Midterm Review Flashcards
What is a function?
It explains why something happens
What is a mechanism/process?
It describes how something happens
What is the overview of the body? (In what order is the body structured)
- Chemical level
- Cells
- Tissues
- Organs
- Systems
- Human organism
What must the body be able to do to maintain homeostasis?
- Detect deviations from normal in the internal environment
- Integrate this information with other relevant information
- Make appropriate adjustments
What is set point?
Normal range for a given system
What are intrinsic controls?
Local controls that are inherent in an organ (within an organ)
What are extrinsic controls?
Regulatory mechanisms initiated outside an organ, accompanied by nervous and endocrine systems
What is the difference between feedback and feedforward loops?
Feedback respond to a change (positive and negative), feedforward anticipates a change
What are the basic components of a feedback loop?
Stimulus, controlled condition, receptors, control centre, effectors, response
What are the components of a feedback loop?
Sensor, control system and effectors
What is an example of a negative feedback loop?
Blood pressure regulation
What is an example of a positive feedback loop?
Contractions during labour, blood clotting
What is a disorder?
General term of derangement of abnormality of function
What is a disease?
More specific term for an illness characterized by a recognizable set of signs and symptoms
What is an example of a feedforward mechanism?
Saliva production prior to eating preps digestion of carbs, food in stomach increases insulin production to promote uptake and storage of nutrients
How are feedforward mechanisms regulated?
Through central command, i.e. when about to exercise our body primes our system for the change during exertion
What are the four types of macromolecules?
Carbs
Proteins
Fat
Nucleic acids
What are the main types of carbs?
Monosaccharides (1 sugar), disaccharides (2 sugar), polysaccharides (many sugars)
What are the monosaccharides?
Glucose, fructose and galactose
What is glucose used for?
ATP
What is fructose used for?
Aid in glycolysis and helps replenish liver glycogen stores
What are the disaccharides?
Sucrose (glucose + fructose), Maltose (glucose + glucose), lactose (glucose + galactose)
What are the polysaccharides?
Starch (amylose and amylopectin), glycogen, cellulose (most naturally abundant polysaccharide), chitin
What are proteins used for?
- Catalyzing chemical reactions
- Synthesizing and repairing DNA
- Transporting materials across cell
- Receiving and sending chemical signals
- Responding to stimuli
- Providing structural support
How many amino acids are required by the body?
20
What are enzymes?
They catalyze chemical reactions
What is an anabolic enzyme?
An enzyme that builds something more complex
What is a catabolic enzyme?
An enzyme that breaks down their substrate
What are examples of some catabolic enzymes used for digestion?
Amylase (carbs), pepsin (proteins in stomach), lipase (fats in S.I) and trypsin (proteins in S.I)
What is an example of a protein hormone?
Insulin
What are the three types of fats?
Fats
Phospholipids
Steroids
What are fats made of?
One glycerol and three fatty acids
What is the difference between saturated fats and unsaturated fats?
Saturated - no double bonds present, maximum amount of H atoms, forms solids
Unsaturated - One or more double bonds present, forms liquid
What are phospholipids and what are they used for?
They’re made up of two fatty acids and a phosphate group and they’re used for the outer layer of cell membranes
What do steroids do?
Play roles in reproduction, absorption, metabolism regulation and brain activity
What is the structure of a steroid?
4 linked carbon rings (fused structure)
What is the most common steroid?
Cholesterol (precursor to vitamin D and many other hormones in the body)
What does energy intake equal?
internal heat produced + external work + internal work + energy storage
What are the three possible states for energy balance?
Neutral, positive (input greater than output, therefore weight gain), and negative (input less than output, therefore weight loss)
How is metabolic rate defined?
Energy expenditure/Unit of time
What is basal metabolic rate (BMR)?
The minimal internal energy expenditure we need to maintain in order for our body’s to function
What are some factors that influence metabolic rate?
Thyroid hormone levels
Sympathetic stimulation (epinephrine or norepinephrine)
Exercise
Daily activities
Sex/gender
Age
What is a competitive inhibitor?
An inhibitor that is similar enough to the substrate it can bind at the active site, competes with substrate
What is non-competitive inhibitor?
The inhibitor binds to a location other than the active site (allosteric site), then it changes the shape of the enzyme
What is an allosteric activator?
Attaches to an allosteric site to increase the enzyme’s affinity for a substance, speeds up reaction rate
What is a cofactor or a coenzyme?
Promotes optimal conformation and function for their respective enzymes
What is feedback inhibition?
A process through which the product regukates its own production
What are the most common fuels for monosaccharides, lipids and proteins?
Glucose, triglycerides (ina process called B-oxidation), and amino acids
What type of reactions are very important in energy transfer?
Oxidation-reduction reactions
What are the three main phases for cellular respiration?
Glycolysis
Kreb’s Cycle
Electron transport chain
What happens during the process of glycolysis?
The breakdown of glucose into pyruvate
What is glycogenolysis?
The breakdown of glycogen into glucose
Where does glycolysis occur?
