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Human Biology: Unit 3 > Chapter 2 - Hormones Help Control The Body > Flashcards

Chapter 2 - Hormones Help Control The Body Flashcards

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1
Q

How is the coordination of the body achieved?

A

Through the activities of the NERVOUS SYSTEM and the ENDOCRINE SYSTEM.

  1. The nervous system exerts control by the transmission of nerve impulses to and from the various tissues.
  2. The endocrine system influences the activity of cells by the release of chemical messengers known as hormones.
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2
Q

What is the endocrine system?

A
  1. The Endocrine System influences the activity of cells by the release of chemical messengers known as Hormones.
    - Made up of ENDOCRINE GLANDS, which secretes hormones
    - Mainly concerned with keeping the environment inside the body fairly constant
    - Controls cellular activities through chemical messengers
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3
Q

What are the two types of glands in the body?

A
  1. EXOCRINE GLANDS

2. ENDOCRINE GLANDS

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4
Q

What do exocrine glands do?

A

Products/secretions Secrete into a duct that carries the secretion to the body surface or to one of the body cavities.

Examples: SWEAT GLANDS, MUCOUS GLANDS, SALIVARY GLANDS, GLANDS OF ALIMENTARY CANAL

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5
Q

What do endocrine glands do?

A

Secretes HORMONES into the EXTRACELLULAR FLUID that surrounds the cells that make up a gland.

  • Secretion USUALLY PASSED into the CAPILLARIES to be TRANSPORTED VIA BLOOD.

AKA ‘ductless glands’

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6
Q

What are Hormones?

A
  • A chemical SECRETED by an ENDOCRINE GLAND
  • AFFECTS the FUNCTIONING of a CELL/ORGAN
  • often CARRIED in the BLOOD
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7
Q

What are the three types of hormones?

A
  1. Proteins: Most common. Secreted by pancreas and pituitary.
  2. Steroids: (Lipid-based) secreted by adrenal cortex and gonads.
  3. Amine: (Amino acids) eg adrenaline and thyroxine
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8
Q

2 main characteristics of hormones:

A
  1. CHANGES the FUNCTIONING OF CELLS VIA CHANGING THE TYPE, ACTIVITIES, OR QUANTITIES OF PROTEINS PRODUCED.
  2. ARE NOT ENZYMES, however, in many cases, hormones CAN exert their influence by CHANGING THE ACTIVITY OF ENZYMES OR THEIR CONCENTRATIONS.
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9
Q

What particular activities can hormones do?

A
  1. ACTIVATE certain GENES in the NUCLEUS so that a particular ENZYME OR STRUCTURAL PROTEIN is PRODUCED
  2. CHANGE the SHAPE/STRUCTURE of an ENZYME that is TURNED ‘ON’ OR ‘OFF
  3. CHANGE the RATE of PRODUCTION of an ENZYME/STRUCTURAL PROTEIN by CHANGING THE RATE OF TRANSCRIPTION/TRANSLATION during PROTEIN PRODUCTION
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10
Q

What can hormones affect?

A
  1. ALL THE CELLS OF THE BODY
  2. ONLY PARTICULAR GROUPS OF CELLS, TARGET CELLS
  3. ONLY PARTICULAR ORGANS, TARGET ORGANS
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11
Q

What are steroid hormones?

A

A hormone derived from the lipid cholesterol

Examples: OESTROGEN, PROGESTERONE, CORTISOL, AND ALDOSTERONE

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12
Q

How do steroid hormones work?

A
  1. Once RELEASED into the BLOOD, the hormones BIND to TRANSPORT PROTEINS, ENABLING them to TRAVEL in the BLOODSTREAM.
  2. When they REACH TARGET CELLS, steroid hormones SEPARATE from the TRANSPORT PROTEINS and DIFFUSE ACROSS THE CELL MEMEBRANE
  3. INSIDE CELL MEMBRANE, they work by COMBINING WITH A RECEPTOR PROTEIN IN CYTOPLASAM OR NUCLEUS.
  4. HORMONE – RECEPTOR COMPLEX ACTIVATES the GENES CONTROLLING THE FORMATION OF PARTICULAR PROTEINS
  5. It does this by BINDING to the PROMOTER SECTION OF A CERTAIN GENE, STIMULATING/INHIBITING TRANSCRIPTION, and therefore protein synthesis.
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13
Q

What are Amine Hormones?

