Biochemistry Notes

...

- Thyroxin inhibits the hypothalamus from producing more TRH

- Draw the chart – TRH(hypothalamus) → TSH (Anti. Pituitary) → T4 (thyroxin thyroid)

- T4 helps with metabolism in the body (the more T4 = faster metabolism)

- Too much of T4 produced can cause accelerated rates of metabolism which can be dangerous as it would influence the pace of activity in almost all tissues. (hyperthyroidism)

- Regulation is required as to much of this hormone being produced would be waste of energy and resources if it’s not in use.

- Hypothyroidism – Has the opposite effect. Lower metabolic rates and slower pace of activity within tissues. Effects individuals ability to carry out daily activities

Explain how the nervous system, endocrine system, and urinary system work together to maintain water balance in the human.

- Nervous system –osmoreceptors detect a change in osmotic pressure.

- Endocrine system –The Hypothalamus cells shrink, when water concentrations low, by losing water. This signals the posterior pituitary to release ADH (made in hypo stored in PP)

- When water concentration is high, cells remain the same and no signal is sent.

- Urinary system –If ADH is released, then the distal tubles and collecting ducts in the nephron become permeable to water and it is reabsorbed.

- If ADH not released, then they remain impermeable and water passed in urine.

Use the following terms to describe the propagation of a nerve impulse: threshold level, depolarization, hyper-polarization, resting potential, all or none. Include a simple sketch.

[pic 3]

- 1 – Cell at resting potential no pulse is passing. The cell is polarized and negative on the inside but positive on the outside

- 2 – Stimulus causes Na channels to open and K channels to close. Depolarization occurs as cell becomes more positive (Na+)

- 3 – once the minimum number of Na required to carry the pulse is reached the threshold level has been reached (-50mV) The all or none theory states that once its reached then nerves will fire to the max.

- 4 –rising stage, cell becomes more positive as Na enters

- 5 – Falling phase, action peak reached. Na channels close and K channels open

- 6 – Depolarization occurs as nerve becomes negative again.

- 7 – Cell dips below resting potential and hyper polarization occurs. (below -70mV).

- 8 –sodium potassium pump restores resting potential.

Describe three possible effects of completely destroying the pituitary gland as a result of a traumatic accident.

- ADH not released – the posterior pituitary stores ADH produced by the hypothalamus. If the pituitary is destroyed, then this hormone can l\no longer be stored or released into the body. This would affect the urination. The distal tubules and collecting ducts would remain impermeable to water without ADH and the individual would have an impact on their water balance. Increased urination.

- TSH not released – the anterior pituitary produces the hormones TSH which then enters the thyroid and releases T4. Without TSH no T4 made and therefore metabolism pays a price. This would affect all of the chemical reactions that take place in the individual’s body. Hypothyroidism would result due to the lack of T4

- GH – Growth hormone not being produced in childhood would shunt growth. This would result in dwarfism. For adults, not as greatly an impact but can cause weakness.

- PRL- The lack prl will lead to the mammary glands being unable to produce milk. This would then effect women when it comes to breast feeding.

Explain how the human body thermoregulates against hot and cold temp. Use sensors, coordinating sensors, and effectors in the explanation.

- The sensors on the skin sense the outer temperature of the environment and then relay the information to the coordinating centre.

- The coordinating centre then integrates the situation and relays the information to the necessary effectors.

- If increased temp – The body senses this and the sweat glands are told to secret and blood vessels dilate. Heat is lost to the environment.

- If decreased temp – The body tells the sweat gland to stop secreting and blood vessels to slow down dilation. If really cold then muscles involuntarily contract. Heat is preserved and created.

Metabolic Processes

- Explain why it is important that aerobic cellular respiration be regulated

- It requires oxygen to take place, don’t want to waste it

- No regulation would result in a waste of energy and resources

- Describe two ways aerobic respiration is regulated by feedback inhibition

- An increase in ATP inhibits the enzyme PFK which catalyses the third reaction in glycolysis. It is activated by decrease in citrate and increase in ADP

- An increase in NADH inhibits pyruvate decarboxylase – an enzyme that removes the CO2 in pyruvate oxidation

Compare and contrast the electron transport chain in CR and Photo

- Cellular Respiration

- Involves the electron carries Ubiquinonoe and Cytochrome C.

- takes place in the inner membrane of the mitochondria

- Proteins involved are Nadh dehydrogenase, cytochrome b1-c, cytochrome oxidase

- Creates a high concentration of protons outside of the membrane

- Produces NAD+ and H2O (byproduct)

- Photosynthesis

- Involves the electron carries PC, Q, FD and enzyme Z

- takes place in the inner membrane of thylakoid in the