In the cytosol of the cell
What is used and what is produced during glycolysis?
Takes 2 ATP and 2 NAD+ to convert 1 glucose into 2 pyruvate, 4 ATP and 2 NADH
What is the rate limiting (on or off switch/allosteric regulation) enzyme in glycolysis?
Phosphofructokinase (PFK)
How do we up regulate glycolysis?
High levels of AMP means that the cell is low on energy and that glycolysis must occur to replenish these stores
How do we down regulate glycolysis?
ATP is a negative regulator of PFK, and citrate building up
Where does the kreb’s cycle take place?
In the matrix of mitochondria
What goes in and comes out of the Krebs cycle?
2 pyruvate and 2 Acetyl CoA make 2 ATP, 8 NADH, 2 FADH2 and CO2 in two cycles
Where does the bulk of ATP come from in cellular respiration?
Electron transport chain
What is the process of chemiosmosis?
It involves the pumping of protons through special channels from the inside of the mitochondria to the outside of the mitochondria (establishes a gradient)
How many ATP do we get from the electron transport chain?
34 ATP (38 ATP from the whole process)
How many ATP can we get out of one NADH and one FADH2?
1 NADH = 3 ATP
1 FADH2 = 2 ATP
What is the real number of ATp generated from cellular respiration?
30-32 ATP
What is fermentation?
When there is not enough oxygen for the body to carry out the full process of cellular respiration the pyruvate from glycolysis get converted to lactic acid and stored to allow glycolysis to continue
What happens to the accumulating lactate?
When it builds up in the muscles it it then transported to the liver via the circulatory system and is then processed there (also used for a fuel source in the brain)
What happens to the to the NADH that is produced during fermentation?
It is used to make the pyruvate and the NAD+ produced from the process of making the pyruvate can therefore be recycled and used for glycolysis again
How do we obtain energy from fat?
Fat is broken down by hydrolysis, then through a process called lipolysis that takes place in the cytoplasm, b-oxidation turns it into acetyl-CoA
How do we use protein as fuel?
They are broken down into amino acids and act as pyruvate/acetyl CoA in the krebs cycle
What is an endocrine hormone?
One that travels in the blood and acts on distant target cells
What is a paracrine hormone?
One that acts on neighbouring cells
What is an autocrine hormone?
One that acts on the same cell that secreted the hormone
What is a lipid-soluble (steroid, thyroid) hormone?
Circulate bound to proteins and diffuse across plasma membranes, bind to receptors within target cells
What are water soluble (amine, peptide and protein) hormones?
Circulate freely in plasma, bind to receptors on the exterior of the cell, activates a second messenger response, can be excitatory or inhibitory
What does up-regulation mean in terms of hormones?
Receptors will become more sensitive in the presence of low concentrations of hormone
What does down-regulation mean in terms of hormones?
Receptors become less sensitive in the presence of high concentrations of hormones
What is the response of a target cell based on?
The hormones concentration in the blood, the number of hormone receptors on the target cell, can be influenced by other hormones (synergistic effect or antagonistic effect)
What is the secretion of hormones regulated by?
Chemical changes in the blood, signals from the nervous system and other hormones
What type of control are most endocrine glands under?
Negative feedback control
What is the main link between the nervous system and the endocrine system?
The diencephalon (the hypothalamus)
What are the 7 hormones released by the hypothalamus?
Thyrotropin releasing hormone (TRH)
Corticotropin releasing hormone (CRH)
Gonadotropin releasing hormone (GnRH)
Prolactin releasing hormone (PRH)
Growth hormone releasing hormone (GHRH)
Growth hormone inhibiting hormone (GHIH) (somatostatin)
Prolactin inhibiting hormone (PIH) (dopamine)
The pituitary is connected to the hypothalamus by what?
The infundibulum
How do the hormones travel from the hypothalamus to the pituitary gland?
Through the hypophyseal portal system
What hormones are secreted from the anterior pituitary?
Human growth hormone (hGH) is secreted by somatotrophs
Prolactin (PRL) is secreted by lactotrophs
Thyroid stimulating hormone (TSH) is secreted by thyrotrophs
Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) are secreted by gonadotrophs
Adrenocorticotropic hormone (ACTH) and melanocyte-stimulating hormone (MSH) are secreted by corticotrophs
What to hormones control hGH?
GHIH and GHRH
What does FSH do in males and females?
Males: stimulates sperm production
Females: initiates follicle development and secretion of estrogens
What does LH do in males and females?
Males: stimulates the interstitial cells to secrete testosterone
Females: stimulates the secretion of estrogen to result in ovulation and stimulates the formation of the corpus luteum and the release of progesterone
What does ACTH do?
Controls the production and secretion of hormones called glucocorticoids by the adrenal cortex
What does the posterior pituitary store and release?
Oxytocin (OT) and Anti-diuretic hormone (ADH)
How is ADH used in the body?
