Response - Homeostasis: Key Terms

Question 1

Homeostasis

Answer 1

The maintenance of a constant internal environment

Question 2

Control mechanism

Answer 2

A set of self-regulating stages comprising of: optimum point, receptor, coordinator, effector and feedback loop

Question 3

Ectotherm

Answer 3

An animal which gains its heat from its external environment

Question 4

Endotherm

Answer 4

An animal which gain its heat from internal metabolic activities

Question 5

Vasodilation

Answer 5

Widening the diameter of arterioles near the surface of the skin, so that warm blood passes close to its surface via capillaries

Question 6

Vasoconstriction

Answer 6

Narrowing the diameter of arterioles near the surface of the skin, so that less blood volume passes close to its surface via capillaries, retaining heat

Question 7

Hypothalmus

Answer 7

Part of the brain next to the pituitary gland; the control centre for the ANS

Question 8

Second messenger model

Answer 8

The way a non-lipid soluble hormone acts on a cell, by triggering production of an intermediary ‘second’ messenger (by activating adenyl cyclase?)

Question 9

Type 1 diabetes

Answer 9

Insulin dependent, due to body being unable to produce insulin

Question 10

Type 2 diabetes

Answer 10

Insulin independent, due to glycoprotein receptors on body cells losing responsiveness to insulin

Question 11

Gluconeogenesis

Answer 11

Conversion of non-carbohydrates into glucose in the liver

Question 12

Glycogenolysis

Answer 12

Breakdown of glycogen to glucose in the liver

Question 13

Glycogenesis

Answer 13

Conversion of glucose into glycogen in the liver

Question 14

Negative feedback

Answer 14

When the feedback causes the corrective measures to be turned off so returns the system to its original level

Question 15

Positive feedback

Answer 15

When the feedback causes the corrective measures to be turned on so the system deviates even further from its original level

Question 16

Osmoregulation

Answer 16

The homeostatic control of the water potential of the blood

Question 17

Nephron

Answer 17

The functional unit of the kdiney

Question 18

Fibrous capsule

Answer 18

An outer membrane which protects the kidney

Question 19

Cortex

Answer 19

A lighter coloured outer region made up of renal (Bowman’s) capsules, convoluted tubules and blood vessels

Question 20

Medulla

Answer 20

A darker coloured inner region made up of loops of Henle, collecting ducts and blood vessels

Question 21

Renal pelvis

Answer 21

A funnel-shaped cavity that collects urine into the ureter

Question 22

Ureter

Answer 22

A tube that carries urine to the bladder

Question 23

Renal artery

Answer 23

Supplies the kidney with blood from the heart via the aorta

Question 24

Renal vein

Answer 24

Returns blood to the heart via the vena cava

Question 25

Renal (Bowman’s) capsule

Answer 25

The closed end at the start of a nephron

Question 26

Proximal convoluted tubule

Answer 26

A series of loops surrounded by blood capillaries which are adapted to reabsorb substance into the blood

Question 27

Loop of Henle

Answer 27

A long, hairpin loop that extends from the cortex into the medulla of the kidney and back again

Question 28

Descending limb of loop of Henle

Answer 28

Narrow, thin walls that are highly permeable to water. The filtrate progressively loses water by osmosis as it moves down the limb

Question 29

Ascending limb of loop of Henle

Answer 29

Wider, with thick walls that are impermeable to water. Sodium ions are actively transported out of this limb which creates a lower water potential in the region of the medulla between the two limbs

Question 30

Distal convoluted tubule

Answer 30

A series of loops surrounded by blood capillaries

Question 31

Collecting duct

Answer 31

A tube into which a number of distal convoluted tubules from a number of nephrons empty

Question 32

Afferent arteriole

Answer 32

A tiny vessel that ultimately arises from the renal artery and supplies the nephron with blood

Question 33

Glomerulus

Answer 33

A many-branched knot of capillaries from which fluid is forced out of the blood

Question 34

Efferent arteriole

Answer 34

A tiny vessel that leaves the renal capsule

Question 35

Blood capillaries

Answer 35

A concentrated network of capillaries that surround the proximal convoluted tubule, the loop of Henle and the distal convoluted tubule and from where they reabsorb mineral salts, glucose and water

Question 36

Ultrafiltration

Answer 36

Filtration assisted by blood pressure

Question 37

Reabsorption of water

Answer 37

Process by which all of the glucose and most other valuable molecules are reabsorbed as well as water in the proximal convoluted tubule

Question 38

Counter-current multiplier

Answer 38

When two liquids flow in opposite directions past one another, the exchange of substance between them is greater than if they flow in the same direction next to each other

Question 39

Osmoreceptors

Answer 39

Cells in the hypothalmus of the brain that detect a change in water potential

Question 40

Antidiuretic hormone (ADH)

Answer 40

A hormone produced by the pituitary gland when a decrease in water potential is detected, which makes the walls f the distal convoluted tubule and collecting duct more permeable to water