Human Systems Flashcards
Types of Invertebrate Circulation
1) No circulatory system
2) Open circulatory system
3) Closed circulatory system
No circulatory system
– use simple diffusion
to distribute nutrients. Includes bacteria,
protista, fungi, invertebrate animals.
Open circulatory system
– pumps fluid called hemolymph into sinuses or hemocoel. Includes some mollusca, arthropoda, Echinodermata.
Closed circulatory system
– Use a pumping heart to move blood through vessels. Includes annelida (earthworms)
Vertebrate Circulation
- Most chordates (eukaryotic vertebrates within
kingdom Animalia) have a closed circulatory
system. Blood is a type of connective tissue due to containing cells surrounded by a matrix.
2-chambered hearts (atrium and ventricle)
– fish. Deoxygenated blood fills the heart and is pumped to the gills for oxygen exchange.
3-chambered hearts (2 atriums and 1 ventricle)
– amphibians and reptiles. Poikilothermic chordates. Alligators and crocodiles are exceptions, they have 4-chambered hearts.
4-chambered hearts (2 atriums and 2 ventricles)
– birds and humans. Homeothermic chordates.
Human Heart - Flow of blood through heart
- Right atrium – Deoxygenated blood is returned here from the upper superior vena cava and the lower inferior vena cava. Blood passes through the right atrioventricular valve (AV valve, or tricuspid valve) to the right
ventricle. AV valve is attached to papillary
muscles, which contract to close the AV valves
and prevent backflow of blood. - Right ventricle – Pumps deoxygenated blood through the pulmonary semilunar valve to the pulmonary artery. Blood enters pulmonary circulation. When the ventricle contracts, the AV valve is closed and the pulmonary semilunar valve is open. When the ventricle relaxes, the AV valve is open to refill the ventricle, and the pulmonary semilunar valve closes to prevent the backflow of blood.
- Left atrium – Oxygenated blood is returned
here from the lungs from the pulmonary vein.
Blood passes through the left AV valve (or
bicuspid, or mitral valve) to the left ventricle. - Left ventricle – Most muscular chamber of
the heart. Pumps oxygenated blood into the
aorta and systemic circulation.
Pulmonary circulation
- moves deoxygenated blood from heart to the lungs and back in order for it to become oxygenated.
Pathway of pulmonary circulation
- Right atrium → tricuspid valve → right ventricle → pulmonary semilunar valve →
pulmonary arteries → lung → pulmonary veins → left atrium
Systemic circulation
- moves oxygenated blood
from the heart throughout the body.
Pathway of Systemic circulation
Left atrium → bicuspid / mitral valve → left
ventricle → aortic semilunar valve → aorta → body → vena cava → right atrium
Human Cardiac Cycle
- The heart needs to contract and relax rhythmically in order to pump blood throughout the body. Cardiomyocytes (heart muscle cells) have automaticity, which means they are self-excitable and able to initiate an action potential without an external nerve.
1) SA Node
2) AV node
The SA node (pacemaker)
- is located in the upper wall of the right atrium and usually initiates the cardiac cycle. It has the greatest automaticity and is most likely to reach threshold to stimulate a heartbeat. It sends a signal to contract both atria to send blood to the ventricles. It also sends a signal to the AV node to initiate contraction.
The AV node
- is located in the lower wall of the
right atrium. The function of the AV node is to
add a brief delay between the contraction of
the atria and the contraction of the ventricles.
It also sends a signal to the bundle of His,
located in the interventricular septum
between the ventricles. The bundle of His
carries the signal to the Purkinje fibers,
which contract the ventricles.
Systole
- occurs right after the ventricles eject their
blood into the arteries they connect to. Therefore, it is the phase of the cardiac cycle where blood pressure is highest in the arteries. The aorta is the blood vessel that experiences the highest blood pressure. - Systole happens between the lub-dub sounds.
Diastole
- occurs right after the atria contract to fill
the ventricles. The myocardium is completely
relaxed at this point. Diastole is the phase of the cardiac cycle where blood pressure is lowest in the arteries. - Diastole occurs between the dub and next lub
sound.
Lub-systole-dub-dystole-lub
heart “lub-dub” sound
- Lub – The atria are relaxed, while the
ventricles are contracting. The noise
comes from the AV valves snapping shut
as the ventricles contract. - Dub – The atria are contracting, while the
ventricles are relaxing. The noise comes
from the semilunar valves snapping
shut.
Signal Transduction
- The heart has intercalated discs that connect
adjacent heart cells (cardiomyocytes). Intercalated discs are made of desmosomes and gap junctions and function to transmit the signal to contract in a coordinated, rhythmic fashion.
Measuring Cardiac Cycle
P wave – atrial depolarization
Q wave – depolarization through interventricular septum
R wave – ventricular depolarization
S wave – completion of ventricular depolarization
T wave – ventricular repolarization
Heart rate (HR)
- is how fast the heart beats. Tachycardia is greater than 100 beats per minute, bradycardia is less than 60 beats per minute.
Stroke volume (SV)
- is the volume of blood pumped from the heart with each beat. Stroke volume is calculated by subtracting end-systolic
volume from end-diastolic volume.
Cardiac output (CO)
- is the stroke volume multiplied by the heart rate. This tells us the volume of blood being pumped by the heart in 1 minute.
CO = HR x SV
Total peripheral resistance (TPR)
- is the total amount of resistance that blood faces when flowing through the vasculature of the body. Vasoconstriction increases TPR, while vasodilation decreases TPR.
Systolic blood pressure
- is the highest pressure in your arteries when your ventricles contract. This is the top number in a blood pressure reading. 120/80 → 120 mmHg is the systolic pressure.