Osmoreceptors monitor osmotic blood pressure and release ADH when blood volume is too low, if the blood volume increases the body will stop secreting ADH
What type pf cells are in the thyroid gland?
Follicular cells and parafollicular cells
What do the follicular cells secrete?
Thyroid hormones (thyroxine T4, and triiodothyronine T3)
What do the thyroid hormones do?
Increase metabolic rate
Help maintain normal body temp
Stimulate protein synthesis
What do the thyroid hormones actively do to the body when released?
Increase the use of glucose and fatty acids for ATP production
Upregulate beta (B) receptors that attach to catecholamines
Work with hGH and insulin to accelerate body growth
What do the parafollicular cells secrete?
Calcitonin (lowers the levels of calcium in the blood)
What does the parathyroid secrete?
Parathyroid hormone (PTH)
What does parathyroid hormone do?
Increases the rate of calcium absorption by kidneys
Promotes formation of calcitriol which helps with reabsorption from the GI tract
Increased osteoclast activity
What hormones are secreted by the adrenal cortex?
Mineralocorticoids (aldosterone) - regulate mineral homeostasis
Glucocorticoids (cortisol) - affect glucose homeostasis
Androgens (DHEA) - masculinizing effects
What does aldosterone regulate?
Major in potassium and sodium balance in the body
What pathway controls the secretion of aldosterone?
The renin-angiotensin-aldosterone (RAA) pathway
What does cortisol help regulate?
Protein breakdown
Glucose formation
Lipolysis
Resistance to stress
Inflammation
Immune responses
What is dehydroepiandrosterone (DHEA) used for?
In females DHEA is used to promote libido and are converted to estrogens
In males it doesn’t play a big role after puberty
What does the adrenal medulla secrete?
Catecholamines (epinephrine and norepinephrine)
What do the Alpha cells in the pancreas secrete?
Glucagon (increase blood sugar)
What do the Beta cells in the pancreas secrete?
Insulin (decrease blood sugar)
What does the thymus do?
Promotes the maturation of T cells
What are examples of anabolic hormones?
Growth hormone, insulin, testosterone and estrogen
What does the pineal gland secrete?
Melatonin
What are examples of catabolic hormones?
Cortisol, glucagon, adrenaline/epinephrine and cytokines
What happens with glucose regulation in a fed state (glucose is high)?
Insulin is released and glucose uptake is increased and stored (get glucose into cells)
What happens with glucose in a fasting state (glucose is low)?
Glucose is released from tissues (liver) and cells into the blood, breakdown of glycogen, formation of ketones
How do cells respond to insulin?
They have insulin receptors on their membranes and respond by mobilizing and inserting glucose-transporter proteins into their membranes, which increases glucose entry
How is glucose regulated in the liver?
Through GLUT2
What is the enzyme that can break down ATP?
ATPase
What are the three methods of energy delivery?
Creatine phosphate
Glycolysis
Oxidative respiration
How does creatine phosphate deliver energy?
In the first few second of exercise it supplies contracting muscles with ATP and enables glycolysis to be initiated
How is glycolysis accomplished in the cytoplasm?
Glycolytic enzymes (phosphofructokinase)
What is AV-O2 difference?
The difference in arterial and venous oxygen concentrations
What is the equation for VO2?
VO2 = Q x (AV-O2)
What does an EEG measure?
Records the pyramidal neurons in the superficial layer of the cortex
What is the order of brain waves from fastest to slowest?
Beta waves - >13 Hz
Alpha waves - 8 -13 Hz
Theta waves - 4 -7.5 Hz
Delta waves - 1 - 3.5 Hz
What is happening when beta waves are observed?
Observed in an awake state, involved in conscious and logical thought, related to problem solving and memory
What is happening when alpha waves are observed?
Promote feelings of relaxation and help us calm down, found in daydreaming, inability to focus and being very relaxed
What is happening when theta waves are being observed?
Helps us improve our intuition and creativity, makes us feel more natural, emotional connection, intuition and relaxation
What is happening when delta waves are being observed?
Found most often in young children = and are associated with the deepest levels of sleep and relaxation, helps us feel rejuvenated and promotes the immune system, natural healing and restorative/deep sleep
What happens in stages 1 - 4 in the sleep cycle?
Stage 1 - more theta activity, loss of alpha
Stage 2 - theta and delta waves’
Stage 3 - higher voltage delta waves
Stage 4 - more than 50% delta slow waves
What happens during REM sleep?
Rapid eye movements, dreaming, loss of muscle tone except for the diaphragm, lasts about 10 minutes per episode, time spent in REM diminishes over time
What are the formed elements of the blood?
Red blood cells, white bloods cells and platelets
What id the primary and other functions of blood?
Primary function is to transport and deliver oxygen and nutrients and remove waste
Other functions include defense/protection and regulation and maintenance of homeostasis
What is the partial pressure of oxygen in arterial blood?
PaO2 = 100mmHg
What is the partial pressure of oxygen in venous blood?
PaO2 = 40mmHg
What is the normal range for blood pH?