A

A hormone composed of AMINO ACID with modified groups.

eg. Melatonin, adrenal hormones epinephrine and norepinephrine, thyroxine.

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14
Q

What are Protein Hormones?

A

A hormone consisting of a LONG CHAIN OF AMINO ACIDS (a protein)

eg. FSH, GROWTH HORMONE, antidiuretic hormone (vasopressin), and oxytocin.

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15
Q

How do AMINE AND PROTEIN HORMONES WORK?

A
  1. Work by ATTACHING TO RECEPTOR PROTEINS ON TARGET CELL, FOUND ON THE SURFACE OF THE CELL MEMBRANE
  2. COMBINATION OF HORMONE with the SPECIFIC RECEPTOR (VIA LOCK AND KEY METHOD)
  3. CAUSES a SECONDARY MESSENGER SUBSTANCE to DIFFUSE THROUGH THE CELL
  4. ACTIVATE PARTICULAR ENZYMES in the CYTOPLASM
  5. THEREFORE, ADJUSTING CHEMICAL ACTIVITY OF THE CELL AND THE SPEED OF REACTIONS WILL EITHER INCREASE OR DECREASE

EXAMPLE:

HORMONE INSULIN BINDS to a RECEPTOR PROTEIN and this LEADS to an INCREASE in GLUCOSE ABSORPTION BY the CELL.

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16
Q

What are HORMONE RECEPTORS and their Characteristics??

A

They are Receptor proteins that are found on the cell membrane

  1. Receptor proteins are SPECIFIC
    - Each type of receptor will bind with only one specific molecule
    - The lock and key analogy can be used to describe this interaction: lock, the receptor protein, will only with the correct key, the binding molecule
  2. Different cells have DIFFERENT TYPES AND NUMBERS of receptor proteins
    - This is why there is variation in the sensitivities of cells to hormones and other substances
  3. There are LIMITED NUMBER of RECEPTOR PROTEINS IN THE MEMBRANE OF EACH CELL
    - When each receptor is bound to a molecule, there can be no further increase in the rate of the cell’s activity.

This means that SATURATION can OCCUR: once all the receptor molecules are occupied by hormone molecules, the ADDITION of more hormones does not produce any greater effect.

Eg. When each insulin receptor in the cell membrane is bound to insulin, the rate of the cell of glucose uptake cannot increase any further, even if the number of insulin increases

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17
Q

What is enzyme amplification?

A

a series of chemical reactions in which the product of one step is an enzyme that produces an even greater number of product molecules at the next step.

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18
Q

Explain the process of enzyme amplification

A
  1. 1 HORMONE MOLECULE DOES NOT cause the Manufacture/ Activation of just ONE MOLECULE OF THE ENZYME
    - Instead, ACTIVATES 1000s of molecules
  2. The hormone TRIGGERS a CASCADING EFFECT in which the NUMBER OF REACTING MOLECULES INVOLVED is INCREASED 100s or 1000s x for EACH STEP along the METABOLIC PATHWAY.
  3. 1 HORMONE MOLECULE can TRIGGER PRODUCTION of more than ONE BILLION ENZYME MOLECULES

Very SMALL STIMULUS = very LARGE EFFECT

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19
Q

What is Hormone Clearance? and how does it occur?

A

How a hormone used for the desired effect is removed from function and from the body.

  1. Once HORMONE PRODUCED the DESIRED EFFECT, then it must be TURNED OFF
  2. ACHIEVED by BREAKING DOWN HORMONE MOLECULES
  3. Some are BROKEN DOWN BY TARGET CELLS
  4. Most are BROKEN DOWN in KIDNEY OR LIVER
  5. DEGRADED HORMONES are then SECRETED in either in BILE OR URINE.
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20
Q

How are hormonal secretions regulated?

A

Body uses FEEDBACK SYSTEMS which body responds to a stimulus and puts in place a response to altering that stimulus.

Positive and negative.

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21
Q

What is negative feedback?

A

NEGATIVE FEEDBACK: response produced by the secretion of the hormone is the opposite of the stimulus that caused the secretion.

NEGATIVE FEEDBACK SYSTEMS – the response causes the stimulus to change in a direction opposite to that of the original change

◼Eg. Concentration of glucose in the blood:

◼Exercise muscles use up glucose

◼Muscles absorb glucose from blood  blood glucose levels fall (stimulus)

◼Liver releases more glucose into blood

◼Blood glucose levels rise again (change is opposite to original stimulus)

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22
Q

What does the hypothalamus and the pituitary gland do together?

