Lecture 1

Question 1

Define homeostasis and conditions defining an organism in homeostasis

Answer 1

• Refers to the maintenance of nearly constant conditions in the internal environment, homestatic mechanism made up of adaptive responses
• An organism is said to be in homeostasis when its internal environment contains the optimum conc. of gases, nutrients, ions, water, optimal temp. and optimal pressure for the health of cells

Question 2

Define stress

Answer 2

• Stress is any stimulus that creates an imbalance in the internal environment

Question 3

List basic differences between extra/intracellular fluid compartments

Answer 3

• Extracellular fluid contains large amounts of Na+, Cl-, and bicarbonate ions plus nutrients
• Intracellular fluid contains large amounts of K+, Mg2+ and phosphate ions

Question 4

Cation most abundant in extracellular

Answer 4

Na+

Question 5

Anion most abundant in extracellular

Answer 5

Cl-

Question 6

Cation most abundant in intracellular

Answer 6

K+

Question 7

Define feedback system

Answer 7

• Circular situation in which information about the status of something is continually reported to a central region

Question 8

Describe negative feedback loop

Answer 8

• Any change in some parameter (i.e, blood pressure) that causes a response which results in a return of the parameter to normal (baseline)
• The response reverts the direction of the initial condition, consists of a series of changes that return the factor towards mean value
• Stabilizing, diminishes original change

Question 9

Describe regulation of arterial blood pressure

Answer 9

• Baroreceptors associated with carotid system sense increase in arterial pressure
• send inhibitory signals to vasomotor receptors in medulla
• heart pumping capacity is reduced and blood vessels dilate
• arterial pressure decreases

Question 10

Describe positive feedback loop

Answer 10

• A change in some parameter causing a response that continues the change, input is intensified

Question 11

Describe childbirth feedback loop

Answer 11

• Stretch of the cervix sends back signals that increase force of uterine contractions which increase the stretch on the cervix

Question 12

Define and calculate Gain

Answer 12

• Gain is the degree of effectiveness with which a control system maintains constant conditions
• Gain = correction/error
• Error is the amount of uncorrected increase in the controlled system

Question 13

Describe the universal structure of cell membranes

Answer 13

• Cell membranes separate the intracellular from the extracellular environment and regulate what leaves/enters
• Basic structure referred to as unit membrane
• Unit membrane is phospolipid bilayer with cholesterol inserted among phospholipids

Question 14

Describe proteins associated with membrane

Answer 14

Integral - Either inserted into membrane on one side or pass through all the way and exposed on both sides
Peripheral - Loosely attached to one surface of the membrane and easily removed, attached by glycophosphatidylinositol = GPI anchored proteins

Question 15

What function is clathrin associated with

Answer 15

• Coated clathrin pits associated with endocytosis, pinocytosis, phagocytosis

Question 16

Describe lysosomes

Answer 16

Contain hydrolytic enzymes at a low pH
• Result of a hydrogen-ion pump
• Primary lysosomes fuse with phagocytic vesicles to form secondary
lysosomes.
• Undigested material is left behind within residual bodies.
• Residual bodies may be eliminated via exocytosis

Question 17

Describe glycolysis

Answer 17

Anaerobic respiration
• Begins with glucose
• Occurs in the cytoplasm of all cells
• Does not require oxygen
• Produces pyruvic acid (lactic acid) and a small amount of ATP

Question 18

Describe kreb’s cycle and etc

Answer 18

Aerobic respiration
Utilizes pyruvic acid from glycolysis
• Can only occur in the mitochondria
• Requires oxygen as the final electron receptor
• Produces carbon dioxide and water
• Produces much more ATP than glycolysis

Question 19

Describe types of locomotion by cells

Answer 19

Amoeboid movement
• Used by macrophages and some other leukocytes
• Cilia and flagella
• Flagella move cells ( The only flagellated cells in humans and other mammals
are sperm cells.)
• Cilia move other material, usually through a layer of mucous that coats a
layer of ciliated cells.
• The cells remain stationary.
• Microtubules:
• Provide tracks on which motor molecules can move cargos.