7.35 - 7.45
How much blood to men and women typically have in their body’s?
Men: 5-6 litres
Women: 4-5 litres
What is in blood plasma?
Water (~91%)
Proteins (~7%)
Other solutes (~2%)
What does anemia mean in terms of hematocrit?
Hematocrit = 30% of blood (low compared to 45%)
What does polycythemia mean?
Too much hematocrit in the blood (=70% of blood)
What are the plasma proteins?
Albumin, globulins and fibrinogen
What does albumin do?
It is produced in the liver and it functions as a binding protein for transporting lipid soluble hormones in the blood
It also is the most significant contributor to the osmotic pressure of blood (pulls water in and helps with blood volume and blood pressure)
What do alpha and beta globulins do?
Alpha and beta globulins are produced in the liver and transport iron, lipids and fat soluble vitamins, aid albumin in contributing to osmotic pressure
What do gamma goblins do?
They are produced by specialized white blood cells and are involved in the immune response and are better know as antibodies or immunoglobulins
What does fibrinogen do?
It is essential for blood clotting
How long do red and white blood cells live for?
Red blood cells live for about 120 days, whereas white blood cells only live for a few hours to a few weeks (with the exception of memory cells)
What is the formation of blood cells called?
Hemopoiesis
Where does hemopoiesis happen before and after birth?
Before: in the yolk sac, the the fetal liver, spleen and lymphatic tissue, and eventually the red bone marrow
After: only in the red bone marrow
What is the hormone that stimulates the production of red blood cells?
Erythropoietin
What is the primary function for erythrocytes?
Pick up oxygen and deliver it to the cells, can also pick up some carbon dioxide and transport it to lungs for exhalation
What do estrogen and testosterone do to EPO?
Testosterone increases the EPO related production of RBC in males
Estrogen decreases the EPO related production of RBC in females
What does NO (nitric oxide) do for blood pressure and blood flow?
NO causes vasodilation which improves blood flow and enhances oxygen delivery
Erythrocytes have what enzyme which catalyzes the conversion of CO2 to carbonic acid?
Carbonic anhydrase
Which cells remove old red blood cells?
Macrophages
What is the difference between red and white blood cells?
Leukocytes - are far less numerous, have a shorter life span, are complete cells (nucleus and organelles), and there are many types
What is the term for when white blood cells leave the bloodstream to attack of defend the body’s tissues?
Emigration
What are the granular leukocytes?
Neutrophils, eosinophils, basophils
What are the agranular leukocytes?
Lymphocytes and monocytes
What is the most common type of leukocyte and why?
Neutrophils (50-70% of WBC), they are rapid responders to a site of infection and are efficient phagocytes with a preference for bacteria
What are the less common types of leukocytes and what are their roles?
Eosinophils (2-4% of WBC) - contains antihistamines and are also capable of phagocytosis
Basophils (<1% of WBC) - intensify the inflammatory response through release of histamines and heparin
What are the three major groups of lymphocytes (20-30% of WBC)?
Natural killer cells
B cells
T cells
What is the role of natural killer cells?
Provide generalized, nonspecific immunity to cells containing foreign or abnormal markers
What is the role B cells?
Produces antibodies which bind to specific foreign or abnormal components of plasma membranes
What is the role of T cells?
Provide cellular-level immunity by physically attacking foreign or diseased cells
What is the role of memory B and T cells?
They are a variety of cells which form after exposure to a pathogen, enabling rapid response upon subsequent exposures
What do monocytes (2-8% of WBC) do?
They form macrophages when they leave blood vessels and function to release antimicrobial and chemotactic signals to attract other leukocytes to the site of infection
What is another name for platelets?
Megakaryocyte
What is involved in the process of hemostasis?
Vascular spasm
Formation of platelet plug
Coagulation (blood clotting)
What is vascular spasm?
The walls of the vessel contract dramatically by way of smooth muscle
What is the platelet plug?
The platelets will clump together, become spiked and sticky and bind to the exposed collagen and endothelial lining, they then release chemicals which contribute to hemostasis
What is coagulation?
A cascade made up of an extrinsic pathway (shorter) and an intrinsic pathway (longer) that both create a mesh of fibrin
What is the process called when the clot breaks down?
Fibrinolysis
What is the lymphatic system responsible for?
Carrying excess fluids to the bloodstream as well as filtering pathogens from our blood
What are the three main functions of the lymphatic system?
- Drain interstitial fluid
- Help carry out immune responses
- Transport dietary fats
What causes interstitial fluid drainage?
Hydrostatic pressure causes the leakage of fluid from capillaries into interstitial space
How much of the remaining interstitial fluid is absorbed by the lymphatic vessels?
15% (absorbed as lymph)
How does the lymphatic system absorb dietary fats?
Through lacteals in the GI tract
What do lymphatic capillaries do?
Vessels where interstitial fluid enters the lymphatic system and becomes lymph, interlaced among many arterioles and venules
What is chyle?
A milky fluid that contains dietary triglycerides and other proteins and lipids; it will eventually enter the liver and then the blood stream
What are lymphatic capillaries made of?
