Endocrine regulation of physiological function Flashcards
Hormones fall into
three major classes:
Polypeptides, steroids,
and amines
which hormones are water soluble?
Polypeptides and most
amines are water soluble(This makes the steroid hormones fat soluble)
what is the difference between water soluble and fat soluble hormones?
Water-soluble hormones
are secreted by
exocytosis, travel freely in
the bloodstream, and
bind to cell-surface
receptors
Lipid-soluble hormones
diffuse across cell
membranes, travel in the
bloodstream bound to
transport proteins, and
diffuse through the
membrane of target cells
They bind to receptors in
the cytoplasm or nucleus
of the target cells
why do you need glucose in stress?- what hormone increases glucose availability?
glucose required for energy: pathways in cell stimulated by adrenaline to increase
glucose availability
give an example of an endocrine gland?
such as the thyroid and
parathyroid glands and testes or
ovaries- they are ductless
give the exocrine glands example
salivary glands, have ducts to carry
secreted substances onto body
surfaces or into body cavities
give examples of organs that also have hormone secretion too.
While the heart, kidneys, and other organs have their primary roles, they also produce hormones, making them part of the endocrine system
positive feedback- Simple neuroendocrine pathway
suckling stimulus, hypothomes to pituitary oxytocin- to Smooth muscle in
mammary glands
Milk release
negative feedback- Simple endocrine pathway
endocrine cell, Low pH in
duodenum, S cells of duodenum, Secretin Pancreatic cells
RESPONSE Bicarbonate release
what coordinates endocrine signalling
The hypothalamus coordinates endocrine signalling
what is the pituitary gland made up of
composed of the posterior pituitary
and anterior pituitary
Posterior pituitary does what?
stores and secretes
hormones that are made in the hypothalamus
what is the other name for the posttrial pituitary
Neural link (PP also known as
neurohypophysis)
Anterior pituitary does what and what is it also called?
makes
and releases hormones
under regulation of the
hypothalamus
Vascular link (AP also known
as adenohypophysis)
ADH target organ
The kidneys tubules
Oxytocin
Mammary glands,
uterine muscles
what does alcohol do?
Alcohol inhibits secretion of ADH = increased volume of dilute urine
Anterior pituitary stimulates a lot more hormones name a few name some with Tropic effects only
FSH and LH, TSH and ACTH(TO ADRENAL CORTEX)
Nontropic effects only
Prolacin and MSH( Melanocytes)
Tropic and
nontropic effects
GH, Liver, bones,
other tissues
what is a tropic hormone
causes secretion of another hormone
the tropic effects of tyroid, THS
If thyroid hormone levels drop in the blood:
The hypothalamus secretes thyrotropin-releasing hormone (TRH).
TRH signals the anterior pituitary to release thyroid-stimulating hormone (TSH).
TSH stimulates the thyroid gland to release more thyroid hormone.
This causes the thyroid to enlarge, resulting in
a goiter how does this happen?
Iodine is needed to produce thyroid hormones.
When there isn’t enough iodine in the diet, the thyroid can’t make enough thyroid hormone, so it compensates by growing larger to try and produce more.
what is TRS
Neurosecretory cells secrete TRH (Thyrotropin-Releasing Hormone) into the blood.
The blood carries TRH to the anterior pituitary.
TRH stimulates the anterior pituitary to release TSH (Thyroid-Stimulating Hormone), also called thyrotropin.
where are the adrenal glands located?
located on top of the kidneys
can you explain what the adrenal glands look like?
Each adrenal gland consists of two glands: adrenal medulla (inner) and adrenal cortex (outer)
The adrenal medulla
Adrenal medulla secretes adrenaline and noradrenaline (fight, flight or freeze)
Adrenal cortex
secretes corticosteroids – glucocorticoids and mineralocorticoids
what are the Glucocorticoids ie give an example
e.g., cortisol-, influence glucose metabolism and the immune system
Mineralocorticoids
eg aldosterone, affect salt and water balance ( think minearals for example salt )
adrenaline has multiple effects what are they?
