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Biology > Grade 12 Human Endocrine System > Flashcards

Grade 12 Human Endocrine System Flashcards

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1
Q

What is the endocrine system?

A
  • Consists of endocrine glands that secrete organic compounds, chemical messengers called **hormones. **
  • Different endocrine glands do not function in isolation -** interact continuously by means of their hormone secretions. **
  • Contributes to maintenance of homeostasis in that all metabolic activities in teh body are controlled and coordinated by the endocrine system.
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2
Q

What is an endocrine gland?

A
  • Ductless glands that release their secretions (hormones) directly into the blood stream.
  • The blood transports the hormones to the target organs where they perform their function.
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3
Q

What is an exocrine gland?

A
  • Glands that release their secretions via ducts to a body cavity or to the outside, e.g. salivary glands that secrete saliva into ducts that open in their mouth cavity.
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4
Q

Define chemical coordination:

A

A slow, prolonged process of communicating information throughout the body by way of chemicals called hormones.
* A variety of hormones are secreted by special glands or tissue called endocrine glands.

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5
Q

What is a hormone?

A
  • An organic chemical substance, usually a protein, sometimes a steroid, secreted by endocrine gland and carried in the bloodstream to target organ(s) where it regulates metabolic reactions.
  • Hormones may be regulated by a negative or postive feedback mechanism. (See example Answer series page 2.2)
  • Hormones do not last long in body and are **broken down by enzymes. **
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6
Q

What is a target organ?

A
  • Although carried by blood throughout body, they only affect certain cells.
  • Specific cells respond to a given hormone
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7
Q

How do exo- and endocrine glands differ?

A
  • Exocrine gland = secretions are carried in ducts to where they are needed e.g. salivary glands, liver, pancreas
  • Endocrine gland = Do not have ducts and their secretions are carried in the bloodstream to their target organs
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8
Q

List the endocrine glands and their most NB hormones:

A
  1. Hypothalamus = ADH (anti-diuretic hormone)
  2. Hypophysis / Pituitary gland = (TSH; FSH; LH; Prolactin; ACTH; ICSH; GH or STH
  3. Thyroid = Thyroxin
  4. Adrenal glands = Aldosterone; Cortisol; Adrenalin
  5. Pancreas = Insulin; Glucagon
  6. Ovary (female) = Oestrogen; Progesterone
  7. Testis (male) = Testosterone
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9
Q

What is a steroid?

A

#

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10
Q

Where is the hypothalumus located?

A

Part of the brain, above pituitary gland

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11
Q

What hormone is secreted by the hypothalumus?

A

ADH (anti-diuretic hormone)

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12
Q

Explain the funciton of ADH: (3 points)

A
  1. Osmoreceptors in blood vessels detect and increase osmolarity (low water levels) of blood.
  2. Conserve water if body is dehydrated – reabsorption from collecting ducts of kidney.
  3. Link between nervous system and endocrine system.
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13
Q

Where is the hypophysis / pituitary gland located?

A
  • Base of brain, attached to hypothalamus by short stalk.
  • Fits into bony cavity of cranium.
  • Anterior and Posterior lobe.
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14
Q

List the most NB hormones secreted by pituitary gland / hypophysis / master gland: (7 hormones)

A
  1. Thyroid stimulating hormone (TSH)
  2. Follicle stimulating hormone (FSH)
  3. Luteinizing hormone (LH)
  4. Prolactin
  5. Adrenocorticotropic hormone (ACTH)
  6. Interstitial cell stimulating hormone (ICSH)
  7. Growth hormone (GH) or STH (somatotropic hormone)
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15
Q

What is the function of TSH?

A

Stimulates thyroid gland to secrete thyroxine.

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16
Q

What is the function of FSH?

A

Stimulates Oogenesis (egg formation) & Spermatogenesis (sperm formation)

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17
Q

What is the function of LH?

A

Stimulates ovulation – release of an egg from ovary and formation of corpus luteum.

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18
Q

What is the function of prolactin?

A

Stimulates production of milk in mammary glands after birth & Maternal instinct.

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19
Q

What is the function of ACTH (Adrenocorticotropic hormone)?

A

Stimulates adrenal cortex to secrete cortisone and aldosterone.

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20
Q

What is the function of interstitial cell stimulating hormone (ICSH)?

A

Stimulates testes to secrete testosterone.

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21
Q

What is the function of growth hormone?

A

Promotes skeletal and muscular growth. How? Stimulates synthesis of proteins.

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22
Q

List growth disorders due to under or over secretion of Growth Hormone:

A

Dwarfism: Under-secretion (hyposecretion) of GH. Body is very short, with body parts in proportion. 91 – 122 cm. Normal mental ability – but no sexual maturity reached.
Treatment: Synthetic GH – by genetically engineered bacteria.

Gigantism: Over-secretion of GH in** children.** Tumour in hypophysis.
Acromegaly – in adults. Bones of face, hands and feet enlarged.

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23
Q

Where is the thyroid located?

