Even though the genetic variability is huge we only have the chromosomes our

Even though the genetic variability is huge we only

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This is also the reason why we tend to look like our parents. Even though the genetic variability is huge, we only have the chromosomes our parents started out with 3/8 Physiology and the Internal Environment
“The study of an animal and its component parts” Cells are very sensitive to the environment around them (pH, temperature, tonicity, etc. must be regulated very carefully) Homeostasis : maintenance of relative constancy of the internal environment Negative Feedback Regulation of Plasma [Glucose] Plasma = blood minus the cell (liquid part of the blood) Clusters of cells inside the pancreas; 1 particular kind of cell is the β cell β cells : sensors, control centers, effectors (a cell or organ that brings about an effect by taking an action β cell senses glucose levels and regulates an action as a result Homeostasis: 90 mg glucose/100 mL blood Stimulus: blood glucose level rises after eating β cells release insulin glucose uptake in cells Specific mechanism: Insulin stimulates the cell to insert glucose transports into the membrane (facilitated diffusion transporters that allow glucose to cross the lipid bi-layer down its concentration gradient GLUT ) Glucose can be converted to glycogen, and it becomes a pool of stored glucose that the body can draw on (for example, when you are sleeping) Eventually, these effects cause a DROP in glucose (negative feedback loop), which keeps glucose at homeostasis. Most control systems in biology are negative feedback systems. Clicker Q : Which is not an example of negative feedback regulation? Low body temperature causes shivering (the point of shivering is to generate body heat) – negative feedback Salty food triggers salt excretion (a rise in plasma glucose will stimulate sodium excretion through urine and feces) – negative feedback Stools in rectum stimulate defecation – positive feedback Exercise stimulates breathing (exercise produces a deficit of oxygen in the body and a build up of CO2 breathing blows off this CO2) – negative feedback Cardiovascular systems The Heart The Need for Circulatory Systems o Diffusion is adequate only over short distances o Tiny, flat, or porous animals can live without a circulatory systems o Paramecium DOES have a circulatory system—constantly circulating a cytoplasm o Glucose can diffuse about 100 micrometers in one second—not fast enough o Hearts are PUMPS Pumps create pressure gradients in fluids Fluids (liquids and gases, e.g. blood) flow down pressure gradients So, at the downstream end of blood vessels, BP is low Heart restores BP to enables re-circulation Left side of the heart is pumping blood into the aorta (HIGH pressure), then into the artieries, then into arterioles, then into capillaries, then into venuoles, then into bigger veins, then back to the heart on the right side of it (LOW pressure). This must be because of a pressure gradient Units are mms of mercury
Maximum pressure of the heart: systolic pressure Minimum pressure of the heart: diastolic pressure o Clicker Question

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