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12 HUMAN BIO ATAR > CH 2 HORMONES > Flashcards

CH 2 HORMONES Flashcards

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1
Q

how do the nervous and endocrine systems coordinate the many functions of the body?

A

nervous - transmits nerve impulses to and from the various tissues.
endocrine - influences activity of cells by the release of chemical messengers called hormones.&raquo_space; endocrine maintains homeostasis.

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2
Q

define homeostasis

A

maintenance of a relatively constant internal environment despite fluctuations in the external environment.

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3
Q

name all of the endocrine glands

12

A

pineal gland, hypothalamus, pituitary gland, thyroid gland, parathyroid glands, thymus, adrenal glands, kidneys, pancreas, ovaries, uterus, testes.

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4
Q

define exocrine glands

A

glands that secrete into a duct that carries the secretion to the body surface or to one of the body cavities. sweat glands, mucous glands & salivary glands are all examples of this.

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5
Q

define endocrine glands

A

secrete hormones into the extracellular fluid that surrounds the cells that make up the gland. the secretion then usually passes into the capillaries to be transported by the blood. ‘ductless glands’.

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6
Q

define hormones

A

special chemicals, secreted by endocrine glands, that are transported throughout the body in the blood. Hormones are only able to influence cells that have the correct receptor for the hormone.

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7
Q

how do hormones influence the functioning of cells?

A

they change the type, activities or quantities of proteins produced.

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8
Q

discuss the possible effects of hormones on enzymes

A
  • changing the activity of enzymes or their concentration.
  • they may activate certain genes in the nucleus so that certain enzymes or structural proteins are produced.
  • they might change the shape or structure of enzymes to turn them on or off.
  • they can also change the rate of production of an enzyme or structural protein by changing the rate of transcription or translation during protein production.
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9
Q

define steroid

A

type of hormone derived from the lipid cholesterol and is lipid soluble (not able to dissolve in water). they have a slow effect, but the effect is long-lasting.

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10
Q

give examples of steroid hormones

A

oestrogen, progesterone, cortisol, aldosterone, testosterone.

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11
Q

explain how a steroid travels through the body and functions on its target cells. (5 steps)

A
  1. steroids are released into the blood.
  2. they bind to transport proteins, enabling them to travel in the bloodstream.
  3. when they reach the target cells, the steroid hormones separate from the transport proteins and diffuse across the cell membrane.
  4. inside the cell they work by combining with a receptor protein in the cytoplasm or nucleus.
  5. the hormone-receptor complex activates the genes, controlling the formation of particular proteins. it does this by binding to the promoter section of a certain gene, stimulating or inhibiting transcription and, therefore, protein synthesis.
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12
Q

define protein and amine hormones

A

types of hormones that are water-soluble. tend to have a quick effect but the response is short-lasting.

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13
Q

explain how protein and amine hormones function on their target cells.

A
  1. hormones attach themselves to receptor proteins in the membrane of a target cell.
  2. the combo of hormone and receptor causes a secondary messenger substance to diffuse through the cell and activate particular enzymes.
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14
Q

why are receptor proteins ‘specific’? (lock and key)

A

receptor proteins are specific, meaning that each type will only bind to a specific molecule. if a receptor protein is a lock, it can only be unlocked by one key, the binding molecule.

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15
Q

discuss ‘saturation’ in relation to receptor proteins.

A

there is a limited number of receptor proteins in the membrane of each cell. when each receptor protein is bound to a molecule, the cell’s activity cannot increase further, e.g. if every protein is occupied by an insulin molecule, glucose up-take cannot increase further. instead, saturation would occur, meaning that once all proteins are occupied, addition of more hormones does not produce any effect.

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16
Q

discuss enzyme amplification

A

one hormone molecule activates thousands of molecules. enzyme amplification means that the amount of molecules affected increases by thousands along every step of the ‘metabolic pathway’. thus, a very small stimulus can produce a large effect.

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17
Q

explain ‘hormone clearance’

A

once hormones have done their job, they must be turned off by being broken down mostly in the liver or kidneys but sometimes in the target cells. the degraded hormones are then excreted either through the bile or urine.

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18
Q

how are hormone secretions controlled?

A

negative feedback systems regulate hormone secretions whereby the response produced by the secretions of the hormone is the opposite of the stimulus that caused the secretion.

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19
Q

why MUST hormone secretions be controlled?

A

any over or undersecretion of a hormone will cause the body to function abnormally. the body must maintain homeostasis

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20
Q

why is the pituitary gland sometimes referred to as the ‘master gland’?

A

the pituitary gland works closely with the hypothalamus to control the functioning of many of the other glands. combined, they can be thought of as the command centre of the body.

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21
Q

discuss key points of the hypothalamus.

