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IB HL Biology II > Unit 6: Hormones, Homeostasis, and Excretion > Flashcards

Unit 6: Hormones, Homeostasis, and Excretion Flashcards

1
Q

Homeostasis (2)

A
  • the process by which organisms maintain a stable internal environment
  • the internal environment is narrow as it fluctuates very little
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2
Q

What are some examples of homeostatic components? (2)

A
  • body temperature
  • blood glucose levels
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3
Q

What two systems are important in maintaining homeostasis? (2)

A
  • nervous system
  • endocrine system
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4
Q

How is the nervous system involved in regulating homeostasis?

A

it send electrical impulses from the central nervous system to neurons to tissues

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5
Q

How is the endocrine system involved in regulating homeostasis?

A

send chemical hormones from glands through lymph and blood to tissues

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6
Q

Homeostatic Mechanisms

A

mechanism that maintains a set point

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7
Q

What is an example of a homeostatic mechanism?

A

negative feedback

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8
Q

Negative Feedback

A

one thing is produced which inhibits/lowers something else

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9
Q

What is an example of negative feedback?

A

body temperature

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10
Q

Positive Feedback (2)

A
  • the body continues the stimulus
  • not a homeostatic mechanism
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11
Q

What is an example of positive feedback?

A

contractions, oxytocin produces uterine contractions right before birth, more oxytocin, more contractions

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12
Q

How is body temperature maintained? (2)

A
  • by a negative feedback system
  • the hypothalamus
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13
Q

How does the hypothalamus regulate body temperature?

A

if body temperature is too high, it send impulses through neurons throughout the body

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14
Q

What are ways to bring body temperature down if it is too high? (3)

A
  1. sweat glands produce sweat for evaporative cooling
  2. metabolic rate can be lowered so that excess heat is not produced
  3. vasodilation
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15
Q

What are ways to bring body temperature up if it is too low? (4)

A
  1. vasoconstriction
  2. shivering
  3. hugging someone
  4. countercurrent heat exchange
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16
Q

Countercurrent Heat Exchange (3)

A
  • bodily process that animals only have
  • arteries carrying warm blood are in blood contact with veins conveying cool blood back toward the core
  • allows heat to transfer from the arteries to veins
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17
Q

What are the 2 hormones produced to regulate blood glucose? (2)

A
  • insulin
  • glucagon
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18
Q

What organ produces insulin and glucagon?

A

the pancreas

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19
Q

Insulin

A

a hormone that is responsible for glucose uptake from the blood to lower glucose concentrations

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20
Q

What happens as a result of the release of insulin? (3)

A
  • glucose is taken up by cells for respiration
  • glucose is stored in the liver and muscles as glycogen
  • glucose is stored as adipose tissue
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21
Q

Glucagon

A

a hormones that is antagonistic to insulin, it releases glucose into the blood

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22
Q

What happens as a result of the release of glucagon? (2)

A
  • glucose is released from glycogen in the liver and muscles
  • blood glucose concentration is increased
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23
Q

Islets of Langerhans

A

cells in the pancreas that regulate glucose concentration

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24
Q

What types of cells in the pancreas release glucagon?

A

alpha cells

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25
Q

What types of cells in the pancreas release insulin?

A

beta cells

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26
Q

When is insulin released?

A

after eating because blood glucose levels are elevated

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27
Q

When is glucagon released?

A

after fasting because blood glucose levels are low

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28
Q

In order, what is broken down after glucose runs out? (3)

A
  • glycogen
  • adipose tissue
  • muscle
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29
Q

Why is it dangerous to breakdown muscle for energy?

A

it decreases the pH of the blood

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30
Q

Diabetes (2)

A
  • a metabolic disease that concerns blood glucose concentration
  • there are two types
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31
Q

Type 1 Diabetes

A

an autoimmune disease where the beta cells of the pancreas are destroyed and thus insulin is not produced

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32
Q

What does being unable to make insulin mean?

A

glucose is not stored away

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33
Q

How is type 1 diabetes treated?

