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Biology Module 5 > Hormonal Communication 5.1.4 > Flashcards

Hormonal Communication 5.1.4 Flashcards

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1
Q

What is the pathway of Hormonal communication?

A

Stimulus->Receptor->Hormone->effector

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2
Q

What is an endocrine gland?

A

-An endocrine gland is a group of specialised cells that secrete hormones directly into the bloodstream
E.g Pancreas

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3
Q

What is an exocrine gland?

A

-A gland which has a duct through which chemicals are released
E.g bile duct

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4
Q

How do steroid hormones affect the cell?

A
  1. They are lipids so soluble and hydrophobic so pass through the membrane
  2. They then bind to steroid hormones receptors forming a hormone-receptor complex which attaches to DNA and controls transcription (becomes a transcription factor)
  3. Receptors are found in the cytoplasm of the nucleus
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5
Q

How do Non-steroid hormones effect the cell?

A
  1. They are hydrophilic so cannot pass directly through the cell membrane
  2. Binds to specific receptors on the surface of the cell membrane of target cells
  3. This triggers a cascade of reactions mediated by chemicals called secondary messengers e.g. adrenaline
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6
Q

Is a non-steroid hormone a peptide?

A

-Yes

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7
Q

What is the hormonal system made of and what are they?

A

-It is made up of endocrine glands and hormones
-Endocrine glands are groups of specialized cells that produce and secrete hormones
-Hormones are chemical receptors

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8
Q

Are hormones specific?

A

-Yes, each hormone will only bind to a specific receptor found on the membranes of target cells

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9
Q

How do first and secondary messengers work?

A

-The first messenger is the hormone that brings the information from the endocrine gland and binds to a receptor on the cell surface membrane
-This activates an enzyme which catalyses the production of a signalling molecule (secondary messenger)
-The secondary messenger activates a cascade of reactions

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10
Q

How does adrenaline work?

A

-First messenger so binds to a receptor on the liver cell which activates an enzyme called adenylyl cyclase
-This increases the production of cyclic AMP which activates a cascade of chemical reactions to increase availability of glucose

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11
Q

What does the pituitary gland control and the 3 main types of hormones produced by the adrenal cortex?

A

-It controls the release of hormones from the adrenal cortex
-The three main hormones are: glucocorticoids, mineralocorticoids and Androgens

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12
Q

What is the function of glucocorticoids?

A

-Helps control the metabolism of carbohydrates, fats and proteins in the liver -Stimulates the breakdown of protein and fats into glucose which increases the amount of energy available so brain and muscles can respond.

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13
Q

What is the function of Mineralocorticoids?

A

-Maintains the blood pressure by controlling sodium and potassium concentration
-Acts on distal convoluted tubules and collecting ducts of the kidney increasing reabsorption of sodium and decreases reabsorption of potassium, this also increases water retention

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14
Q

What is the function of Adrenaline?

A

-Increases heart rate, quickly sending blood to brain and muscles
-Rapidly raises glucose concentration levels by converting glycogen to glucose in the liver

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15
Q

What is the function of noradrenaline?

A

-Works with adrenaline in response to stress, producing increased heart rate
-Widening of pupils, air passages and narrowing of blood in non-essential organs (higher blood pressure)

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16
Q

What are the two major roles of the pancreas?

A

-Controls glucose concentration and digestion

17
Q

What are the three most important digestive enzymes produced by the pancreas?

A

-Amylase: breaks down starch into simple sugars
-Proteases: breaks down proteins into amino acids
-Lipases: breaks down lipids into fatty acids and glycerol

18
Q

How are digestive enzymes secreted and Hormones in the pancreas tissue?

A

-Each acinus (gland in pancreas) has a central duct where digestive enzymes are secreted, this joins up to the main pancreatic duct where it is then released into small intestines
-Islet of Langerhans are supplied with capillary networks, hormones are secreted directly into blood here.

19
Q

What is the name of the exocrine tissue involved in production of digestive tissue?

A

-Acini

20
Q

Which two cells are found in the islet of Langerhans and what does each type of cell produce?

A

-Alpha cells: produce and secrete glucagon
-Beta cells: produce and secrete insulin

21
Q

What is the difference in appearance between the islet of Langerhans and Pancreatic acini?

