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PRIN > PRIN 8 Homeostasis > Flashcards

PRIN 8 Homeostasis Flashcards

1
Q

What is normal core body temp?

A

36.8 C

normal rectal is 0.6 C higher

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2
Q

What happens when we have the disturbance of loss of water as sweat?

A

Drop in blood sodium concentrations are sensed by Osmoregulators in Ant. Hypothalamus

Triggers Hypothalamic supraoptic & preoptic nuclei including thirst center

Effector:
Post Pit increases ADH = increased H20 absorption
Brain cortex increases thirst sensation

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3
Q

Negative Feedback Loop Template

A

Regulated Variable
Sensor
Controller
Effector

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4
Q

Bad Example of Positive Feedback Loop

A

Significant loss of blood volume triggers drop in arterial pressure
Weakening of the heart causes a further decrease in heart’s ability to pump
…DEATH

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5
Q

Blood clotting is what type of feedback loop

A

Postive Feedback Loop

Clotting factors within it act on enzymes that further the clotting process

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6
Q

Childbirth is what type of feedback loop?

A

Positive Feedback Loop
Uterine Contractions cause pressure against cervix and releases oxytocin
RESULT: Oxytocin stimulates more uterine contractions

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7
Q

What are the 3 components of the ANS?

A

(1) Afferent
(2) CNS
(3) Efferent`

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8
Q

Where are most ANS centres found?

A

in Nuclei in the brain stem and hypothalamus

(eg) NTS
Nucleus Tractus Solitarii

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9
Q

Uniqueness of Epinephrine

A

acts as BOTH a neurotransmitter AND a hormone

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10
Q

Origins of Sympathetic & Parasympathetic NS

A

Sympathetic:
CN III, VII, IX, X,
S2-S4

Parasympathetic:
T1-L2

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11
Q

Which neurotransmitters do pre-ganglionic fibres use in the Parasympathetic NS?

A

Ach

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12
Q

Which neurotransmitters do pre-ganglionic fibres use in the Sympathetic NS?

A

Ach

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13
Q

Which neurotransmitters do post-ganglionic fibres use in the Parasympathetic NS?

A

Ach

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14
Q

Which neurotransmitters do post-ganglionic fibres use in the Sympathetic NS?

A

NE to Adrenal Medulla
(via Sym Chain Ganglia)

Ach to sweat glands

NE / E to blood vessels
(from liver)

NE to other targets

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15
Q

What is the Paravertebral Ganglion?

A

Same as Sympathetic Chain Ganglia

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16
Q

What is an Ionotrophic Receptor?

A

Ion Channel Receptor
Nicotinic
Na+/K+

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17
Q

What is a Metabotropic Receptor?

A

G Protein / 2nd Messenger Receptor

Muscarinic

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18
Q

What are the 2 types of Cholinergic receptors?

A

via Ach

(1) Nicotinic
Na+/K+

(2) Muscarinic
G-Protein

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19
Q

What are the 5 types of Adrenergic receptors?

A

ALL coupled via G-proteins

a1 vasoconstriction
a2 GI sphincter constriction
B1 increase cardiac output
B2 dilate skeletal muscle arterioles & dilate bronchioles
B3 lipolysis in adipose tisse
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20
Q

a1

A

vasoconstriction

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21
Q

a2

A

GI sphincter constriction

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22
Q

B1

A

increase cardiac output

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23
Q

B2

A

dilate skeletal muscle arterioles

dilate bronchioles

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24
Q

B3

A

lipolysis in adipose tisse

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25
Q

Examples of non-peptide NANC

A

NANC = non-adrenergic / non-cholingeric

GABA, Serotonin, Histamine, Dopamine, ATP, NO

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26
Q

Examples of peptide NANC

A

NANC = non-adrenergic / non-cholingeric

Substance P, Somatostatin, Enkephalin
Vasoactive Intestinal Peptide (VIP)
Cholecystokinin (CCK)
Galnanin

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27
Q

Where does E / NE release from?

What does it stimulate?

A

released from adrenal medulla

stimulates skeletal muscle glycogenolysis

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28
Q

What is meant by Paradoxical co-inactivation?

A

May occur during intense conflict behaviors

-uncertainty between active or passive response

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29
Q

What is meant by Vaso-vagal Reflex?

