lines body cavities and organs, and forms glands. It functions in protection, absorption, secretion,

and sensation. Connective tissue supports, binds, and protects other tissues and organs. It consists of cells,

fibers, and ground substance. It is found in bones, cartilage, tendons, ligaments, adipose tissue, blood, and

lymph. Muscle tissue contracts to produce movement. It is composed of muscle cells or fibers that contain

actin and myosin filaments. It is found in skeletal muscles, cardiac muscle, and smooth muscle. Nervous

tissue conducts electrical impulses and processes information. It consists of neurons and glial cells. It is

found in the brain, spinal cord, and nerves.

3. What are the three main components of a feedback loop? How do negative feedback and positive feedback

differ?

- The three main components of a feedback loop are a sensor, a control center, and an effector. A sensor

detects a change in a variable and sends a signal to the control center. The control center compares the

signal with a set point and sends a command to the effector. The effector produces a response that restores

the variable to its normal range. Negative feedback is a feedback loop that opposes or counteracts the

initial change and reduces the output. Positive feedback is a feedback loop that amplifies or reinforces the

initial change and increases the output.

4. What are the two major fluid compartments in the human body? What are the subdivisions of each

compartment? What are the main solutes in each compartment?

- The two major fluid compartments in the human body are the intracellular fluid (ICF) and the extracellular

fluid (ECF). The ICF is the fluid inside the cells, accounting for about two-thirds of the total body water.

The ECF is the fluid outside the cells, accounting for about one-third of the total body water. The ECF can

be further subdivided into interstitial fluid (the fluid between cells), plasma (the fluid portion of blood),

lymph (the fluid in lymphatic vessels), cerebrospinal fluid (the fluid in the brain and spinal cord), synovial

fluid (the fluid in joint cavities), aqueous humor (the fluid in the eyes), and serous fluid (the fluid in serous

membranes). The main solutes in the ICF are potassium ions, magnesium ions, phosphate ions, proteins,

and organic molecules. The main solutes in the ECF are sodium ions, chloride ions, bicarbonate ions,

proteins, glucose, oxygen, carbon dioxide, hormones, and nutrients.