Endocrine 1 Flashcards
(129 cards)
1
Q
Glands defn
A
Epithelial tissue derivatives specialised for secreting.
2
Q
Epithelial tissue defn
A
Functional grouping of cells specialised in the exchange of material between the cell and it’s environment, lines and covers various body surfaces and cavities and forms secretory glands.
3
Q
Secretion defn
A
Release from a cell in response to appropriate stimulation of specific products that have been produced by the cell.
4
Q
Two major communication systems
A
– nervous system
– endocrine system
5
Q
Name 4 types of chemical messengers
A
1) Autocrine / Paracrine
2) Neurotransmitter
3) Neurohormones
4) Hormones
6
Q
What are neurohormones and distribution?
A
- hormones released into blood by neurosecretory neurons
* distributed through blood to distant target cells
7
Q
What are hormones?
A
- long-range messengers
* secreted into blood by endocrine glands in response to appropriate signal and act on distant target cells
8
Q
What are Autocrine / Paracrine and effect
A
- local chemical messengers
* exert effect on neighbouring cells (paracrine) or on same cell (autocrine)
9
Q
What are neurotransmitters?
A
- short-range chemical messengers
* diffuse across narrow space (synapse) to act on adjoining target cell (another neuron, a muscle, or a gland)
10
Q
Autocrine meaning
A
Can act on itself
11
Q
Paracrine meaning
A
Can act on another cell close-by
12
Q
What are neurotransmitters released from?
A
Synaptic vesicles
13
Q
What does a neurotransmitter bind?
A
A receptor
14
Q
What does receptor activation cause?
A
Stimulates the cells
15
Q
Where do neurotransmitters diffuse?
A
Across synapse between two cells
16
Q
Release of neurohormones
A
Released from synaptic vesicles by neuron
17
Q
Where are neurohormones released into?
A
The blood
18
Q
Where are hormones released from?
A
Released from endocrine gland into blood
19
Q
Where are hormones transported?
A
In blood
20
Q
What do a hormones target cell express?
A
Specific receptors
21
Q
Structure of the nervous system
A
Wired system of neurons
22
Q
Structure of the endocrine system
A
Wireless system of glands
23
Q
Chemical messenger in nervous system
A
Neurotransmitter
24
Q
Chemical messenger in endocrine system
A
Hormones
25
Target site (length) in nervous system
Very close
26
Target site (length) in endocrine system
Far away
27
Distance of action of nervous system
Across synaptic cleft
28
Distance of endocrine of nervous system
Carried by blood
29
Speed of response of nervous system
milliseconds
30
Speed of response of endocrine system
mins to hours
31
Duration of action of nervous system
milliseconds
32
Duration of action of endocrine system
mins to days
33
Major function of nervous system
fast precise responses
34
Major function of endocrine system
long duration responses
35
NB - differences between hormones and neurotransmitters travel
Neural messages can only travel along existing nerve tracts; hormonal messages can travel in the circulatory system; thus any cell receiving blood is potentially able to receive a message.
36
NB - Differences between Hormones and Neurotransmitters
Neural messages are digital, all-or-none events that have rapid onset and offset; neural signals can take place in milliseconds; plus, electrical signal can travel along myelinated axons at speeds up to 100 meters per sec! Hormonal messages are analog, graded events that can take seconds, minutes or hours to occur.
37
What does interaction of a hormone with its receptor lead to?
A genomic response whereby the hormone activates genes that regulate protein synthesis (e.g., up-regulation: synthesis of a receptor for that hormone).
38
What are cell with receptors for the hormone called?
Target cells
39
What do hormones affect?
Cell morphology and size (including development of muscle and neuronal cells), and affect cell death (apoptosis) throughout the nervous system.
40
Hormonal Effects (understand)
• Sufficient number of receptors must be available for hormonal effects to occur.
• Popular belief that individual differences in behavior reflects differences in hormone concentrations. For example, it is assumed that roosters that crow frequently have more testosterone than roosters that seldom crow (or that aggressive men have higher T).