A

some stressors like sight of blood or public speaking cause parasympathetic predominance

Fall in blood pressure and syncope

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30
Q

Describe autonomic control of ventilation

A 
TYPE 1 (GLOMUS) CELLS
"Carotid Body" located in Carotid Sinus

Sense drop in O2, drop in pH, or rise in CO2 and trigger a reflex an action potential sending a message to increase ventilation

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31
Q

What is Dysautonomia?

A

Rare neurological condition with partial or complete autonomic failure

Autoimmune destruction of ANS neurons

Most patients recover

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32
Q

Orthostatic Hypotension

A

“head rush”

common in the elderly

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33
Q

Autonomic Failure in the Elderly

A

demyelination of preganglionic ANS neurons
40% of patients over 65 have orthostatic hypotension
4% have body temp <35C
10% show urinary incontinence

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34
Q

What is Diabetic Neuropathy?

A

Hyperglycemia reduces GF secretion, suppresses brain blood flow, causes ischemia, and increases production of reactive oxygen species

These factors result in damage and destruction of autonomic neurons

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35
Q

What is Alcoholic Neuropathy?

A

Alcohol causes de-myelination and destruction of axons in spinal nerves.

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36
Q

Primary Endocrine Glands

A

HEAD:
Pineal Gland
Hypothalamus
Pituitary Gland

MEDIASTINUM:
Parathyroid Gland
Thymus

ABDOMEN:
Adrenal Gland
Pancreases
Ovaries/Testes

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37
Q

Secondary Endocrine Glands

A

**Not immediately associated with endocrine, BUT do have individual cells that secrete hormones

Heart 
Stomach
Liver 
Kidney
Small Intestines
Skin
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38
Q

FOUR Chemical Classes of Hormones

A

(1) Peptides & Proteins
(2) Steroids
(3) Amines
(4) Eiocosanoids

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39
Q

In what cells are testosterone produced?

A

Leydig Cells

produce testosterone in testis

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40
Q

Examples of Steroid Hormones

A

(1) Gonads (testis & ovaries) produce Testosterone & Estrogen
(2) Adrenal Cortex produces Aldosterone & Cortisol
(3) Placenta producing Estrogen & Progesterone

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41
Q

Examples of Amines Hormones

A

MODIFIED AMINO-ACIDS
(1) Der. of TYROSINE: E, NE, Dopmaine, T3, T4 (Catecholamines)

(2) Der. of TRYPTOPHAN: Serotonin, Melatonin
(3) Der. of HISTIDINE: Histamine

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42
Q

Examples of Eicosanoids Hormones

A

(1) Prostaglandins: Allergic & Inflammatory Responses
(2) Prostacyclins: blood clotting
(3) Thromboxanes: Vasoconstriction
(4) Leukotrines: Gastric Acid secretion

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43
Q

How is most Hormone Secretion Regulated?

A

Negative Feedback Loops

(eg) Ant. Pituitary releases TSH
Thyroid releases Thyroid Hormones which then act on the Ant. Pit and inhibit release of TSH

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44
Q

What is the most common delivery method of hormones in the body?

A

Endocrine:

secreted INTO blood and act on a different tissue

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45
Q

What is the Neuroendocrine delivery mode?

A

Specialized neurons release hormones into blood

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46
Q

What is the Paracrine delivery mode?

A

Endocrine Cells secrete hormones into the ECM to be picked up by LOCAL cells

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47
Q

What is the Autocrine delivery mode?

A

Endocrine Cells secrete hormones into the ECM to be picked up by the SAME cell

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48
Q

What is the Intracrine delivery mode?

A

Horomones act WTIHIN the cell of origin

do not leave cell

49
Q

What type of receptor does E/NE act on?

A

7 Transmembrane G-Protein coupled Receptors

small molecules (E/NE) bind within the transmembrane domains, whereas larger one bind the N-Terminus

50
Q

Describe:

Single Transmembrane Spanning Receptors

A

*Span membrane only once
GROUP 1:
Possess intrinsic TK activity:
(Insulin, IGF-1, EGF receptors)

GROUP 2:
Interact with intracellular proteins that possess kinase activity
(GH receptor)

51
Q

What are the 4 most common second messenger systems?