Diastolic blood pressure
- is the pressure in your arteries while the heart is relaxing between beats. This is the bottom number in a blood pressure reading. 120/80 → 80 mmHg is the diastolic pressure.
Mean arterial pressure (MAP)
- is the average arterial pressure during one complete cardiac cycle. It is calculated by multiplying your cardiac output by your total peripheral resistance.
MAP = CO x TPR
MAP = (HR x SV) x TP
Vessels transport blood to and from the heart in a closed circulatory system. _____ move blood away from the heart, while _____ move blood toward the heart.
1) Arteries
2) Veins
______ are where blood pressure is the highest due to the ______ from the heart. They branch off into smaller arteries called ______. This is where we see the greatest ______ of blood pressure. Arterioles branch further into ______, which are vessels that are 1 cell thick and diffuse gas and nutrients to the ______. (Even though arterioles see the greatest drop in BP, they are not where BP is lowest. BP is lowest in the ______)
1) Arteries
2) hydrostatic power
3) arterioles
4) drop
5) capillaries
6) interstitial fluid
7) veins
_______ also collect waste and CO2 and enter a _______, which then connects to a vein, which brings the blood _______ to the heart. Blood moves back to the heart by a series of valves within the veins that _______ of blood. _______ are a type of valve in veins. _______ squeeze the veins to push the blood _______, it is not the pumping of the heart that moves blood through the veins.
1) Capillaries
2) venule
3) back
4) prevents backflow
5) Pocket valves
6) skeletal muscles
7) forward
Veins contain _____ blood by volume than arteries and have the _____ blood pressure of all vessels.
1) more
2) lowest
_______is a mechanism that protects our blood vessels from damage. When a tear in our blood vessels occurs, the blood clotting cascade then ‘plugs’ the tear, sealing any vessel leaks.
1) Blood clotting
The blood clotting cascade is an example of a
_________. Damaged tissues release a signal that attracts _________ to the site → each platelet will then release a signal to attract more platelets → a clot is formed.
1) positive feedback mechanism
2) platelets
Blood Clotting Process
- Tissue damage – Damaged tissue tears
blood vessel walls, exposing their collagen. - Platelet activation – Exposed collagen
triggers platelet activation. Platelets will
adhere and aggregate at the site of the
tear, forming a platelet plug. - Thromboplastin release – Activated
platelets release the tissue factor
thromboplastin that converts
prothrombin (inactive precursor) →
thrombin (active form). - Formation of clot – Activated thrombin
converts fibrinogen (inactive precursor) →
fibrin (active form). Fibrin strands
polymerize with other fibrin strands, and
attach platelets to form a blood clot
(hemostatic plug).
Components of Blood
1) Plasma
2) WBC (leukocytes)
3) Platelets (Thrombocytes)
4) RBC (erythrocytes)
Plasma
-contains water, proteins, nutrients,
hormones, and makes up most of the blood
volume. Makes up ~55% of blood volume.
White blood cells (leukocytes)
- are our immune cells and defend against infection. The most common white blood cell is the neutrophil.
Platelets (thrombocytes)
-are cytoplasmic cell fragments that do not have a nucleus, they are responsible for clotting. Large bone marrow cells called megakaryocytes are the precursor to platelets. Platelets release factors that help convert fibrinogen into fibrin, which creates a ‘net’ to stop bleeding. Many of the clotting factors are synthesized with Vitamin K, a deficiency in Vitamin K will lead to increased bleeding. Platelets are also immune cells that function in the innate immunity. Leukocytes and thrombocytes make up <1% of blood volume.
Large bone marrow cells called ______ are the precursor to platelets. Platelets release factors that help convert ______ into ______ , which creates a ‘net’ to stop bleeding. Many of the clotting factors are synthesized with ______ , a deficiency in ______ will lead to increased bleeding. Platelets are also immune cells that function in the innate immunity. Leukocytes and thrombocytes make up ______ of blood volume.
1) megakaryocytes
2) fibronogen
3) fibrin
4) Vitamin K
5) vitamin K
6) <1%
Red blood cells (erythrocytes)
- are responsible for transporting oxygen attached to hemoglobin. Mature red blood cells are anucleate (they don’t have a nucleus) in order to maximize the amount of space they have to carry hemoglobin and oxygen, making them very flexible. Makes up ~45% of blood volume.
Blood types
- Red blood cells (erythrocytes) have antigens on their surfaces. These antigens are little sugars and proteins that mark our blood as a certain type. Blood types are described as follows.
● Type A blood - has ‘A’ antigen
● Type B blood - has ‘B’ antigen
● Type AB blood - has both ‘A’ and ‘B’ antigen
● Type O blood - has neither ‘A’ or ‘B’
antigens
If a person receives a blood transfusion with the incorrect blood type, their immune system will cause the _____ (clumping together) of antibodies of that blood type.
1) agglutination
In addition to blood type A and B, your body also has another surface protein called the _____ . You either have the factor _____ or you do not _____ . If a donor is Rh(+) , they _____ donate to someone who is Rh(-), because the donor has antigens on the surface of the blood cell.
1) Rhesus factor (Rh)
2) Rh+
3) Rh-
4) cannot
A _____ (blood donor who can donate to anyone) is _____. O blood type has neither A nor B surface antigens, and _____ blood also does not have an Rh surface antigen. This means there are no blood cell surface antigens that would stimulate
immune clearance by someone receiving the O (-) blood.
1) universal donor
2) O-
3) O-
A _____ is _____ . Because an _____ person has both A and B cell surface antigens, as well as an Rh surface antigen, they can receive any blood type and not mount an immune response. Any blood cell surface antigen they receive would be something their blood cells already have.
