HES 111 MIDTERM 1 Flashcards
What are the two main classes of hormones?
Amino acid based and Lipid based.
What are the two hormone types Amino acid based hormones can be broken up into?
Amine hormones and Peptide hormones.
What kind of hormone can a lipid hormone further be divided into
Steroid hormone.
What are three ways these hormones behave differently
They travel differently in the blood, they respond differently to how their target cells recognize and receive them and they have different half lives.
Are Amino acid based hormones hydrophobic or hydrophilic and are they big or small?
Usually large and hydrophilic
How to amino acid based hormones bind?
They bind to a receptor on the plasma membrane of their target cells
Are steroid hormones hydrophilic or hydrophobic?
Hydrophobic
How do steroid hormones bind to receptors?
Bind to receptors in the cytosol or even within the nucleus of their target cell.
Hormones circulate in the blood until what 2 things happen?
They are taken up by their target cell or broken down (metabolized)
The rate of which hormones are broken down depends on…
Their structure and whether they are bound to carrier proteins.
What is half life?
The amount of time it takes for concentration of hormone to reduce by half in the blood.
Do hydrophobic hormones have long or short half life? About how long and why do they have this amount of half life.
They have the longest half life. Usually minutes to hours. They are bound to carrier proteins in the blood.
Do hydrophilic hormones have long or short half life? How long and why do they have this half life.
Shorter half life seconds to minutes because they are not generally bound to carrier protein.
What is the endocrine system?
A series of organs throughout the body that secrete hormones in response to a stimulus.
What is a neuroendocrine organ and what are some common ones?
A hybrid between nervous system and endocrine system. Some examples are the pineal gland, and hypothalamus.
What is the difference between a hormone and a neurotransmitter?
Hormones travel in the blood andb are secreted by an endocrine cell—- Endocrine cell, blood, target cell.
Neurotransmitters travel across the synaptic cleft— Synaptic cleft, target cell.
What is a neurohormone?
Secreted by a neuron and travels in the blood.
What produces its own hormones for secretion from the posterior pituitary and also directs secretion of other hormones from the anterior pituitary
The hypothalamus
What is the pituitary gland seperated into?
Anterior and posterior pituitary
What 2 hormones are secreted by the hypothalamus in the posterior pituitary
Anti Diuretic Hormone and oxytocin
What does ADH do?
Water reabsorption back into the blood
What does oxytocin do?
Uterine contraction and milk release.
What is a tropic hormone?
A hormone that triggers the release of another hormone
What does the anterior pituitary gland secrete
Many tropic hormones.
What is the main function of the growth hormone?
Regulate growth of target tissues?
What are the short term effects of the growth hormone
Fat breakdown, inhibit glucose uptake in skeletal muscle
What is the goal in the short term effects of the growth hormone
Make glucose and fatty acids available for use for fuel.
What are the long term effects of the growth hormone and what does the growth hormone release during long term effects
Protein synthesis, cell division, increased glucose uptake by cells.
Secretes Insulin like growth factor
What does the thyroid gland do?
Regulates metabolism, Regulates body temperature, sets the basal metabolic rate
What does the thyroid gland produce and secrete
calcatonin
What hormone is secreted in response to low blood calcium
Parathyroid hormone.
What are the effects when there is an increase in blood calcium levels
stimulates osteoclasts, increases the absorption of calcium by small intestine and increase reabsorption of calcium in the kidneys.
What two neurohormones does the adrenal medulla secrete
epinepherine and norepinepherine.
What steroid hormone does the adrenal cortex release
aldosterone
why is aldosterone important
Important for regulation of fluid electrolyte and pH balance in the blood
What does cortisol do?
promotes catabolic reactions in order to provide fuel for stress.
Pancreatic islets which are little islands of cells consist of what kind of cells
alpha beta and delta cells
What type of cells is insulin produced and secreted by?
beta cells
When is insulin released
secreted in a response to increase blood glucose
what type of cells is glucagon produced and secreted by?
alpha cells
When would glucagon be secreated?
In response to decrease blood glucose
What is the fibrous pericardium
The outer layer of connective tissue
What is the serous pericardium
inner membrane that folds under itself to form 2 layers.
Where is the parietal layer fused to?
fused to the inner surface of the fibrous pericardium
Where is the visceral layer?
inner layer closests to the heart wall
What is the pericardial cavity and what is it filled with
between the parietal and visceral layer and is filled with serous fluid.
What are the three layers of the heart
epicardium, myocardium, and endocardium
What does the epicardium include?
includes a thin layer of connective tissue containing fat deposits
What is the myocardium and what does it contain
the main component that makes up the wall of the heart and mostly cardiac cells and contains pacemaker cells and connective tissue
What is the endocardium
the inner most layer of the heart wall that faces the lumen of the heart chambers.
What are the 4 chambers of the heart
Two atria and two ventricles
Where do the atria receive blood from and where do they pump the blood
receive blood from veins and pump blood into the ventricles through one way valves.