A

Hypothalamus and pituitary gland work together to CONTROL THE FUNCTIONING OF MANY OF THE OTHER GLANDS.

  • Pituitary gland is often known as MASTER GLAND
  • they can be thought of as the COMMAND CENTRE FOR THE BODY
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23
Q

Explain the hypothalamus (LOCATION, ROLES, REGULATES

A

LOCATION: The part of the brain lying just below the thalamus and above the pituitary gland
- SIZE OF ALMOND

ROLES:
- in both nervous and endocrine systems, serves as a connection between both systems

REGULATES:
- BASIC FUNCTIONS of the Body: (HOMEOSTATIC MECHANISM) TEMPERATURE, WATER BALANCE, HEART RATE, INCREASING/DECREASING THE SECRETIONS OF OTHER GLANDS.

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24
Q

MANY FUNCTIONS OF THE HYPOTHALAMUS ARE CARRIED OUT THROUGH THE PITUITARY GLAND. explain how.

A
  1. The hypothalamus secretes RELEASING FACTORS, which STIMULATE the secretion of a hormone, or INHIBITING FACTORS, which slow down the secretion of a hormone.
    - FACTORS TRAVEL THROUGH BLOOD VESSELS TO THE ANTERIOR LOBE OF THE PITUITARY GLAND, affecting the secretion of its hormones.
  2. OTHER HORMONES are PRODUCED BY HYPOTHALAMUS and PASS ALONG the NERVE FIBRES to the POSTERIOR LOBE of the PITUITARY GLAND WHERE THEY ARE OFTEN RELEASED.
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25
Q

What are Releasing factors?

A

A hormone whose purpose is to control the release of another hormone.

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26
Q

What are Inhibiting Factors?

A

A hormone that slows the release of another hormone.

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27
Q

Explain the Pituitary Gland. (another name, LOCATION, SIZE, STRUCTURE)

A

Is an endocrine gland

Pituitary gland = HYPOPHYSIS

LOCATION: under the hypothalamus and is joined to the hypothalamus by a stalk called the infundibulum.

SIZE: - approximately large pea-size, 13mm DIAMETER

STRUCTURE:

  • Anterior (front and big) and posterior lobe (back and smaller)
  • each which functions separately
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28
Q

What is the INFUNDIBULUM?

A
  • AKA STALK

The stalk-like structure that joins the pituitary gland to the hypothalamus.

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29
Q

Explain the Anterior LOBE of the Pituitary Gland (LOCATION, STRUCTURE, ROLE, OTHER NAME, CONTROLLED BY)

A

LOCATION: Front and larger structure of the pituitary gland

STRUCTURE. HAS NO NERVES CONNECTING it to the hypothalamus

CONNECTED by a COMPLEX NETWORK OF BLOOD VESSELS LYING IN THE INFUNDIBULUM.

ROLE: RELEASES a NUMBER OF HORMONES that REGULATE A GREAT RANGE OF BODILY ACTIVITIES.
- can manufacture some of these hormones

CONTROLLED: SECRETIONS of the anterior lobe are in turn controlled by the RELEASING/INHIBITING FACTORS secreted by the HYPOTHALAMUS.

OTHER NAME: adenohypophysis

30
Q

What are the hormones secreted by the anterior pituitary gland?

A
  1. FOLLICLE STIMULATING HORMONE (FSH)
  2. LUTENSINING HORMONE (LH)
  3. GROWTH HORMONE (LH)
  4. THYROID STIMULATING HORMONE (TSH)
  5. ADRENOCORTICOTROPIC HORMONE (ACTH)
  6. PROLACTIN (PRL)
31
Q

What are gonadotropins? types and what they do?

A
  1. GONADROTROPINS - are hormones that affect the gonads. (OVARIES/TESTES)
  • FOLLICLE STIMULATING HORMONE (FSH)
    • STIMULATES the FOLLICLE DEVELOPMENT that contains eggs in the OVARIES in females.
    • STIMULATES PRODUCTION AND MATURATION OF SPERM in TESTES in males
  • LUTENISING HORMONE (LH)
    • AFFECTS OVARIES IN FEMALES: OVULATION AND MAINTENANCE OF THE CORPUS LUTEUM
  • AFFECTS TESTES IN MALES, STIMULATES INTERSTITIAL CELLS TO SECRETE TESTOSTERONE
32
Q

EXPLAIN GROWTH HORMONE (AND OTHER NAME)

A

(GH) or SOMATOTROPIN

  • A.P secretes
  • AFFECTS ALL CELLS for growth and protein synthesis
  • – SKELETON - growth
  • – INCREASES the RATE OF AMINO ACIDS TAKEN UP BY CELLS and built into proteins

— secreted throughout life as it helps to MAINTAIN the SIZE OF ORGANS ONCE MATURITY IS REACHED.