A

taking insulin injections

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34
Q

In what states of health can patients with type 1 diabetes be in? (2)

A
  • hyperglycemic
  • hypoglycemic
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35
Q

Hyperglycemic

A

without insulin, resting muscles cannot take up glucose, so muscle, proteins, and fat are broken down rather than glucose

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36
Q

What is a possible result of hyperglycemia? (2)

A
  • ketoacidosis, where dehydration occurs and pH of blood drops
  • can result in coma and death
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37
Q

hypoglycemia

A

leads to coma and death if left untreated

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38
Q

Type 2 Diabetes (2)

A
  • insulin resistant diabetes where the patient has elevated levels of insulin
  • cells have lost the ability to recognize insulin
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39
Q

How do cells lose the ability to recognize insulin?

A

over time, too much blood sugar accumulates and it reduces the body’s ability the to recognize insulin

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40
Q

What is the result of a reduced ability to recognize insulin?

A

glucose is stored away more slowly

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41
Q

How is type 2 diabetes treated? (3)

A
  • diet
  • exercise
  • medication
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42
Q

How is exercise a form of treatment for type 2 diabetes?

A

activity can remove some of the excess glucose in the blood

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43
Q

What state of health is a patient with type 2 diabetes in?

A

hyperglycemic

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44
Q

How is fiber helpful to someone with type 2 diabetes?

A

it helps get rid of toxins

45
Q

What happens if type 2 diabetes is left untreated? (2)

A
  • sugar will deposit in various areas of the body which can cause blindness or limb loss
  • liver and kidneys can have decreased function
46
Q

What hormones does the thyroid produce? (2)

A
  • T3
  • T4
47
Q

What is another name for the T4 hormone?

A

thyroxine

48
Q

What are the functions of thyroxine? (3)

A
  • increases body temperature
  • regulates bone growth and neural development
  • regulates fat, carb and protein metabolism
49
Q

What is required to produce thyroxine?

A

iodine (salt)

50
Q

What happens as a result of an iodine deficiency?

A

a goiter appears

51
Q

What glands also regulate hormone levels? (2)

A
  • hypothalamus
  • pituitary glands
52
Q

Which hormones affect hunger and satiety? (2)

A
  • leptin
  • ghrelin
53
Q

Leptin (2)

A
  • released by adipose tissue to decrease hunger
  • this acts on the hypothalamus
54
Q

Ghrelin

A

released by the GI tract and is released when the stomach is empty, and stops release when the stomach is stretched

55
Q

How does leptin relate to obesity?

A

obesity often leads to cells being resistant to leptin even though levels are higher in blood

56
Q

What can throw off the balance of leptin and ghrelin?

A

dramatic weight loss

57
Q

Melatonin (3)

A
  • regulates the sleep cycle
  • anticipates darkness
  • released in darkness
58
Q

Where is melatonin produced?

A

the pineal gland

59
Q

What disrupts melatonin? (2)

A
  • light from phones
  • jet lag from travelling across time zones
60
Q

What hormone does melatonin interact with?

A

leptin

61
Q

Excretion

A

the removal of the wastes created by metabolic activities

62
Q

Why is excretion crucial for organisms?

A

the products are harmful to keep

63
Q

What is the primary waste product in plants? (2)

A
  • oxygen
  • must be excreted because it is reactive
64
Q

What is the primary waste product in animals? (2)

A
  • carbon dioxide, which comes from cellular respiration
  • must be excreted because it lowers the pH of the blood
65
Q

What does protein digestion result in?

A

surplus amino acid components, which must be removed

66
Q

What do fish excrete?

A

ammonia

67
Q

What do birds excrete? (2)

A
  • pasty insoluble liquid
  • this is because they do not carry much water
68
Q

What do mammals excrete? (2)

A
  • urea in their urine
  • whether or not it is concentrated or diluted depends on the mammal’s water intake
69
Q

What are the components of the kidney? (6)

A
  • renal vein
  • renal artery
  • ureter
  • medulla
  • pelvis
  • cortex
70
Q

Urea

A

a nitrogenous waste product which humans remove in urine

71
Q

What is advantageous to do in excretion?

A

conserve as much water as possible

72
Q

How is water balance achieved?

A

balancing salt and hormone concentration in the kidney

73
Q

What processes is the kidney responsible for? (3)

A
  • filtration
  • reabsorption
  • secretion
74
Q

How is water lost? (3)

A
  • sweating
  • urination
  • breathing
75
Q

How is salt lost?