1) universal acceptor
2) AB+
3) AB+
Fetal Circulation:
A fetus gets the oxygen and nutrients from the
_____ via the _____, which gets its
oxygen from its mother. Because the fetus gets its oxygen through the placenta, the blood in its heart does not need to go to the _____(it is not exposed to air). Instead, oxygenated blood in the _____ goes to the left atrium via the _____ (hole in the heart).
1) placenta
2) umbilical cord
3) pulmonary system
4) right atrium
5) foramen ovale
Fetal circulation
has a few unique structures:
1) Umbilical Vein
2) Ductus Venosus
3) Ductus arteriosus
4) umbilical artery
Umbilical vein
- Carries oxygenated blood
from the placenta to the fetus via the
umbilical cord. This differs to veins within
the rest of the mother, as veins otherwise
carry deoxygenated blood from the tissues.
Ductus venosus
- Connects the umbilical
vein to the inferior vena cava, allowing
oxygenated blood coming from the
umbilical vein to flow into the inferior vena
cava and mix with oxygen-poor blood
(blood is now slightly oxygen rich).
Ductus arteriosus:
- Connects the
pulmonary artery to the aorta, allowing
oxygen-poor blood to leave the pulmonary
artery and enter the descending aorta,
preventing oxygen-poor blood from
traveling to the brain.
Umbilical artery:
- Carries deoxygenated
blood from the fetus to the placenta. This
differs from arteries within the rest of the
mother, as arteries otherwise carry
oxygenated blood to the tissues.
_____ and _____ from the fetus is removed from the _____ to the _____ . There is no mixing of the mother’s and fetus’ blood in the placenta; the _____ provides an exchange of gas and nutrients across a barrier.
1) waste
2) CO2
3) right ventricle
4) ubmilical cord
5) placenta
Erythroblastosis Fetalis:
- If the mother has Rh (-) blood type and the fetus has Rh (+) blood, during labor, the fetal Rh (+) blood will enter the mother’s
system, and she will develop anti-Rh antibodies. This will not pose a problem in the first pregnancy, but if the mother becomes pregnant again with another Rh (+) fetus, the mother’s anti-Rh antibodies will attack the fetus, because antibodies are small enough to cross the placental barrier.
The lymphatic system
- is a subsystem of the circulatory system that regulates fluid levels and produces immune cells. Its components are lymph nodes, lymph vessels, adenoids (lymphatic tissue), the spleen, and the thymus.
Nutrient and gas exchange occur at the level of the _____. _____ pushes fluid out of the capillaries on the arterial end into interstitial space. _____, a type of osmotic pressure, brings fluid back into the capillaries at the venule end. However, not all the fluid is reabsorbed from the interstitial space into the venule. _____ collect the remaining fluid, called _____, which consists of interstitial fluid, bacteria, fats, and proteins.
1) capillaries
2) Hydrostatic Pressure
3) Oncotic pressure
4) lymphatic capillaries
5) lymph
The lymphatic capillaries merge together to form
larger vessels that travel to the heart. Along the
way, the lymph is filtered through ______,
which are centers for the ______ to eliminate infections.
1) lymph nodes
2) immune response system
Lymph vessels have ____ pressure (like veins), but
the constriction of ____, in conjunction
with the ____ present in the lymphatic
vessel walls allows for the propulsion of lymph via
____. This allows fluid to move towards the
heart, and backflow of fluid is prevented with a
system of valves, similar to veins.
1) No
2) skeletal muscles
3) smooth muscles
4) peristalsis
Solute concentration
- influences lymph volume. If
there is an increased amount of proteins (ex.
albumin) within the blood vessels, water will flow
into these vessels, reducing the amount of water
left in the interstitial fluid and decreasing lymph
volume.
Respiration:
-the exchange of gases between the
outside environment and the inside of an
organism.
Cnidaria (respiration)
- are small invertebrates that use
simple diffusion for respiration due to the lack
of a circulatory system. Almost all cells must be
in direct contact with the environment.
Environment must be moist for diffusion to
happen.
Annelida (respiration)
- includes earthworms that also use
simple diffusion for respiration but have a
closed circulatory system. They use a slimy
mucus to facilitate the transport of oxygen
into their closed circulatory system.
Arthropoda (respiration)
- are invertebrates, such as
insects and crustaceans, that have an open
circulatory system with hemolymph, a fluid
similar to blood. Gas exchange happens
mainly through the tracheal system for
insects and through book lungs for
arachnids.
Fish (respiration)
- Fish are a part of the phylum Chordata and
have a closed circulatory system with blood
to transport gas. Fish have gills with a large
surface area for gas exchange and use
countercurrent exchange to efficiently
absorb oxygen and remove carbon dioxide
from their blood.
Lungs
-are located in the thoracic cavity and are
covered by the rib cage. The left lung has two lobes
and is smaller than the right lung, which has three
lobes.
The pleura
- covers the lungs and is a dual-layered
membrane composed of the parietal layer (outer
layer) and the visceral layer (inner layer).
The diaphragm
- is a large skeletal muscle at the
bottom of the lungs and is involved in inspiration
and expiration. This is the only organ that only and
all mammals have.
The pleural space
- is a fluid-filled space in between
the parietal and visceral layers. This space is at a
lower pressure than the atmosphere, and creates
the intrapleural pressure.
Inspiration or inhalation
- involves the
contraction of the diaphragm (pulls lungs
downwards) and the external intercostal
muscles (expands the rib cage). These
contractions cause the pressure of the
intrapleural space to decrease and the volume
of the lungs to increase, bringing air into
the lungs.
Expiration or exhalation
- involves the
relaxation of the diaphragm and the
external intercostal muscles, bringing the
lungs back up and closing up the rib cage
through elastic recoil. This causes the
pressure of the intrapleural space to
increase and the volume of the lungs to
decrease, driving air out of the lungs. The
internal intercostal muscles can also
contract during a more forced expiration,
closing the rib cage even more.