33
Q

EXPLAIN THYROID STIMULATING HORMONE ( AND OTHER NAME)

A
  • THYROTROPIN (TSH)
  • STIMULATES PRODUCTION AND RELEASE OF HORMONES FROM THE THYROID GLAND.

TARGET ORGAN - thyroid gland

34
Q

EXPLAIN ADRENOCORTICOTROPIC HORMONE (ANOTHER NAME)

A
  • ADRENOCORTICOTROPIN (ACTH)
  • Controls the production and release of some of the hormones from the cortex of the adrenal glands

target organ - adrenal cortex

35
Q

EXPLAIN PROLACTIN (ANOTHER NAME)

A

LACTOGENIC HORMONE (PRL)

  • Works with other hormones to initiate and maintain milk supply and production in females

TARGET ORGAN - MAMMARY GLAND

36
Q

Explain the POSTERIOR LOBE of the Pituitary Gland (LOCATION, STRUCTURE, ROLE, OTHER NAME, CONTROLLED BY)

A

LOCATION: REAR AND SMALLER PART OF THE pituitary gland

STRUCTURE: joined to the hypothalamus via NERVE FIBRES that COEM FROM NERVE CELL BODIES in the hypothalamus and PASS through the INFUNDIBULUM to the posterior lobe.

another name: neurohypophysis

ROLE: (not a true endocrine gland because it does not secrete substances)

  1. DOES NOT MANUFACTURE HORMONES, ONLY STORES AND RELEASES HORMONES PRODUCED IN SPECIAL NERVE CELLS IN HYPOTHALAMUS OF THE BRAN.
  2. these Cells have long extensions that pass through the infundibulum to the posterior lobe
  3. hormones manufactured in the cells move down the extensions and are stored ready for release into the bloodstream
  4. triggered by the NERVE IMPULSES INITIATED in the hypothalamus and are conducted along the cell extensiosn.
37
Q

What does the posterior lobe of the pituitary gland secret?

A
  1. oxytocin (OT)

2. Antidiuretic hormone (ADH)

38
Q

EXPLAIN OXYTOCIN

A

OT

  • stimulates the CONTRACTION of the muscles of the UTERUS
  • released in large quantities during labor
  • stimulates CONTRACTIONS OF CELLS in the MAMMARY GLANDS resulting in the RELEASE OF MILK during BREASTFEEDING

TARGET ORGANS - UTERUS AND MAMMARY GLANDS

39
Q

EXPLAIN ANTIDIURETIC HORMONE

A

ADH OR VASOPRESSIN
TARGET ORGAN: KIDNEYS

MAIN EFFECTS - reabsorption of water

Causes the KIDNEYS TO REMOVE WATER FROM URINE THAT IS FORMING

  • the WATER IS RETURNED TO BLOODSTREAM
  • in this way, ADH HELPS RETAIN FLUID WITHIN THE BODY
  • AT HIGH CONCENTRATIONS, CAN ALSO CAUSE CONSTRICTION OF SMALL ARTERIES, ARTERIOLES
  • why the alternative name is vasopressin
40
Q

LIST THE ENDOCRINE GLANDS

A
  1. HYPOTHALAMUS
  2. PITUITARY GLAND
  3. PINEAL GLAND
  4. THYROID GLAND
  5. PARATHYROID GLAND
  6. THYMUS
  7. ADRENAL GLANDS
    - CORTEX AND MEDULLA
  8. GONADS
  9. OTHER ADRENAL TISSUES
41
Q

What is the pineal gland?

A

LOCATED deep inside the brain

  • size of a pea (in children)
  • after puberty, it gradually decreases in size
  • IN ADULTS it is just a TINY LUMP of FIBROUS TISSUE

Role:

  • Functions of the hormones it secretes, remains something of a mystery, but it is
  • KNOWN TO MANUFACTURE AND SECRETE THE HORMONE MELATONIN - A hormone secreted by the pineal gland that regulates sleep patterns.
  • production of melatonin is STIMULATED BY LIGHT AND INHIBITED BY DARKNESS.
42
Q

Explain the Thyroid. (LOCATION, STRUCTURE, ROLE, OTHER NAME, CONTROLLED BY)

A

LOCATION: in the NECK, just BELOW the Larynx.

