Ch 14 h

Question 1

What is an Endocrine gland?

Answer 1

a group of cells specialised to secrete chemicals (hormones) directly into the bloodstream.
e.g. Pancreas and Adrenal glands

Question 2

Pituitary gland

Answer 2

Endocrine gland at the base of brain
Makes Several Hormones; for Growth, balancing w.p. of blood (ADH), and Gonadotrophins (control development of ovaries and testies/reproduction)
controls functions of many other endocrine gland

Question 3

What is an Exocrine gland?

Answer 3

a group of cells specialised to secrete chemicals/hormones through DUCTS into organs/ surface of the body.
e.g. Salivary or Sweat glands

Question 4

What are hormones?

Answer 4

Chemical Messengers - carry info from one part of the body to another.
Hormones can be steroids, proteins, glycoproteins, polypeptides, amines, or tryosine derivatives.

Question 5

What causes hormones to be Secreted?

Answer 5

Hormones are secreted when a gland is stimulated; e.g. as result of Change in Concentration of a particular Substance, or as a result of another Hormone or a Nerve Impulse.

Question 6

Transport and initial Action of (endocrine) hormones?

Answer 6

Endocrine Hormones travel in the blood plasma all around the body. They Diffuse out the blood upon reaching their target organ, and bind to a specific receptor on their target cell’s membrane or cytoplam.
Once bound to receptor they stimulate the target cell to produce a response.

Question 7

The Type of hormone determines its effect on a target cell:

Action of Steroid Hormones?

Answer 7

Steroid Hormones: lipid-soluble so pass through cell-surface membrane and binds to receptor in cytoplasm or nucleus, forming a hormone-receptor complex (acts as transcription factor which facilitates or inhibits transcription of specific gene). E.g. Oestrogen

Question 8

The Type of hormone determines its effect on a target cell:

Action of Non-Steroid Hormones?

Answer 8

Non-Steroid hormones: Hydrophilic so bind to receptor on cell-surface membrane of target cell, triggering a cascade reaction, mediated by second-messengers. E.g. Adrenaline

Question 9

Hormonal Vs Neuronal communication

Answer 9

Hormonal : Slower, less specific communication. Not broken down as quickly as neurotransmitters, so have longer lasting and widespread effect.

Question 10

Adrenal glands:

Answer 10

Located on top of each kidney

Made of 2 parts; adrenal cortex + adrenal medulla, surrounded by a capsule.

Question 11

What is the Adrenal Cortex?

Answer 11

Outer region of the glands.

Produces hormones vital to life, e.g. Cortisol & Aldosterone

Question 12

What is the Adrenal Medulla?

Answer 12

Inner region of the glands

Produces Non-Essential hormones, e.g. Adrenaline

Question 13

Types of Hormones produced by the Adrenal Cortex:

Answer 13

Glucocorticoids: release is controlled by the hypothalamus
e.g. Cortisol (helps regulate metabolism and blood pressure in response to stress) & Cortecosterone.

Mineralocorticoids: e.g. Aldosterone (control blood pressure by maintaining salt/water balance in blood) Its relase is triggered by the Kidney

Androgens: Small amounts of sex hormones, small impact yet important after the menopause.

Question 14

Types of Hormones produced by the Adrenal Medulla:

Answer 14

released when sympathetic nervous system is stimulated (stress)
Adrenaline (increase HR & blood glucose conc)
Noradrenaline (increase HR & blood pressure)

Question 15

Pancreas; Role as Exocrine Gland

Answer 15

Pancretic Acini Produces digestive enzymes and an alkaline fluid; Pancreatic Juice, secreted into ducts, then the duodenum
Amylases - break down starch
Proteases - breakdown protein (trypsin)
Lipases - break down lipids

Question 16

Pancreas; Role as Endocrine Gland

Answer 16

Islets of langerhans = small regions of endocrine tissue responsible for producing Insulin and Glucagon, and secreting them dircetly into the bloodstream

Question 17

Increase Blood Glucose by :

Answer 17

Eating foods high in Starch or Sucrose
Glyogenolysis
Gluconeogenesis (liver makes glucose from glycerol & amino acids)

Question 18

Decrease Blood Glucose by:

Answer 18

Respiration

Glycogenesis (produce glycogen)

Question 19

Role & Action of Insulin

Answer 19

produced by Beta cells of Islets of Langerhans if blood glucose concentration is too High.
binds to glycoprotein receptor on cell-surface membrane, causing glucose transport protein channels to open (change in tertiary structure) and allow glucose to enter (for respiration or storage as glycogen or fat)