• Not necessarily true! – Individual differences in behavior can reflect hormone concentrations, pattern of hormone release, numbers and location of hormone receptors, and the efficiency of those receptors in affecting gene
transcription.
• Hormones rarely change the function of a cell; rather, they alter the rate of normal cellular function.
– Thus, hormones affect cell morphology and size (including development of muscle and neuronal cells), and affect cell death (apoptosis) throughout the nervous system.
• Although hormones obviously affect behavior, it is also true that behavior can influence hormonal levels and hormonal effects.
41
What are the two hormone catagories based on solubility?
– Hydrophilic (lipophobic, water soluble)
| – Lipophilic (hydrophobic, water insoluble)
42
What are the two hydrophilic hormones?
1. Peptide hormones
| 2. Catecholamines
43
What are the two lipophilic hormones?
3. Thyroid hormone
| 4. Steroid hormones
44
What are the four types of hormones?
1. Peptide hormones
2. Catecholamines
3. Thyroid hormone
4. Steroid hormones
45
Structure of peptide
Amino acids
46
Solubility of peptide
hydrophilic
| lipophobic
47
Receptors of peptide (location)
on cell surface
48
Place of peptide synthesis
In endoplasmic reticulum
49
Storage of peptide
Granules
50
Secretion of peptide
Exocytosis of granules
51
Blood transport of peptide
Free hormone
52
Hormones of peptide, x 9
```
hypothalamic,
pituitary, pineal,
pancreas,
parathyroid, GIT,
kidney, liver, heart
```
53
Structure of catecholamine
Tyrosine derivative
54
Solubility of catecholamine
- Hydrophilic
| - Lipophobic
55
Structure of Thyroid hormone
Iodinated tyrosine derivative
56
Solubility of thyroid
- Lipophilic
| - Hydrophobic
57
(location) Receptors of catecholamine
On cell surface
58
Place of catecholamine synthesis
In cytosol
59
Storage place of catecholamine
Granules
60
Secretion of catecholamine
Exocytosis of granules
61
Blood transport of catecholamine
Plasma bound
62
Hormone of catecholamine synthesis and storage in ....
Adrenal medulla
63
Receptor location of thyroid
inside cell
64
Place of synthesis of thyroid hormones
organelles
65
Storage of thyroid hormone
Colloid
66
Secretion of thyroid hormone
Endocytosis of colloid
67
Blood transport of thyroid hormone
Plasma bound
68
Name a thyroid hormone x 1
Thyroid follicular
69
Structure of steroids
Cholesterol derivative
70
Solubility of steroids
- Lipophilic
| - Hydrophobic
71
Receptor location of steroids
Inside cell
72
Synthesis location of steroids
Intracell
73
Storage of steroid as..
Lipid droplets
74
Secretion of steroids by..
Diffusion
75
Blood transport of steroids
Plasma bound
76
Steroid hormones x 2
- Adrenal cortex gonads
| - Vit D
77
What are steroid hormones derived from?
Cholesterol
78
Synthesis of steroids
79
Cholesterol pathway
80
2 types of receptors
* surface receptors
| * nuclear receptors
81
Surface receptors binding
– bind peptides & catecholamines
| – at cell membrane
82
Nuclear receptors binding
– bind thyroid & steroid hormones
| – inside the cell
83
What do extracellular chemical hormone bind to?
Surface receptor
84
What does receptor activation alter in surface receptors?
– channel function
| – second-messenger systems
85
How can all cells be exposed to hormones? (surface receptors)
Circulation
86
What do steroid receptors bind?
Steroid hormone
87
What does the hormone-receptor complex become?
A transcription factor (alters gene transcription)
88
What does each steroid receptor bind?
A unique DNA sequence (response element within an enhancer region)
89
What does steroid binding alter?
