Endocrine system Flashcards
1
Q
Endocrine gland
A
ductless gland that secretes hormones directly into the blood
2
Q
Exocrine gland
A
releases substances onto an external surface via a duct
3
Q
function of the endocrine system
A
regulate a range of bodily functions & maintain homeostasis by secreting hormones
4
Q
structure of endocrine system
A
glands and organs that produce and secrete hormones
hormones circulate in the blood to target cells
5
Q
what is a gland
A
organ that secretes substances (often hormones)
6
Q
What endocrine gland sits on top of the kidneys?
A
Adrenal gland
7
Q
What endocrine gland sits on top of the thyroid gland?
A
Parathyroid gland
8
Q
What endocrine gland is most anterior pituitary or pineal gland?
A
Pituitary gland
9
Q
What endocrine gland is most posterior? Pituitary or pineal gland.
A
Pineal gland
10
Q
Where is Growth hormone released from?
A
Anterior Pituitary gland
11
Q
Function of Growth hormone
A
Regulates growth and physical development
12
Q
Where is Adrenocorticotropic hormone released from?
A
Anterior Pituitary gland
13
Q
Function of Adrenocorticotropic hormone
A
Stimulates the adrenal glands to secrete steroid hormones, mainly cortisol
14
Q
Where is Luteinising hormone (LH) released from?
A
Anterior Pituitary gland
15
Q
Function of Luteinising hormone (LH)
A
Controls oestrogen and testosterone production as well as ovulation
16
Q
Where is Follicle stimulating hormone (FSH) released from?
A
Anterior Pituitary gland
17
Q
Function of Follicle stimulating hormone (FSH)
A
Controls the production of eggs and sperm
18
Q
Where is Prolactin released from?
A
Anterior Pituitary gland
19
Q
Function of Prolactin
A
Stimulates milk production
20
Q
Where is Thyroid stimulating hormone (TSH) released from?
A
Anterior Pituitary gland
21
Q
Function of Thyroid stimulating hormone (TSH)
A
Stimulates the thyroid gland to secrete thyroid hormones
22
Q
Where is Oxytocin produced and released from?
A
produced by Hypothalamus, secreted by Posterior pituitary gland
23
Q
Function of Oxytocin
A
Helps with lactation, childbirth
24
Q
Where is Anti-diuretic hormone (ADH) produced and released from?
A
produced by Hypothalamus, secreted by Posterior pituitary gland
25
Function of Anti-diuretic hormone (ADH)
Increases water reabsorption in the kidneys
26
Where is Corticotropin-releasing hormone (CRG) released from?
Hypothalamus
27
Function of Corticotropin-releasing hormone (CRG)
Stimulates the adrenal glands to release corticosteroids - metabolism and immune response
28
Where is Growth hormone-releasing hormone (GHRH) released from?
Hypothalamus
29
Function of Growth hormone-releasing hormone (GHRH)
Stimulates anterior pituitary gland to secret growth hormone
30
Where is Triiodothyronin (T3) released from?
Thyroid gland
31
Function of Triiodothyronin (T3)
Regulate body temperature, metabolism and heart rate
32
Where is Thyroxine (T4) released from?
Thyroid gland
33
Function of Thyroxine (T4)
Regulate body temperature, metabolism and heart rate
34
Where is Calcitonin released from?
Thyroid gland
35
Function of Calcitonin
decrease blood calcium levels
36
Where is Melatonin released from?
pineal gland
37
Function of Melatonin
regulate sleep and wake cycles
38
Where is Parathyroid hormone (PTH) released from?
Parathyroid gland
39
Function of Parathyroid hormone (PTH)
increase calcium levels
40
Where is insulin released from?
pancreas (beta cells)
41
Function of insulin
Decrease BSL by increasing uptake of glucose into the cells and storing as glycogen in the liver
42
Where is Glucagon released from?
pancreas (alpha cells)
43
Function of Glucagon
increase BSL by breaking down glycogen into glucose
44
Where is Adrenaline and Noradrenaline released from?
Adrenal gland medulla
45
Function of Adrenaline and Noradrenaline
fight or flight response eg. increase HR
46
Where is Cortisol released from?
Adrenal gland cortex
47
Function of Cortisol
Influences metabolism blood sugar levels and has anti inflammatory effects
48
Where is Aldosterone released from?
Adrenal gland
49
Function of Aldosterone
Helps to main the bodys salt and water levels which in turn regulates blood pressure
50
Three Major Components of the Endocrine System
1. Endocrine Glands
- Specialised Cell Clusters or organs that work together to produce and secrete hormones
2. Hormones
- Chemical Substances secreted by glands into the circulatory system in response to stimulation
3. Receptors
- Protein molecules that bind specifically with hormones to trigger specific physiological change in the target cell.