STRUCTURE:

  • BUTTERFLY SHAPE
  • Consists of 2 lobes THAT LIE ON EACH SIDE OF THE TRACHEA.
  • JOINED by a NARROW PIECE of TISSUE that LIES ACROSS THE FRONT OF THE TRACHEA. CALLED THE ISTHMUS

ROLE:
- Control of body’s metabolism.
- Has FOLLICULAR CELLS in the gland which SECRETE 2 HORMONES.
- CALLED: THYROXINE (T4) AND TRIIODOTHYRONINE (T3)
Target affects - most cells

CONTROLLED BY:

  • Anterior lobe of the pituitary gland
  • releases TSH
  • Reaches thyroid gland via bloodstream which stimulates the release of hormones.
  • Thyroxine or triiodothyronine
  • reaches target cells
  • increase of cell metabolism
  • REGULATION OF CALCIUM AND PHOSPHATE LEVELS IN THE BLOOD. (DECREASE WHEN TOO HIGH)
  • through the RELEASE OF CALCITONIN BY C-CELLS IN THE THYROID GLAND.
  • NOT CONTROLLED BY A.PIT.
43
Q

What are T3 AND T4 made up of and their differences?

A

Both hormones are based on the 2 molecules of the AMINO ACID TYROSINE.
Target cells- most cells

T4 is THYROXINE

  • has 4 iodine atoms attached
  • much LESS ACTIVE
  • 80% Produced by the thyroid gland
  • ONCE RELEASED ENZYMES CONVERT T4 INTO T3
  • LONGER HALF-LIFE (shelf life analogy) (5-7 days)

T3 is TRIIODOTHYRONINE

  • has 3 iodine atoms attached
  • 4x MORE ACTIVE
  • 20% produced by the thyroid gland
  • SHORTER HALF-LIFE (1 DAY)
44
Q

Explain how thyroxine is used:

A

Thyroxine is an AMINE HORMONE that controls the body’s METABOLISM.
- broken down by the body when released into T3.

  • BY REGULATING REACTIONS IN WHICH COMPLEX MOLECULES ARE SYNTHESISED FROM SIMPLE ONES.

OVERALL EFFECT of THYROXINE is to bring about the RELEASE of ENERGY, and some of the ENERGY RELEASED in the form of HEAT - MAINTAIN BODY TEMPERATURE.
- ALSO THE CONSUMPTION OF OXYGEN - needed for cell metabolism.

45
Q

Explain how CALCITONIN IS USED and its effects on calcium and phosphate levels in the blood.

A

VICE VERSA

Calcitonin is produced by the Thyroid gland and released via the C-cells.

WHEN CALCIUM CONCENTRATION IN THE BLOOD INCREASES:
thyroid gland RELEASES CALCITONIN
— REDUCES REABSORPTION OF CA by the KIDNEYS
— REDUCES THE BREAKDOWN OF BONE.

WHEN CONCENTRATION OF PHOSPHATE IS HIGH IN THE BLOOD.

  • – CALCITONIN ACTS TO MOVE PHOSPHATE INTO BONE
  • – REDUCES PHOSPHATE REABSORPTION IN KIDNEYS

ALLOWING PHOSPHATE AND CALCIUM CONCENTRATIONS TO DECREASE.

46
Q

Explain the Parathyroid gland. (LOCATION, STRUCTURE, ROLE, OTHER NAME, CONTROLLED BY)

A

LOCATION: REAR SURFACE of the LOBES of the THYROID GLAND.

STRUCTURE: 4 parathyroid glands (some may have more)
- size of a pea.

ROLE:

  • to SECRETE PARATHYROID HORMONE (PTH/PARATHORMONE)
  • which INCREASE CALCIUM LEVELS in the BLOOD and
  • INCREASE the PHOSPHATE EXCRETION in the URINE.
47
Q

Explain the PARATHYROID HORMONE.