Question 20

Insulin Lowers blood glucose concentration by:

Answer 20

increasing rate of absorbtion of glucose by cells
increasing cellular respiration rate (increasing need)
Increasing rate of glycogenesis
increasing rate of glucose conversion to fat
Inhibit release of glucagon by a-cells

Question 21

Role & Action of Glucagon

Answer 21

produced by Alpha cells of Islets of Langerhans if blood glucose levels are too Low.
Binds to glucagon receptors on liver and fat cells, causing glycagon to be broken down into glucose to be released into the blood

Question 22

Glucagon Raises blood glucose concentration by:

Answer 22

Glycogenolysis
Reducing glucose uptake by liver cells
Increasing Gluconeogenesis - conversion of amino acids and glycerol into glucose in the liver

Question 23

Control of Insulin Secretion :

by Beta Cells

Answer 23

at normal blood glucose levels, K+ channels in plasma membrane of B cells are open, so K+ ions diffuse out the cell. the inside of the cell is at a potential of -70mV
When glucose levels rise:
Glucose enters cell by glucose transporter and is metabolised in the mitochondria = ATP is produced.
ATP binds to ATP sensitive K+ channels, causing them to close.
K+ cant diffuse out the cell = p.d reduces to -30mV and Depolarisation occurs.
Depolarisation causes the Voltage-Gated Ca2+ ion channels to open = Ca2+ ions enter the cell, causing secretory vesicles containing Insulin to fuse with the cell-surface membrane and release Insulin by Exocytosis.

Question 24

Type 1 Diabetes

Answer 24

(B cells) unable to produce Insulin 
Unknown Cause (autoimmune?), no prevention or cure
Treatment with regular Insulin Injections after measuring blood glucose concentrations and calculating dosage required.

Question 25

Type 2 Diabetes

Answer 25

Patient cannot effectively use insulin to control blood sugar levels - either B cells do not produce enough insulin or the body cells do not respond properly to insulin (often because glycoprotein receptor doesn’t work)
largely a result of Excess weight & Physical Inactivity
Treat with low-sugar diet plan and regular exercise.

Question 26

Fight or Flight Response

Answer 26

Autonomic Nervous System Detects Threat
Hypothalamus communicates with Sympathetic nervous system and the Adrenal-Corical system.`
HR increases = more O2 around body
Pupils dilate = more light for better vision
Blood Glucose levels rise = increase respiration
smooth muscle in airway relaxes = more O2 in lungs

Question 27

Action of Adrenaline

Answer 27

Adrenaline is hydrophilic so binds to cell-surface receptor
Adenylyl cyclase is activated
Adenylyl cyclase triggers conversion of ATP into cAMP (Cyclic Adenosine Mono-Phosphate) in the cytoplasm of the target cell.
cAMP activates Protein Kinases which phosphorylate, hence activate other enzymes (glycogen - glucose)

Triggers liver cells to undergo glycogenolysis so glucose is released into blood so respiration can increase so more energy is available for muscle contraction

Question 28

Second Messenger Model

Answer 28

First messenger (e.g. adrenaline) can cause many Secon messenger (cAMP) molecules to be formed.
At each stage the number increases, so is said to have a Cascade effect

Question 29

Increaising and Decreasing Heart Rate

Answer 29

impulses through Sympathetic nervous system, Accelerator nerve = Increases HR
impulses through Parasympathetic nervous system, Vagus nerve = Decreases HR

Question 30

Baroreceptors

Answer 30

Pressure Receptors present in the aorta, vena cava, & carotid arteries
Detect change in Blood Pressure
If blood pressure is too high , impulses are sent to the medulla to decrease HR - medulla oblongata sends impulse to SAN down Vagus nerve (parasympathetic) to decrease HR, reducing blood pressure back to normal.

Question 31

Chemoreceptors

Answer 31

Chemical Receptors, present in the aorta, carotid arteries, and medulla.
Detect change in levels of chemicals, e.g. CO2 (dissolves forming carbonic acid) as is sensitive to blood pH.
Decrease in blood pH = too much CO2, so must increase HR so blood flows quickly to lungs to exhale CO2.

Question 32

Hormonal Control of Blood Pressure

Answer 32

Adrenaline & Noradrenaline are released during time of stress. These affect the pacemaker region of the heart; increase frequency of impulses produced by the SAN