A
  • Two lobes of butterfly-shaped gland
  • found on either side of the trachea just below the larynx (voice box)
  • in the front of the neck.
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24
Q

What hormone is released by thyroid?

A

Thyroxin
(which needs iodine for its production).

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25
Q

What is the function of thyroxin?

A
  1. Increases** basal metabolic rate** – production of body heat. How? Controls rate of cellular respiration.
  2. Normal functioning of heart.
  3. Normal functioning of nervous system – increasing nervous activity and sharpening alertness and reflexes.
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26
Q

Thyroxin is kept constant in blood by a negative feedback system. Discuss in detail.

A

Keeping thyroxin in blood constant - Negative feedback:
Interaction btw thyroid and pituitary gland

a) Pituitary detects decreased level of thyroxin – secretes more TSH
b) TSH stimulates thyroid to secrete more thyroxine, returning its level to normal.
c) **Higher level of thyroxine inhibits further TSH secretion.
See diagram Answer series page 2.5

27
Q

List disorders due to too little or too much thyroxin:

A
  • Hypothyroidism - myxoedema (adults) & cretinism (children)
  • Hyperthyroidism
28
Q

Explain the disorder of hypothyroidism:

A

Producing too little thyroxin – low metabolic rate. **
**Adults = myxoedema: **
* Mental and physical sluggishness / decline
* low blood pressure,
* slow heart and respiratory rate,
* low body term.

Children = cretinism. Child doesn’t grow physically, immature sexual development and mentally retarded. Cannot be reversed.

Treatment? Iodine supplements or synthetic iodine.

29
Q

Discuss the disorder of hyperthyroidism:

A

Producing too much thyroxin – high metabolic rate.
* High body temp and sweating
* Increased heart rate and blood pressure.
* Muscular tremors and nervousness.
* Swollen thyroid gland.
* Weight loss

Treatment? #

30
Q

Where is the adrenal gland located?

A

Located at the top of each kidney.
* Outer cortex
* Inner medulla.

31
Q

What hormones are secreted by adrenal gland?

A

Adrenal cortex:
1. Aldosterone
2. Cortisol

Adrenal medulla:
3. Adrenalin

32
Q

What is the function of ALDOSTERONE? (4)

A

Steroid hormone
1. Regulates ionic balance of the tissue fluid
1. Increases reabsorption of sodium and chloride ions from the filtrate in the renal tubes (kidney)
1. This facilitates movement of potassium ions from blood to filtrate.
1. Help to regulate electrolytic levels – vital for osmoregulation

33
Q

What is the function of CORTISOL? (2)

A
  1. Increases body’s ability to resist stress of all kinds.
  2. Anti-inflammatory.
34
Q

What is the function of ADRENALIN? (10)

A
  1. Secreted during stressful conditions – fight or flight.
  2. Prepares body for emergency.
  3. Accelerates and strengthens heart rate – more oxygen and glucose transported to muscles – cellular respiration – more energy to muscle activity.\
  4. Increases blood pressure – more blood to muscles, heart and brain
  5. Accelerates conversion of glycogen to glucose – increase blood glucose
  6. Increases rate and depth of breathing - dilating bronchi. More oxygen absorbed – faster energy release
  7. Increased muscle tone of skeletal muscle – faster response
  8. Increases sweat production – cool body down during activity.
  9. Pupils dilate – better vision during emergency
  10. Restricted digestive activity
35
Q

What is the pancreas and where is it located?

A

Made up of two types of cells -
* Exocrine pancreatic cells – secrete pancreatic juice into pancreatic duct, that leads to duodenum. Aids chemical digestions – digestive enzymes.
* **Islets of Langerhans **(small groups of endocrine cells) – secrete hormones directly into bloodstream. alpha & beta cells

36
Q

What hormones are released by the PANCREAS?

A
  1. Glucagon – produced by alpha cells.
  2. Insulin – produced by beta cells.
37
Q

What is the function of the pancreas?

A

Both – control level of blood sugar / glucose in blood.
Health human – 3.5 – 5.5 mmol/litre of blood

**1. Glucagon: **Secreted when blood glucose level drops below normal and it increases the glucose level.

**2. Insulin: **Secreted when blood glucose level rises above normal and it decreases the glucose level.

38
Q

What is glucose?

A
  • Simple sugar derived from digesting carbohydrates that are eaten.
  • Is a source of cellular energy.
39
Q

Glucose in the blood is regulated by the pancreas through a negative feedback mechanism. Discuss the process in detail where blood glucose rises ABOVE NORMAL (e.g. eating carb rich meal) !!!!

A

**Glucose concentration in blood rises above normal (when eating meal rich in carbs), **
a) beta cells in pancreas detects the increase and
b) responds by secreting insulin in bloodstream.
c) Insulin then stimulates absorption of glucose from blood into body cells & conversion of glucose to glycogen in the liver and muscles.
d) Glucose is removed from blood which decreases glucose concentration.
e) This decrease is detected by beta cells and insulin secretion is inhibited.

