Human and Social Biology - EOT

end of term review

Explain what'll happen to an organism if excretion does not occur.

toxic waste substances produced in the body's metabolism will build up and kill the body's cells.

Whye egestion is not considered excretion

egestion only deals with the removal of undigested dietary fibre and this fibre is not produced in the body's metabolism.

Outline how urine is produced in the kidneys.

Blood enters the glomerulus under high pressure, forcing small molecules like water, glucose, amino acids, salts, and urea into the Bowman's capsule—this forms the filtrate. As the filtrate moves through the nephron, essential substances are reabsorbed: glucose, amino acids, and water in the proximal tubule; more water and salts in the loop of Henle and distal tubule. The remaining fluid, mostly urea, excess water, and salts, enters the collecting duct, where more water may be reabsorbed. The final urine flows to the bladder via the ureter for storage and excretion.

Andrew plays tennis all day in the hot sun and drinks very little water. What effect will his behavior have on the quantity and concertation of his urine?

Andrew will produce a small quantity of urine concerted with urea and salt. The hypothalamus will detect his behavior and stimulate his pituitary gland to secrete ADH. Andrew's blood will transport the ADH to the kidneys where it'll make the walls of the second convoluted tubule and collecting duct more permeable to water. Most of the water will be reabsorbed from the filtrate in Andrew's kidney back into the blood.

After a meal rich in carbs, the blood glucose level rises. How does the body function to return the level to normal?

The pancreas detects the rise in the blood glucose level and increases secretion of insulin in the blood. The insulin stimulates the body cells to absorb glucose for respiration and the liver cells to convert excess glucose to glycogen and stores it. As a result, the blood glucose level returns to normal.

distinguish between heat and temperature.

heat is the total amount of energy contained by an object and it is measured in joules (J) while temperature is a measure of how hot or how cold an object is and it is measured in degrees Celsius.

Explain why negative feedback mechanisms are important in homeostasis.

they help keep internal conditions stable. When the level of something in the body (like temp or blood sugar) changes, receptors detect this change and send signals to effectors. The effectors then respond in a way that reverses the change, bringing the level back to normal. This prevents the body from going too far in one direction and keeps conditions within a healthy range.

Define homeostasis

how the body maintains balance in the internal environment

What is osmoregulation

the process by which the body maintains the balance of water and salts (solutes) to keep the internal environment stable.

What are the three major parts of the kidney in order?

cortex ---> medulla ---> Pelvis

difference between receptors and effectors?

receptors detect stimuli and effectors carry out responses to stimuli

How does the body fix risen blood sugar levels?

the pancreas detects the increase and releases insulin. Insulin signals body cells to absorb glucose from the bloodstream and store it, especially in the liver and muscles as glycogen.

How does the body fix low blood sugar levels?

the pancreas releases a hormone called glucagon. Glucagon signals the liver to break down stored glycogen into glucose and release it into the bloodstream. This raises blood sugar levels back to normal and helps keep the body supplied with energy, especially the brain.

What does the cardiovascular system consist of?

heart, blood vessels, blood cells

What is the makeup of plasma?

90% water 10% dissolved substances