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IB HL Biology > D.5 Hormones and metabolism > Flashcards

D.5 Hormones and metabolism Flashcards

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1
Q

What are hormones involved in regulating?

A
  • Metabolism
  • Development
  • Homeostasis
  • Digestion
  • Excretion
  • Sleep
  • Reproductive cycles
  • Growth
  • Secondary sexual characteristics
  • Sensory perception
  • Mood
  • Hunger
  • Birth
  • Lactation
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2
Q

Hormones are produced by the ___ system

A

Endocrine

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3
Q

How are hormones distributed throughout the body?

A

They are often released directly into the bloodstream by endocrine glands.

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4
Q

Why is the endocrine system considered to be one system?

A

Even though the glands of the endocrine system are scattered throughout the body, they are still considered to be one system because they have similar functions and mechanisms of influence.

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5
Q

What are endocrine glands?

A

Special groups of cells that secrete hormones into the blood.

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6
Q

What are the major endocrine glands?

A
  • The pituitary, pineal, thymus, thyroid, and adrenal glands, and the pancreas.
  • In addition, men produce hormones in their testes and women produce them in their ovaries.
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7
Q

Diagram showing the development of endocrine glands

A
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8
Q

Which organs play a part in the endocrine system?

A
  • In addition to the major endocrine glands, other organs have some hormonal activity as part of their function.
  • These include the stomach, small intestines, heart, thymus and placenta.
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9
Q

What is the target tissue of a hormone?

A
  • The target tissue of a hormone consists of cells that have receptor sites for a given hormone.
  • In some cases, the target tissue is found in a single gland or organ.
  • In other cases, the target tissue is scattered throughout the body so that many areas are affected.
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10
Q

Where are hormones produced?

A

Endocrine glands

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11
Q

Define hormones

A

Chemical messengers secreted by cells or glands of the endocrine system that control and regulate the activity of other cells or glands in other parts of the body.

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12
Q

How are hormones classified?

A

Acording to their chemical composition, mainly either proteins or steroids.

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13
Q

What kinds of hormones are most of the hormones in the human body?

A

Proteins or protein derivatives.

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14
Q

What are the steroid hormones in the human body?

A

Sex hormones (oestrogen, progesterone, testosterone) and those from the adrenal cortex (aldosterone, cortisol and estradiol).

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15
Q

Examples of protein or peptide derivative hormones in the human body

A
  • Epinephrine (adrenaline)
  • Thyroxin
  • Insulin
  • Glucagon
  • Oxytocin
  • Prolactin
  • Growth hormone (somatotropin)
  • ADH (vasopressin)
  • Thyroid stimulating hormone (TSH)
  • Follicle stimulating hormone (FSH)
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16
Q

Site of production for insulin

A

Pancreas (beta cells)

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17
Q

Site of production for glucagon

A

Pancreas (alpha cells)

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18
Q

Site of production for oxytocin

A

Hypothalamus

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19
Q

Site of production for prolactin

A

Pituitary

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20
Q

Site of production for growth hormone (somatotropin)

A

Anterior pituitary gland

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21
Q

Site of production for ADH (vasopressin)

A

Hypothalamus

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22
Q

Site of production for follicle-stimulating hormone (FSH)

A

pituitary gland

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23
Q

Target organs for insulin

A

Muscle cells and fat cells

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24
Q

Target organs for glucagon

A

Liver

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25
Q

Target organs for oxytocin

A

Uterus, mammary glands

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26
Q

Target organs for prolactin

A

Mammary glands

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27
Q

Target organs for growth hormone (somatotropin)

A

Muscle, liver, bones

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28
Q

Target organs for ADH (vasopressin)

A

Kidney

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29
Q

Target organs for follicle-stimulating hormone (FSH)

A

Ovary/testes

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30
Q

Main functions of insulin

A

Promote absorption of glucose.

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31
Q

Main functions of glucagon

A

Convert stored glycogen to glucose.

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32
Q

Main functions of oxytocin

A

Birth and lactation

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33
Q

Main functions of prolactin

A

Milk production, metabolism

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34
Q

Main functions of growth hormone (somatotropin)

A

Growth

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35
Q

Main functions of ADH (vasopressin)

A

Water reabsorption, homeostasis.

36
Q

Main functions of follicle-stimulating hormone (FSH)

A

Maturation of follicle/sperm production.