Tidal volume
- is the volume of air that moves
through the lungs between a normal inhalation
and exhalation.
Inspiratory reserve volume
- is the maximum
volume of air that can be inhaled further after a
normal inhalation is already taken in.
Expiratory reserve volume
- is the maximum
volume of air that can be exhaled further after a
normal exhalation is already released.
Residual volume
- is the minimum amount of air
that needs to be present in the lungs to prevent
collapse.
Functional residual capacity
- is the entire volume
of air still present in the lungs after a normal
exhalation. It is also the sum of the expiratory
reserve volume and the residual volume.
FRC=ERV + RV
Vital capacity
- is the maximum amount of air that
can be exhaled after a maximum inhalation. It is
the sum of the inspiratory reserve volume, tidal
volume, and expiratory reserve volume.
Total lung capacity
- is the sum of the vital
capacity and the residual volume: it is the
maximum volume the lungs could possibly hold at
any given time.
Refer to page 78 DAT Bootcamp
The nasal cavity contains ______ (secrete mucus) and ______ (move mucus and trapped debris) that work in tandem with each other.
1) goblet cells
2) ciliated epithelial cells
The pharynx
- is at the beginning of the throat
after the nasal cavity. Under the control of the
epiglottis, it diverts air and food into the
larynx and the esophagus.
The larynx
- receives air and contains the
voice box. The upper respiratory tract
refers to the nasal cavity, pharynx, and
larynx. On the other hand, the esophagus
receives food and connects to the stomach.
The trachea
- is below the larynx and has
reinforced cartilage along with ciliated
epithelial cells to filter air.
Next are the two main ___________,
which branch into smaller ________ and
eventually into alveoli. The lower
respiratory tract refers to the trachea,
bronchi, bronchioles, and ________. Alveoli
contain________ epithelial cells (structural
support) and________ epithelial cells (produce
surfactant). ________ is a substance that
prevents the alveoli from collapsing by
reducing surface tension.
1) left and right bronchi
2) bronchioles
3) alveoli
4) type 1
5) type 2
6) surfacant
Overall Pathway of Air
Nasal Cavity → Pharynx → Larynx → Trachea →
Bronchi → Bronchioles → Alveoli
Differences in ________ allow gases to flow
from areas of ________ pressure to areas of ________
pressure through simple diffusion. This is required
for ________ (gas exchange between
inspired air and lung alveolar capillaries) and
________ (gas exchange between
blood and tissues).
1) partial pressure
2) high
3) low
4) external respiration
5) internal respiration
Oxygen:
Air → Blood → Tissues
Carbon Dioxide:
Tissues → Blood → Air
Erythrocytes (red blood cells)
- contain hemoglobin. Hemoglobin is tetrameric and has
a heme cofactor in each of its four subunits.
Heme cofactors are organic molecules that
contain iron atoms, which bind oxygen. Thus,
each hemoglobin can carry up to four oxygen
molecules.
Oxyhemoglobin
- (HbO2) transports most of the oxygen traveling in the blood.
Cooperativity
- describes the process by which
the binding of one oxygen molecule to
hemoglobin makes it easier for others to bind
due to changes in the shape of the hemoglobin
polypeptide. This also works in reverse, allowing
efficient unloading of oxygen in body tissues.
Carboxyhemoglobin (HbCO)
- is produced when
carbon monoxide outcompetes oxygen for
hemoglobin binding. Carbon monoxide poisoning
occurs as a result, because oxygen can no longer
be transported efficiently.
Carbaminohemoglobin
- (HbCO2 ) is a form of hemoglobin that transports carbon dioxide.
However, carbon dioxide is much more soluble in blood than oxygen, so most of the carbon dioxide is dissolved in blood as bicarbonate
anion (HCO3-).
Reduced hemoglobin
- (H+Hb) is produced by H+ ions binding to hemoglobin, outcompeting
oxygen and lowering oxygen binding affinity (less HbO2). On the other hand, carbon dioxide binding affinity is increased (more HbCO2).
Myoglobin
- is a single peptide with one heme
cofactor. It has a much higher affinity for oxygen
than oxyhemoglobin and is found within cardiac
and skeletal muscle cells to bring oxygen in. Also,
myoglobin has a hyperbolic oxygen dissociation
curve because it does not undergo cooperativity
(hemoglobin’s curve is sigmoidal).
The oxygen dissociation curved to be able
- reveals the relationship between the saturation of hemoglobin
with oxygen in the blood and the partial pressure
of oxygen. Certain conditions will shift this curve
either left or right.
A right-shifted curve (oxygen dissociation curve)
- corresponds to a lowered
affinity for oxygen in hemoglobin. Below are the
main reasons for a right-shifted curve.
Affected by:
1) decrease in pH
2) high partial pressure of Co2
3) 2,3-diphosphoglycerate (2,3-DPG) aka 2,3-bisphosphoglycerate (2,3-BPG):
4)Increased body temperature:
Bootcamp Mnemonic: CADET Increase → Right shifted curve
CADET, face Right!
CADET = Carbon dioxide, Acid,
2,3-Diphosphoglycerate, Exercise and
Temperature.
Decreased pH (right-shift curve)
- a lower pH means there is a higher concentration of protons (H+), which
produces reduced hemoglobin. Reduced hemoglobin (H+Hb) has a lowered affinity for binding oxygen, resulting in less HbO2
High partial pressure of carbon dioxide (right-shift curve)
-more carbon dioxide is converted to bicarbonate anions (HCO3-) and protons (H+), which lower oxygen binding affinity through decreased pH.
