the study of functions of the body parts (how they work).

  tissues are groups of cells that arise from common ancestor cells and work together to perform a particular function.

                               ·         Four types of tissue:

  ·         Epithelial

·         Muscle

       ·         Connective

 ·         Nervous

 (uses the energy from catabolism) to build the body's structural and functional components.

 includes motion of the whole body, individual organs, single cells, or even organelles inside the cells.

the formation of new cells for growth, repair, or replacement, or the production of a new individual.

Homeostasis

• Cells need relatively stable conditions to function effectively and contribute to survival of the body as a whole.
• This stability is HOMEOSTASIS.
• Definition: a condition in which the body’s internal environment remains within certain physiological limits.
• Example: regulation of the volume & composition of body fluids (watery solutions found inside and outside cells).

Homeostasis

• ICF: intracellular fluid (fluid found inside cells)
• ECF: extracellular fluid (fluid found outside cells; 3 types)
• If contained within spaces between cells –“interstitial fluid”
• Surrounding blood cells; contained within blood vessels – “plasma”
• Contained within lymphatic vessels – “lymph”
• What is found dissolved in ICF & ECF? – gases like O₂, nutrients like glucose, electrically charged particles (ions like Na⁺, Cl^-), wastes

Homeostasis

• H₂O and solutes in the plasma filter out into interstitial fluid…the same volume of fluid passes back from the interstitial space to the blood (capillary exchange)
• *** An organism is said to be in homeostasis when conditions in the internal environment are maintained within physiological limits.

• Stress: any stimulus that tends to create an imbalance in the internal environment
• Stimulus: any stress that changes a controlled condition
• Internal (↓ blood glucose, ↑ acidity of ECF) or external (physical stimuli – heat, cold, loud noises; from our surroundings – work, social, etc.)
• Generally the body can handle stress – things the body does not handle well include death of a loved one, poisoning, or overexposure to extreme temperatures
• If the body couldn’t handle stress, simple exercise could kill us (ex: lactic acid build-up)

Stress and homeostasis

• The nervous system regulates homeostasis by detecting changes within the system and then sending messages to organs to counteract stress (ex: blood ↑ CO₂ during exercise, brain is notified and tells heart to pump faster and the breathing rate to increase…allows more CO₂ to be delivered to the lungs to be breathed out, thus altering the CO₂ levels to a more appropriate level).
• Hormone function works more slowly

Definition: cycle of events where information regarding a condition is continually monitored and reported to central control region

Consists of three (3) basic components:

• Control Center: determines the value at which some aspect of the body should be maintained (ex: HR, BP, bld acid, bld glucose, body temp, breathing rate); determines appropriate action based on the messages it receives.
• Receptor: monitors changes in the controlled condition and sends input to the control center (ex: exercise or being in a hot environment tells the brain that temp has increased).
• Effector: receives information (output) & produces a response (ex: increased secretion by sweat glands)

• Negative Feedback Systems (p 10): response to the original stimulus is reversed (most are this)
• Maintain conditions that require frequent monitoring and adjustment (body temp & blood glucose).
• Positive Feedback Systems (p 11): response intensifies original stimulus (blood clotting, labor contractions)
• Important for conditions that do not occur often and do not require fine-tuning
• Generally shut-off by some mechanism outside the system if part of a normal physiological response

Definition: pathological process with a definite set of characteristics where part of the body is not carrying out its normal functions

• Local v. Systemic
• Understand “local” is used when something is happening in a specific area (“localized swelling”)
• “Systemic” is a term used when something is more widespread (“systemic infection”)
• Signs v. Symptoms
• Signs are things you can measure (BP, HR, etc.)
• Symptoms are things you cannot measure; they are subjective (nausea, etc.)