Endocrine System Flashcards
1
Q
What is the function of glands?
A
- Produce and secrete hormones
- Main function is to maintain homeostasis and promote permanent structural changes
2
Q
What are Exocrine Glands
A
- Exo meaning “outside”
- Secrete their products/hormones into duct as opposed to directly into the bloodstream
- Excrete chemicals for elimination
- Ducts carry secretions to the surface of the skin or into a body cavity
3
Q
What are Endocrine Glands
A
- Endo meaning “inside”
- Secrete or release chemicals that are used inside the body
- Do not have ducts
- Release hormones directly into blood stream to be carried to “target tissues”
- Carry hormones
4
Q
What are hormones?
A
- Messengers that are responsible for telling some parts of the body to start/stop doing something
- Hormones are released directly into the blood stream
- Travel in the blood stream to target tissues
- Each target cell has specific receptor sites to which the specific hormone can attach or bind to
5
Q
What are the 2 main functions of the receptor sites?
A
- Recognize and bind to their particular hormone
- Initiate an appropriate signal
- Once attached, the “message” to alter the cellular function is delivered
6
Q
What is an agonist in a cell?
A
Molecule that binds and triggers a response by that cell that produce some kind of action
7
Q
What is an antagonist in a cell?
A
- Bind to a cell and block the action of an agonist
- Widely used as drugs
8
Q
What is a feedback system?
A
Maintain an optimal internal operating environment in the body (positive or negative)
9
Q
What do negative feedback mechanisms do?
A
- Work until the variable is back to its original state
- A chemical is released to stimulate the release of what is needed in the body. Once the normal levels are reached, the stimulating hormone is blocked, resulting in a stopping of the feedback system.
10
Q
What do positive feedback mechanisms do?
A
- Enhance the original stimulus
- Ex. childbirth and oxytocin
11
Q
The release of hormones is regulated by…
A
- Chemical factors
- Other hormonal factors
- Neural control
12
Q
Disease occurs when…
A
- Normal cell signalling is interrupted
- Usually, feedback mechanisms are disrupting
- Leading to inappropriate cell function
13
Q
Hypothalamic- pituitary system
A
- Controls the function of multiple peripheral endocrine organs
- Considered part of the endocrine system because it sends signals to the adrenal gland to release epinephrine or norepinephrine
- Produces its own hormones, ADH, oxytocin
14
Q
What is the Hypothalamus?
A
- Not a gland
- Contains several control centers for the body functions and emotions
- Primary link between endocrine and nervous system
Responsible for: - Releasing hormones
- Maintaining daily physiological cycles
- Controlling appetite
- Managing sexual behaviours
- Regulating emotional responses
15
Q
What is the Pituitary Gland?
A
- “Master Gland”
- Its secretions control or regulate the secretions of so many other endocrine glands
- Attached to hypothalamus
- Divided into 2 regions:
- Anterior pituitary
- Posterior pituitary
16
Q
What 6 hormones does the anterior pituitary gland produce?
A
- Growth hormone- regulates growth, metabolism, and body composition
- Thyroid-stimulating hormone- stimulates thyroid to secrete its hormones
- Adrenocorticotropic hormone- stimulates the adrenal glands to secrete their hormones, principally cortisol
- 3 gonadotropic hormones- act on the ovaries or testes to stimulate sex hormone production, egg and sperm maturity
17
Q
What 2 hormones does the posterior pituitary glands secrete?
A
- ADH- AKA vasopressin, controls water balance and BP
- Oxytocin- stimulates uterine contraction during labour and milk secretions for breastfeeding
18
Q
What does the thyroid do?
A
- Found at the front of the neck, below the Adams Apple
- Primarily influences metabolic rates in the body
- Also plays a small role in development
- Secretes thyroxine
19
Q
What is thyroxine?
A
- A major metabolic hormone produced by the thyroid that stimulates energy production in cells
- Increases the rate at which cells consume oxygen and use carbohydrates, fats, and proteins
- Ex. when the body is cold, increased cellular metabolism creates heat
20
Q
What is Iodines role in producing thryoxine?
A
- Without proper levels of iodine, thyroxine cannot be produced
- Individuals physical and mental growth are diminished
21
Q
What is calcitonin?
A
- Maintains normal calcium levels in the blood
- Is secreted when thyroid detects high levels of calcium
- Stimulates the bone-building cells to absorb the excess calcium, and kidneys to absorb and excrete calcium
22
Q
What is the parathyroid?