2,3-diphosphoglycerate (2,3-DPG) aka
2,3-bisphosphoglycerate (2,3-BPG) (right-shift curve)
- accumulates in cells that undergo anaerobic
respiration as a result of the loss of oxygen.
This compound decreases oxygen binding
affinity so more oxygen is released from
hemoglobin to fuel aerobic respiration.
Increased body temperature (right-shift curve)
-: correlates to
more cellular respiration, which uses up
oxygen and produces more carbon dioxide.
Thus, hemoglobin will need to unload more
oxygen for tissues to use and have decreased
oxygen binding affinity.
A left-shifted curve (oxygen dissociation curve)
- corresponds to an increased
affinity for oxygen in hemoglobin. Below are the
main reasons for a left-shifted curve.
Affected by:
1) increased pH
2) Low partial pressure of carbon dioxide:
3) Fetal hemoglobin:
4) Decreased body temperature:
Increased pH (more basic) (A left-shifted curve)
- fewer protons (H+) to produce reduced hemoglobin (H
+Hb), so more oxyhemoglobin (HbO2) remains.
Low partial pressure of carbon dioxide(A left-shifted curve)
- less carbon dioxide is converted to bicarbonate
anions (HCO3-) and protons (H+), leading to increased oxygen binding affinity through increased pH.
Fetal hemoglobin(A left-shifted curve)
- binds oxygen better than
adult hemoglobin to help give oxygen to the
fetus.
Decreased body temperature(A left-shifted curve)
- less cellular respiration, so hemoglobin isn’t influenced to
unload more oxygen and has an increased
oxygen binding affinity.
Bohr effect
- hemoglobin has decreased oxygen
affinity when carbon dioxide is high. Carbon
dioxide is converted to bicarbonate anions and
protons, which produce reduced hemoglobin
(H+Hb).
Haldane effect
- hemoglobin has increased
carbon dioxide affinity when oxygen is low. As a
result of low oxygen, reduced hemoglobin
(H+Hb) levels are higher and have a greater
affinity for carbon dioxide.
The bicarbonate buffering system
-is the main extracellular buffering system in the body. It maintains our blood pH of 7.4 and can be described by the equation below:
CO2 + H2O ↔ H2CO3 ↔ HCO3- + H+
Carbonic acid (H2CO3)
Bicarbonate anion (HCO3–)
The Bicarbonare buffering system is catalyzed by ______ in
both directions based on concentrations. ______ is an enzyme present in ______.
1) carbonic anhydrase
2)carbonic anhydrase
3) RBC
Carbonic Anhydrase in RBC
- In erythrocytes (red blood cells) in the
systemic circulation, the partial pressure of
carbon dioxide is low. As a result, carbon
dioxide continuously diffuses in from the
tissues, and is converted into bicarbonate
and protons. Bicarbonate is able to diffuse
out of the cell, however, protons (H+) cannot
leave. As some bicarbonate diffuses out, this
creates a positive charge within the
erythrocyte, and chloride ions (Cl-) must
diffuse into the blood cell to cancel out the
positive charge of the protons. This process
is known as the chloride shift. - Influx of protons causes the pH to decrease
within the erythrocyte, resulting in the
conversion of oxyhemoglobin into reduced
hemoglobin. Reduced hemoglobin has lower
affinity for O2, leading to release of oxygen
which diffuses to the tissues.
The phosphate buffering system
- is the main intracellular buffer system in humans that
regulates our body’s intracellular pH.
Gas Exchange in Lungs
- Blood travels to the lungs through bulk flow.
- Since most of the carbon dioxide is present
in the blood plasma as bicarbonate ions
(HCO3-), the bicarbonate ions re-enter
erythrocytes at the lungs and chloride ions
leave through the reverse chloride shift. - The bicarbonate buffer system equation
proceeds in the reverse direction, producing
carbon dioxide and water. The carbon
dioxide exits into the alveoli as gas while
oxygen enters the blood, forming
oxyhemoglobin.
The medulla oblongata
- is located in the brain
and controls the diaphragm to regulate
respiratory rate. Central chemoreceptors and
peripheral chemoreceptors signal to the medulla.
Central chemoreceptors
-are located in the medulla oblongata and contained within the
blood-brain barrier. Since carbonic anhydrase is present in the cerebrospinal fluid, carbon dioxide
is converted into bicarbonate ions and protons here. However, protons cannot exit through the blood-brain barrier. As carbon dioxide accumulates, acidity increases and is directly sensed by central chemoreceptors, which signal
to the medulla oblongata to increase breathing rate.
Peripheral chemoreceptors
- surround the aortic
arch and carotid arteries. These peripheral
chemoreceptors directly sense oxygen, carbon
dioxide, and proton levels to signal to the medulla
oblongata. When carbon dioxide is high and
oxygen is low, peripheral chemoreceptors signal to
the medulla oblongata to increase breathing rate.
Respiratory acidosis
– lowered blood pH occurs
due to inadequate breathing (hypoventilation).
Respiratory alkalosis
- increased blood pH
occurs due to rapid breathing
(hyperventilation).
Metabolic acidosis (lowered blood pH) and
metabolic alkalosis (increased blood pH)
- occur as a result of imbalances in carbon dioxide, oxygen,
or proton levels.
Pathogens:
-harmful microorganisms that cause
disease. Common diseases caused by bacterial
pathogens include gonorrhea, tuberculosis,
leprosy, and syphilis.
Viruses can also be pathogens. Common viral
infections include HIV, AIDS, influenza, measles,
and herpes.
Leukocytes:
- white blood cells.
Lymphocytes:
- white blood cells found mainly in
the lymphatic organs (T cells, B cells, natural killer
cells) that originate from the bone marrow. T cells
mature in the thymus while B cells mature in the
bone marrow.
