Hormonal Communication

Question 1

Describe islets of langerhans

Answer 1

Large spherical clusters made of endocrine pancreas tissue, secrete and produce hormones
Within islets are different cells classified according to the hormone they secrete
Alpha cell, produce and secrete glucagon
Beta cells, produce and secrete insulin
Alpha cells are larger and more numerous than beta cells within an islets

Question 2

Describe the acini

Answer 2

Small berry like clusters, exocrine tissue, produce and secrete digestive enzymes
Enzymes secretes into ducts which lead into pancreatic ducts
Released into the duodenum, top of the small intestine

Question 3

Where are the islets of langerhans and acini found

Answer 3

Pancreas

Question 4

Target tissue

Answer 4

Any tissue which contains a large number of target cells

Question 5

Target cells

Answer 5

Cells that posses specific receptors that a specific hormone will bind to in order to produce a response

Question 6

Hormones

Answer 6

Released by endocrine glands
Carried in blood
Act as Chemical messengers

Question 7

Exocrine gland

Answer 7

Secretes chemcials into ducts which carry hormone to another place in body

Question 8

Peptide hormones

Answer 8

Hormones made of amino acids
E.g Adrenaline, insulin, glucagon
Cannot pass through phospholipid bilayer

Question 9

Steroid hormones

Answer 9

Lipid based
Can pass through phospholipid bilayer
Have direct effect on DNA
E.g cortisone

Question 10

How glucose level is increased

Answer 10

Diet- eating carbohydrate rich foods which get broken down into sugars (glucose)
Glycogenolysis- glycogen stored in the liver+muscle cells are broken down into glucose
Gluconeogenisis- production of “new “ glucose from breaking down non carbohydrate sources e.g lipids and amino acids

Question 11

Detection of high levels of glucose

Answer 11

Detected by beta cells in islets of langerhans

Secrete insulin into blood stream

Question 12

How insulin lowers blood glucose

Answer 12

Increase uptake of glucose by cells,
Increased respiratory rate of cells,
Increased rate of glycogenesis increased conversion of glucose to glycogen
Inhibit release of glucagon from alpha cells

Question 13

Causes of decrease in blood glucose

Answer 13

Respiration- glucose in blood is used by cells to release energy, during exercise more glucose is needed
Glycogenesis- production of glycogen, excess glucose is taken out of diet and turned into glycogen

Question 14

Detection of lower levels of blood glucose

Answer 14

Alpha cells in islets of langerhans

Secrete glucagon into bloodstream

Question 15

How glucagon raises blood glucose concentration

Answer 15

Glycogenolysis- the liver breaks down its glycogen store
Reducing amount glucose absorbed by the liver cells
Increasing gluconeogenesis - increasing the conversion of AA + glycerol into glucose

Question 16

Control of insulin secretion

Answer 16

• at normal level of glucose potassium channels are open ( -70mv resting potential inside cell)
• when glucose levels rise, glucose enters the cell via glucose transporter
• glucose is metabolised inside the mitochondria, resulting in production of ATP
• ATP binds to ATP sensitive potassium channel causing the channels to close
• potassium ions can no longer diffuse out of the cell, depolarisation occurs, potential difference rises to -30mv
• depolarisation causes the voltage gated calcium channels to open
• calcium ions enter the cell causing secretory vesicles to release the insulin they contain by exocytosis

Question 17

Name Hormone secreted from the adrenal cortex

Answer 17

aldosterone, cortisol

Question 18

Which gland is ductless

Answer 18

Endocrine gland

Question 19

Cell whose metabolism is altered by the binding of a hormone

Answer 19

Target cell

Question 20

Difference between hormonal and neuronal

Answer 20

Hormones are secreted into the blood stream via gland whereas, neuronal- electrical impulses are carried by synapses.
Hormones bind to target receptors to trigger a response whereas electrical impulses stimulate a response in an effector
Hormonal is a slower response compared to neuronal which is much faster
Hormonal is a widespread long lasting response whereas neuronal is a localised short lasting response