37
Q

Examples of steroids

A
  • Cortisol
  • Oestrogen
  • Progesterone
  • Testosterone
38
Q

Site of production of oestrogen

A

Ovary, placenta, liver, muscle and brain, as well as the fat cells

39
Q

Site of production of progesterone

A

Ovary

40
Q

Site of production of testosterone

A

Testes, ovary and adrenal cortex

41
Q

Target organs of oestrogen

A

Many organs

42
Q

Target organs of progesterone

A

Uterus

43
Q

Target organs of testosterone

A

Many organs

44
Q

Main functions of oestrogen

A

Secondary sexual characteristics, accelerate metabolism, and increase uterine growth and endometrium.

45
Q

Main functions of progesterone

A

Maintain endometrium

46
Q

Main functions of testosterone

A

Secondary sexual characteristics, anabolic effect.

47
Q

What is the lifespan of hormones and how are they secreted?

A

Hormones have a limited lifespan and are secreted in pulses.

48
Q

Feedback mechanisms for hormones

A
  • Hormones have a limited lifespan and are secreted in pulses.
  • This determines the need to control their production though feedback mechanisms.
  • These can be positive or negative feedback mechanisms, although the latter is more common.
49
Q

Define negative feedback

A

When the output of a pathway inhibits inputs to the pathway.

50
Q

When do diseases occur?

A

When there is a problem in positive and negative feedback control mechanisms, as the concentration could be too high or too low.

51
Q

What are the stages in which the concentration of hormones can be controlled?

A
  • Synthesis
  • Delivery
  • Elimination
52
Q

Synthesis as a way of controlling the concentration of hormones

A

The rate of production can be regulated by positive or negative feedback.

53
Q

Delivery as a way of controlling the concentration of hormones

A

In endocrine glands, this is regulated by blood flow.

54
Q

Elimination as a way of controlling the concentration of hormones

A

Hormones are metabolised and excreted once their half-life is over.

55
Q

Flow diagram showing an example of how the hypothalamus and pituitary glands are involved in the negative feedback of a hypothetical endocrine gland

A
56
Q

Steroid hormones

A
  • Steroid hormones are lipophilic (fat-loving) – meaning they can freely diffuse across the plasma membrane of a cell
  • They bind to receptors in either the cytoplasm or nucleus of the target cell, to form an active receptor-hormone complex
  • This activated complex will move into the nucleus and bind directly to DNA, acting as a transcription factor for gene expression
  • Examples of steroid hormones include those produced by the gonads (i.e. estrogen, progesterone, and testosterone)
57
Q

Diagram of how steroid hormones work

A
58
Q

Peptide hormones

A
  • Peptide hormones are hydrophilic and lipophobic (fat-hating) – meaning they cannot freely cross the plasma membrane

-They bind to a specific receptor at the cell surface of a target cell

  • Binding to the receptor triggers a secondary messenger inside the cell (examples include cyclic AMP, or cAMP)
  • The secondary messenger activates a signaling cascade, which leads to the phosphorylation of specific enzymes, activating or inactivating them
  • Changing the activity of enzymes changes the activity of the cell
  • Peptide hormones include insulin, glucagon, leptin, ADH, and oxytocin
59
Q

Diagram showing how peptide hormones work

A
60
Q

Diagram showing action of steroid and peptide hormones

A
61
Q

What is epinephrine?

A

A peptide hormone produced by the adrenal glands in response to stress and during exercise.

62
Q

What is human growth hormone (HGH) or Somatotropin?

A
  • A protein hormone synthesised by the anterior pituitary gland.
  • It is involved in the regulation of bone and muscle growth.
63
Q

How can HGH be used in sports?

A

To induce anabolic effects

64
Q

What is the effect of HGH on the body?

A
  • It has been proven that HGH significantly reduces body fat mass and increases body cell mass and sprint capacity when administered together with testosterone.
  • Anabolic steroid hormones have several adverse effects, as they can produce sexual and mental problems and it increases the risk of coronary heart disease (CHD).
65
Q

What are some of the adverse effects of anabolic steroid hormones?

