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Biology > B3.2 The endocrine system > Flashcards

B3.2 The endocrine system Flashcards

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1
Q

What does the endocrine system consist of?

A

Glands, hormones and receptors

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2
Q

Endocrine glands

A

Ductless glands that secrete (release) hormones into the blood stream

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3
Q

Are Sweat, Salivary and tear glands part of the endocrine system?

A

No, they are part of the exocrine system. these glands secrete substances onto an epithelial surface by way if duct.

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4
Q

Hormones

A

chemical messengers which are secreted by endocrine glands in 1 part of the body and carried via the blood steam to target organs elsewhere in the body.

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5
Q

endocrine system duration of response?

A

long

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6
Q

Adrenaline

A
  • hormone secreted by the adrenal glands in ‘stressful’ situation to prepare body for ‘fight or flight’ response
  • — fight or fight is done to prepare the body for intense physical actions by:
  • adrenaline binds to receptors in the heart that causes the heart muscle to contract more frequently and forcefully to increase the heart rate & blood pressure. consequently the blood flows to the muscles increases and the cells receive more O2 and glucose for increased respiration
  • adrenaline also binds to the receptors in the liver causing the lover to break down its glycogen stores to release glucose. By increasing the blood glucose level, there is more glucose in the blood to be transported to the cells for increased respiration.
  • Breathing rate increases to cope with extra demand for O2
  • once the stress / situation stops or is removed adrenaline will stop being produced and the body system returns to its previous state.
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7
Q

Thyroxine

A
  • hormone secreted by the thyroid gland in order to regulate the body’s metabolic rate (the speed at which the body transfers chemical stores in order to perform functions such as growth)
  • the thyroid stimulating hormone (THS) which is released from the pituitary gland, stimulates the release of thyroxine
  • negative feedback is the system that ensures the thyroxine levels in the blood are normal. it is important in keeping the other internal conditions at a constant. - - when thyroxine levels are too high the secretion of TSH from the pituitary gland is inhibited / stopped / slowed.
  • the thyroid gland converts iodine into thyroxine by combining it with an amino acid called tyrosine. if iodine is lacking from the diet the thyroid gland will enlarge in its attempt to produce thyroxine - produces large swelling called a goitre.
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8
Q

Oestrogen and Progesterone

A

Role - ovulation and menstruation
Gland - ovaries
target organs - uterus, pituitary gland
Oestrogen and progesterone –> pituitary glands and hypothalamus –> LHRH –> pituitary –> LH and FSH –> uterus

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9
Q

Testosterone

A

Role - gives body its masculine characters - changes during puberty sand sperm production
Gland - testes
target organs - various

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10
Q

ADH

A

Anti-diuretic hormone regulates water level in the bloodstream
gland - pituitary gland
helps control blood pressure by acting on kidneys and blood vessels. conserves the fluid volume of your body by reducing the amount of water passed out in urine.

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11
Q

Pituitary Gland

A

The ‘master gland’ - secretes nine hormones that directly regulate many body functions.
Disorders - gigantism is if too much growth hormone is produced in early childhood. too little growth hormone produced can result it pituitary dwarfism.

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12
Q

Negative feedback

A

A type of control that keeps internal conditions constant in the body.
any change away from normal level brings about mechanisms to reverse the change and bring the levels back to normal - if body temp decreases heating mechanism is activated (shivering), if body temp increases cooling mechanism is activated (sweating)

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13
Q

Controlling Thyroxine if needed

A
  • Thyroxine controls how much energy is available to cells. the hypothalamus detects if more is needed. it causes the pituitary gland to release TSH (thyroxine stimulating hormone.) this causes the Thyroid to release thyroxine. this increases the metabolic rate and energy available to cell
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14
Q

Negative feedback practical

A

Equipment - beaker, Bunsen burner, safety mat, tripod, gauze, thermometer, safety glasses
Half - fill beaker with water
Heat water to exactly 50 degrees Celsius and try to maintain it at this temp for 10 mins

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15
Q

Controlling Thyroxine if not needed

A

Hypothalamus detects when cells have enough energy. It then stops the pituitary gland from producing TSH. the thyroid gland stops producing thyroxine and less energy is released to cells.

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16
Q

Stages in the menstrual cycle - the follicle

A
  • girls are born with thousands of follicles (potential eggs) in each ovary
  • At puberty some of the follicles start to develop - the cell divides by meiosis halving the number of chromosomes in the nucleus
  • A follicle starts to develop at the start of the cycle - it enlarges and fills with fluid - after 2 weeks it bursts and releases the egg - this is ovulation. Follicle cells left behind form the yellow body (corpus luteum) which supports the lining of the uterus during pregnancy.
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17
Q

Stages in the menstrual cycle - the uterus lining

A
  • the uterus lining starts to thicken with blood vessels and glands
  • if fertilisation occurs the egg cell divides by mitosis to form a ball of cells and this implants in thickened uterus.
  • If fertilisation does not occur the egg dies and the yellow body and uterus lining break down and are lost during menstruation
  • the menopause occurs between the ages 45 and 55 when the menstrual cycle stops
18
Q

Hormones produced by the ovary

A
  • Oestrogen - repairs lining of uterus, stimulates pituitary gland to produce LH.
  • Progesterone - maintains lining of uterus, inhibits production of FSH by the pituitary gland.
  • Corpus luteum ( yellow body or empty follicle) produces progesterone
  • placenta - takes over production when corpus luteum degenerates
19
Q

Levels of hormones during….