40
Q

Glucose in the blood is regulated by the pancreas through a negative feedback mechanism. Discuss the process in detail where blood glucose drops BELOW NORMAL !!!!

A

a) alpha cells in pancreas detects decrease
b) Responds by secreting glucagon into blood
c) Glucagon stimulates conversion of glycogen to glucose in liver
d) Liver releases glucose into blood - increased glucose concentration in blood.
e) Increased glucose detected by alpha cells and glucagon secretion inhibited.

(Study diagram on page 44 of textbook – Homeostatic control of glucose)

41
Q

What is Diabetes melllitus?

A
  • Metabolic disease / autoimmune – characterised by high glucose levels in blood
  • Chronic – cannot be cured
  • Normal conditions – glucose levels in blood kept constant by hormones insulin and glucagon. Insulin stimulates absorption of glucose from blood to body cells.
  • When insulin is absent/ functions ineffectively = most glucose remains in blood.
  • Causes an increased blood glucose level – hyperglycaemia.
  • Body cells do not receive enough glucose for cellular transpiration which releases energy for body functions.
42
Q

Explain the most prevalent symptoms of diabetes mellitus:

A
  • Frequent urination – at night
  • Increased thirst
  • Tingling hands or feet
  • Increased hunger
  • Weight loss
  • Repeated infections
  • Slow wound healing
  • Impaired vision
  • Exhaustion and dizziness
43
Q

What is the effect of hyperglycaemia / diabetes?

A
  • High blood glucose levels cause cells to lose water by osmosis – dehydration
  • May fall into coma and damage organs beyond repair
  • Long-term complications = blindness, kidney failure, cardiovascular disease
44
Q

What is Type 1 Diabetes and how is it treated?

A

Type 1:
Loss of insulin-producing beta cells in pancreas. Body attacking and destroying own beta cells.
Little or no insulin produced.

Treatment = daily insulin injections, adapted diet, regular testing of blood sugar levels

45
Q

What is Type 2 Diabetes and how is it treated?

A

Type 2:
Insulin resistance – pancreas produces insulin, but body cells cannot use it effectively.
Lifestyle disease – by overweight, age, inactivity.
Treatment: Maintenance of normal body mass; balanced diet; regular exercise; oral medication or insulin

46
Q

Where is the testes located?

A

Suspended outside body between legs and enclosed in sac, the scrotum.

47
Q

What hormone is secreted by the testes?

A
  1. Testosterone:
    Secreted by interstitial cells (Leydig cells), which occur in connective tissue between seminiferous tubules of testes.
48
Q

What is the function of testosterone?

A
  • Secondary male sexual characteristics e.g. deeper voice, facial hair, greater muscle mass.
  • Role in development of male sex organ during puberty
  • NB for sperm maturation & sperm quality
49
Q

Where are the ovaries located?

A

Located in the abdominal cavity on either side of the uterus.

50
Q

Which hormones are secreted by the ovaries?

A
  1. Oestrogen:
    Secreted by developing follicles in ovaries
  2. Progesterone:
    Secreted by corpus luteum in ovaries
51
Q

What is the function of oestrogen?

A
  • Secondary female sexual characteristics e.g. breasts, broader hips, fat layer under skin etc.
  • Role in dev of female sex organs during puberty
  • Thickening of endometrium (lining of uterus) and preparation of uterus for implantation
  • Inhibits FSH
52
Q

What is the function of progesterone?

A
  • Thickening of the endometrium and maintenance of endometrium during pregnancy
  • Suppress release of hormones FSH and LH
53
Q

Discuss in great detail the process of HOMEOSTASIS:

A

Study in textbook.

54
Q

How are hormones used in sport?

A

#

55
Q

Define homeostasis:

A

The maintenance of a constant internal environment in the human body

56
Q

Define body fluid:

A
  • includes blood plasma in the blood,
  • tissue fluid between cells and
  • cytoplasm inside cell.
57
Q

Define negative feedback system:

A
  • When the detection of a deviation from the normal results in a reaction that counteracts the change and returns it to normal.
  • The return to normal is detected and the correction action is switched off.
58
Q

The composition of bodily fluids constantly varies. List 7 conditions that MUST be kept constant for cells to function optimally:

A
  1. Blood glucose levels
  2. Water balance
  3. Ion and salt balance
  4. Oxygen and CO2
  5. Body temperature
  6. pH / acidity
  7. metabolic waste
59
Q

List 5 organs that function together to maintain a constant internal environment in the body:

A
  1. Liver
  2. Kidneys
  3. Skin
  4. Lungs
  5. Pancreas
60
Q

What is the function of receptors?

A

Detect changes

61
Q

State 2 ways in which information can be transmitted to the effectors: Receptors transmits info

A
  1. by means of hormones (chemical messengers) in the blood
  2. OR through nerve impulses via neurons
62
Q

State the function of effectors:

A
  • implement the reaction and correct the deviation
  • returning to levels of normal
63
Q
A

Biology (25 decks)

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