51
Where is oestrogen released from?
ovaries
52
Function of Oestrogen
to control the development of female secondary sexual characteristics
To stimulate the growth of the lining of the uterus
To regulate the female menstrual cycle
53
Where is Testoterone released from?
testes
54
Function of Testerone
To produce sperm
To control development of male secondary characteristics
To regulate sex drive
55
5 Cellular Responses To Hormones
1. Secretion
- Induces secretory reactivity of the cell
2. Transport
- Alters Plasma Membrane Permeability or membrane potential (or both) by opening or closing ion channels
3. Activation or Deactivation
- Activates or deactivates important enzymes
4. Synthesis
- Stimulates the synthesis of proteins, regulatory molecules, and enzymes, within the cell
5. Proliferation
- Stimulates mitosis or cellular proliferation
56
What makes a target cell
the presence of a specific receptor for each particular hormone
57
3 types of stimulus that controls Hormone Synthesis
1. Humoral Stimuli (Blood-borne)
2. Neural Stimuli:
3. Hormonal Stimuli:
58
Humoral Stimuli (Blood-borne)
o Stimulated by humoral factors - factors within the blood.
o Usually occurs according to the concentration of ions within the blood.
59
Neural Stimuli
o CNS helps to regulate the secretion of hormones by:
o HYPTHALAMUS – Controls pituitary hormones
o Often NS stimuli in response to hypoxia, nausea, pain, stress and some drugs can affect ADH levels.
60
Hormonal Stimuli
o Release of hormones in response to hormones produced by other endocrine glands. (e.g., the interaction between the hypothalamus and the pituitary gland).
61
5 Factors that Impact Hormone Activity
- Transport
- Concentration and Half-Life
- Permissive Effect
- Antagonistic Effect
- Synergistic Effect
62
Factors that Impact Hormone Activity
Transport
Hormone specific transport proteins bind to hormones (while inactive). Release is triggered in low concentration areas, thus acting as a reservoir for hormones, which allows the distribution of hormones.
Also protects the hormone from potential degradation.
63
Factors that Impact Hormone Activity
Concentration and Half-Life
Accumulation in tissue, active metabolites, and receptor interactions.
Biological half-life (elimination half-life):
- Time it takes for a substance to lose half of its physiological activity
Plasma half-life:
- Time it takes for the hormone concentration in blood plasma to half
64
Factors that Impact Hormone Activity
Permissive Effect
Effect the action of the second hormone if:
- Enhances the responsiveness of the target organ to the second hormone.
- Increases the activity of the second hormone.
e.g., oestrogen has a permissive effect for progesterone.
65
Factors that Impact Hormone Activity
Antagonistic Effect
Hormones that act to return body conditions to acceptable limits from opposite extremes. e.g., Insulin and glucagon.
66
Factors that Impact Hormone Activity
Synergistic Effect
2 or more hormones combine to produce effects greater than the sum of their individual effects (additive or complementary).
67
Lipid-Based (Steroid) Hormone Signalling
1. Hormone binds to receptor-chaperone complex.
2. Receptor changes shape, releasing the chaperone molecule.
3. Hormone-receptor complex acts as a transcription factor
4. Complex binds to hormone response element, promoting DNA transcription produce mRNA for specific genes
5. mRNA is translated into proteins,
6. Proteins can be enzymes that catalyse biochemical reactions and cause response of the cell
68
Amino Acid-Based Hormone Signalling
1. Amino acid based hormone binds to receptors embedded in the plasma membrane
2. Receptor changes shape and displaces GDP
3. GDP is converted into GTP
4. G protein binds to GTP resulting in G protein activation
5. Activated G protein binds to and activates adenylate cyclase
6. Adenylate cyclase converts ATP into cAMP, activating enzymes that either inhibit or activate.
69
Hypothalamus & Anterior Pituitary Gland
1. Hypothalamic neurons secrete releasing or inhibiting hormones into the hypophyseal portal system
2. Hypothalamic hormones travel through the hypophyseal portal system to the anterior pituitary where they stimulate or inhibit glandular cells to release hormones made in the anterior pituitary.
3. Anterior pituitary hormones are secreted into the secondary capillary plexus (blood vessels) for distribution throughout the body.
70
Hypothalamus & Posterior Pituitary Gland
1. Hypothalamic neurons synthesise
- Oxytocin is made primarily by the paraventricular neurons.
- Antidiuretic hormone (ADH) is made by the supraoptic neurons.
2. Oxytocin and ADH are transported through the hypothalamic hypophyseal tract to the posterior pituitary.
3. They are then stored in axon terminals in the posterior pituitary.
4. When these hypothalamic neurons fire, they release the stored hormones into the blood for distribution throughout the body.
71
Hypothalamus & Thyroid Relationship
1. When thyroid hormone levels are low, the hypothalamus produces thyrotropin
releasing hormone (TRH).
2. TRH stimulates the anterior pituitary to produce thyroid stimulating hormone
(TSH)
3. TSH signals the thyroid to increase production of its hormones.
4. When thyroid hormone levels are high, feedbacks the hypothalamus and anterior pituitary to cause a decrease in production of TRH and TSH.