A
  • located at base of brain, below thalamus, above pituitary gland. size of an almond.
  • has roles in both the nervous and endocrine systems and serves as a connection between the two systems.
  • regulates basic functions of body e.g. body temp, water balance and heart rate.
  • increases/decreases secretions of other glands through releasing/inhibiting factors
  • many functions carried out through pituitary gland
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22
Q

explain the function of releasing/inhibiting factors.

A

releasing factors stimulate the release of a hormone while inhibiting factors slow down the secretion of a hormone. these hormones travel through blood vessels to the anterior lobe of the pituitary gland, affecting the secretions of its hormones.

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23
Q

discuss key points of the pituitary gland/hypophysis

A
  • size of a pea, lies just under the hypothalamus and is joined to it by a stalk called the infundibulum.
  • split into 2 lobes; anterior and posterior
  • anterior not connected to hypothalamus through nerve fibres, rather by a network of blood vessels lying in infundibulum.
  • posterior connected through nerve fibres running through infundibulum that come from cell bodies in the hypothalamus. does not secrete substances, only stores them.
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24
Q

list the 6 hormones secreted from the anterior lobe of the pituitary gland and state their abbreviations.

A
  • follicle-stimulating hormone (FSH)
  • luteinising hormone (LH)
  • growth hormone (GH)
  • thyroid-stimulating hormone (TSH)
  • adrenocorticotropic hormone (ACTH)
  • prolactin (PRL)
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25
Q

what are gonadotropins?

A

gonandotropins (FSH & LH) affect the gonads, ovaries and testes.

26
Q

what are the functions of follicle-stimulating hormone?

A

in females, FSH stimulates developments of follicles that contain eggs in ovaries. in males, FSH stimulates the production and maturation of sperm in testes.

27
Q

what are the functions of luteinising hormone?

A

LH in females works with FSH to bring out ovulation and form the corpus luteum. in males, LH stimulates interstitial cells in testes to secrete male sex hormones.

28
Q

what are the functions of growth hormone?

A

GH aka somatotropin, stimulates body growth, particularly of the skeleton.

  • it increases the rate at which amino acids are taken up by the cells and built into proteins.
  • is secreted throughout life as it helps maintain the size of organs once maturity is reached.
29
Q

what are the functions of thyroid-stimulating hormone?

A

TSH aka thyrotropin, stimulates production and release of hormones from the thyroid gland.

30
Q

what are the functions of adrenocorticotropic hormone?

A

ACTH aka adrenocorticotropin, controls production and release of some of the hormones from the cortex of the adrenal glands.

31
Q

what are the functions of prolactin?

A

PRL aka lactogenic hormone works with other hormones to initiate and maintain milk production in females.

32
Q

what are the alternative names for the anterior lobe and the posterior lobe (of the pituitary gland)?

A

adenohypophysis (anterior) and neurohypophysis (posterior)

33
Q

where do the hormones stored in the posterior lobe come from?

A

hormones stored in the posterior lobe of the pituitary gland are made in special cells of the hypothalamus and are sent down to the PL along the infundibulum via long cell extensions.

34
Q

list the 2 hormones stored in the posterior lobe of the pituitary gland and state their abbreviations.

A
  • oxytocin (OT)

- antidiuretic hormone (ADH) / vasopressin

35
Q

what is the function of oxytocin?

A

OT stimulates contraction of the muscles of the uterus. it is released in large quantities during labour. it also stimulates contraction of cells in the mammary glands, resulting in release of milk during breast-feeding.

36
Q

what is the function of antidiuretic hormone?

A

ADH causes the kidneys to remove water from the urine that is forming. this water is returned to the bloodstream. ADH helps to retain fluid within the body. at higher concentrations it can also cause constrictions of small arteries, the arterioles (hence, ‘vasopressin’).

37
Q

discuss key points of the pineal gland.

A
  • found deep inside the brain
  • secretes melatonin, which is involved in the regulation of sleep patterns.
  • production of melatonin by the pineal gland is stimulated by darkness and inhibited by light.
  • responsible for your ‘biological clock’
38
Q

discuss key points of the thyroid gland.

A
  • located in the neck, just below the larynx.
  • consists of two lobes on either side of the trachea and are joined by a narrow tissue that lies across the front of the trachea.
39
Q

list the hormones secreted by the thyroid gland and state their abbreviations.

A
  • thyroxine (T4)

- triiodothyronine (T3)

40
Q

compare thyroxine and triiodothyronine.

A
  • T3 has 3 iodine atoms while T4 has 4 iodine atoms.
  • T4 is much less active than T3 but lasts longer
  • approximately 80% of thyroid hormones produced are T4 while only 20% are T3.
  • once released, enzymes convert T4 into T3.
41
Q

discuss the function of thyroxine.