Blood glucose level
increases.,
Blood vessel dilates,
increasing flow to
skeletal muscle.,
Blood vessel constricts,
decreasing flow to
intestines.
what do the testis often produce?
primarily synthesize androgens, mainly
testosterone,
what hormone is mainly responsible for female development?
Oestrogens, most importantly oestradiol, are
responsible for maintenance of the female reproductive
system
what is involved in pregnancy development- maintains the uterus
progesterone is primarily involved in
preparing and maintaining the uterus for pregnancy
for the synthesis of sex hormones is controlled by what?
gonadotropins and follicle-stimulating hormone and
luteinizing hormone
where are the follicle-stimulating hormone and
luteinizing hormone form?
anterior pituitary
Gonadotropin secretion is controlled by gonadotropin releasing hormone from the……..
hypothalamus
what is an endocrine disorder?
Endocrine disease results when a gland produces too much (excess) or
too little (deficiency) of an endocrine hormone, called a hormone
imbalance- This can be due to the development of lesions (such as nodules or
tumours) in the endocrine system, which may or may not affect
hormone levels
the pancreas endocrine beta cells produce what?
b(beta) cells
Site of insulin synthesis and
secretion
the alpha cells of the pancreas produce what?
glucagon
insulin is considered what type of hormone and why ?
Anabolic hormone- Promotes cellular uptake of glucose, fatty
acids, and amino acids and enhances their
conversion into glycogen, triglycerides,
and proteins, respectively
when is insulin secreted?
Primary stimulus for secretion is
increase in blood glucose
concentration
one major sign of diabetes?
Urine acquires sweetness from excess
blood glucose that spills into urine
type 1 diabetes?
Characterized by lack of insulin
secretion (autoimmune destruction
of b cells)
type 2 diabetes
Characterized by normal or even
increased insulin secretion but
reduced sensitivity of insulin’s target
cells
the flow of the fluids into the compartments of the body
External Environment → Plasma (Blood) → Interstitial Fluid → Cytosol (Inside Cell)
what is the cardiac cycle?
The heart contracts and relaxes in a rhythmic cycle called the
Contraction:
systole
Relaxation:
diastole
The flow form the heart is what type of direction?
unidirectional
Cardiac output- what is the calculation.
Heart rate (beats/min) x stroke volume (mls/beat)
Exercise does what to this: Exercise: increases several fold.
elite athletes would have what at rest?
low heart rate and high
stroke volume - high stroke volume to pump loads of blood- low heart rate- as it is so efficient
can you relate the heart to the nervous system?
Parasympathic:
Innervates SA node
Slows heart rate
Sympatheic:
Innervates SA node
Increases heart rate-
Exercise: decreased parasympathetic activity & increased sympathetic activity
what is the signal passing like?
Signals (yellow)
from SA node
spread through
atria.
Signals are
delayed at AV
node.
p wave
atrial depolarisaion
QRS complex
ventricular depolarisaion
T wave:
ventricular repolarisation
Abnormal Heart Rates for example, Tachycardia-
fast
Bradycardia
slow
Fibrillation
Loss of coordination of electrical activity. Can be corrected
by defibrillation
what is the blood veins relationaship?
Ventricle - artery - arteriole - capillary - venule - vein - atrium. VAACVVA- Intuitive as artery- arteriole
what is inside every vein and artery?
endothelium
in accordance to a vein what is the basal laminin ?
The basal lamina is a thin layer of extracellular matrix (a sheet-like structure) that lies beneath the endothelial cells in the wall of a vein.
what is the core concept of haemodynamic?
Fluids (eg. air, blood) move
from regions of higher
pressure to lower pressure
down a pressure gradient
put in order of highest to lowest pressure.
Aorta (highest pressure — blood just pumped out of left ventricle)
Arteries
Arterioles
Capillaries
Venules
Veins
Venae Cavae (lowest pressure — returning blood to the heart)
breathing follows bolyles law- but what does this mean?