A
  • Increase in size of testes and ovaries, impaired spermatogenesis, growth of breasts in males.
  • Psychiatric disturbance.
  • Toxic to the liver.
  • Dyslipidemia (raised LDL and triglycerides and reduced HDL).
  • Hypertension.
  • Increased coagulation and platelet aggregation.
  • Exaggerated left ventricle growth.
66
Q

Hypothalamus

A
  • The hypothalamus is the section of the brain that links the nervous and endocrine systems to maintain homeostasis
  • It receives information from nerves throughout the body and other parts of the brain and initiates endocrine responses
  • It secretes neurochemicals (called releasing factors) into a portal system that target the anterior lobe of the pituitary gland
  • It also secretes hormones directly into the blood via neurosecretory cells that extend into the posterior pituitary lobe
67
Q

Pituitary Gland

A
  • The pituitary gland lies adjacent to the hypothalamus and is in direct contact due to a portal blood system
  • The pituitary gland receives instructions from the hypothalamus and consists of two lobes (anterior and posterior lobe)
68
Q

Anterior lobe of the pituitary

A
  • The anterior lobe is also called the adenohypophysis (‘adeno’ = relating to glands)
  • The hypothalamus produces releasing factors, which are released into portal vessels by neurosecretory cells
  • The releasing factors cause endocrine cells in the anterior pituitary to release specific hormones into the bloodstream
  • An example of a releasing factor is GnRH, which triggers the release of LH and FSH from the anterior pituitary
69
Q

Posterior lobe of the pituitary

A
  • The posterior lobe is also called the neurohypophysis (‘neuro’ = relating to nerves)
  • The posterior lobe releases hormones produced by the hypothalamus itself (via neurosecretory cells)
  • These neurosecretory cells extend into the posterior lobe from the hypothalamus and release hormones into the blood
70
Q

Diagram of endocrine signaling via the pituitary

A
71
Q

What is the function of the oxytocin released by the posterior pituitary gland?

A

It acts on the uterus, increasing contraction during childbirth, and breasts, inducing milk discharge in lactation.

72
Q

What is the function of FSH and LH?

A

They are involved in the growth of follicles and ovulation respectively in ovaries in females, and in sperm formation in testes in males.

73
Q

What is the function of TSH?

A

It is a hormone that induces the thyroid gland to produce thyroxin and other thyroid hormones.

74
Q

What is the function of ACTH?

A

It acts on the adrenal glands, inducing the production of steroid hormones such as cortisol.

75
Q

What is the function of somatotropin or growth hormone (GH)?

A

It stimulates growth, cell reproduction and regeneration in bones and soft tissues.

76
Q

Diagram showing ontrol of the pituitary gland by the hypothalamus

A
77
Q

What is the function of prolactin?

A

It is involved in milk production.

78
Q

Why do breasts increase in size during pregnancy?

A
  • Because of an increase in lobules and alveoli.
  • The release of estrogen and progesterone from the placenta and prolactin from the anterior pituitary causes this breast development.
79
Q

What kind of glands are mammary glands?

A

Exocrine glands

80
Q

Give the name of two major endocrine hormones involved in the initiation and control of lactation

A

Prolactin and oxytocin

81
Q

Overview of the role of hormones in breastfeeding

A
  • The production and secretion of milk by maternal mammary glands following birth is called lactation
  • It is predominantly controlled and regulated by two key hormones – oxytocin and prolactin
82
Q

Explain the role of prolactin in breastfeeding

A
  • Prolactin is responsible for the development of the mammary glands and the production of milk
  • It is secreted by the anterior pituitary in response to the release of PRH (prolactin-releasing hormone) from the hypothalamus
  • The effects of prolactin are inhibited by progesterone, which prevents milk production from occurring prior to birth
83
Q

Explain the role of oxytocin in breastfeeding

A
  • Oxytocin is responsible for the release of milk from the mammary glands (milk ejection reflex)
  • It is produced in the hypothalamus and secreted by neurosecretory cells that extend into the posterior pituitary
  • Oxytocin release is triggered by the stimulation of sensory receptors in the breast tissue by the suckling of an infant
  • This creates a positive feedback loop that will result in continuous oxytocin secretion until the infant stops feeding
84
Q

What is milk secretion an example of?

A

An exocrine gland controlled by the pituitary gland that at the same time is controlled by the hypothalamus.

85
Q

Which hormone requires iodine for its synthesis?

A

Thyroxine

86
Q

Growth hormone

A

Growth hormone (also known as somatotropin) is an anabolic peptide hormone that stimulates growth

  • It acts directly to reduce the formation of adipose cells (i.e. fewer nutrients stored as fat)
  • It acts indirectly via insulin growth factor (IGF) – produced by the liver – to increase muscle mass and bone size

Due to its role in promoting growth and regeneration, it is used by some athletes as a performance enhancer

  • The use of human growth hormone is banned in sports, with proven cases of doping strictly punished
  • Traditional urine testing could not detect doping, which historically made bans difficult to enforce
  • Recent blood tests can now identify between natural and artificial variants of growth hormone

IB HL Biology (68 decks)

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