The innate immune system
- is the first line of defense and generates a nonspecific immune
response (generalized). There are two parts:
1) External Immunity
2) Internal Immunity
External immunity
- physical/physiological barriers preventing
pathogen entry. These barriers include
skin, mucous membranes, and chemical
secretions.
Internal immunity
- internal defenses activated by the innate immune system to
neutralize pathogens that have entered.
The body’s Internal immunity is
composed of inflammatory response,
complement proteins, phagocytic and
natural killer cells.
The ______ are the first layer of innate
immunity:
- outer walls
Includes:
1) skin
2) cilia
3) stomach acid
4) symbiotic bacteria
If these barriers are penetrated, the rest of the
immune system will kick in.
Skin
- consists of a thick epidermis, and
dermis. Also mucous membrane to trap
pathogens and lysozyme to break down
bacterial cell walls. Has sebaceous glands to
secrete oil (sebum) as a barrier. Sebum also
has antimicrobial properties.
Cilia
- hair-like projections in the respiratory
tract that sweep away debris and pathogens.
Stomach acid
- gastric acid that kills microbes
due to low pH.
Symbiotic bacteria
- outcompete pathogenic
bacteria and fungi.
Innate Immunity: Inflammatory Responses.
______ are a type of leukocyte responsible for
the first part of the inflammatory response, known
as ______:
1) Mast Cells
2) rally signalling
Rally Signaling
- Mast cells sit in the tissue in preparation
for injury. - If there is an injury, mast cells will release
histamine, which dilates blood vessels. - This increases blood flow and makes
vessels more permeable to let immune cells
into the tissues.
5 Signs of Inflammation
1) Swelling
2) Loss of function
3) increased heat
4) Pain
5) Redness
Swelling (5 Signs of Inflammation)
- permeable capillaries result in fluids
leaking into tissues.
Loss of function(5 Signs of Inflammation)
- body part with
inflammation becomes less usable.
Increased heat(5 Signs of Inflammation)
- increased blood flow results
in a higher temperature.
Pain(5 Signs of Inflammation)
- throbbing pain caused by swelling,
which puts continuous pressure on nerve
endings.
Redness(5 Signs of Inflammation)
- increased blood flow causes
redness of skin.
A ______ can also occur due to the inflammatory
response; this is controlled by the ______ and
causes a ______ to kill pathogens with
______ temperatures.
1) fever
2) brain
3) systemic response
4) higher
Diapedesis
-is the process by which cells move
from the capillaries to the tissues in order to fight
pathogens.
Chemotaxis
- is the method by which cells move
in response to a chemical signal. Immune cells
use chemotaxis to move to the tissues.
Granulocytes
-are cells in the innate immune
system with specific granules in their cytoplasm.
The four types of granulocytes include:
1) neutrophils,
2) eosinophils,
3) basophils,
4) mast cells.
Never Let Monkeys Eat Bananas
Neutrophils
- phagocytes in innate immunity
that make up over half of all leukocytes.
Neutrophils are the most common type of
leukocyte found in blood and are one of the
first cells to be recruited to a site of
inflammation.
Lymphocytes
- B cells, T cells, and natural
killer cells. B and T cells are part of adaptive
immunity and must be activated. Natural
killer (NK) cells are part of innate immunity
and attack virally-infected cells + cancerous
cells. NK cells use perforin (create holes) and
granzyme (stimulate apoptosis) to lyse cells.
B and T cells are the most common type of
leukocyte found in lymph.
Natural killer (NK) cells
- are part of innate immunity
and attack virally-infected cells + cancerous
cells.
NK cells use ______ (create holes) and
______ (stimulate apoptosis) to lyse cells.
B and T cells are the most common type of
leukocyte found in lymph
1) perforin
2) granzyme
Macrophages/Monocytes
- phagocytes in innate immunity. Monocytes are the
immature form found in blood vessels and
macrophages are the mature form after
diapedesis. Can also act as antigen-presenting
cells to activate adaptive immunity.
Eosinophils
- part of innate immunity and
have granules that can be released to kill
pathogens, especially parasites.
Basophils
- least numerous leukocyte;
contains granules with histamine
(vasodilation) and heparin (an anticoagulant
to prevent blood clotting). Very similar to
mast cells, except basophils circulate as
mature cells while mast cells circulate as
immature cells.
Dendritic cells
- are also part of innate immunity
and scan tissues using pinocytosis (cell drinking)
and phagocytosis (cell eating). They act as
antigen-presenting cells like macrophages,
migrating to the lymph nodes to activate
adaptive immunity.
Macrophages and dendritic cells use ______ to recognize conserved parts of _____. Binding to these receptors triggers
_______ and activates the innate immune
system.
1) toll-like receptors (TLR’s)
2) microbes
3) phagocytosis
Interferons
- are secreted by virally-infected cells
and bind to non-infected cells to prepare them for
a virus attack. Also, interferons help activate
dendritic cells.
Platelets
- are also a type of immune cell involved
in activating the innate immune system. These
anucleate cells regulate macrophages and
dendritic cells.
Innate Immunity: The ___________ is a group of
approximately 30 proteins that aid immune cells
in fighting pathogens. While small, these proteins
turn each other on through the activation of a
________, producing a large effect.
Upon recognizing a pathogen, a chain reaction of
________ is triggered for the proteins to
activate each other.
1) complement system
2) complement cascade
3) protease activity
Complement protein actions include:
● Tags antigens for phagocytosis in a process
called opsonization
● Amplifies inflammatory response Eg. binds to
mast cells for increased histamine release
● Forms a membrane attack complex (MAC),
which pokes holes in pathogens and lyses
them
The adaptive immune system
- is a specific immune response (targets specific antigens).