A

(1) Cyclic Nucelotides
(2) Inositol phosphates & DIacylgylcerol
(3) Ca2+ and Calmodulin
(4) TK

52
Q

Describe 2nd Messenger System:

(1) Cyclic Nucleotides

A

Involves:
7 transmembrane receptor
G-Protein (a,B,y)
Adenylyl cylcase (AC)

End result: production of cAMP

53
Q

When is the G-Protein activated?

A

when bound to GTP

54
Q

What are examples hormones produced via Cyclic Nucleotides?

A 
ACTH
LH, FSH
Glucoagon
PTH
Catecholamines:
E, NE, Dopmaine, T3, T4
55
Q

What are catecholamines?

A

Derivatives of Tyrosine:

E, NE, Dopmaine, T3, T4

56
Q

Describe 2nd Messenger System:

(2) Inositol phosphates & Diaglycerol

A

PIP2 … IP3 / DAG
also utilizes A G protein(q) which activates PLC

2nd messengers:
IP3 releases Ca2+ from intracellular stores
DAG activates PKC … ser/thr

57
Q

What are examples hormones produced via Inositol phosphates & Diaglycerol?

A

GnRH
GRH
Oxytocin
TRH

58
Q

Describe 2nd Messenger System:

Ca2+ & Calmodulin

A

Within the cell, Ca2+ can bind to calmodulin

Complex then acts on enzymes

59
Q

What are HREs?

A

Hormone Response Elements

Specific DNA regions that acted on by Intracellular Receptor * Respective Hormone

60
Q

What are the modes of heat transfer from the body?

MOST common to LEAST common

A

(1) Radiation (60%)
(2) Evaporation (22%)
(3) Convection (15%)
(4) Conduction (3%)

61
Q

What is the most accurate temperature?

A

Rectal Temperature

(0.3 to 0.5C higher than oral

62
Q

What temperatures defines Hypothermia & Hyperthermia?

A

Hypo 40C

63
Q

What is the Hypothalamic Set Point?

A

CORE BODY TEMP
(head & trunk)
equilibrium state to which temperature is regulated

64
Q

How do we produce heat?

A 
Shivering
Non-shivering (BAT)
Peripheral Vasoconstriction
Piloerection
Increased HR, metabolism
Behavioral adpations`
65
Q

How do we lose heat?

A

Sweating
Vasodilation
Skin Relaxation (hairs lie flat)
Behavioural adaptations

66
Q

What senses temperature changes?

A

Peripheral Thermoreceptors (free nerve endings in skin, oral cavity)

Mostly A delta and C fibres

Transient receptor potential (TRP) channels open, depolarize nerve endings

67
Q

Where do the Peripheral Thermoreceptors send their message?

A

crosses midline at level of spinal cord

Targets: Hypothalamus & Cerebral Cortex

68
Q

Important Nuclei of Hypothalamus & Role in Temperature Regulation

A

PREOPTIC AREA
senses heat or cold, can initiate effectors for heat loss or heat production

ANT. HYPOTHALAMUS
senses heat & initiates heat loss effectors

POST. HYPOTHALMAUS
initiates heat production/retention

69
Q

A lesions in which part of the Hypothalmus could cause hypothermia ?

A

Posterior Hypothalamus
lesion causes hypothermia
(PH induces heat production)

70
Q

How do we achieve vasodilation in the periphary?

A

due to inhibiting sympathetic pathways that act on a-adrenergic receptors on smooth muscle of arteries and arterioles

71
Q

How does Non-shivering thermogenesis work?

A

Brown Adipose Tissue (BAT)
*present in newborns and adults
UCP permits H+ into mitochondrial matrix = ruins H+ gradient
*acts as an uncoupler

72
Q

“I’m too cold”

What happens

A

Pre-optic Area senses and does 2 things:

(1) stimulates release of TRH to increase basal metabolism (fat, heart, skeletal muscle)
(2) communicates with Post H. which instructs Spinal cord to initiate
(i) Shivering
(ii) Sympathetic Activity

73
Q

I’m too hot!

What happens?

A

Ant H/PreOptic Area:

(1) initiates sweating
(2) inhibits sympathetic response normally responding to cold

74
Q

What defines fever?

A

An a.m. oral temperature of > 37.2 °C
OR a p.m. oral temperature of > 37.7 °C
(circadian rhythm is retained during fever)

Fever associated with signs of infection/inflammation (increased C-reactive protein, neutrophils)

75
Q

What is a Pyrogene?

