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Cells to systems > Lecture 21 > Flashcards

Lecture 21 Flashcards

1
Q

How do cell communicate

A

using signalling molecules

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2
Q

Where are the receptors

A 
• Cell surface
• Signal transduction
pathways
• Second messengers
• Intracellular receptors
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3
Q

Where are hormone produced

A

• Endocrine organs

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4
Q

What are the hormonal signalling molecules

A

• peptide, amine derived, steroids,

eicosanoids

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5
Q

What are the ways of signalling

A 
Hormonal 
Electrical
External
Mechanical
Immunological
Metabolic
Dissolved gases
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6
Q

What are external ways of signalling

A

• odorants, taste, light

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7
Q

What are immunological ways of signalling

A

• cytokines, chemokines

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8
Q

How does chemical cell

communication

A 
• Extracellular signal binds to
receptor
• Signal is transduced into an
activation or inactivation
response through a cascade
of intracellular messengers
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9
Q

What are the signal pathway for chemical cell communication

A 
Multiple, hierarchical steps
 Amplification
 Activation of multiple pathways
within the cell
 Antagonism by feedback
mechani
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10
Q

What does the signalling molecule physiologic effect depends on

A

• Depends largely on the concentration of signalling
molecules in blood and extracellular fluid
• Nanomolar-Picomolar 10-9 -10-12 M
• Is also dependent on the number of receptors, their
distribution and developmental expression

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11
Q

• The concentration of hormones and other signalling
molecules seen by target cells is determined by three
factors:

A

1) Rate of production
2) Rate of delivery
3) Rate of degradation and elimination

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12
Q

What does feedback imply

A

implies a mechanism for changing rate of

production or secretion

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13
Q

What determine the level and duration of hormonal effects

A 
• Lifespan in blood
• Extent of binding to
plasma proteins
• Metabolic
inactivation
• Excretion
• Number & sensitivity
of receptors
• Upregulation
• Downregulation
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14
Q

What do cells in direct contact(adjecent) to each other signal each other

A

Gap

Junctions

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15
Q

What is the use of gap junction

A 
Allow direct electrical and chemical
communication between cells.
 Signals are passed through gap
junctions from the cytosol of one cell
to the cytosol of the next cell
 Quick signalling
 Important in propagating changes in
electrical potential through tiss
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16
Q

How do lung cilia move in unison and heart move in unison

A

on

via gap junction signal

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17
Q

How contact is made between two cell

A 
Contact is made between a
membrane-bound signalling
molecule on the surface of
one cell and a
complementary receptor on
the surface of another cell
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18
Q

What does endocrine mean

A

If the molecule acts on

distant cells or tissues it is

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19
Q

What does paracrine mean

A

• Signal acts on neighbouring

cells

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20
Q

What does autocrine mean

A

• Signal acts on on the same
cell that released the signal
molecules
• Self-inducing

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21
Q

What is one thing the target cell must have in order to receive the signal

A

Target cell must have the
correct receptor for the
signal molecule

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22
Q

What are the examples of autocrine signalling

A

IL-1 produced by monocytes

IL-2 produced by lymphocyt

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23
Q

How fast does paracrine signalling degrade

A 
The signalling molecule is
rapidly taken up by cells or
broken down by extracellular
enzymes
• Often results in a signalling
concentration gradient
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24
Q

