Chapter 6 Application

Question 1

Harvey showed that:

Answer 1

• Blood flow is unidirectional
• Valves prevent backflow
• Blood is NOT consumed in body
• Arteries pump blood out, veins in
• Predicted presence of fine vessels that linked arteries to veins

Question 2

Dialysis Tubing

Answer 2

• models absorption by the epithelium of the intestine
• distilled water used
• cola drink contains mix of substances used to model digested + undigested food in intestine
• water outside bag is tested to see if substances in the cola have diffused through dialysis tubing
• glucose & phosphoric acid should diffuse through the tubing but caramel which has larger polymers of sugar should not

Question 3

Coronary arteries

Answer 3

• provide the heart muscle tissue w/ oxygen & nutrients
• branch from aorta

Question 4

Coronary thrombosis (Occlusion)

Answer 4

formation of a clot that occludes coronary artery & causes heart attack
- coronary arteries blocked w/ calcified fatty substance called plaque
- if deposits of plaque in coronary arteries rupture, blood clots form
- plaque is composed of fatty acids + cholesterol
- artery wall begins to occlude
- reduces width of lumen of artery
- surface of arterial wall = roughened
- causes platelets to break, initiating formation of clot called thrombosis
- leads to heart attack (uncoordinated contraction called fibrillation)

Question 5

Atherosclerosis

Answer 5

• hardening of arterial blood vessels
• artery wall thickens / formation of plaque within arteries
• accumulation of fatty materials like cholesterol, triglycerides, some calcium
• reduces elasticity of artery walls
• increases blood pressure
• inflammatory response in walls of arteries caused by accumulation of macrophages & white blood cells

Question 6

Causes of coronary artery disease

Answer 6

• high blood cholesterol levels
• smoking
• high blood pressure
• high blood sugar levels, usually due to diabetes
• genetic factors

Question 7

Florey & Chain + Penicillin testing

Answer 7

• their first test was on 8 mice infected with a bacterium that causes a fatal pneumonia
• all 4 treated mice recovered, but untreated mice died
• tested on man close to death
• began to recover but supplies ran out
  he died

Question 8

Causes of emphysema

Answer 8

• emphysema is a chronic disease of the lungs where the alveoli of the lungs are damaged & enlarged, causing breathlessness
• cilia that line the airways & expel mucus are damaged & cease to function
• mucus builds up in lungs & causes infections
• toxins in cigarette smoke & polluted air cause inflammation & damage to white blood cells that fight infections in lungs
• a protease (trypsin) is released from inflamed cell & damaged white blood cells
• this enzyme digests elastic fibers in the lungs & eventually causes complete breakdown of alveolus walls

Question 9

Consequences of emphysema

Answer 9

• SA for gas exchange reduces so oxygen saturation of blood falls and exercise is more difficult
• lungs lose their elasticity, making it difficult to exhale (Shortness of breath)
• mucus in lungs causes coughing and wheezing

Question 10

Causes of lung cancer

Answer 10

• smoking –> tobacco contains mutagens
• passive smoking –> passing on carcinogens
• air pollution –> diesel exhaust fumes, nitrogen oxides from vehicles, smoke
• radon gas –> leaks out of rocks esp. granite
• asbestos & silica –> dust from these materials causes cancer if deposited on lungs

Question 11

Consequences of lung cancer

Answer 11

• difficulties breathing
• persistent coughing
• coughing up blood
• general fatigue
• chest pain
• loss of appetite
• weight loss

Question 12

Harvey & Sexual Reproduction

Answer 12

• was taught the “seed & soil” theory of Artistotle
• male produces a seed, which forms an egg when it mixes w/ menstrual blood - the egg develops into a fetus inside the mother
• tested this theory using a natural experiment
• deer only become sexually active during the autumn
• examined the uterus of female deer during mating season by slaughtering & dissecting them
• expected to find eggs developing in the uterus immediately after mating (copulation) but only found signs of something developing in females 2 or 3 months after start of mating season
• thought this falsified Artistotle’s theory
• he concluded that offspring CANNOT be the result of mating - which was false
• the issue was that he didnt have the technology (microscopes) to see gametes

Question 13

Cholinergic synapses

Answer 13

• synapses that use ACh are called cholineric synpases
• pre-synaptic neuron secretes ACh into synaptic cleft
• diffuses across synapse
• binds to receptors in post-synaptic membrane
• ACh broken down in synaptic cleft
• by enzyme cholinesterase
• produces acetyl groups and choline
• choline reabsorbed by pre-synaptic neuron

Question 14

Neonicotinoid pesticides

Answer 14

• bind to ACh receptors in post-synaptic membranes of cholinergic synapses in insects
• cholinesterase does not break down these pesticides so they remain bound to receptors
• prevents ACh from binding (inhibitor)
• block synaptic transmission, killing insect
  sadly honey bees are also killed :(

Question 15

Jet lag

Answer 15

• experienced when travelling rapidly b/w time zones
• caused by SCN & pineal gland continuing to set a circadian rhythm to suit the timing of day & night at point of departure
• time impulses sent by ganglion cells to SCN when they detect light helps to adjust to new regime
• melatonin pills can be taken

Question 16

symptoms of jet lag

Answer 16

• sleep disturbance
• fatigue
• headaches
• irritability

Question 17

HIV

Answer 17

infects a type of lymphocyte that plays a vital role in antibody production
- over several years, these lymphocytes are gradually destroyed
- without active lymphocytes, antibodies cannot be produced
- leads to AIDs

Question 18

Transmission of HIV

Answer 18

• transfer of body fluids
• through small cuts or tears in different organs
• in traces of blood on hypodermic needles shared by drug abusers
• across placenta
• in transfused blood

Question 19

Tidal volume

Answer 19

the volume of air taken in or out with each inhalation or exhalation

Question 20

Monitoring ventilation rate

Answer 20

• Inflatable chest belt is placed around thorax
• Air is pumped in with a bladder
• Pressure sensor used to measure pressure variations inside the chest belt due to chest expansions
• Ventilation rate can be deduced and relative size of ventilations (not absolute size)

Question 21

Monitoring tidal volumes

Answer 21

• Measured with spirometer
• Made using a bell jar, with volumes marked on it, placed in a pneumatic trough
• Tube used to breathe out into the bell jar so expired volume can be measured
• Tidal volume is deduced by how much the lung volume increases or decreases with each ventilation
• Rate = number of ventilations / time

Question 22

Leptin & obesity

Answer 22

• breeding experiments showed that obese mice had 2 copies of a recessive allele, ob
• ob/ob mice injected w/ leptin their appetite declined
• energy expenditure increased & body mass dropped by 30% in a month
• large clinical trial carried out on humans
• 73 obese volunteers injected themselves w/ either leptin or placebo
• induced skin irritation, swelling, & only 47 patients completed it
• results varied widely
• body mass was quickly regained
• disappointing outcomes
  MOST CASES OF OBESITY ARE NOT DUE TO INSUFFICIENT LEPTIN SECRETION BUT TO TARGET CELLS IN HYPOTHALAMUS BECOMING RESISTANT TO LEPTIN