A

sweating

76
Q

Nephron (2)

A
  • functional unit of the kidney
  • these are supplied with blood by a renal artery which receive about 20% of cardiac output
77
Q

What does the nephron consist of? (6)

A
  • glomerulus
  • Bowman’s capsule
  • proximal convoluted tubule
  • loop of Henle
  • distal convoluted tubule
  • collecting duct
78
Q

What is the purpose of a nephron?

A

to balance the good and the bad

79
Q

Where do conserved products from the blood go?

A

back into the bloodstream to the body

80
Q

Where do waste products from the blood go?

A

through the ureters to the bladder to exit the body

81
Q

Glomerulus

A

a bundle of blood vessel that allows for filtration of small solutes via a pressure gradient

82
Q

Where is the glomerulus located?

A

within the Bowman’s capsule

83
Q

Where does blood enter and exit in the glomerulus? (3)

A
  • blood enters through the afferent arteriole
  • blood exits through the efferent arteriole
  • both branch off from the renal artery
84
Q

How does filtration in the glomerulus occur? (2)

A
  • filtration occurs as blood pressure forces fluid of from the the blood in the glomerulus into the lumen
  • the porous capillaries are permeable to water and small solutes, but not blood cells or large molecules such as proteins
85
Q

How does pressure play a role in the ultrafiltration of the glomerulus? (4)

A
  • there is a pressure difference between the afferent and efferent arterioles
  • the afferent arteriole has more space, so pressure is lower
  • the efferent arteriole has less space, so pressure is higher
  • this pressure helps sift out smaller molecules
86
Q

How has filtered blood changed after going through the glomerulus?

A

it is 20% of the original volume

87
Q

What does filtrate contain after going through the glomerulus? (5)

A
  • salt
  • electrolytes
  • glucose
  • vitamins
  • urea
88
Q

Proximal Convoluted Tubule (PTC) (2)

A
  • nutrients must be absorbed back into circulation so it pumps things out of the urine
  • solute transport substantially changes the composition of the filtrate
89
Q

How are nutrients moved in the PTC?

A

via active transport for reabsorption

90
Q

What nutrients are reabsorbed in PTC? (3)

A
  • glucose
  • amino acids
  • vitamins
91
Q

What is the structure of the PTC? (2)

A
  • single layer of cells for easy transport
  • microvilli to increase surface area
92
Q

What is an important function of the PTC?

A

reabsorption of most of the salt and water from the initial filtrate

93
Q

How does Na+ move across PTC?

A

actively

94
Q

How does Cl- move across the PTC?

A

passively

95
Q

How does water move across the PTC?

A

via osmosis

96
Q

Where does most water and glucose go from the PTC?

A

back into circulation rather than being excreted in the urine

97
Q

What happens to glucose in the PTC for diabetics?

A

there is an increased blood glucose, so not all of it is reabsorbed

98
Q

Loop of Henle (2)

A
  • composed of the descending and ascending limbs, main role is to increase solute concentration in the medulla
  • reabsorption of water continues as the filtrate moves into the descending limb of the LoH
99
Q

Descending Limb (2)

A
  • freely permeable to water, but not to salt
  • for water to move out by osmosis, the interstitial fluid bathing the tubule must be hypertonic to filtrate
100
Q

What is the purpose of the descending limb?

A

to increase water absorption

101
Q

Ascending Limb (2)

A
  • permeable to salt, but not water
  • as filtrate goes up the ascending limb, NaCl is secreted out of the tubule into the interstitial fluid
102
Q

What is the purpose of the ascending limb?

A

to pump salt

103
Q

What is filtrate like when it leaves the LoH?

A

it still has relatively large amount of water

104
Q

Collecting Duct(2)

A
  • where water is released depending on the body’s need for it
  • permeable to water, but not salt or urea
105
Q

How does urine become more concentrated?

A

as water is reabsorbed by osmosis

106
Q

What does the collecting duct do if the body is in need of water? (3)

A
  • more water will be reabsorbed by the collecting duct
  • the hypothalamus produces and the posterior pituitary releases Anti-Diuretic Hormone (ADH)
  • ADH creates aquaporins in the duct for water to pass through
107
Q

What does the collecting duct do if the body is not in need of water? (3)

A
  • if there is excess water in the body, ADH is not released
  • water can be excreted along with urine
  • this is negative feedback because ADH prevents additional water loss
108
Q

Why does alcohol inhibit ADH? (2)

A
  • alcohol is mainly composed of water
  • this is why people get dehydrated

IB HL Biology II (7 decks)

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