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biomolecules and cells module 5 > - > Flashcards

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1
Q

4 ways in which organisms can increase the rate of gas exchange

A

increase surface area, maximise the partial pressure gradient, minimise the amount of diffusion that occurs in an aqueous medium (as diffusion works better in gas form) and have a thin barrier of exchange

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2
Q

does increased temperature increase or decrease the solubility of oxygen in water

A

decrease

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3
Q

does increased salinity increase or decrease the solubility of oxygen in water

A

decrease

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4
Q

how does air enter the lungs

A

through trachea, which splits into bronchi, then even smaller bronchioles, to alveoli

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5
Q

what surrounds alveoli

A

capillaries

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6
Q

what is the role of surfactant

A

a phospholipoprotein that lines the inside of alveoli walls, lowering surface tension so that the alveoli don’t collapse

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7
Q

what carries O2 in the blood

A

haemoglobin

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8
Q

how does the partial pressure of oxygen impact its tendency to bind to haemoglobin `

A

higher partial pressure makes it more likely to bind

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9
Q

why does CO2 need to be transported out of the body

A

because it dissolves in liquid to form HCO3- if left to accumulate

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10
Q

how is CO2 transported out of the body

A

it will either disolve in the plama or in the blood cell, some bicarbonate ions are then able to haemoglobin

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11
Q

what is myoglobin

A

an oxygen storing molecule in muscle cells, with a higher affinity to oxygen than haemoglobin

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12
Q

role of chemoreceptors

A

detects oxygen and CO2 partial pressure, and pH, and sends signals to the central nervous system to control the rate of breathing

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13
Q

what determines sex in humans

A

the presence/absence of the SRY (sex determining region on the Y chromosome)

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14
Q

why is female considered the “default” sex

A

because if SRY is absent, the person will always be female

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15
Q

what are the 3 main sex hormones

A

testosterone, progesterone and estrogen

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16
Q

what is the common precursor for the sex hormones

A

cholesterol

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17
Q

true or false, a woman is born with all the eggs she will ever have in her life time

A

true

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18
Q

what is the role of the follicular cells surrounding an oocyte

A

to nourish the oocyte and release estrogen

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19
Q

how many primary oocytes are recruited at the start of the ovarian cycle

A

6-12

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20
Q

is the primary oocyte haploid or diploid

A

diploid

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21
Q

what are the 2 specialised cells that make up the follicle (other than the oocyte)

A

granulosa and theca cells

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22
Q

role of granulosa cells

A

provide estrogen and prepare the egg for fertilisation

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23
Q

role of theca cells

A

the primary steroid producing cells - they produce androgens (male hormones) which are then converted to estrogen by the granulosa cells

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24
Q

what does the follicle become following the release of the egg

A

the corpus luteum

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25
Q

what is the main hormone that the corpus luteum produces

A

progesterone

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26
Q

what does progesterone do

A

prevent the ovarian cycle from occuring

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27
Q

what happens to the corpus luteum if pregnancy does not occur

A

it will degenerate, and the resultant drop in progesterone will trigger menstruation

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28
Q

what is folliculogenisis

A

the development of the follicle

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29
Q

true or false, the meiosis of a primary oocyte produces 4 ovum

A

false, it produces 1 mature egg and 3 polar bodies

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30
Q

when does a primary oocyte undergo meiosis 1

A

at the time of ovulation

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31
Q

when does the secondary oocyte undergo meiosis

A

at fertilisation

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32
Q

what is the name of the uterus lining

A

the endometrium

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33
Q

describe the process of the uterine cycle and the hormones involved

A

estrogen produces by developing follicles stimulates the thickening of the endometrial lining, after ovulation, projesterone produced by the corpus luteum stimulates vascularisation (thickening of blood vessels), a drop in progesterone (if fertilisation does not occur) will result in menstruation (shedding of the lining)

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34
Q

what is the role of vascularisation

A

to increase blood supply to the uterus and meet the developing embryos nutrient requirements

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35
Q

where in the brain is a major control centre for the regulation of the ovarian cycle

A

the hypothalamus

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36
Q

explain the HPG axis (hypothalamo-pituitary-gonadal axis)

A

the hypothalamus releases gonadotrophin releasing hormone (GnRH) in pulses, which act on the anterior pituitary gland, causing it to produce the gonadotrophins FSH (follicle stimulating hormone) and LH (lutenising hormone)

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37
Q

role of LH

A

stimulates theca cells to produce androgens, which are then converted to estrogen

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38
Q

role of FSH

A

stimulates folliculogenesis and stimulates granulosa cells to convert androgens to estrogen

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39
Q

explain the feedback acting on the HPG axis

A

low levels of estrogen exert negative feedback on the HPG axis, supressing the release of LH and FSH. Once. a threshold of estrogen levels is reached (as a result of a buildup from the mature follicle), the axis will switch to a positive feedback loop, causing a surge in the release of LH and FSH (mostly LH), triggering ovulation. once the corpus luteum forms, high estrogen levels, in the presence of progesterone, will exert negative feedback on the axis, therefore inhibiting FSH and LH release.