The rate of transcription
90
Surface receptor domains
* ligand binding domain (LBD)
* 7 transmembrane domains (TMDs)
* G-protein coupled
91
Mechanism of surface receptor
* peptide hormone binds to receptors on the surface of the cell
* activates G-protein
* induces intracellular signals
92
Give 6 neuropeptide examples
- Prolactin
- Adrenocorticotrophic hormone (ACTH)
- Antidiuretic hormone (vasopressin)
- Oxytocin
- Insulin
- Somatostatin
93
Nuclear receptor domains
* Hormone/Ligand binding domain (LBD)
* DNA binding domain binds steroid response element (SRE).
* Nuclear Localization Signal (NLS) covered by heat shock proteins (HSP)
94
Nuclear receptor mechanism
* binding of hormone induces detachment of HSP; uncovers NLS
* receptor + hormone enters nucleus
* acts as a transcription factor
95
Nuclear receptors x 5 examples
Estrogen, Glucocorticoid (Cortisol),
Mineralocorticoid (Aldosterone), Progesterone,
Androgen (Testosterone)
96
How can one hormone influence the activity of another hormone?
By regulation of its receptor
97
Why might target cell be unresponsive?
Due to lack of receptors (physiological, genetic, disease)
98
3 types of receptor regulation
Permissiveness
Synergism
Antagonism
99
Permissiveness
One hormone is required for another hormone to work
100
Synergism
– actions of several hormones are complimentary
| – combined effect is greater than sum of separate effects
101
Antagonism
– one hormone inhibits another hormone’s receptors
| – reduces effectiveness of second hormone
102
What are endocrine glands derived from?
Epithelial tissue
103
What are endocrine glands composed of?
Clumps of secretory cells
104
What are endocrine glands surrounded by?
capillaries
| fenestrated
105
Do endocrine glands have a duct system?
no!
106
Do exocrine glands have ducts
Yes
107
Primary endocrine organs
– discrete organs
– main function is endocrine hormone release
– pituitary, thyroid, parathyroid, adrenal and pineal glands
108
Secondary endocrine organs
– dispersed in organs
– have other major functions
– heart, kidney, liver, etc.
109
What is the study of endocrine regulation?
Neuro-Endocrinology
110
What is neuro-endocrinology?
The study of how the brain regulates Pituitary hormone secretion
111
What do neuroendocrine cells release?
Neurohormones
112
Where are neuroendocrine cells found?
* adrenal medulla
* thyroid
* Pancreas / islet of Langerhans
* pituitary cells
* renin-secreting cells
* gastro-intestinal tract
* lower respiratory tract
113
What is endocrine gland secretion triggered by?
- hormones
- neurotransmitters
- metabolic factors
114
What are two types of feedback loops
- long-loop
| - short-loop
115
What can feeedback be?
- excitatory
| - inhibitory
116
Diagram of hypothalamus short and long loop negative feedback
117
Example of positive and negative feedback
Positive Feedback -
e.g. Hormone 3 activates Gland 2
Negative Feedback -
e.g. Hormone 3 inhibits Gland 1
118
What do trophic hormones regulate?
secretion other of hormones (either releasing or inhibitory)
119
Example of a trophic hormone
Thyroid-stimulating hormone (TSH)
120
Where is TSH secreted from?
Anterior pituitary
121
What does TSH stimulate?
Thyroid hormone secretion from thyroid gland
122
What does TSH maintain?
Maintains structural integrity of thyroid gland
123
TSH basic pathway
124
Disease of endocrine system
- Hyposecretion
| - Hypersecretion
125
Cause of primary hyposecretion
```
• due to abnormality within gland
• causes
– genetic
– dietary (eg lack of iodine)
– chemical or toxic
– immunologic (autoimmune diseases)
– cancer
– surgery (removal / Iatrogenic)
– idiopathic (unknown)
```
126
Cause of secondary hyposecretion
Deficiency of tropic hormone
127
Cause of hypersecretion
– tumours continuously secrete hormone
| – immune factors
128
Cause of primary hypersecretion
Too much hormone secreted due to abnormality within gland
129
Cause of secondary hypersecretion
Excessive stimulation of gland causes oversecretion