Where do ventircles eject blood into and where do they carry blood to?
eject blood into arteries and carry blood through systematic or pulmonary circuits
What are the two major systemic veins
superior and inferior vena cava
What is the major systemic artery
aorta
What are the major vessels of pulmonary circulation
right/ left pulmonary arteries and right/left pulmonary veins
Are the ventircles smaller or larger than the atria
larger and thicker
is the right atrium small/ large thin/thick walled and anterior or posterior
larger, thinner walled and more anterior
is the left atrium small/ large thin/thick walled and anterior or posterior
smaller, thicker walls, and more posterior
what are the right and left ventircles seperated by
interventricular system
What are the valves between the atria and ventricles called
AV valves
Where is the tricuspid valve located
between right atrium and right ventricle
where is the bicuspid valve located
between left atrium and left ventricle
What is the valve between the ventricles and pulmonary artery and aorta called
semilunar valves
where is the pulmonary valve located
between right ventricle and pulmonary trunk
where is aortic valve located
between left ventircle and aorta
what does high pressure in the ventricle cause
causes blood flow that pushes aortic valve open
what does high pressure in the ventricle cause
pushes the blood up to the valve, closing it
what happens when there is pressure from the blood flowing backwards in the aorta
closes the aortic valve
what happens when there is pressure from the blood in the left atrium
pushes the mitval valve open
What are 99% of cells in the myocardium
Myocytes
What do myocytes generate?
Generate action potentials when membrane is depolarized to treshold.
What cells are the source of contraction of the heart muscles
myocytes
what is the name of cells that make up 1%
pacemaker cells
What do pacemaker cells generate
generate spontaneous rythmic action potentials
Do pace maker cells contribute to the contractile force of the heart
No
Why are myocytes striated
Because they contain contractile proteins (actin and myosin) that are organized in the same way as skeletal muscle fibres.
What does each myocyte contain that allows for high energy demands
many mitochondria
What structures join myocytes together
intercalated discs join myocytes together.
What two things are interecalated discs made up of?
Desmosomes and gap junctions
The sponatanous action potentials that pacemaker cells undergo spread where?
They spread quickly from cell to cell via gap junctions through the cardiac conduction system.
What do the pacemaker cells “set”
they set the pace of the heart
What does the delayed conduction through the AV node allow for
allows the atria to fully depolarize and contract before the ventricles.
Describe the slow initial depolarization phase for pacemaker cell AP’s
More positive ions leak in than leak out of HCn channels in the plasma membrane which causes the membrane to slowly depolarize to threshold.
Describe the full depolarization phases of a pacemaker cell AP’s
at treshold, voltage gated calcium channels open and calcium enters the cell causing the membrane to depolarize.
Describe the repolarization phase for pacemaker cells AP’s
Calcium channels close and voltage gated potassium channels open causing potassium outflow and membrane repolariation
Describe the minimum potential phase for pacemaker cells AP’s.
Potassium channels remain open and the membrane hyperpolarizes. This opens HCN channels and the cycle repeats.
How are AP’s transmitted from pacemaker cells to myocytes
through gap junctions
What do the oction potentials in myocytes signal
they signa contraction (excitation contraction coupling)
Describe the rapid repolarization phase
volatage gated sodium channels open and na enters depolarizing the membrane
Describe the initial repolarization phase
sodium channels close and potassium channels open and potassium begins to leave the cell causing repolarization.
Describe the plateau phase
calcium channels open and calcium enters the cell as potassium exits, prolonging the depolarization.
How much does the plateau phase legthen the cardiac AP
lenghtens it by 200-300msec.
Does the plateau phase prevent tetanus
yes prevents tetanus (another AP cant fire right after)
What is ECG and what does it stand for?
Electrocardiogram and it is an important for examining the function of the heart. It gives us a picture of the electrical activity ocuring in all cardiac muscle cells over a period of time.
The electrical changes shown on the ECG reflect what?
They reflect the depolarization and repolarization of cells
What does the P wave reflect
Reflects depolarization of all the myocytes of the left and right atria
What does the QRS complex reflect?
Refelcts depolarization of all the myocytes of the left and right ventricles.
What does the T wave reflect?
Reflects repolarization of all the myocytes of the left and right ventricles
What does the R-R Interval represent
entire duration of a cardiac cycle
What does the P-R interval reflect
Duration of atrial depolarization and AV node delay
What does the Q-T interval relfect
Entire duration of a ventricular action potential
What does the S-T segment reflect
Reflects the ventricular plataue phase
Each cardiac cycle consists of one period of… and one period of …
contraction (systole) and relaxation (
What are the four cardiac cycle phases?
filling, contraction, ejection, relaxation
Describe the cardiac cycle (step 1: ventricular filling phase)
Blood flows down its pressure gradient from atria into ventricles. Most of the blood passively drains into the ventricles and then the atria contracts to eject the remaining blood
Describe the isovolumetric contraction phase (step 2)
All valves are closed during this phase and it is called isovolumetric because the pressure in the ventricles is not yet high enough to push open the semilunar valves.
Describe the ventricular ejection phase (step 3)
At rest, about 70mL of blood is pumped from each ventricle. The AV valves are still closed and pressure opens the SL valves and blood is ejected into the pulmonary artery and aorta.
