BIOS255 Comprehensive Exam Review
Homeostasis - ANS * Presence of stable internal environment
* Failure to maintain homeostasis leads to illness or death
Homeostatic Regulation - ANS Physiological adjustment to preserve homeostasis in variable
environments
Feedback - ANS Stimulation of a receptor triggers response that changes environment at that
receptor
Negative Feedback - ANS * Effector opposes or negates the original stimulus
* Minimizes change
* Primary mechanism of homeostatic regulation in the body
* Dynamic process: Set point varies with varying environments & activity levels
Negative Feedback Receptors - ANS Temperature receptors in skin & brain are stimulated &
send signals to the control center
Negative Feedback Control Center - ANS The temperature control center received information
from the two sets of temperature receptors & sends commands to the effectors
Negative Feedback Effectors - ANS Sweat glands & smooth muscle in the walls of blood
vessels supplying the skin respond
Positive Feedback - ANS * Stimulus produces a response that exaggerates or enhances the
original change (rather than opposing it)
* Tends to produce extreme responses
* Does not restore homeostasis
Positive Feedback Loop - ANS * Escalating cycle
* Typically occurs when a potentially dangerous or stressful process must be completed quickly
before the body can restore homeostasis
Steps of Positive Feedback in Blood Clotting - ANS 1. Damage to cells in the blood vessel wall
releases chemicals that begin the process of blood clotting
2. The chemicals start chain reactions in which cells, cell fragments, & soluble proteins in the
blood begin to form a clot
3. As clotting continues, each step releases chemicals that further accelerate the process
4. This escalating process is a positive feedback loop that ends with the formation of a blood
clot, which patches the vessel wall & stops the bleeding
, Epithelial Tissue - ANS * Epithelia
* Glands (Exocrine & Endocrine)
Functions of Epithelial Tissue - ANS * Provide physical protection
* Control permeability
* Provide sensation
* Produce specialized secretions
Characteristic of Epithelial Tissue - ANS * Specialized contacts with other cells
* Polarity (different ends of cell do different things)
* Avascularity (NO blood supply)
* Regeneration (can divide to make new cells)
* Cellularity (lots of cells in close contact)
Characteristics of Epithelial Tissue: Specialized Contacts - ANS Epithelial cells are held close
together by cell junctions
Features of Epithelial Tissue - ANS * Surfaces: Apical surface-Faces exterior of body or internal
space; Base- Attached to underlying tissues
* Polarity: Refers to structural differences between exposed & attached surfaces
Connective tissue overview - ANS * Varies widely in appearance & function (Found throughout
the body, but never exposed to surface)
* Ranges from highly vascular to avascular
* Many contain sensory receptors that detect pain, pressure, temperature, & other stimuli
3 basic components shared by connective tissues - ANS 1. Specialized cells
2. Extracellular protein fibers
3. Fluid called ground substance
Extracellular Protein Fibers - Reticular Fibers - ANS Strong & form branching network
Extracellular Protein Fibers - Collagen Fibers - ANS Thick, very strong
Extracellular Protein Fibers - Elastic Fibers - ANS Slender, very stretchy
Connective Tissue Ground Substance - ANS * Clear & colorless
* Viscous (syrupy) due to presence of proteoglycans & glycoproteins
* Allows substances to travel between blood capillaries & cells
Cartilage overview - ANS * Matrix is a firm gel containing chondroitin sulfates (cartilage),
polysaccharide dervatives
* Only 1 type of cell (chondrocyte)
Homeostasis - ANS * Presence of stable internal environment
* Failure to maintain homeostasis leads to illness or death
Homeostatic Regulation - ANS Physiological adjustment to preserve homeostasis in variable
environments
Feedback - ANS Stimulation of a receptor triggers response that changes environment at that
receptor
Negative Feedback - ANS * Effector opposes or negates the original stimulus
* Minimizes change
* Primary mechanism of homeostatic regulation in the body
* Dynamic process: Set point varies with varying environments & activity levels
Negative Feedback Receptors - ANS Temperature receptors in skin & brain are stimulated &
send signals to the control center
Negative Feedback Control Center - ANS The temperature control center received information
from the two sets of temperature receptors & sends commands to the effectors
Negative Feedback Effectors - ANS Sweat glands & smooth muscle in the walls of blood
vessels supplying the skin respond
Positive Feedback - ANS * Stimulus produces a response that exaggerates or enhances the
original change (rather than opposing it)
* Tends to produce extreme responses
* Does not restore homeostasis
Positive Feedback Loop - ANS * Escalating cycle
* Typically occurs when a potentially dangerous or stressful process must be completed quickly
before the body can restore homeostasis
Steps of Positive Feedback in Blood Clotting - ANS 1. Damage to cells in the blood vessel wall
releases chemicals that begin the process of blood clotting
2. The chemicals start chain reactions in which cells, cell fragments, & soluble proteins in the
blood begin to form a clot
3. As clotting continues, each step releases chemicals that further accelerate the process
4. This escalating process is a positive feedback loop that ends with the formation of a blood
clot, which patches the vessel wall & stops the bleeding
, Epithelial Tissue - ANS * Epithelia
* Glands (Exocrine & Endocrine)
Functions of Epithelial Tissue - ANS * Provide physical protection
* Control permeability
* Provide sensation
* Produce specialized secretions
Characteristic of Epithelial Tissue - ANS * Specialized contacts with other cells
* Polarity (different ends of cell do different things)
* Avascularity (NO blood supply)
* Regeneration (can divide to make new cells)
* Cellularity (lots of cells in close contact)
Characteristics of Epithelial Tissue: Specialized Contacts - ANS Epithelial cells are held close
together by cell junctions
Features of Epithelial Tissue - ANS * Surfaces: Apical surface-Faces exterior of body or internal
space; Base- Attached to underlying tissues
* Polarity: Refers to structural differences between exposed & attached surfaces
Connective tissue overview - ANS * Varies widely in appearance & function (Found throughout
the body, but never exposed to surface)
* Ranges from highly vascular to avascular
* Many contain sensory receptors that detect pain, pressure, temperature, & other stimuli
3 basic components shared by connective tissues - ANS 1. Specialized cells
2. Extracellular protein fibers
3. Fluid called ground substance
Extracellular Protein Fibers - Reticular Fibers - ANS Strong & form branching network
Extracellular Protein Fibers - Collagen Fibers - ANS Thick, very strong
Extracellular Protein Fibers - Elastic Fibers - ANS Slender, very stretchy
Connective Tissue Ground Substance - ANS * Clear & colorless
* Viscous (syrupy) due to presence of proteoglycans & glycoproteins
* Allows substances to travel between blood capillaries & cells
Cartilage overview - ANS * Matrix is a firm gel containing chondroitin sulfates (cartilage),
polysaccharide dervatives
* Only 1 type of cell (chondrocyte)
