Week 6: Endocrine system

Question 1

Endocrine system organisation
1. Glands secrete various ….. into the blood
2. Hormones circulate in blood to …. …..
3. ….. cells react to the chemical messages

Answer 1

1. Hormones
2. Target tissues
3. Receptor

Question 2

Endocrine system: Stimulation
* Hormonal eg ACTH – released from …. ….. signalling for adrenal cortex to release ……., which work with the immune system to reduce inflammation, stimulate ….. and ……

• Humoral eg insulin – released from …. of the pancreatic islets in response to elevated blood glucose to stimulate uptake into cells by ……
• Neural – eg adrenaline/noradrenaline – …… released from adrenal medulla stimulated by increase in sympathetic nervous activity (fight or flight response)

Answer 2

Anterior pituitary
Glucocorticoids
Lipolysis
Gluconeogenesis
B-cells
Glut4
Catecholamines

Question 3

Hormone release: Determining factors
* Quantity …..
* Rate of …… into blood
* Quantity of …… proteins present, eg sex-hormone binding globulin, corticosteroid-binding globulin, growth hormone binding globulin
* Rate of …..
* Changes in ….. ……

Answer 3

Synthesised
Secretion
Transport
Catabolism
Plasma volume

Question 4

Hormone release: patterns
* Chronic regulation – homeostatic maintenance of ….. ….. in blood over extended period
* Acute regulation – rapid change in hormone concentration as a response to ….. ……
* …… regulation – natural variations in hormone concentration occurring at relatively consistent frequency/time (eg daily, monthly) and levels

Answer 4

Hormone concentration
External stimuli
Cyclic

Question 5

Steroid hormones
* ….. soluble
* Diffuse through …. ……. – receptors located within the cell
* Chemical structure is derived from, or is similar to, …..
* Secreted by ….. ….(cortisol & aldosterone), ovaries (oestrogen & progesterone), testes (testosterone), placenta (estrogen & progesterone)
* General target response is to induce ….. ……

Answer 5

Steroid hormones
* Lipid soluble
* Diffuse through cell membranes – receptors located within the cell
* Chemical structure is derived from, or is similar to, cholesterol
* Secreted by adrenal cortex (cortisol & aldosterone), ovaries (oestrogen & progesterone), testes (testosterone), placenta (estrogen & progesterone)
* General target response is to induce protein synthesis

Question 6

Non-steroid hormones
*…..-….. soluble

• Cannot diffuse through cell membranes – receptors located on ….. …..
• Two types: ….. ….. …… eg adrenaline/noradrenaline from adrenal medulla, thyroxine from thyroid or …../….. hormones eg insulin, glucagon from pancreas, IGF from liver
• General target response is to induce new …… or modify existing ones

Answer 6

Non-lipid soluble
Cell membrane
Amino acid derivative or protein/peptide hormones
Proteins

Question 7

Hormone transport and reception
* Hormones travel in the blood to their ….. …… …..
* Receptors are …… specific and follow a …. ….. ….. only the correct hormone will fit in the correct receptor
* Each cell can have between …… and …… specific receptors

Answer 7

Specific target organs
Hormone, lock and key model
2,000 & 10,000

Question 8

Hormone target cell specificity

Hormones alter cellular reaction of specific target cells by:
1. Stimulating ….. to alter …. ….. rate
2. Altering ….. activity rates
3. Altering cell membrane transport via ….. ……
4. Inducing …… activity

Answer 8

Hormone target cell specificity

Hormones alter cellular reaction of specific target cells by:
1. Stimulating DNA to alter protein synthesis rate
2. Altering enzyme activity rates
3. Altering cell membrane transport via secondary messengers
4. Inducing secretory activity

Question 9

Hormone receptor binding

A target cell’s activation is dependent upon:
* …… …… in the blood
* Number of target cell ……
* Receptor sensitivity to available …… – can be up and down regulated

Answer 9

Hormone concentration
Receptors
Hormone

Question 10

Hormone action: steroid vs non-steroid

Steroid hormone action
1. Steroid hormones enter target cell through ….. …..
2. Hormones bind with specific receptor ….. in ….. or …..
3. Hormone receptor …… activates cell DNA
4. DNA …… mRNA
5. …… leaves the cell nucleus
6. mRNA …… protein synthesis in cytoplasm

Nonsteroid hormone action
1. Non-steroid hormones bind to …… ……. on cell membrane
2. Hormone receptor complex activates …… …… within the cell
3. Adenylate cyclase forms a …… messenger, ….. …… …… adenosine monophosphate (cAMP)
4. cAMP activates protein …… that lead to cellular changes and hormonal effects