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40
Q

what the the 2 main phases of the menstrual cycle

A

the follicular (including menstruation and ovulation) and the luteal phase (following ovulation)

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41
Q

what is endometriosis

A

a condition of the reproductive system where endometrial cells will grow in parts of the body other than the uterus, and will undergo the normal uterine cycle, including rapid proliferation, vascularisation and the shedding of the lining (as they still have progesterone and estrogen receptors)

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42
Q

the fertilisation of the egg causes the release of which hormone

A

Human chorionic gonadotrophin (HCG)

43
Q

what is the role of HCG

A

to stimulate the corpus luteum to continue producing progesterone and estrogen to maintain the pregnancy

44
Q

what makes up the testes

A

seminiferous tubules

45
Q

what is the rete testes

A

where the seminiferous tubules come together before being channelled to the epididymis

46
Q

do the final stages of sperm maturation occur before or after they enter the epididymis

A

after

47
Q

what are the 2 specialised cells (other than sperm) found in seminiferous tubules

A

sertoli and leydig

48
Q

what is the role of sertoli cells

A

nurture the developing sperm (the male equivalent of granulosa cells)

49
Q

what is the role of leydig cells

A

produce testosterone (equivalent of theca cells)

50
Q

true or false, males are born with all of the sperm they will have in their life time

A

false

51
Q

what cells convert testosterone to estrogen (in males), allowing spermatogensis to occur

A

sertoli cells

52
Q

what is dihydrotestosterone

A

an androgen, more potent than testosterone, that binds to the same receptors, just with a much higher affinity

53
Q

explain spermatogenesis

A

diploid male germ cells undergo mitosis to form spermatogonium and then another mitotic division to form the primary spermatocyte. Will then undergo meiosis to become the secondaty spermatocytes after the first division and spermatids after the second. They will then undergo differentiation and maturation to become spermatozoa

54
Q

what haoppens to the spermatozoa during maturation

A

they lose the bulk of their cytoplasm and extremely condesne their DNA to enhance mobility `

55
Q

how does the DNA of sperm become super condensed

A

histones are replaced with protamines, that compact the DNA so tightly that they render it useless until fertilisation occurs

56
Q

what is the role of the acrosomal vesicle and where is it located

A

located in the sperm head, contains the enzymes necessary to dissovle the shell and the mucus covering the egg

57
Q

why is the mid-piece of the sperm loaded with mitochondria

A

to provide the sperm with the energy required to swim as fast as possible

58
Q

how does the HPG axis work in males

A

GnRH from the hypothalamus also stimulates the anterior pituitary to release FSH and LH. Testosterone exerts negative feedback on the axis, suppressing GnRH secretion and therefore LH release. When testosterone levels drop, GnRH will be released again. Sertoli cells also release inhibin during spermatogensis, which acts directly on the anterior pituitary, inhibitng FSH secretion

59
Q

role of LH in males

A

stimulates leydig cells to produce testosterone

60
Q

role of FSH in males

A

stimulates spermatogenesis by acting on Sertoli cells

61
Q

how does the oral contraceptive pill work

A

contrains progesterone and estrogen, causing the supression of the release of GnRH (as they exert negative feedback on the HPG axis) and therefore prevents the surge of LH that would typically cause ovulation. Also increases cevix mucus thickness, making it harder for sperm to enter, and reduces the thicknesses of the endometrial lining, hampering implantation

62
Q

what is BPA

A

an endocrine disrupter that mimic estrogen by binding to estrogen receptors

63
Q

what is a heterotroph

A

an organism that gain their energy from other organisms

64
Q

what are essential nutrients

A

nutrients such as amino acid that an organism cannot produce themselves

65
Q

what are the 2 main types of digestion

A

mechanical and enzymatic/chemical

66
Q

explain digestion in the mouth

A

mechanical digestion from the teeth and jaws as well as digestion as the food is mixed with amylase containing saliva, which hydrolyses starch to form smaller saccharides