A

released by the parathyroid gland (PTH OR PARATHORMONE)

  1. Normal level of Ca in the blood
  2. Ca LEVELS to LOW in the BLOOD
  3. Parathyroid gland RELEASES PARATHORMONE
  4. WORKS
    - in BONE: INCREASED Ca RELEASE into the BLOOD
    - in INTESTINES: INCREASED Ca ABSORBED FROM DIGESTION OF FOODS.
    - in KIDNEYS: INCREASED CALCIUM REABSORBED into the blood from the urine. Phosphorus is excreted in the urine.
  5. Negative Feedback
48
Q

Calcium and Phosphate levels work together, how?

A
  • The amount of phosphate in the blood affects the level of calcium in the blood.
  • Calcium and phosphate in the body react in opposite ways: as blood calcium levels rise, phosphate levels fall.
  • A hormone called parathyroid hormone (PTH) regulates the levels of calcium and phosphorus in your blood.
  • The phosphate builds up in your body and binds to calcium. This causes your calcium levels to decrease, which may weaken your bones.
49
Q

Explain the Thymus. (LOCATION, STRUCTURE, ROLE, OTHER NAME, CONTROLLED BY)

A

LOCATION: in the Chest ABOVE THE HEART and just BEHIND THE STERNUM.

Structure: Largest in infants, decrease in size and shrink after puberty.

Role: SECRETE A GROUP OF HORMONES CALLED THYMOSINS.

50
Q

What do thymosins do?

A

Hormones secreted from the thymus to INFLUENCE THE MATURATION OF DISEASE FIGHTING T-LYMPHOCYTES.

51
Q

Explain Adrenal Glands (LOCATION, STRUCTURE, ROLE, OTHER NAME, CONTROLLED BY)

A

LOCATION: 2 adrenal glands
- one immediately above each kidney

Structure:

  • Each adrenal gland has an INNER ADRENAL MEDULLA
  • OUTER ADRENAL CORTEX

– structure and function different
Each adrenal gland is really 2 separate endocrine glands.

52
Q

Explain the Adrenal Medulla role

A

Produces 2 hormones and releases them into the bloodstream.

  1. Adrenaline ( epinephrine )
    - similar effect of the sympathetic division of the autonomic nervous system
    - fight-or-flight
  2. Noradrenaline ( norepinephrine)
    - similar effect
53
Q

Explain the Adrenaline (AKA, ROLE)

A

Amine hormone secreted by the Adrenal Medulla helps to prepare the body for reaction to a threatening situation: that is concerned with ‘FIGHT OR FLIGHT’ RESPONSES.

also called epinephrine

TARGET: MOST BODY TISSUES

54
Q

Explain Norardenalaine

A

Amine hormone secreted and produced by the Adrenal medulla and has effects similar to those of adrenaline.
in particular: It INCREASES THE RATE AND FORCE OF THE HEARTBEAT.

TARGET: MOST BODY TISSUES

AKA Noraepinerphrine.

55
Q

Explain the Adrenal Cortex role.

A

the outer part of the adrenal gland.

  • MORE THAN 20 DIFFERENT HORMONES ARE PRODUCED COLLECTIVELY known as CORTICOSTEROIDS.
  • 2 main: aldosterone and cortisol
56
Q

Explain Corticosteroid:

A

Any group of more than 20 hormones secreted by the adrenal cortex: 2 main are aldosterone and cortisol

57
Q

Explain aldosterone

A

a corticosteroid that acts on the kidney to REDUCE the AMOUNT of SODIUM IONS and INCREASE the AMOUNTS of POTASSIUM IONS in URINE (EXCRETION).

TARGET CELL: KIDNEYS

58
Q

Explain Cortisol

A

cortisol which, related to hormones,

  • PROMOTES NORMAL METABOLISM
  • HELPING THE BODY WITHSTAND STRESS
  • REPAIR DAMAGED TISSUES

TARGET CELL: MOST BODY CELLS

59
Q

Explain the PANCREAS. (LOCATION, STRUCTURE, ROLE, OTHER NAME, CONTROLLED BY)

A

LOCATION: soft organ approximately 15cm long
- lies BELOW the STOMACH and ALONGSIDE the DUODENUM (first part of the small intestine)

BOTH AN EXOCRINE AND ENDOCRINE GLAND

ROLE AND STRUCTURE

  1. EXOCRINE GLAND
    - SECRETES DIGESTIVE ENZYMES INTO THE SMALL INTESTINES VIA PANCREATIC DUCT
  2. THE ENDOCRINE PART
    - made up of CLUSTERS of special cells called ISLETS OF LANGERHANS (ALSO CALLED PANCREATIC ISLET)

SECRETES 2 IMPORTANT HORMONES
- INSULIN AND GLUCAGON

60
Q

Explain the islets of Langerhans

A

Clusters of endocrine cells in the pancreas: secrete hormones insulin and glucagon

61
Q

Explain Insulin, ROLES AND HOW IT IS CONTROLLED

A

Secreted by the BETA CELLS OF THE ISELETS OF LANGERHANS.