Answer 10

Plasma membrane
Proteins, cytoplasm, nucleus
Complex
Transcribes
mRNA
Translates

Receptor protein
Adenylate cyclase
Second
Cyclic adenosine monophosphate (cAMP)
Kinase

Question 11

Endocrine glands
* Many endocrine glands in the body that release different …….
* These glands are generally …… between biological sexes, with the exception of the sex glands (ovaries, testes)
* However a small number of individuals are born with …… sets of sex glands (Intersex)
* Many glands are controlled by the …… and …… gland

Answer 11

Hormones
Identical
Both
Hypothalams & pituitary

Question 12

Pituitary
* Once considered the “….. gland” for its regulation of other glands’ functions
* Attached to hypothalamus by ….. axons and portal ….
* Various hormones released by pituitary, including regulators for the ….., ….. and …. glands

Answer 12

Master
Neuronal, veins
Adrenal, thyroid & sex

Question 13

Antidiuretic hormone (vasopressin)
* Plays an essential role in body …… (3)
* In response to ……. or ……, ADH released to increase water …… in the kidneys to maintain homeostasis
* During exercise sweating causes loss of ….. ….., increasing osmolarity
* Receptors sense …… ….. and …… ….., signalling for vasopressin release
* ADH increases, …… retention and …….

Answer 13

1. Osmotic balance, blood pressure regulation and kidney function
2. hypovolaemia or hypernatremia, reabsorption
3. Plasma volume
4. Blood volume and pressure change
5. H20 retention and vasoconstriction

Question 14

Growth hormone
* Promotes muscle growth and hypertrophy by facilitating?
* Directly stimulates ….. metabolism (……)
* Levels are elevated during ….. exercise in proportion to exercise …..

Answer 14

Amino acid transport
Fat metabolism (Lipolysis)
Aerobic, intensity

Question 15

Thyroid

Triiodothyronine (T3) and thyroxine (T4)
* Increases …… and …… synthesis
* Increase size and number of …… in cells
* Promote rapid cellular uptake of ……
* Enhance …… and ……
* Increases ….. availability for oxidation

Calcitonin
* ……. calcium – important in children (decrease osteoclast activity)

Answer 15

Protein, enzyme
Mitochondria
Glucose
Glycolysis and glycogenesis
FFA

Metabolises

Question 16

Adrenal medulla

Catecholamines (…… & ……)
* Stimulated by …… nervous system to prepare you for immediate action
* Increase rate and force of …….
* Increase FFA availability for …..
* Increase …… rate, ….. and release of glucose and ….. into blood
* Force more blood to go to the skeletal muscles through ….. and …… of specific vessels

Answer 16

Adrenaline & noradrenaline
Sympathetic
Heart contraction, blood pressure and respiration
Oxiation
Metabolic, glycogenolysis, FFA
Vasodilation, vasoconstriction

Question 17

Adrenal cortex

Mineralocorticoids (eg ……)
* Maintain …… balance in …… fluids

Glucocorticoids (eg …..)
* Maintain consistent ….. …… levels between meals

…… (eg oestrogen, testosterone)
* Released in addition to those released by reproductive organs but in lesser amounts

Answer 17

Aldosterone
Electrolyte, extracellular
Cortisol, plasma glucose
Androgens

Question 18

Pancreas

Insulin – secreted when plasma glucose levels are elevated (hyperglycaemia)
* Facilitates glucose transport ….. cells (……)
* Promotes …….
* …… gluconeogenesis
* Increased …… with exercise (increased uptake per receptor)

Glucagon – secreted when blood plasma glucose concentrations are …… normal (hypoglycaemia)
* Increased …….
* Increased ……
* ….. response with training

Answer 18

Into, GLUT4
glycogenesis
Inhibits
Sensitivity
Below
Glycogenolysis
Gluconeogenesis
Blunted

Question 19

Hormone effects: glucose metabolism
* Four hormones primarily contributing to glucose release and metabolism – what are they?

• When CHO is depleted, hormones accelerate …… to ensure muscles get the energy they need
• Rate of …… breakdown into FFA and glycerol may partly determine the rate at which muscles use ….. as a fuel source during exercise

Answer 19

Adrenaline, noradrenaline, glucagon, cortisol
Lipolysis
Triglyceride, fat

Question 20

Blood composition: Blood volume

• Total blood volume is approximately …..L in adults
• ~….ml/kg in newborns
• ~…./kg in children
• ~….ml/kg in adults
• Total blood volume increases with training (and some environment stressors)
• Composition typically maintained around …..%:…..% for plasma and living components, respectively

Answer 20

5L
90
75
70
55:45

Question 21

Blood volume: Hematocrit

• Proportion of total …. ….. that is red blood cells (RBC)
• Lower %Hct results in reduced ….. and greater …. rate
• Higher %Hct results in lower flow rate due to ……. viscosity, RBC aggregation (…..) and ….. ….. resulting in greater shear stress

Answer 21

Blood volume
Viscosity, flow
Increased
Clustering
Vascular friction

Question 22

Erythrocytes (RBCs)
* Typical volumes are approximately:
- …..-….. x ….. in females
- ….-…. x …. in males
* RBCs turned over/replaced every ….. days
* …… stimulates new RBC formation in bone marrow
* Young RBCs – ……. – are smaller and very …..

