Exam 1 Part 2 Study Guide
* Maintenance of constant conditions in the internal environment. Composition, temperature and volume of extracellular fluid do not change significantly under normal conditions Know the components of a homeostatic control mechanism
* Regulated Variable- Regulated to stay within relatively narrow limits * Set Point- normal desire value
* Error Signal- difference between the actual value and the set point * Sensors- cells sensitive to variable
* Integrating Center- sensors relay signals to IC compares the regulated variable to the set point and makes the appropriate response * Effectors- receive signal from IC and effectors bring about the final response What is negative feedback, give an example in the human body. * If a regulated variable increases, the system responds by making it decrease and vice versa. Minimizes changes in physiological variables * Example:
* Cruise control in a car- operates to keep the speed of the car steady at a certain desired point * Car goes from level ground up a hill- car begins to slow down * Control mechanism detects a difference between the actual speed and the desired speed, feeds more gas to engine, car’s speed increases * Car’s speed reaches desired point and the system throttles back to maintain that speed * As long as speed is maintained- system makes no further adjustments to the flow of gas What is positive feedback.
* Response of the system goes in the same direction as the change that sets it in motion. Allows a variable to change rapidly in response to a stimulus * Example:
* Females- pituitary gland secretes a hormone luteinizing hormone (LH) stimulates ovaries to secret hormones called estrogens (regulate reproductive function) * Rise in plasma estrogen concentration trigger an increase in the secretion of LH stimulates estrogen secretion enhances LH secretion even more * Result rapid rise in plasma LH (LH surge) triggers ovulation
Review the function of the cell organelles
CELL PART| STRUCTURE| FUNCTION|
PLASMA MEMBRANE| Lipid bilayer with scattered proteins and cholesterol molecules| Maintains boundary of cell and integrity of cell structure; embedded proteins serve multiple function| NUCLEUS| Surrounded by double- layered nuclear envelope| Houses the DNA, which dictates cellular function and protein synthesis| Nucleolus| Dark oval structure inside the nucleus| Synthesis of RNA| CYTOSOL| Gel-like fluid| Cell metabolism, storage|
MEMBRANOUS ORGANELLES| | |
Rough Endoplasmic Reticulum| Continuous with the nuclear envelope; flatted sacs dotted with ribosomes| Protein synthesis and post-translational processing| Smooth Endoplasmic Reticulum| Continuous with rough ER; tubular structure w/o ribosomes| Lipid synthesis and post-translational processing of proteins; transport of molecules from ER to Golgi apparatus; calcium storage| Golgi Apparatus| Series of flattened sacs called cisternae near the ER (cis face/trans face)| Post-translational processing; packaging and sorting of proteins| Mitochondria| Oval-shaped, with an outer membrane and an inner membrane w/ folds called cristae that project into the matrix| ATP synthesis| Lysosomes| Granular, saclike; scattered throughout cytoplasm; single membrane| Breakdown of cellular and extracellular debris| Peroxisomes| Similar in appearance to lysosomes, but smaller| Breakdown of toxic substances; including hydrogen peroxide| NONMEMBRANOUS ORGANELLES| | |
Vaults| Small, barrel- shaped| Unknown; possibly transport of molecules between nucleus and cytoplasm| Ribosomes| Granular organelles composed of proteins and rRNA; located in cytosol or on surface of rough ER| Translation of mRNA to synthesize proteins| Centrioles| Two cylindrical bundles of protein filaments...