Formed by a simple layer of epithelial cells, one way valves are used call endothelial flaps what allow fluid to pass through when interstitial pressure is high
How is lymph moved through the body?
Movements of the body
Contraction of skeletal muscles during body movements
Movements associated with breathing
What are the two lymphatic trunks in the body?
Right lymphatic duct (only receives lymph from upper right side of the body)
Thoracic duct (receives all remaining lymphatic trunks)
Where does the lymph get dumped into the circulatory system?
At the junction of the jugular and subclavian veins in the neck
What are the primary lymphoid organs?
Red bone marrow (where B cells mature)
Thymus (where T cells mature)
What is the Major Histocompatibility Complex - MHC?
Prevents B and T cells from attacking self-antigens found on the surface of a cell’s plasma membrane
What are the secondary lymphoid organs?
Lymph nodes
Spleen
Lymphatic nodules (e.g. tonsils)
What do lymph nodes do?
They help cleanse the lymph of pathogens and debris as the lymph travels through the sinuses
What cells await activation in the lymph nodes?
B cells, T cells, plasma cells and accessory cells
What does the red pulp in the spleen do?
Functions as filtration system of the blood (phagocytize RBCs) and is the platelet storage centre
What does the white pulp of the spleen do?
Functions to mount adaptive B and T cell responses in the body
What are lymphoid nodules?
Dense cluster of lymphocytes without a surrounding fibrous capsule, areas that are routinely exposed to environmental pathogens (e.g.67ntonsils)
What is the difference between innate immune response and adaptive immune response?
Innate: relatively rapid, but is nonspecific
Adaptive: slower in its development initially, but much more effective at attacking pathogens because of the highly specific response
What are the two lines of defense in the innate immune response?
- Barrier defense systems (skin, mucous)
- Internal defense mechanisms (phagocytes, NK cells, inflammation, antimicrobial proteins and fever)
How do antimicrobial substances work in the innate immune response?
Lymphocytes and macrophages produce interferons which attack virus infected cells
Iron-binding proteins limit the amount of available iron
Complement proteins augment immune responses and antibacterial proteins
What are the two ways NK cells can induce apoptosis?
Fas ligand - send chemical signals to the outside of the cells to induce apoptosis
Perforins and granzymes - which enter the cells and induce apoptosis from within
What does inflammation do for the innate immune response?
Inflammation brings in phagocytic cells to the damaged area to clear the cellular debris
What are the 4 parts of the inflammatory response?
- Tissue injury (histamines, prostaglandins, kinins)
- Vasodilation (increases heat and redness)
- Phagocyte emigration (attracts neutrophils, monocytes and macrophages which engulf damaged tissue
- Tissue repair
What do B cells do for the adaptive immune response?
They can recognize and bind to foreign antigens, which are then broken down and and expressed into the Antigen-Major Histocompatibility complex (MHC)
What do cytokines do for the immune response?
The function as signaling molecules that allow cells to communicate with each other
What do helper T cells do for adaptive immunity?
- Activates cytotoxic T cells
- Activates B cells immune responses
What are the two main types of adaptive immune responses?
Cell-mediated immunity (involves cells attacking other cells)
Antibody-mediated immunity (antibodies bind to antigens)
How does the cell mediated immunity work?
Macrophages eat something foreign and signal helper T cells
Then the helper T cell has a T-cell receptor which has a shape to recognize specific targets
If the foreign antigen on the macrophage matches the receptor it becomes an active T cell
The active helper T cell then stimulates cytotoxic T cells that will target and destroy the pathogen
After the pathogen is destroyed only a few cells will remain as memory cells
How does antibody-mediated (humoral) immunity work?
Macrophages eat something foreign and signal helper T cells
Helper T cells then stimulate specific B cells which makes antibodies against the antigen
One the B cell is found and simulated it is then cloned through clonal selection
The cloned B cells then turn into plasma cells which produce a lot of antibodies (which are secreted in large amounts into the bloodstream)
Once the infection is dealt with memory cells remain
What are The 5 classifications for antibodies (immunoglobulins) for antibody-mediated immunity?
Neutralize Antigen (block release of toxin)
Agglutinate (clump pathogens together)
Enhance Phagocytosis (increase susceptibility)
Activate Complement (aid immune system)
Immobilize bacteria (inhibit cilia/flagella)
What is an example of artificially acquired passive immunity?
Injection of antibodies directly into individual, injection of rattlesnake anti-venom
What is an example of artificially acquired active immunity?
Vaccinations
What is an example of naturally acquired active immunity?
Getting sick and recovering, long lasting results from B and T cells
What is an example of naturally acquired passive immunity?
When mothers pass on their antibodies through breastfeeding
Where is the heart located?
In the mediastinum
How do the lungs promote blood flow into the heart?
During spontaneous breathing when pleural pressure becomes negative (inhale) there is a gradient between venous pool and the heart
What is unique about cardiac muscle?
