Bio 1002 Chapter 32

What is homeostasis, and does it mean internal conditions never change?

Homeostasis is the ability to maintain an internal environment within a narrow range of normal values for optimal cell function. No, it does not mean conditions never change; it means the body continually responds to fluctuations to keep them within a useful, workable range.

What are the three core components of a homeostatic system, and what are their roles?

• Receptor / Sensor: Detects a change in the internal or external environment (ex: temperature receptors in the skin).

• Control Center: Compares the condition against a set point and coordinates a response (ex: the hypothalamus in the brain).

• Effector: Acts to correct the change and return conditions to normal (ex: sweat glands, shivering muscles, or a furnace output).

What is the difference between Negative and Positive Feedback? Give a biological example of each.

• Negative Feedback: Counteracts and reverses a change to maintain homeostasis (most common). Ex: Sweating to lower body temperature when it rises, or shivering to warm up.

• Positive Feedback: Amplifies a change until a specific event is completed (rare). Ex: Uterine contractions during childbirth becoming stronger and stronger until delivery.

What is the hierarchy of organization in animal bodies from smallest to largest?

Cells →→ Tissues →→ Organs →→ Organ Systems.

What are the four major categories of animal tissues?

1. Epithelial tissue

2. Connective tissue

3. Muscle tissue

4. Nerve tissue

What are the main functions of Epithelial Tissue?

• Covers internal/external surfaces, lines hollow organs and ducts, and forms glands for protection and exchange.

What are the structural features Epithelial Tissue?

• Thin sheets anchored to a noncellular basement membrane. Lacks blood vessels (relies on diffusion) and constantly regenerates.

What are the layer classifications of Epithelial Tissue?

• Simple (one layer thick, where the cells touch the basement membrane, ex: squamous in lungs, cuboidal in kidney tubules) vs. Stratified (multiple layers thick to withstand wear and tear, ex: skin epidermis).

• What are the two main cell types in Nerve Tissue and what do they do?

• Neurons: Generate and conduct electrical signals (consisting of dendrites, cell body, axon, and axon terminals).
  
  

• Glial Cells: Surround, support, electrically insulate, and protect neurons while regulating interstitial fluid.

What are the three layers of the skin, and what major tissue types are found in each?

1. Epidermis (Outer layer): Stratified epithelial tissue; cells fill with waterproof keratin protein and die to form a protective shield.
   
   

2. Dermis (Middle layer): Loose connective tissue containing blood vessels, nerves, glands, and muscle tissue to help regulate body temperature.
   
   

3. Hypodermis (Below dermis): Adipose (fat) tissue used for insulation and energy storage.

What are the three main categories of Connective Tissue?

• Loose Connective Tissue

• Dense Connective Tissue

• Specialized Connective Tissue

What is the function of loose connective tissue?

• Flexible tissue cushioning organs (includes adipose/fat tissue for energy and insulation

What is the function for dense connective tissue?

• Tightly packed collagen fibers providing major strength in one direction; found in tendons (muscle-to-bone) and ligaments (bone-to-bone).

What is the function of specialized connective tissue?

• Cartilage (shock absorber at joints), Bone (hardened calcium/collagen matrix), and Blood/Lymph (fluid matrix for transport and immune defense).

• What are the three types of Muscle Tissue?

• Skeletal Muscle

• Cardiac Muscle

• Smooth Muscle

Skeletal Muscle

• Striated (striped) appearance, multinucleated, voluntary control, moves the skeleton.

Cardiac Muscle

• Striated, involuntary, found only in the heart, connected by intercalated discs that allow electrical signals to spread rapidly for coordinated pumping.

Smooth Muscle

• Non-striated ("smooth"), involuntary, slow, and sustained contractions; found in the walls of the digestive tract, blood vessels, and uterus.