A

Fever inducing substance (endogenous or exogenous)
Examples:
(1) Tumors: lymphoma
(2) Autoimmune disorders: rheumatoid arthritis, lupus
(3) Tissue damage: surgery, infarction
(4) Infectious disease: AIDS, malaria, influenza, gastroenteritis o Lipopolysaccharide (LPS: bacterial cell wall)
(5) Used for experimental study of fever
(6) Drugs (antibiotics)
(7) Fever of unknown causes (persist for several days-weeks)

76
Q

Describe temporal pattern of Simple Fever

A

Set point suddenly set to high value (eg) 39C
BRAIN IS TELLING BODY TO BE HOT
Therefore, heat conservation via sympathetic kicks in: Vasoconstriction, Piloerection, Shivering

“Crisis” is the fever breakpoint (usually after 36 hrs)

77
Q

How do Pyogenes cause fever?

A

Neutrophils, Macrophages/monocytes migrate to site of damage/infection and release cytokines
TNF, IL-1 & IL-6, Interferons

78
Q

How do blood cytokines tell the brain to start a fever?

A

Cytokines are biggish can only cross the BBB where it is leaky. Occurs at OVLT, right next to the pre-optic/AH

OVLT: organum vasculosum of the lamina terminals

79
Q

What is the final step in generating fever?

A

Cytokines (IL-1,6, TNF-a) stimulate the production of prostaglandin E2 (PGE2) in endothelial cells of brain vessels

PGE2 diffuses into preoptic/anterior hypothalamus and reduces firing rate of warm-sensitive neurons, thereby inhibiting heat loss mechanisms.

PGE2 increases firing rate of cold-sensitive neurons, thereby increasing heat gain mechanisms.

Net effect is a resetting of the hypothalamic set point to a new higher value

80
Q

How can we treat fever?

A

NSAIDs (ibuprofen or aspirin) inhibit PGE2 synthesis via cyclo-oxygenase

Corticosteroids blocks inflammation by inhibiting PLA2 & COX

(note: PLA2 is used to make arachidonic acid & COX converts arachidonic acid to prostaglandins)

81
Q

When might Intermittent fever occur?

A

Malaria

causes multiple temperature spikes

82
Q

In an OGTT, what glucose values are diagnostic for Diabetes Mellitus?

A

Fasting > 6.1 mmol/L

End of OGTT > 10.0 mmol

83
Q

What is Pre-Diabetes?

A

Revealed by glucose levels:
Impaired Glucose Tolerance (IGT)
Impaired Fasting Glycaemia (IFG)

84
Q

What are normal glucose levels?

A

3.3 - 8.0 mM

normal physiological range with variable nutritional availability

85
Q

What are the 3 sources of blood glucose?

A

(1) Intestinal absorption (diet)

(2) Glycogenolysis
breakdown of glycogen (muscle and liver)

(3) Gluconeogenesis
production of glucose from precursors
(liver/cortex of kidney)

86
Q

Postprandial
VS
Post-absorptive

A

**Postprandial:
Immediately after a meal.
Insulin UP
Counter-regulators LOW

**Post-absorptive
Once blood glucose levels drop below ideal
Insulin DOWN
Counter-regulators UO

87
Q

What happens to consumed glucose?

A

(1) Used for immediate energy
(2) Stored as glycogen in skeletal muscle and liver till saturated
(3) Excess glucose is shunted to FA synthesis

88
Q

During fasting, when do glycogen stores become depleted?

A

24 hours

89
Q

What defines hypglycemia?

A

below 3.3 mM/L

90
Q

Where is Insulin produced?

A

β-cells of Liver (comprise

60-80% of the islet)

91
Q

What is C-Peptide?

A

Pro-Insulin becomes processed within secretory vesicles to produce Insulin & C-Peptide.

C-peptide is a surrogate marker for insulin. It is produced in a 1 to 1 ratio to insulin. Therefore, C-peptide conc reveals endogenous insulin

92
Q

HOW is insulin released?

A

(1) Glucose is imported into cell and undergoes glycoylsis & cellular respiration
(2) Excess ATP closes K+ channel blocking it from entering the cell
(3) Lack of K+ in cell causes depolarization
(4) Depolarization activates voltage-gated calcium channel
(5) Rise in intracellular Ca+ causes exocytosis of insulin granules

93
Q

What are the Incretin Hormones?