Roles:

  1. BLOOD REDUCES the amount of GLUCOSE in the Blood (blood sugar level).
    - does this by PROMOTING THE UPTAKE OF GLUCOSE FROM THE BLOOD BY THE CELLS OF THE BODY.
  2. LIVER, insulin causes the CONVERSION of GLUCOSE — GLYCOGEN AND FAT.
  3. SKELETAL MUSCLES - FORMATION OF GLYCOGEN FROM GLUCOSE
  4. FAT STORAGE – GLUCOSE TO BE CONVERTED INTO FAT

CONTROLLED:
THE LEVEL OF SECRETION of insulin by the pancreas is DETERMINED BY THE AMOUNT OF GLUCOSE IN THE BLOOD and is controlled Through NEGATIVE FEEDBACK SYSTEM.

62
Q

EXPLAIN GLUCAGON. AND ROLE

A

A hormone produced in the pancreas and secreted by the ALPHA CELLS OF THE ISLETS OF LANGERHANS

Role:
- acts in the opposite way of insulin
Works to INCREASE BLOOD SUGAR LEVELS
- BY PROMOTING THE BREAKDOWN OF GLYCOGEN TO GLUCOSE IN THE LIVER

  • ALSO STIMULATES THE BREAKDOWN OF FAT IN THE LIVER and in the FAT STORAGE TISSUES.
63
Q

What are gonads?

A
  • primary reproductive organs (ovaries and testes)
  • their role is to produce sperm and egg
  • also part of the endocrine system glands because they produce hormones.
  • eg ANDROGENS, OESTROGEN, PROGESTERONE
64
Q

Explain Androgen. example and where are they produced?

A

Any of the male sex hormones produced by the testes: responsible for the development and maintenance of the male sex characteristics.

Eg. Testosterone

males - produced in the TESTES
females - produced in the OVARIES, ADRENAL GLANDS AND FAT CELLS
- however much lower in females.

65
Q

Explain Testosterone

A

An androgen hormone PRODUCED IN THE TESTES to

  • STIMULATE SPERM PRODUCTION
  • SKELETON GROWTH
  • MUSCLE GROWTH
  • DEVELOPMENT OF MALE CHARACTERISTICS

TARGET CELL- MANY TISSUES OF THE BODY

66
Q

Explain Oestrogen

A

Female sex hormone PRODUCED in the OVARIES

  • STIMULATE DEVELOPMENT OF FEMALE SEX CHARACTERISTICS
  • REGULATE MENSTRUAL CYCLE

TARGET CELL - MANY TISSUES OF THE BODY

67
Q

EXPLAIN PROGESTERONE

A

Female sex hormone PRODUCED by the OVARIES.

  • REGULATES MENSTRUAL CYCLE AND PREGNANCY
  • PREPARES MAMMARY GLANDS FOR MILK SECRETION

TARGET CELLS: UTERUS AND MAMMARY GLANDS

68
Q

What are endocrine tissues?

A

tissues that are not called endocrine glands that secret hormones.

69
Q

Example of ENDOCRINE TISSUES:

A
  1. STOMACH AND SMALL INTESTINE - secretes a hormone that coordinates the exocrine glands of the digestive system
  2. KIDNEYS - secrete a hormone called ERYTHROPOIETIN (EOP) - a hormone that stimulates the production of RBCs by the BONE MARROW
  3. HEART - secretes a hormone that helps REDUCE BLOOD PRESSURE
  4. PLACENTA - secrets a NUMBER of HORMONES during pregnancy that help
    - MAINTAIN pregnancy
    - STIMULATE DEVELOPMENT OF FOETUS,
    - STIMULATE MAMMARY GLANDS OF MUM.
70
Q

Explain the placenta

A

the organ that supplies nutrients to, and removes wastes from the foetus, also produces a number of hormones including oestrogen and progesterone.

Human Biology: Unit 3 (5 decks)

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