Branch freely, have intercalated disks bound by desmosomes and contain gap junctions
What is autorhythmicity?
The ability to initiate their own electrical potential at a fixed rate which are able to spread through gap junctions
What are the two major types of cardiac cells?
Myocardial contractile cells (~99%) - conducts impulses and are responsible for contractions
Myocardial conducting cells (~1%) - form conduction system of the heart, initiate and propagate the action potential which travel throughout the heart
What is the SA node?
How cardiac rhythm is established (sinus rhythm), highest inherent rate of depolarization (pacemaker of the heart)
What does the AV node do?
This location ensures that the impulse passes through the AV node before reaching the ventricles, critical pause allows for extra filling of the ventricles
What is the intrinsic firing rate of each component of the conduction system from fastest to slowest?
SA node (80-100 bpm)
AV node (40-60 bpm)
AV bundle (30-40 bpm)
Bundle branches (20-30 bpm)
Purkinje fibres (15-20 bpm)
What does a conductive cell action potential look like?
Spontaneous depolarization due to initial slow influx of Na+ (prepotential), potassium will vary repolarization (i.e. more mean its more negative and will slow down heart rate)
What does a contractile cell action potential look like?
Rapid depolarization with Na+, then a plateau while Ca2+ is released and then repolarization, they also demonstrate a much more stable resting phase (-80mV to -90mV)
What is the advantage of cardiac action potentials having a longer refractory period?
- Prevents tetanus
- Reduces fatigue
- Enables adequate filling time for chambers
What does the P wave represent?
The depolarization of the atria
What does the QRS complex represent?
The depolarization of the ventricles
What does the T wave represent?
The repolarization of the ventricles
What does the PR interval measure?
The beginning of atrial depo. to the inital QRS complex
What does the QT interval measure?
Ventricular depo. to ventricular repo. (may be changed by ischemia, or conduction impairments)
What are the mechanical events in the cardiac cycle?
Late diastole
Atrial systole
Isovolumic ventricular contraction
Ventricular ejection
Isovolumic ventricular relaxation
What is end diastolic volume (EDV)?
End of atrial systole before ventricular contraction ventricles contain ~130 mL of blood
What is end systolic volume (ESV)?
End of ventricular systole the ventricles contain ~50-60 mL of blood
What is the difference between EDV and ESV?
Stroke volume (SV) about 70-80 mL
What causes the “lub” sound?
The closing of the atrioventricular valves
What causes the “dub” sound?
The closing of the semilunar valves
What is cardiac output?
The volume of blood ejected from the heart in one minute
CO = HR (beats/minute) x SV (mL/beat)
What are the three main contributors to SV?
- Preload (Frank-Starling law of the heart)
- Contractility
- Afterload
What is the Frank-Starling mechanim/law?
The greater the stretch of the ventricular muscle, the more powerful the contraction, which in turn increases SV (increasing preload)
What are the two factors that influence heart rate?
- Autonomic nervous system: downregulated by parasympathetic, up regulated by sympathetic
- Endocrine system / hormones: adrenal medulla releasing hormones and increased levels of K+ decrease HR
What factors affect stroke volume?
Venous return
Filling time
Autonomic innervation
Hormones
Vasodilation and vasoconstriction
How is heart rate affected by exercise?
Increases linearly with exercise until it plateaus
How is stroke volume affected by exercise?
Decreased filling with exercise, SV will will initially increase, but eventually will plateau and SV could end up decreasing
What happens to CO during exercise?
CO increases with exercise, initially as result of both SV and HR, but later more driven by HR
What are the three layers in blood vessels?
- Tunica interna
- Tunica media (smooth muscle and elastic fibres)
- Tunica externa
What makes up the tunica interna?
Lining it is endothelium, helps to detect pressure and NO
Then a basement membrane and an internal elastic membrane which allows for stretch/distend with pulse pressure
What makes up the tunica media?
Thickest wall of the arteries, consists of layers of smooth muscle that perform vasoconstriction and vasodilation
What makes up the tunica externa?
Primarily of collagenous fibers with some elastic fibers, thickest layer in veins, hold vessel in position
What are the arteries closest to the heart know as?
Elastic arteries
What are arteries further from the heart called?
Muscular arteries
What is the primary site of both resistance and regulation of blood pressure?
Arteriole
What are the three types of capillaries?
Continuous
Fenestrated
Sinusoid
Where are continuous capillaries found and what can they exchange?
Almost all vascularized tissues, can exchange metabolic products, small hydrophobic molecules, hormones and leukocytes
Where are fenestrated capillaries found and what can they exchange?
In the kidneys and small intestine for nutrient absorption, permeable to larger molecules
Where are sinusoid capillaries found and what can they exchange?
Found in the liver, spleen, bone marrow, lymph nodes and many endocrine glands including the pituitary and adrenal glands, allow passage pf the largest molecules like plasma proteins and cells
What is a metarteriole?
Type of vessel that has characteristic of both a capillary and an arteriole
What do the precapillary sphincters do for the metarterioles?