An antigen
- is an immunogenic foreign molecule
and is the target of the immune response. The
epitope is the important part of the antigen that
is recognized by the immune cell.
The immune system recognizes self proteins from
non-self proteins using the _______, which is
found on the surface of cells. Thus, foreign
antigens and foreign MHC will be identified as
enemies by the immune system.
1) major histocompatibility complex (MHC)
include:
MHC Class 1 MHC Class 2
MHC Class I
- is a surface molecule present on all
nucleated cells, and each genetically different
individual will have a different MHC I molecule.
_______ that have different _______ may
lead to failure and rejection, so
immunosuppressants are given to transplant
patients. Also, _______ occur when
the immune system attacks self MHC I.
1) organ transplants
2) MHC 1
3) autoimmune diseases
MHC Class II
- is a surface molecule present on
antigen-presenting cells (dendritic cells,
macrophages) and is used to present foreign
antigens to activate immune cells.
Identical twins have identical ______molecules. This allows
identical twins to donate organs to each other
without the need for immunosuppression (the
donated organ cells won’t be marked as foreign).
1) MHC
B cells
- control antibody-mediated immunity
(humoral immunity) by managing the
production and release of antibodies. They can
also act as antigen-presenting cells.
B cell receptors (BCRs)
- are located on B cells
and bind to antigen epitopes either free-floating
or on APCs. Each B cell has a unique BCR.
The clonal selection model
- describes the development of one type of BCR for every B cell.
Through clonal expansion, these B cells divide
into either plasma cells (antibody-secreting cells)
or memory B cells (to be activated later in case
of another attack).
Antibodies (immunoglobulins)
- are structurally identical to BCRs but freely circulate in blood and
lymph. They can tag antigens for phagocytosis,
neutralize the antigen by coating it, or activate
the complement system. Antibodies contain light
chains and heavy chains that are linked
together by disulfide bonds. In addition, the
variable region recognizes different antigens
while the constant region is the same for
antibodies within the same class. As
glycoproteins, the five classes of antibodies all
contain a sugar residue that assists in
attachment to other cells.
Antibodies contain_____ and _____ that are linked
together by _____. In addition, the
_____ region recognizes different antigens
while the _____ region is the same for
antibodies within the same class. As
glycoproteins, the five classes of antibodies all
contain a sugar residue that assists in
attachment to other cells.
1) light chain
2) heavy chains
3) disulfide bonds
4) variable
5) constant
The 5 classes of antibodies include:
1) IgM
2) IgA
3) IgE
4) IgD
5) IgG
IgM
– present in a pentameric form and is the
largest antibody. The first antibody to be
produced; activates the complement system.
IgA
- present in a dimeric form and found
most abundantly in bodily secretions.
Newborns receive passive immunity
through breast milk containing IgA. Also, IgA
mainly binds pathogens externally, outside
of circulation.
IgE
- monomer that is present on basophils
and mast cells as antigen receptors. When
bound to an allergen, it triggers histamine
release and an allergic reaction. Think Ig
sneEze.
IgD
- monomer that we have very little
information about. Only small amounts are
produced.
IgG
- monomer that is the most abundant
antibody in circulation. Also the only antibody
that can cross the placenta to give fetus
passive immunity. Helps the complement
system to cause opsonization (tags antigens
and subsequent phagocytosis).
Memory B cells
- survive for a long time and lay
dormant until reactivated by the same antigen
that triggered the original clonal expansion.
They are the key to vaccinations because
vaccines cause memory B cell production for
later reactivation. After reactivation, memory B
cells cause massive antibody production.
T cells
- control cell-mediated immunity by
directly acting on cells instead of sending
antibodies out.
T cell receptors (TCRs)
-are unique just like BCRs,
binding only to one type of antigen per T cell.
Thus, T cells also undergo clonal selection just
like B cells.
T cells must bind to antigens presented on _________to be activated.
- APC (antigen-presenting cells)
There are two ways antigens may be presented to T cells:
1) MHC I presentation
2) MHC II presentation
MHC I Presentation:
- T cells differentiate into
CD8/CD8+ T cells (cytotoxic T cells), which
directly kill infected cells through perforin
(poke holes) and granzymes (cause apoptosis).
However, T cells are different from natural
killer cells because they are more specific and
require antigen presentation.
MHC II Presentation:
- T cells differentiate into
CD4 T cells (helper T cells), which release
interleukins to boost both innate immunity
and adaptive immunity. These interleukins help
attract innate immune cells and increase
proliferation of other T and B cells.
Passive immunity
- refers to the immunity one
organism gains from receiving the antibodies
from another organism that already has that
immunity. For example, a fetus gains passive
immunity through the placenta (IgG) while a
newborn gains passive immunity through breast
milk (IgA). The fetus and newborn are referred
to as immuno-naive because they do not yet
have their own active immunity.
Active immunity
- refers to the immunity an
organism gains from being infected once already
by a pathogen. A vaccination introduces the
antigen or pathogen in a deactivated state to
stimulate active immunity, which is referred to as
artificial immunity in this case and induces
memory B and T cell formation.
The neuron
- is the most basic unit of the nervous
system. It has three parts: the soma (cell body),
dendrites (extensions that receive signals), and
the axon (sends signals out).
The Axon include:
1) Axon hillcock
2) Myelin Sheath
3) Nodes of Ranvier
Axon hillock
- area where the axon is
connected to the cell body. Responsible for the
summation of graded potentials.
Myelin sheath
- fatty insulation of the axon
that speeds up action potential propagation by
stopping ion exchange. The myelin sheath is
formed by oligodendrocytes (in the central
nervous system) and Schwann cells (in the
peripheral nervous system). Thicker
myelinated neurons fire signals faster.