A
- 4 tiny glands located in the neck that control the body’s calcium levels (when they are low)
- Assist in the regulation of calcium
Parathyroid hormone: - Acts as an agonist to calcitonin
- Secreted when the calcium blood levels are low
- Causes bone dissolving cells to break down bone and release calcium
23
Q
What are the adrenal glands?
A
- Two parts:
- Adrenal cortex and adrenal medulla
- Both produce hormones
- Located above the kidneys
24
Q
What hormones do the adrenal glands secrete?
A
- Corticosteroids- group of steroid hormones produced in the cortex of the adrenal glands
- 2 main- mineralocorticoids (aldosterone) and glucocorticoids (cortisol)
- They regulate:
- Metabolism
- Balance of salt and water
- Immune system
- Sexual function
25
Q
Epinephrine and Norepinephrine
A
- Catecholamines that are responsible for most of the adrenaline that circulates the body
- Coping with physical and emotional stress
- Increase the heart and respiratory rates and BP
26
Q
Adrenocorticotropic hormone (ACTH)
A
- Catecholamine that is released during times of stress
- Targets the adrenal cortex and causes it to secret cortisol
- This then stimulates body cells to increase their energy production
27
Q
Aldosterone
A
- Catecholamine that stimulates the kidneys to reabsorb sodium from the urine and excrete potassium
- When sodium is reabsorbed into the blood, water follows
- Increases blood volume and blood pressure
- Reduces the amount of salt and water lost through the sweat and salivary glands
28
Q
Fight or flight response
A
- Body’s reaction to physical or emotional stress
- Secretes small amounts of norepinephrine and large amounts of epinephrine
- Norepi raises blood pressure by vasocontriction
- Epi stimulates SNS
- Stimulates the liver to convert glycogen to glucose for use as energy
- Both hormones increase oxygen and glucose in the blood and faster circulation of the blood to the brain, heart and muscles
29
Q
What is the pancreas?
A
- A digestive gland
- Considered both an endocrine and exocrine gland
- Secretes digestive enzymes into the duodenum through the pancreatic duct
30
Q
What does the pancreas do as an endocrine gland?
A
- Functions mostly to regulate blood sugar levels
- Secretes insulin, glucagon, and somatostatin (inhibits secretions of other hormones)
31
Q
What does the pancreas do as part of the GI system?
A
- Secretes pancreatic juice into the duodenum through the pancreatic duct
- This juice contains bicarbonate which neutralizes acid in the stomach and breaks down carbs, proteins, and fat
32
Q
What are the Islets of Langerhans?
A
- Endocrine component of the pancreas
- Cell groups within the pancreas
- Organ within and organ
- Responsible for the regulation of blood glucose levels
33
Q
What is Glucagon?
A
- Hormone secreted by the pancreas
- Produced by alpha cells
- Secreted when the body’s blood glucose levels fall
- Raises the glucose level
- Stimulates the liver to change glycogen into sugar
- Glucagon is a hormone that helps released the stored sugars that somebody already has- you must have stored glycogen for it to work takes up to 20 minutes sometimes
- Dextrose- basically sugar water, raises blood sugar very fast
34
Q
What is Insulin?
A
- Hormone secreted by the pancreas
- Allows for storage of glycogen
- From beta cells
- Enables cells to uptake glucose and allows for the storage of glycogen (for later use), fats and proteins
- Responsible for the removal of glucose from the blood for storage
- Secreted when blood glucose levels are elevated
- Only hormone that decreases the blood glucose levels
35
Q
What is the role of Glucagon?
A
- Glycogenolysis: conversion of glycogen into glucose from stores in the liver (releases)
- Glucogenesis: conversion of nutrients into glucose molecules (stores)- happens first
- Increases the use of fat and amino acids for energy production
36
Q
What is Somatostatin?
A
- Produced in the delta cells of the pancreas, the nervous system and GI tract
- Inhibits the release of other hormones including both insulin and glucagon
37
Q
When is somatostatin released?
A
- Somatostatin is released in response to stresses like exercise, stress, and hypoglycemia
- Insulin agonist -> decreases insulin action on the cell membrane, reducing the capacity of muscles, adipose tissues and the liver to absorb glucose -> blood glucose levels rise
38
Q
Insulin release = ?
A
Lower blood sugar levels
39
Q
Glucagon release = ?
A
Higher blood sugar levels
40
Q
Somatostatin release = ?
A
Higher blood sugar levels
41
Q
What are Gonads?
A
- Main source of sex hormones
42
Q
What are Testes?
A
- Located in the scrotum
- Produce hormones called androgens: testosterone and controls puberty
43
Q
What are Ovaries?
A
- Release eggs
- Secrete the hormones estrogen and progesterone