A

…. the menstrual period - Oestrogen and progesterone levels drop
…. before ovulation - Oestrogen peaks
…. after ovulation - progesterone peaks

20
Q

Hormones produced by the pituitary gland

A
  • FSH (follicle stimulating hormone) - causes follicle to develop, stimulates ovary to produce oestrogen
  • LH (luteinising hormone) - cases ovulation to take place, stimulates production of progesterone by the ovary.
21
Q

Interactions

A

FSH stimulates production of Oestrogen
Oestrogen stimulates production of LH (LH –> ovulation)
LH stimulates production of Progesterone
Progesterone inhibits/prevents production of FSH
Oestrogen inhibits/prevents production of FSH

22
Q

Mechanical methods of contraception

A
  • IUD/IUS (intra-uterine device/system)/coil - prevents sperm getting through uterus/implantation- may also contain hormones
  • Diaphragm/cap - stops sperm entering uterus
  • Condom - stops sperm entering woman’s body
  • Femidom - like a condom but in woman
23
Q

Chemical methods of contraception

A
  • Oral contraceptive pill - oestrogen and progesterone inhibit/prevent FSH - no eggs mature. Taken everyday by the woman
  • Implant/injection - slow release hormones lasts up to 3 yrs
  • Spermicides - cream inserted into vagina containing sperm killing chemicals - normally used with diaphragm
24
Q

Natural methods of contraception

A
  • Abstinence - don’t have sex

- Rhythm method - avoiding sex around time of ovulation. Can take temp or check viscosity of cervical mucus.

25
Q

Surgical methods of contraception

A
  • only to be used if couple are sure they don’t want any more children
  • Vasectomy - sperm tubes are cut and tied
  • Female sterilisation - oviducts are cut and blocked
26
Q

IVF = In-vitro fertilisation

A
  • for couples who may have difficulty falling pregnant
  • the woman is given sex hormones (normally FSH) so she produces lots of eggs which are then harvested
  • sometimes a drug is given to make the pituitary gland insensitive to oestrogen
  • The man’s sperm are mixed with the eggs in a dish in a laboratory
  • the fertilised eggs are implanted into the woman’s uterus
27
Q

Artificial insemination (AI)

A
  • This is when semen is artificially inserted in the vagina using a syringe
28
Q

The menstrual cycle

A
  • typically lasts 28 days
    1. cycle starts when menstruation starts at day 1 - this is the process of the uterus lining breaking down and being released.
    2. eventually the uterus lining will build up from day 4-14
    3. By day 14 an egg has developed in the ovary and is released (ovulation)
    4. The uterus lining is then maintained for the remaining 14 days, if no egg has implanted (nothing has been fertilised) onto the uterus wall by day 28, the lining starts to break down, marking the beginning of a new cycle which is repeated
29
Q

Plant hormone

A
  • chemical messengers produced in one part of a plant (source) and has an effect on another part (target) of the same plant.
  • also called plant growth regulators
  • Controls - pattern of growth and development and responses to environmental conditions
30
Q

Auxin

A

a plant hormone that controls cell elongation and cell division - therefore controlling the plant movements as a result of different rates of cell elongation

31
Q

Different types of tropism

A
  • Phototropism
  • Geotropism / gravitropism
  • Hydrotropism
32
Q

Geotropism / Gravitropism

A

The growth of a living organism in response to gravity.
Positive geotropism is the growth of an organism (i.e. plants) towards the centre of the earth (roots of a plant)
Negative geotropism is the growth of an organism (i.e. plants) away from the centre of the earth (stem/leaves of a plant)

33
Q

Importance of geotropism

A
  • Provides firm anchorage for roots

- ensures the plant can get an adequate supply of water and mineral salts

34
Q

Phototropism

A

The growth response of an living organism on response to light direction
Positive phototropism - living organisms grow towards the light, for example stems are positively phototropic
Negative phototropism - living organisms grow away from the light, for example roots are negatively phototropic

35
Q

Importance of Phototropism

A

Enables leaves to be in a position receive as much sunlight as possible for photosynthesis.

36
Q

Hydrotropism

A

The growth of living organisms in response to water. Hydrotropism is the directed growth of the root in relation the gradient in moisture, it begins in the root cap with the sensing of the moisture

37
Q

Positive and negative hydrotropism

A

Positive and negative phototropism exist in living organisms and its direction of growth depends upon a stimulus or gradient in water concentration.
Growing towards water - positive phototropism
Growing away from water - negative phototropism

38
Q

Importance of hydrotropism

A

Ensures a plant gets enough water as a raw material for photosynthesis and enough mineral salts to maintain normal growth

39
Q

Experiment - showing geotropism in seedlings

A

leave in darkness to avoid any stimulus from light
the radicles in the diagram show positive geotropism
Advantages seedlings have of showing this geotropism - roots grow down, deep into the soil to provide a firm anchorage underground and absorb water and mineral salts into the soil

40
Q

What is a Clinostat?

A
  • used for controlling experiments
  • contains a cork disk which can be set to rotate in a vertical or horizontal plane by motor
  • used to make factors uniform (evenly distributed)

Biology (12 decks)

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