Tightly regulate blood flow from the metarteriole to the capillaries it supplies
What are the primary sites for emigration or diapedesis?
Venules and capillaries?
What is another function of veins?
Blood reservoirs, due to their high capacitance (capacity to distend)
What are the three main ways substances can cross capillary walls?
Diffusion
Transcytosis
Bulk flow
What are the two mechanisms that drive bulk flow?
Filtration and reabsorption
How does filtration work in terms of bulk flow?
Volumes of fluid move from higher pressure in capillaries to a lower pressure in the tissues
How does reabsorption work in terms of bulk flow?
Movement of fluid from an area of high pressure in the tissues to an area of lower pressure in the capillaries
Which pressure has to do with the filtration of blood?
Blood hydrostatic pressure
Which pressure has to do with the reabsorption of blood?
Osmotic pressure, draws fluid back in driven by osmotic concentration gradients
What are the contributors to the osmotic concentration gradient?
Albumin, alpha and beta globulins
What is Starling’s Law of capillaries?
NFP = (BHP + IFOP) - (BCOP + IFHP) (85% is reabsorbed)
The difference between systolic and diastolic pressure is what?
Pulse pressure (should be at least 25% of systolic pressure)
What is mean arterial pressure?
Represents the “average” pressure of blood in the arteries (can calculate by adding 1/3 systolic pressure to 2/3 of diastolic pressure, or adding 1/3 of pulse pressure to diastolic pressure)
What are the 5 main variables which affect blood flow and blood pressure?
Cardiac output
Compliance
Volume of blood
Viscosity of blood
Blood vessel length and diameter
How does CO affect blood pressure?
Increasing CO will increase BP
Decreasing CO will decrease BP
How does compliance affect blood pressure?
For example, when arteries are stiff compliance is reduced and resistance increases which will increase blood pressure
How does blood volume affect blood pressure?
If blood volume decreases pressure and flow decrease and therefore BP goes down (dehydration, vomiting, diarrhea or bleeding)
If blood volume goes up, pressure and flow increase and therefore BP increases (salt and water intake)
How does blood viscosity affect blood pressure?
Blood viscosity is directly proportional to resistance and inversely proportional to flow, more viscosity, less flow more resistance, higher BP, for example
Controlled by formed elements and plasma proteins
How does vessel length affect blood pressure?
Vessel length is directly proportional to resistance, longer vessels have greater resistance causing lower flow, for example
How does vessel diameter affect blood pressure?
When a vessel diameter gets smaller (or decreases) it will increase BP through friction and resistance, When a vessel diameter gets larger (or increases) it will decrease BP through less friction and less resistance
Poiseuille’s law - R (resistance)= 1/r^4
What is blood pressure predominantly determined by?
Blood volume, vascular resistance and cardiac output
What two factors maintain the pressure gradient between the veins and the atria?
Atria pressure
The two physiological pumps
What are the the pumps that maintain pressure with the atria?
The skeletal muscle pump and the respiratory pump
What are baroreceptors?
Specialized stretch receptors located within areas of blood vessels and send impulses to the cardiovascular centre in the medulla oblongata to regulate BP (found primarily in aorta and carotid sinuses)
What happens if blood pressure falls or rises and the stretch receptors detect it?
If BP falls, it initiates sympathetic reflexes to accelerate HR, increase forces of contraction and promote vasoconstriction
If BP rises, parasympathetic reflexes are initiated and they do the opposite
What do chemoreceptors do for BP?
They monitor O2, CO2 and H+ (pH), are located close to the baroreceptors and transmit their information to the cardiovascular centre and the respiratory centre
What sends signals to the medulla oblongata and how does it respond?
Input - from higher brain centres, from baroreceptors, from proprioceptors, and from chemoreceptors
Output - Heart decreased rate (parasympathetic)
Heart increased rate (sympathetic)
Blood vessels vasoconstriction (sympathetic)
What can the endocrine system do to help regulate blood pressure?
Release catecholamines as well as hormones that can control and regulate blood volume (aldosterone, ADH)
What happens when blood becomes more concentated?
The thirst response is triggered, osmoreceptors monitor the amount of solutes in the blood, if levels are too high hypothalamus will be alerted and thirst will be triggered
What does atrial natriuretic hormone (ANH) do?
Antagonist to angiotensin II, promotes loss of Na+ and water, secreted by cells in atria when blood volume is high enough to cause extreme stretching
What do chemical signals do to precapillary sphincters?
Trigger:
Dilation - allow blood flow as a result of NO from endothelial cells
Constriction - shuts off blood flow as a result of endothelins (vasoconstrictors) released from endothelial cells
What is short term blood pressure control?
Baroreceptors and cardiovascular system
What is long term blood pressure control?
Renal/blood volumes
What is the valsalva maneuver?
Forced expiration against a closed glottis
Causes an increase in intrathoracic pressure leading to a reduction in preload for the heart
What is phase I of the valsalva maneuver?