67
Q

what transports food from the mouth to the stomach

A

the oespohagus

68
Q

describe digestion in the stomach

A

the stomach is incredibly acidic, which kills pathogens and denatures proteins making them easier to disgest. Utilises enzymes such as pepsin and other proteases.s

69
Q

what regulates the release of food from the stomach to the small intestine

A

the pyloric sphincter

70
Q

what are the 3 parts of the small intestine

A

duodenum, jejunum and ileum

71
Q

role of the duodenum

A

enzymatic digestion occurs here, due to digestive fluids released from the liver and pancreas.

72
Q

what does the liver produce

A

bile, which is a mixture of acids, salts, phospholipids and cholesterol that emulsifies lipids, allowing them to be digested

73
Q

where is bile stored

A

the gallbladder

74
Q

what is the hepatopancreatic duct

A

the small channel shared by the pancreas and the liver that leads to the duodenum

75
Q

what are micelles

A

small droplets of emulsified fat (by bile)

76
Q

what is chyme

A

the “food” from the stomach

77
Q

role of the jejunum

A

absorption of nutrients

78
Q

role of iluem

A

absorption of nutrients

79
Q

how is surface area increased in the small intestine

A

with a highly folded surface, contianing protusions called villi (which themselves have microvilli)

80
Q

what enzymes are present in the small intestine

A

peptidases (which breaks down polypeptides), lactase, sucrase, and maltase (which break down oligosaccharides)

81
Q

role of the large intestine/colon

A

absorption of water

82
Q

role caecum

A

a microbe containing blind-ended sac that allows for the digestion of fibre (cellulose)

83
Q

what is a generalist diet

A

an animal that is able to consume a wide range of foods (such as humans)

84
Q

what is a specialist diet

A

an animal with a very restricted diet (and therefore usually a very niche digestive system) such as ant eaters which only eat ants (myrmecophagy)

85
Q

how do foregut eaters get nutrients

A

the caecum is located before the stomach, allowing cellulose to be digested. Some microbes wash down the digestive system, providing the animal with additional protein/nutrients

86
Q

how do hindgut eaters get nutrients

A

caecum is located after the gut, and therefore these animals will not gain protein from organisms that wash through the system

87
Q

what releases gastrin

A

cells lining the stomach when they detect the presence of food

88
Q

role of gastrin

A

stimulates the stomach to secrete digestive fluids and increase stomach movement. Also reduces the pH of the stomach when it gets too high

89
Q

where is secretin produced

A

the duodenum

90
Q

role of secretin

A

stimulates the pancreas to secrete digestive fluid which contains bicarbonate ions to neutralise the acidity of chyme

91
Q

role of cholecystokinin (CCK)

A

stimulates the gall bladder to release bile and the pancreas to release digestive enzymes. It is secreted in the presence of fats and lipids in the chyme.

92
Q

explain the action of ghrelin

A

when the stomach is empty, ghrelin is released, and detected by the hypothalamus, stimulating appetite and preparing the stomach to receive food

93
Q

role of leptin

A

leptin levels increase, and are secreted by adipose tissue (fat cells) and detected by the hypothalamus when fat mass increases, resulting in appetite suppression,

94
Q

how does low sleep impact ghrelin and leptin levels

A

inceased ghrelin and decreased leptin

95
Q

what is produced when microbes ferment fibre

A

short chain fatty acids

96
Q

what is osmoregulation

A

the control of homeostasis of water and solutes

97
Q

what is an osmoconformer

A

an organism that has the same osmotic concentrations in their internal environment as the external environment

98
Q

what is an osmoregulator

A

an organism that has different osmotic concentrations in their internal environment, to the external environment

99
Q

what does stenohaline mean

A

an organism that must live within a narrow salinity range (as they cannot regulate internal salinity levels)

100
Q

what does euryhaline mean

A

organisms that can live within a wider range of salinities

101
Q

high osmolarity means ______ water potential

A

low

102
Q

challenge faced by marine animals (in regards to osmoregulation)

A

body fluid is hypotonic (less concentrated) to sea water and therefore body fluid is lost to the water. This means that the body has too much salt and not enough water.

103
Q

challenge faced by freshwater animals

A

body is hypertonic to the water, and therefore water is gained via osmosis and ions are lost to diffusion. Too much water, not enough salt.

biomolecules and cells module 5 (1 decks)

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