At constant temp, pressure and volume are inversely related
inhalation
Diaphragm contracts (moves down).
Lung volume increases, pressure would decrease ( ie this happens when lung gets larger )
exhalation
EXHALATION: Diaphragm relaxes (moves up).
Lung volume decreases: Pressure in lung
increases above atmospheric P
Spirometry is what-
Pulmonary function test
what is the general composition of air
79% Nitrogen
21% Oxygen
Trace amounts carbon dioxide, helium,
argon, etc
Each haemoglobin protein can bind how many oxygen
molecules
4
how much carbon dioxide acc enters the blood?
Only about 7% of CO2 from respiring cells
diffuses into the blood and is transported in
blood plasma, bound to hemoglobin
what happens when plasma is infected with Co2
The remainder diffuses into erythrocytes and
reacts with water to form H2CO3, which
dissociates into H+ and bicarbonate ions (HCO3
–)
Reac1on catalyzed by carbonic anhydrase
what is the Bohr shift?
CO2 produced during cellular respiration lowers blood pH and decreases the affinity of
hemoglobin for O2
where is the breathing centre of the brain?
medulla oblongata of the brain
how does the medulla know to regulate the depth of breathing?
Medulla regulates the rate and depth of breathing in response to pH changes in the cerebrospinal fluid
(influence of CO2) weird i know but cerebrospinal fulid is also in spine and brian.
what is normal oxygen consumption at rest?
Normal oxygen consump1on at rest approximately
250ml/min- females 20% less.
Physiology Research Focus: hypoxia
insufficient oxygen in in body- surroundings.- High altitude to a physiologist starts around 1500m
(5000ft), the altitude where the body senses
changes in the oxygen level
Precapillary sphincters
small muscles- located in junctions- act as valves.
Thoroughfare
channel
direct pathway between arteriole and capillaries
lymph vessels
Blind ending capillaries
Large vessels empty into subclavian vein
what is the main function of lymph vessels?
Major functions
Tissue drainage
Return leaked plasma proteins
Absorption of digested fat
Defence (lymph nodes)
what is Oedema
swelling caused by excess fluid or institute fluid. Reason blockage or increased capillary pressure from kidney disease or lack of protein in blood.
how could an airplane flight cause oedema
Aeroplane flight (via decompression & immobility)- can cause Increased venous pressure
what does regulate plasma composition?
kidneys- urine is acc unfiltered plasma
urine system refinement?
Filtration: Filtering of plasma
Reabsorption: Reclaiming valuable
solutes
Secretion: Adding nonessential solutes
and wastes to the filtrate
Excretion: Processed filtrate containing
nitrogenous wastes is released from the
body
what is the vasa recta?
the specialised blood vessels in the kidney.
Bowman’s capsule
its filtrates contains salts, glucose, amino acids, vitamins,
nitrogenous wastes, and other small molecules
the proximal tubules
Reabsorption of ions, water, and nutrients takes place
Molecules transported actively and passively from the filtrate into the interstitial fluid and then
capillaries
As the filtrate passes through the proximal tubule, materials to be excreted become concentrated
Some toxic materials are actively secreted into the filtrate
Descending Limb of the Loop of Henle
Reabsorption of water continues through channels formed by aquaporin proteins-
Ascending Limb of the Loop of Henle
Salt but not water is able to diffuse from the tubule into the interstitial fluid
The filtrate becomes increasingly dilute
Distal Tubule
The distal tubule regulates the K+ and NaCl concentrations of body fluids
The controlled movement of ions (H+ and HCO3
–) contributes to pH regulation
Collecting Duct
Carries filtrate through the medulla to the renal pelvis
One of the most important tasks is reabsorption of solutes and water
Urine is hyperosmotic to body fluids
Antidiuretic hormone
is also called vasopressin
ADH molecules released from the posterior pituitary bind to and activate membrane
receptors on collecting duct cells
what regulates the concentrations of solutes in the blood?