A
  • controls body metabolism by regulating reactions in which complex molecules;
      • are broken down to release energy
      • are synthesised from simple ones.
  • overall effect: bring out the release of energy and, because the released energy is in the form of heat, to maintain body temperature.
42
Q

discuss the role the thyroid gland plays in relation to calcium and phosphate.

A
  • plays a role in regulating the levels of calcium and phosphate levels in the blood through the release of calcitonin by C-cells.
  • when the concentration of phosphate in the blood increases, the thyroid gland releases calcitonin, which reduces the reabsorption of calcium at the kidneys and the breakdown of bone.
  • if the concentration of phosphate is too high, calcitonin acts to move phosphate into bone and reduces its reabsorption by the kidneys.
  • these actions allow calcium and phosphate concentrations to decrease.
43
Q

discuss the key points of the parathyroid glands.

A
  • located in the rear surface of the lobes of the thyroid gland. usually around 4 parathyroid glands.
44
Q

name; the hormone secreted by the parathyroid glands, its abbreviation and its function.

A
  • parathyroid hormone (PTH) / parathormone

- increases calcium levels in the blood and phosphate excretion in the urine.

45
Q

discuss the key points of the thymus.

A
  • located in the chest just above the heart and behind the sternum. begins to shrink after puberty.
  • secretes a group of hormones called thymosins
  • thymosins influence the maturation of disease-fighting cells called T-lymphocytes.
46
Q

explain the location and structure of the adrenal glands.

A
  • two adrenal glands located immediately above the kidneys

- each gland has an inner structure called the adrenal medulla and an outer adrenal cortex

47
Q

discuss the function of adrenaline.

A
  • adrenaline helps the body to prepare for a reaction to a threatening situation (concerned with fight or flight responses)
48
Q

discuss the function of noradrenaline.

A
  • aka norepinephrine has effects similar to those of adrenaline.
  • in particular, it increases the rate and force of the heartbeat.
49
Q

define corticosteroid.

A

any of a group of more than 20 hormones secreted by the adrenal cortex. the main two are aldosterone and cortisol.

50
Q

discuss the function of aldosterone.

A

acts on the kidney to reduce the amount of sodium and increase the amount of potassium in the urine.

51
Q

discuss the function of cortisol.

A

with related hormones, cortisol promotes normal metabolism, helping the body to withstand stress and to repair damaged tissues.

52
Q

discuss the key points of the pancreas

A
  • both an exocrine gland and an endocrine gland.
  • the exocrine part secretes digestive enzymes into the small intestine through the pancreatic duct.
  • the endocrine part is made up of clusters of special cells called islets of langahans. these cells secrete insulin and glucagon.
  • insulin is secreted by the beta cells of the islets of langahan while glucagon is secreted by the alpha cells.
53
Q

discuss the function of insulin in different structures of the body.

A
  • in the blood: reduces BGL by promoting the up-take of glucose from the blood by the cells of the body.
  • in the liver: causes the conversion of glucose to glycogen and fat.
  • in skeletal muscles: causes formation of glycogen from glucose.
  • in fat storage tissue: causes glucose to be converted into fat.
54
Q

how is secretion of insulin controlled?

A

the level of insulin secreted by the pancreas is determined by the amount of glucose in the blood and is controlled through a negative feedback system.

55
Q

discuss the function of glucagon.

A
  • acts in opposite way to insulin
  • works to increase the blood glucose level, mainly by promoting the breakdown of glycogen to glucose in the liver.
  • also stimulates the breakdown of fat in the liver and in fat storage tissues.
56
Q

what are the gonads?

A

the testes and the ovaries.

57
Q

what are androgens?

A
  • any of the male sex hormones produced by the testes; responsible for the development of the male sex characteristics
  • females also produce them in the ovaries, adrenal glands and fat cells (levels much lower in females than males)
58
Q

what are oestrogen and progesterone?

A
  • the female sex hormones produced by the ovaries.
  • stimulate the development and maintenance of the female sex characteristics.
  • together with the gonadotropic hormones of the pituitary gland, they also regulate the menstrual cycle, and are involved with changes that occur during pregnancy.
59
Q

other endocrine tissues secrete hormones. give some examples.

A
  • the stomach and small intestine both secrete hormones that coordinate the exocrine gland of the digestive system.
  • the kidneys secrete hormones, including erythropoietin (EPO) - a hormone that stimulates the production fo red blood cells by the bone marrow.
  • the heart secretes a hormone that helps reduce blood pressure.
  • the placenta secretes a number of hormones during pregnancy that help to maintain the pregnancy, stimulate development of the foetus and stimulate the mother’s mammary glands.
60
Q

define amine hormone.

A

a hormone composed of an amino acid with modified groups.

61
Q

define negative feedback.

A

feedback that reduces the effect of, or eliminates, the original stimulus.

62
Q

define protein hormone.

A

a hormone consisting of a long chain of amino acids.

12 HUMAN BIO ATAR (13 decks)

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