A

GIP & GLP-1
Released from intestinal endocrine cells during a meal to act on the pancreas and augment insulin production

GIP: Glucose-dependent Insulinotropic
GLP-1: Polypeptide Glucagon-Like Peptide-1

94
Q

How is the rate of glucose absorption different between IV and digestive?

A

IV glucose does not trigger Incretin and therefore there is a lower Insulin release.
Ingested glucose triggers a more powerful insulin response.

95
Q

Once released in the blood and encountering the tissues, what does Insulin bind to and what does it do?

A

Insulin binds to its own TK receptor and causes an intracellular cascade that promotes GLUT 4 translocation to membrane

96
Q

Where is GH produced?

A

produced in somatotrophs of the anterior pituitary

Released during a prolonged fast

97
Q

Hierarchy of Counter regulation

Order in which regulators are released

A 
Insulin – 4.6 mM
Glucagon – 3.8 mM
Epinephrine – 3.8 mM
GH - 3.7 mM
Cortisol – 3.2 mM

Hypoglycemia ~3.0 mM
Hypoglycemia is rare

98
Q

Type 1 DM

A

5-10% of diabetes

Autoimmune destruction of β-cells = no insulin

99
Q

Type II DM

A

Defective insulin secretion and insulin resistance
B Cells become exhausted and eventually fail
Genetic and environmental
Risk factor: obesity

100
Q

What causes hands and feet to get cold?

A

NE released from the sympathetic nerve endings to alpha receptors on blood vessel walls

a1 = vasoconstriction

101
Q

In our hypothermic case, why was old Mary not shivering?

A

Two Possibilities:

(1) Her glycogen stores were used up and she was was past the shivering stage
(2) Some elderly people do not shiver

102
Q

What is Therapeutic hypothermia?

A

Intentionally induced hypothermia during surgery.

Cerebral metabolism is reduced by 7% per 1 degree C

103
Q

What is the danger of warming a hypothermic patient too quickly?

A

Hypovolemic Shock

104
Q

What is Hashimoto’s thyroiditis?

A

Hypothyroidism
Due to Iodine def (issue mostly in developing countries)
Presentation of goiters

105
Q

What is the role of Peripheral Thermoreceptors?

A

To sense temperature changes in the peripheral and to induce vasoconstriction even before the core temp has dropped.
They anticipate changes ahead of time.

106
Q

Is Alchohol warming?

A

Provides short-term warming sensation
But, as a vasodilator it inhibits the body’s own peripheral vaso-constriction mechanisms. Thus, heat is lost and the core temp drops.

Alcohol speeds hypothermia.

107
Q

The G-protein coupled receptors consist of a single polypeptide chain which crosses the membrane seven times.

Where does peptide hormone binding occur?

A

(1) N-terminal extracellular domain.

OR

(2) first extracellular loop

108
Q

The release of this neurotransmitter results in vasoconstriction

Which Hormone?

A

NE

109
Q

Where is glucocorticoid released from?

A

cortex of the adrenal gland.

110
Q

cAMP production involves what components?

A

(1) 7 transmembrane receptor
(2) G-protein
(3) Adenylyl cyclase

111
Q

During cAMP production, when the horomone binds to the receptor, what happens?

A

GDP is exchanged for GTP causing change in G protein subunits

Result: GTP-alpha subunit is released from G protein

112
Q

What does GTP-alpha subunit do?

A

Binds to adenylyl cyclase (AC)

AC converts ATP to cAMP

113
Q

What does cAMP do?

A

activates PKA

114
Q

What are the major means of heat loss in water?

A

conduction

convection

115
Q

Peptide / Protein Hormones

Examples:

A

Insulin

Vasopressin (ADH)

116
Q

Steroid Hormones

Examples:

A 
Testosterone
Estrogen
Progesterone
Aldosterone
Cortisol
117
Q

Amine Hormones

Examples:

A

(1) Tyrosine - E, NE, Dopamine, Thyroid H.
(2) Tryptophan - Seretonin, Melatonin
(3) Histidine - Histamine

118
Q

Eicosanoid Hormones

Examples:

A

Prostaglandins (allergy / inflamm response)

Prostacyclins (blood clotting)

Thromboxanes (vasoconstriction)

Leukotrines (gastric acid secretion)

PRIN (13 decks)

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