Osmoreceptor cells are specialized neurons located in the hypothalamus
where does ADH work on
ADH acts on the kidneys, particularly the distal convoluted tubules and collecting ducts, increasing their permeability to water.
NORMAL
BLOOD OSMOLARITY
285–295 mOsm/L
what is blood pressure?
Blood pressure is a force exerted in all
directions, including against the walls of
blood vessels
what also helps regulate blood pressure?
The recoil of elastic arterial walls plays a role in
maintaining blood pressure
what dissipates high blood pressure
The resistance to blood flow in the narrow
diameters of tiny capillaries and especially
arterioles dissipates much of the pressure
what is systolic pressure?
is the pressure in the arteries
during ventricular systole; it is the highest
pressure in the arteries
Diastolic pressure
is the pressure in the arteries
during diastole; it is lower than systolic
pressure
flow
pressure gradient / resistance to flow
Poiseuille’s Law or resistance to flow
R=length x velocity / radius^4
Is a major inducer of vasodilation
Nitric oxide
Is a potent inducer of vasoconstriction
The peptide endothelin- produces by the epithelial cells
Vasoactivity influenced by
nerves, hormones and local effects in tissues
explain the role of Metabolism on vasoactivity-
decreased O2 causes dilation, heat causes dilation
Hormones explain hormones role of vasoacrivity
Histamine dilates,
ADH/Vasopressin constricts)
Total Peripheral Resistance
The summed resistance throughout the circulation
Blood pressure for a healthy young adult
human at rest should
<120 mm Hg at
systole and 70 mm Hg at diastole
MAP=
CO x TPR or HR x SV x TPR
what is TPR:
Total peripheral resistance:
vasoconstriction preformed by veins does what
Increases blood pressure
what are the types of Baroreceptors?
A fibres (myelinated)
Low pressure (30-90 mmHg)
Important at rest
C fibres (unmyelinated)
High pressure (70-140 mmHg)
Increasingly active at higher pressures
what are baroreceptors?
Specialised nerve endings that respond to stretch of vessel wall
Indirect response to changes in Blood pressure.
locations of baroreceptors?
Carotid sinus & aortic arch
what is a key feature of baroreceptors?
for short term regulation ,Eg in hypertension they reset within 1-2 days
when blood pressure rises or falls what happens- what does the barorespetrs do?
When blood pressure rises or falls, these baroreceptors send signals to a part of the brainstem called the NTS (Nucleus Tractus Solitarius), located in the medulla oblongata.
lets say we want a calming effect. What should you do?
The NTS sends signals to the nucleus ambiguus, which then sends vagus nerve signals to the heart.
This slows down the heart rate (HR) — a calming effect.
say we are stressed-
Hypothalamus & Amygdala
These areas process emotions and stress.
They can inhibit or override the baroreceptor reflex, allowing your blood pressure to rise temporarily as part of the fight-or-flight response.
Angiotensin II
raises blood pressure and
decreases blood flow to the kidneys
It also stimulates the release of the
hormone aldosterone, which
increases blood volume and pressure
why does hypertension occur?
peripheral flow resistance
Primary/essential hypertension
Mostly via aspects that affect arteriolar smooth muscle
Cumulative effect of genetic, lifestyle & environmental
factors
difference between hypertension and high blood pressure?
hight blood pressure is temporary- by stress, exercise, caffeine, pain, or anxiety
Hypertension- A chronic (long-term) medical condition where blood pressure is consistently high.
5% of cases, secondary
to disturbance of normal physiological function
e.g. renal diseases, adrenal disease
drug treatment of hypertention: Thiazide diuretics
Inhibit Na+/K+/Cl- exchange in distal renal tubule
b-blockers:
Reduce HR & contractility
a-blockers:
Reduce sympathetic tone; dilate arteriolar smooth muscle
L-type Ca2+ channel blockers
relaxation of vascular smooth muscle → reduced
resistance
ACE inhibitors:
Diuretic actions; Inhibit aldosterone formation