A

-Islet of Langerhans: lightly stained and Large spherical dusters
-Pancreatic acini: Darker stained and small clusters

22
Q

Why would blood glucose concentration increase?

A

-Diet: eating carbohydrate rich foods
-Glycogenolysis: glycogen stored in the liver and muscles is brocken down and released into blood stream as glucose
-Gluconeogenesis: production of glucose from carbohydrate sources

23
Q

Why would blood glucose concentration decrease?

A

-Respiration: some of the glucose in the blood is used to release energy
-During exercise: more glucose is needed to release energy for muscles to contract
-Glycogenesis: Glucose is converted into glycogen and stored in liver and muscle cells

24
Q

How does the negative feedback of blood glucose level work? (when blood glucose level rises)

A

1.Blood glucose rises and is detected by beta cells in pancreas which release insulin
2.Insulin increases cellular respiration, the conversion of glucose to glycogen, glucose to fat and absorption of glucose into cells
3. This causes blood glucose levels to fall

25
Q

How does the negative feedback of blood glucose level work? (when blood glucose level falls)

A

1.Blood glucose levels fall and is detected by alpha cells which produce and release glucagon
2. This increases the conversion of glycogen to glucose, amino acids to glucose and causes an uncontrolled quantity of glucose to enter from intestines
3. Blood glucose levels rise

26
Q

What does it mean when insulin and glucagon are antagonistic hormones?

A

-They work against each other

27
Q

How do beta cells maintain a p.d of 70mV when blood glucose concentration is low or at a normal level?

A

-k+ channels are open and Ca2+ channels are closed, K+ ions move out of the cell keeping the cell membrane at 70mV

28
Q

How do Beta cells release insulin when blood concentration is too high?

A
  1. As blood glucose concentration has increased glucose will move into beta cell via a glucose transporter and is metabolised producing ATP
  2. Excess ATP causes K+ channels to close preventing K+ ions from diffusing out causing a change of P.D. (-70 to -30mV)
  3. This causes Ca2+ channels to open and Ca2+ ions diffuse in, this increase stimulates vesicles containing insulin to fuse with cell surface membranes
  4. Insulin is released by exocytosis into the blood
29
Q

How does insulin act on liver cells?

A
  1. Insulin binds to complementary receptors on target cells
  2. This activates the enzyme tyrosine kinase which causes phosphorylation of the inactive enzyme.
  3. This triggers a cascade of enzyme-controlled reactions
30
Q

What are the effects of insulin?

A

-Glycogenesis, more glucose is converted to fats and is used in respiration
-Vesicles containing glucose transporters proteins fuse with cell surface membranes making them more permeable to glucose
-Glucagon is inhibited

31
Q

What are the effects of glucagon?

A

-Insulin is inhibited
-Glycogenolysis and gluconeogenesis( amino acids and fats into glucose)
-More fatty acids are used in respiration

32
Q

What is diabetes and type 1 and type 2?

A

-Diabetes is the inability to control blood glucose concentration
-Type 1: unable to produce insulin, autoimmune response that normally develops in childhood
-Type 2: either body cells do not properly respond to insulin or the amount produced is too little

33
Q

What are the consequences of insufficient quantity of insulin?

A
  • Blood glucose is not removed quickly so stores of glycogen are too low and blood glucose concentration inside cells is too low
34
Q

What are the risk factors of Type 2 diabetes?

A

-Obesity, high sugar diet, sedentary lifestyle, family history and afro or Asian heritage

35
Q

How is type 1 diabetes treated?

A

-They can receive regular injections of insulin
-Insulin pump therapy: constantly pumps insulin into blood through a permanent needle
-Pancreas and islet cell transplantation
-Stem cells

36
Q

Why is insulin produced by genetically engineered bacteria rather than from pigs?

A

-Less moral objections
-Cheaper and lower risk of rejection
-Human insulin is faster acting and more effective

37
Q

What are type 2 diabetes treatment?

A

-Lose weight and exercise regularly
-Insulin injections
-Take medication to slow down absorption of glucose, reduce the amount of glucose released by liver and increase the amount of insulin released from pancreas

Biology Module 5 (4 decks)

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