The myelin sheath is
formed by _______ (in the central
nervous system) and ______ (in the
peripheral nervous system). _____
myelinated neurons fire signals faster.
1) oligodendrocytes
2) Schwann Cells
3) thicker
Mnemonic: COPS
Central NS: Oligodendrocytes
Peripheral NS: Schwann cells
Nodes of Ranvier .
- gaps between myelin
sheaths where ion exchange occurs.
Propagation of the action potential occurs
here, jumping from gap to gap (node to node)
in a process called saltatory conduction
Steps of action potential:
- At resting potential, the membrane potential of the neuron is around -70mV and is maintained by Na +/K + ATPases, which pump 3 Na+
ions out and 2 K+ions in, powered by hydrolysis of one ATP. K+ leak channels are also present and help maintain resting
potential through passive K+leakage. - When a stimulus causes threshold potential to be reached (around -55mV in neurons), voltage-gated Na+ channels open up, letting Na+ in, resulting in depolarization of the neuron. K channels are closed.
- Next is repolarization of the neuron due to the opening of voltage-gated K+ channels, letting K+ out, and the closing of Na channels. This causes the membrane potential to become less positive since positive ions are
leaving. This is the absolute refractory period- no stimulus can cause an action potential. - When the membrane potential becomes even more negative than the normal resting potential, this is known as hyperpolarization. This results in a relative refractory period being established, during which another action
potential can be fired, but it requires a much stronger stimulus. - The membrane potential returns to normal resting potential through the pumping of Na+/K+ ATPases and K+ leak channels.
At resting potential, the membrane potential of the neuron is around ______ and is maintained by ______, which pump ______ Na+
ions out and ______ K+ ions in, powered by hydrolysis of one ATP. ______ are also present and help maintain resting
potential through passive K+leakage.
1) -70mV
2) Na+/K+ ATPase
3) 3
4) 2
5) K+ leak channels
When a stimulus causes threshold potential to be reached (around _____ in neurons), _____ open up, letting Na+ in, resulting in depolarization of the neuron. K channels are _____.
1) -55mV
2) voltage-gated Na+ channels
3) closed
_____ of the neuron occurs due to the _____ of voltage-gated K+ channels, letting K+ out, and the closing of Na channels. This causes the membrane potential to become _____ positive since positive ions are
leaving. This is the _____ - no stimulus can cause an action potential.
1) repolarization
2) opening
3) less
4) absolute refractory period
When the membrane potential becomes even more _____ than the normal resting potential, this is known as _____. This results in a _____ being established, during which another action potential can be fired, but it requires a much _____ stimulus.
1) negative
2) hyperpolarizatoin
3) relative refractory period
4) stronger
The absolute refractory period
-refers to the period after the initiation of the action potential
during which another action potential cannot be
fired no matter how powerful the stimulus is. It is
due to the inactivation of voltage-gated Na+
channels after they open.
The relative refractory period
- refers to the period after the action potential fires during which
a stronger than normal stimulus could cause
another action potential to be fired.
The synapse
- is the space between two
neurons.
The ______ neuron sends the
signal and releases ______ into the
synapse, while the postsynaptic neuron
receives the signal by interacting with the
released _______.
1) presynaptic
2) NT (neurotransmitters)
3) NT (neurotransmitters)
Steps of synaptic transmission:
- Action potential reaches the end of the
presynaptic axon, causing voltage gated
calcium channels to open and letting Ca2+
ions into the neuron. - The Ca2+ ions cause synaptic vesicles to fuse
and undergo exocytosis, releasing
neurotransmitters into the synapse. - The neurotransmitters (described in the table
on the next page) bind to ligand-gated ion
channels on the postsynaptic neuron,
producing graded potentials (depolarizations
or hyperpolarizations of the membrane). - These graded potentials summate at the axon
hillock and an action potential will fire if the
summation of graded potentials is higher than
the threshold potential of neurons.
An excitatory postsynaptic potential (EPSP)
- is a graded potential that depolarizes the membrane.
In an EPSP, excitatory neurotransmitters cause Na+
ion gates to open and let Na+ ions flow into the cell.
An inhibitory postsynaptic potential (IPSP)
- is a graded potential that hyperpolarizes the
membrane. Inhibitory neurotransmitters cause K+
ion gates to open and let K+ ions flow out of the
cell. Another IPSP type allows influx of Cl-,
allowing negative Cl- ions in.
Glial cells
- are non-neuronal cells in the nervous
system that help support and surround neurons.
They are divided into microglial cells and
macroglial cells.
Microglial cells
- are macrophages that protect the
central nervous system (CNS).
Macroglial cells have many subtypes:
1) astrocytes
2) schwann cells
3) oligodendrocytes
4) satellite cells
5) ependymal cells
Astrocytes
- are the most abundant glial cell
and form the blood-brain barrier. They also
help recycle neurotransmitters and provide
blood supply to the CNS neurons.
Schwann cells
- form the myelin sheath in the
peripheral nervous system (PNS).
Oligodendrocytes
- form the myelin sheath in
the central nervous system (CNS).
Satellite cells
- have the same functions as
astrocytes but instead help PNS neurons.
Ependymal cells
- produce cerebrospinal fluid
(CSF), which cushions the CNS.
Different NT:
Amino Acids:
Glutamate
Gamma-aminobutyric acid(GABA)
Glycine
Amino acid derived:
Epinephrine
Norepinephrine
Dopamine
Serotonin
Neuropeptides:
Short chain amino acids (e.g.: substance P)
Gasotransmitters:
Nitric Oxide
Other:
Acetylcholine
Glutamate
- main excitory NT of CNS; most abundant of vertebrate NS; NT of neuromuscular junction in invertebrates
GABA
- inhibitory NT of the brain