What is endocrine signalling

A 
• Intercellular communication
involving a molecule
produced by one cell that
acts on distant cells or
tissues
• Called hormones
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25
Where are endocrine distributed
• Distributed in blood
26
What are the 4 types of hormones
* Four types of hormones * Peptides and proteins * Steroids * Amines * Eicosanoids
27
What are the classical hormones
* Insulin * Adrenalin * Thyroxine
28
What are the neurohormones
``` • Oxytocin • Antidiuretic hormone • Hypothalamic releasing and inhibiting hormones Act like classical hormones, but are released into blood from neurones ```
29
What are the main hormone producing organs in animals
* Hypothalamus * Anterior pituitary * Thyroid gland * Adrenal gland * Pancreas * Ovaries * Testes
30
What hormone does hypothalamus produce and what it hormone
``` (oxytocin, antidiuretic hormone via posterior pituitary & hormones that act on the anterior pituitary) ```
31
What hormone does anterior pituitary produce
( thyroid stimulating hormone, growth hormone)
32
What hormone does thyroid glad produce
(thyroid | hormones)
33
What hormone does adrenal gland produce
(cortisol, | adrenalin/epinephrine)
34
What hormone does pancreas produce
insulin
35
What hormone does ovaries produce
(oestrogen)
36
What hormone does testoesproduce
(testosterone)
37
How does the physiological response-driven negative feedback cycle
Endocrine gland > hormone > target organ(s) > physiological effects > circulating component (eg. blood glucose) --(negative feedback--> endocrine gland
38
what does pancreatic islet cells do
``` Increased blood glucose stimulates insulin release • Resulting decrease in blood glucose provides negative feedback ```
39
What is the function of the hypothalamus
Functionally diverse region of the brain Located in the diencephalon below the thalamus and above the pituitary Composed of anatomically distinct nuclei
40
What is the hypothalamus made of
Composed of anatomically distinct nuclei
41
What is pituitary gland
Complex endocrine & neuroendocrine organ | Located in the sella turcica at the base of the brain inferior to the hypothala
42
What are the two parts of pituitary gland
arts • Anterior pituitary (adenohypophysis) - endocrine • Posterior pituitary (neurohypophysis) - neuroend
43
What is the role of hypothalamus?
Acts as an integrating centre • Influences physiological and behavioural processes essential for survival.
44
What is | Hypothalamus & Pituita connected together with
Connected to the pituitary via the infundibulum (pituitary stalk) which contains vascular and neural connections
45
What is the key role of the regulating pituitary
``` controls anterior pituitary through inhibiting & releasing hormones These are released into the hypothalamo-hypophyseal portal system ```
46
Whereis Posterior pituitary
Collection of axons whose cell bodies lie in the hypothalam Made up of neural tissue
47
What is anterior have alot of
. Anterior pituitary | Collection of endocrine cells
48
What is the sequence of classical hormones to the target tissues
Hypothalamus (hypothalamic-releasing and release-inhibiting hormones (e.g. TRH) > transferred through hypothalamic-hypophysial portal vessels > anterior lobe of pituitary > releases anterior lobe hormones (e.g. TSH) >target tissues (e.g. thyroid gland
49
How do neurohormones send signal to target tissue
hypothalamus > posterior lobe of pituitary (releasing posterior lobe hormones (e.g. ADH) > target tissue (e.g. kidney ``` Travel down axons via hypothalamohypophyseal tract Neurophysins serve as low affinity carrier proteins Stored in nerve axon terminals Nerve impulse causes release Released into a plexus of blood capillaries ```
50
What are the large neuroscretory neurons
1. supraoptic nucleus | 2. paraventricular nucleus
51
How is the hormones not diluted in the systemic circulation
• Direct vascular connection allows delivery of regulatory hormones directly to anterior pituitary without dilution in the systemic circulation
52
Where does the Hypothalamic neurohomones target
``` • Secreted into a capillary bed in the lower hypothalamus • Enter hypophyseal portal veins between the hypothalamus and anterior pituitary (veins between 2 capillary beds) • Portal veins branch into a capillary bed in anterior pituitary • Pituitary endocrine cells respond to hypothalamic neurohomones and produce classical hormones that are released into the systemic circulation ```
53
What is the structure of Gonadotrophin releasing hormone (GnRH)
Peptide | 10 aa
54
What is the structure of Growth hormone releasing hormone (GHRH)
Single chain | 44 aa
55
What is the structure of Growth hormone inhibiting hormone (GHIH) or Somatostatin (SS)
Peptide | 14 aa
56
What is the structure of Thyrotropin releasing hormone (TRH)
Peptide | 3 aa
57
What is the structure of Dopamine (DA)
Catecholamine
58
What is the structure of Corticotrophin releasing hormone [CRH]
Single chain | 41 aa
59
what is the action of Gonadotrophin releasing hormone (GnRH)
Stimulates luteinizing hormone (LH) & folliclestimulating hormone (FSH) release by gonadotrophs
60
what is the action of Growth hormone releasing hormone (GHRH)
Stimulates GH release by | somatotrophs
61
what is the action of Growth hormone inhibiting hormone (GHIH) or Somatostatin (SS)
Inhibits GH release by | somatotrophs
62
what is the action of Thyrotropin releasing hormone (TRH)
Stimulates TSH secretion | by thyrotrophs
63
what is the action of Dopamine (DA)
Inhibits prolactin (PRL) release and secretion by lactotrophs
64
what is the action of Corticotrophin releasing hormone [CRH]
Stimulates adrenocorticotropic hormone (ACTH) release by corticotrophs.
65
What are the five main cell types in anterior pituitary
``` Thyrotrophs Corticotrophs Lactotrophs Gonadotrophs Somatotrophs ```
66
What does the anterior pituitary cell, Thyrotrophs produce
Thyroid stimulating hormone (TSH)
67
What does the anterior pituitary cell, Corticotrophs produce
Adrenocorticotropic hormone (ACTH)
68
What does the anterior pituitary cell, Lactotrophs produce
Prolactin (PRL)
69
What does the anterior pituitary cell, Gonadotrophs produce
``` Follicle stimulating hormone (FSH) Luteinising hormone (LH) ```
70
What does the anterior pituitary cell, Somatotrophs produce
Growth | hormone (GH)
71
What is the primary function of Thyroid stimulating hormone (TSH)
Stimulates release & production of thyroid | hormones
72
What is the primary function of Adrenocorticotropic hormone (ACTH)
Stimulates release & production of | glucocorticoids
73
What is the primary function of Prolactin (PRL)
Stimulates and sustains milk production
74
What is the primary function of Follicle stimulating hormone (FSH)
Females: stimulates egg formation (growth & development of ovarian follicles) Males: helps stimulate sperm formation
75
What is the primary function of Growth | hormone (GH)
Stimulates postnatal somatic growth & development (IGF-I & II) Mobilizes fat stores, stimulates protein synthesis, inhibits insulin
76
What is the primary function of Luteinising hormone (LH)
Females: stimulates ovulation, corpus luteum formation, estrogen & progesterone secretion Males: promotes testosterone secretion, sperm release
77
What is endocrine axis driven negative feedback and what are they
``` it is a three tiered response 1. Hypothalamic releasing & inhibiting hormones • Example - thyrotropinreleasing hormone 2. Production of tropic hormones in anterior pituitary • Example – thyroid stimulating hormone 3. Production & secretion of hormones from peripheral glands • Example – T4 and T3 from the thyroid gland ```

Cells to systems (25 decks)

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