Answer 22

4.3-5.2 x 106 (to the power of 6) in females
5.1-5.8 x 108 (to the power of 8) in males
120
Erythropoietin
Reticulocytes, elastic

Question 23

Haemoglobin
* Normal ranges are:
- …..-…..g/ml in females
- …..-…..g/ml in males
* Hb4 + 402 –> Hb408
* Hb increases 02 carrying capacity of blood by …..-….. fold
* ~197ml of

Answer 23

12-16
13-18
65-70

Question 24

Exercise & haematological response

Training effects
* ……, ….. count and total ….. …. can increase with training
* Increases in PV can result in ….. haematocrit, despite RBC count increasing
* Here, RBC increased by ……% and PV by …..% however Hct is 2.2% lower (dilutional anaemia)
* Still performance greatly improved due to greater total blood volume, increased blood flow and greater 02 carrying capacity

Answer 24

Plasma volume, RBC count and total blood volume
Decreased
6.7%, 9.1%

Question 25

Anaemia & sports
* RBC destruction > RBC replacement leads to …..
- …… deficiency
- GI and urinary tract (haematuria) …..
- Mechanical …… (measure haptoglobin)
- Osmotic damage
* Gastrointestinal (GI) ….. through anti-inflammatory drugs, mechanical or ischemia
* Psuedoanaemia (Sports/dilutional anaemia)

Answer 25

Anaemia
Dietary
Bleeding
Haemolysis
Loss

Question 26

Erythropoietin production

Controls
* Erythropoietin (EPO) – direct stimulus for …… production
* ……. hormone
* ….. major producer of EPO
* Liver ….. contributor
* Stimulus for production is based on the …….

Stimulus
* …… or excess RBC destruction (runners haemolysis)
* …… 02 availability (altitude, sickness)
* Increased …… demands for 02
* Negative feedback control – blood borne EPO stimulates bone marrow cells already committed to increase RBC production

Answer 26

Erythrocyte
Glycoprotein
Kidney
Minor
Ability to transport sufficient 02 to meet tissue demands

Haemorrhage
Reduced
Tissue

Question 27

Erythropoietin – …… hormone
* Genetically ……
* Originally for …… failure patients
* Now endurance athletes use/abuse
* Can increase %Hct from …..-…..%
* When combined with ….. can have fatal effects eg heart failure

Answer 27

Recombinant
Engineered
Renal
45-65%
Dehydration

Question 28

Erythropoietin – sex differences
* Testosterone stimulates EPO production in ……
* Female sex hormones ….. stimulate EPO production
* May explain:
- Increase in ….. in males
- Increase in ….. in males

Answer 28

Kidneys
Don’t
RBC’s
HB

Question 29

Exercise & haemoconcentration
* Blood pressure and … contraction force fluid ….. of plasma
* Muscles accumulate ….. and thus draw fluid from plasma
* Sweating results in plasma volume ….. from ….. fluid losses
* Can drop …..-….% with exercise
* Post-exercise ….. may contribute to the restoration (and supercompensation) of plasma volume after exercise bouts
* Changes in PV are very …… (…. …..)
* Trained athletes can increase by …..% after training

Answer 29

Out
Metabolites
Reduction, ECV
10-20%
Hypotension
Transient (3 days)
20%

Question 30

Exercise and blood

Short-term effects

Viscosity increased due to:
* …… plasma volume (sweating, fluid shift)
* …… plasma total proteins (fibrinogen)
* …… RBC accumulation

Increased plasma osmolarity
* Due to fluid losses from …..
* Increased …… per litre of fluid (eg electrolytes)
* Alters osmotic gradients, may draw fluid from ….. …… (ICV)

Long-term effects
* Increased …., …. and …. (….%)
* …… %Hct
* …….. young RBC
- Increased 2,3 DPG (02 transport)
- Increased ……. – elastic membrane
* V02max inversely related to:
- …..
- …… ……

Answer 30

Decreased
Increased
Increased

Sweat
Solutes
Intracellular volume

Increased PV, RBC and TBV (20%)
Decreased
Increased
Deformability
HCT, Blood viscosity