Question 21

Outline the hormonal and nervous mechanisms involved in the control of the heart rate

Answer 21

Hormones ( adrenaline) are released into blood stream, having a direct effect on SAN causing it to produce more electrical impulses increasing HR due to the fight/flight response
Controlled nervously by the vagus nerve and the accelerator nerve which decrease and increase heart rate respectively.
Barco/ chemo receptors stimulate a particular nerve centre in the medulla oblongata linked by a motor neurone directly to SAN
Chemo receptors detect a increase in co2 levels, leading to an increase is heart rate

Question 22

Where are insulin moleuces synthesised

Answer 22

Ribosmes are the RER in beta cells in the pancreas

Question 23

Purpose of homeostatic mechanisms

Answer 23

To keep their internal body conditions near constant

Question 24

Endocrine system

Answer 24

Sectres hormones, chemcial messangers, into the blood which transmit infomation from one part of fhe organism to another to bring about change
They alter the activity of target organs

Question 25

Definition of a gland

Answer 25

Group of cells that produce and relsease one or more stubstances

Question 26

How hormones bring about a response

Answer 26

Transported round the body in the blood to target cells/tissues to bring about a response Only affect cells with receptors that the hormone can bind to Receptors must be complimentary

Question 27

Adrenal glands

Answer 27

2 small glands located at the top of the kidney Adrenal cortex - outer reigon of glands, produces hormones that are vital to life such as cortisol and aldosterone Adrenal medulla - inner reigon of the gland which produce non essential hormones such as adrenaline

Question 28

Adrenal cortex and the hormones they secrete

Answer 28

Production of hormones by the adrenal cortex is controlled by the hormones released from the pituarty gland 3 types of hormone: Glucocorticoids - includes cortisol, help regulate metabolism Mineralcorticoids - produces aldosterone which help maintain blood pressure by regulating water and salt concentrations Androgens - small amounts of male and female sex hormones

Question 29

Adrenal medulla

Answer 29

Hormones of the adrenal medulla are released when the sympathetic nervous system is stimulated Hormones secreted are: adrenaline - increases the heart rate sending blood quickly to the muscle and brain, also converts glyogen to glucose liver Noradrenaline - works with adrenaline in response to stress prodlucing effects such as increased heart rate, widening of pupils, widening of air passages, and vasoconstriction in non essential organs

Question 30

Exocrine and endocrine function of the pancreas

Answer 30

Exocrine -secretes pancreatic jucie into the small intestine | Endocrine - produce insluin and glucagon

Question 31

Detection and action of a decrease in blood glucose

Answer 31

Detected by alpha cells Alpha cells secrete glucagon which binds to recptors in the cell surface membranes of liver cells activating the G protein Activated G protein activates the enzyme adenyl cylase Adenyl cyclase catalyses the conversion of ATP to cyclic AMP, which activates protien kinases that catalyses the breakdown of glycogen to glucose, glycogenolysis Enzyme cascade amplifys the orginal glucagon signal

Question 32

Glycogenesis

Answer 32

Synthesis of glycogen from glucose molecules Triggered by insluin Removes glucose molecues from the blood stream

Question 33

Glycogenolysis

Answer 33

Breakdown of glycogen to produce glucose molecues Glucagon triggers this process Releases moee glucose molecules into the bloodstream

Question 34

Gluconeogenesis

Answer 34

Synthesis of glucose molecues from non carbohydrates moleclues Glucagon triggers this reaction Enzymes convert molecues such as fatty acids and amino acids into glucose molecules

Question 35

What is diabetes

Answer 35

Condition where homeostatic control of blood glucose has failed or deterioated Insulin function is disrupted which allows blood glucose concentration to rise Known to have glucose in urine Dehydration

Question 36

Exocrine function of the pancreas

Answer 36

Secretes digestive enzymes into the pancreatic duct which carries the enzymes to the duodenum and then the small intestine does not directly enter blood

Question 37

Why use a mean

Answer 37

To reduce the effect of outliers / anomalous results