Hormonal Communication Flashcards
Define hormones
Molecules released by endocrine glands that act as chemical messengers carried in the blood plasma
What are steroid hormones
Molecules that pass through lipid membrane and bind to receptors to form hormone receptor complex (HRC)
Act as a transcription factor
Define peptide and protein hormones
Bind to specific receptors on cell surface membrane abs triggers a cascade reactions mediated by second messengers
Define exocrine glands
Glands that secrete chemicalsinto ducts which carry the hormone to another place.
Define endocrine glands
Group of cells which are specialised to secrete chemicals known as hormones and are secreted directly into the blood stream
What is a target cell
Cells that possess the specific receptors that a specific hormone will bind to in order to have an effect on that cell.
What is target tissue
target tissue is any tissue which contains a number of target cell grouped together.
What is an adrenal glands
Example of an a doctrine glands
Consist of 2 main areas: central medulla and an outer cortex
Cortex produce steroid hormones e.g aldosterone and cortisol
Medulla produces adrenaline
What is the difference between the nervous and endocrine system
POS- Brian,spinal cord, neurones / glands
TOM- electrical impulse/ chemical hormone
Effector - muscle or glands/ target cells in specific tissue
When are hormones secreted
Gland is stimulates
Can occur as a result of a change in concentration e.g blood glucose
Outline the secretion of insulin
Normal blood glucose concentration levels, PD =-70mV, blood glucose concentration rises, glucose enters the cell by a glucose transporter, metabolised production of ATP, ATP binds to potassium channels and causes them to close, potassium ions can’t get through the membrane, beta cells less negative, depolarisation occurs, voltage gated calcium channels open
Why is it important that blood glucose concentration remains stable
Maintains constant blood water potential
Constant concentration of respiratory substrate
Define negative feedback
Self regulatory mechanisms return internal environment when there is fluctuation
Define glycogenesis,glycogenolysis and gluconeogenesis
Glycogenesis- liver converts glucose into glycogen
Glycogenolysis - liver hydrolyses glycogen into glucose
Gluconeogenesis- liver converts glycerol and AA into glucose
Outline the role of glucagon when blood concentration decreases
@ cells in Islets of Langerhans in pancreas detect and secrete glucagon
Glucagon bind to surface receptor on LC and activates enzymes for glycogenolysis & gluconeogenesis
Outline what happens when blood glucose concentration increases
B cells in Islets of Langerhans in pancreas detect, secret insulin
Insulin binds to surface receptor on target cells
Increase cellular glucose uptake
Activate enzymes for glycogenesis (liver and muscles )
Stimulate adipose tissue to synthesis fat
Describe how insulin leads to a decrease in blood glucose concentration
Increase permeability of cells to glucose
Triggers inhibition of enzymes for glycogenolysis
How is insulin secretion controlled
B cells have potassium and calcium ion channels to maintain p.d -70mV
Glucose enter via facilitated diffusion
Respiration of glucose produces ATP, ATP gated k+ ion channels close, so k+ no longer diffuse out of cell
P.d in cell becomes more positive - depolarisation.
Ca2+ channel open, exocytosis of insulin
Describe the exocrine functions of the pancreas
Secrete digestive enzymes e.g amylase,trypsin and lipase
to the duodenum via the pancreatic tract
Explain the causes of Type 1 diabetes mellitus and how it can be controlled
Body can’t produce insulin because autoimmune response,attack beta cells
Treatment: injecting insulin
Explain the causes of Type 2 diabetes mellitus and how it can be controlled
Glycoprotein receptors are damaged/ insensitive to insulin
Obesity
Treatment: controlling diet and exercise regime
Using a named example, explain the function of an endocrine gland
Produce and secrete hormones Adrenal gland(medulla) and adrenaline
Describe the pathway triggered by a stimulus in hormonal communication
Stimulus detected -> gland stimulated -> hormone secreted-> travel in blood (plasma)-> target cell -> binds to receptor/triggers response
A person is getting chased by a bear, state and describe the changes that may occur in the body to increase the persons chance of survival
Detected by sympathetic nervous system -> triggers the adrenal glands to secrete hormones -> from the adrenal medulla -> adrenaline causes blood glucose concentration to increase, widen air passage, raises blood pressure -> increased rate of respiration
State the difference between endocrine and exocrine glandular tissue
Hormones are produced by endocrine tissue whereas substances such as enzymes are produced by exocrine tissue
Describe what is meant by negative feedback
Feedback which causes any corrective measures to be reduced or switched off, allowing the system to return to its original levels
Describe the role of glucagon in blood glucose concentration
Glucagon is responsible for increasing blood glucose concentration, binds to receptors on liver cells and causes GLYCOGENOLYSIS
Describe the changes that take place inside beta cells to cause the release of insulin in the presence of high blood glucose concentration
Glucose enters the cell via glucose transporter, glucose is metabolised, ATP generated, binds to potassium channels; close, cell becames depolarised, calcium ion channels open, causes vesicle to release insulin, exocytosis
Explain how hormones return blood glucose concentration to normal after a meal
Blood glucose concentration level rise, detected by beta cells in islets of Langerhans,release insulin into blood, bind to glycoprotein receptors on cell surface membrane -> cell will absorb more glucose, increases, glycogenesis
State and explain two physical responses which occur as a result of ‘fight or flight’ response
Heart rate increases - pump oxygenates blood around the body
Pupil dilation - take in as much light as possible
Explain why people often feel cold in times of stress
Less blood in the skin to keep it warm, blood has been redirected to muscles to aid movement