Corresponds to the onset of strain, is associated with a transient rise in blood pressure because of the emptying of large veins and pulmonary circulation
What is phase II of the valsalva maneuver?
When positive intrathoracic pressure leads to decreased venous return for the heart, therefore reduced preload and reduced SV, fall in blood pressure activating baroreceptors
What is phase III of the valsalva maneuver?
Leads to release of strain which leads to a sudden dip in BP, release of positive pressure leads to expansion of the pulmonary vascular bed
What is phase IV of the valsalva maneuver?
The overshoot of the blood pressure above baseline, which is because of normal venous return resuming after the stimulation in phase II, reflex bradycardia
What is a conducting zone?
Not directly involved in gas exchange, warms and humidifies air, route for incoming and outgoing air and removes debris and pathogens (generation 0-16)
What is a respiratory zone?
Where gas exchange occurs (generation 17-23), the walls are muscular and can either undergo bronchoconstriction or bronchodilation, contain alveoli
What are type I and type II alveolar cells?
Type I - Highly permeable to gases, ~97% of all alveolar cells
Type II - Secretes pulmonary surfactant, acts as a lubricant for lungs and reduces surface tension
What are the major mechanisms that drive pulmonary ventilation?
Atmospheric pressure, alveolar pressure and intrapleural pressure
What is elasticity?
The pull of the lungs inwards and away from the thoracic wall
What two things compete against negative intrapleural pressure?
Elasticity and alveolar fluid surface tension
What two things want the chest to pull outwards?
The chest wall itself (compliance) and pleural cavity surface tension
What happens during inspiration (airflow into the lungs)?
Atmospheric pressure is greater than intra-alveolar pressure, air flows in
What happens during expiration (airflow out of the lungs)?
Pressure in the lungs becomes greater than atmospheric pressure, air flow out
What muscles are used during normal inspiration?
Diaphragm and external intercostals
What are all the muscles used for forced inspiration?
Diaphragm, external intercostals, pectoralis minor, scalenes and sternocleidomastoid
What muscles are used for forced expiration?
Internal intercostals and abdominal muscles
What is tidal volume (TV)?
The amount of air that normally enters the lungs during quiet breathing
What is inspiratory reserve volume (IRV)?
Produced by deep inhalation, it represents the extra volume that can be brought into the lungs
What is expiratory reserve volume (ERV)?
Amount of air you can forcefully exhale past a normal tidal expiration
What is residual volume?
Amount of air left in your lungs after a max exhale, keeps alveoli from collapsing
What is total lung capacity (TLC)?
TLC = TV + IRV + ERV + RV
What is vital capacity (VC)?
VC = TV + IRV + ERV
What is inspiratory capacity (IC)?
IC = TV + IRV
What is functional residual capacity (FRC)?
FRC = RV +ERV
What is respiratory rate?
Total number of breaths in each minute
What is the dorsal respiratory group (DRG) responsible for?
Maintaining constant breathing rhythm by stimulating the diaphragm and external intercostals for inspiration, activity in the DRG ceases for expiration
What is the ventral respiratory group (VRG) responsible for?
Forced inhalation and forced expiration, triggers the accessory muscles to contract for both processes
What does the pons do for the respiratory system?
Helps inhibit DRG and provide additional control for depth of inspiration
What is the Hering-Breuer (inflation) reflex?
Stretch receptors in the lungs are triggers when the lungs are over inflated, potentially a protective mechanism during exercise
What is Dalton’s law?
All gases exert their own pressure, and these pressures can be combined into a total pressure
What is PO2 and PCO2 in alveolar air?
PO2 = 105 mmHg
PCO2 = 40 mmHg
What is PO2 and PCO2 in oxygenated blood?
PO2 = 100 mmHg
PCO2 = 40 mmHg
What is PO2 and PCO2 in systemic tissue cells?
PO2 = 40 mmHg
PCO2 = 45 mmHg
What is PO2 and PCO2 in deoxygenated blood?
PO2 = 40 mmHg
PCO2 = 45 mmHg
What is Henry’s law?
The concentration of gas in a liquid is directly proportional to the solubility and partial pressure of that gas
How is the majority (~98.5%) of of oxygen transported in the blood?
Attached to hemoglobin, the rest (~1.5%) is dissolved in the blood
What happens when the first O2 is bound to the hemoglobin?
A conformational change, which allows the next couple O2 molecules to attach more readily than the first one
What is it called when there is an oxygen on all four Heme sites?
Saturated (100%)
What is an oxygen-hemoglobin dissociation curve?
It is a graph that describes the relationship of partial pressure to the binding of O2 and its subsequent dissociation from heme
What causes the oxygen-hemoglobin dissociation curve to shift right (low affinity)?
Increased:
- pCO2
- [H+] (lower pH)
- 2,3-DPG
- Temperature
What causes the oxygen-hemoglobin dissociation curve to shift left (high affinity)?
Decreased:
- pCO2
- [H+] (higher pH)
- 2,3-DPG
- Temperature
How is CO2 transported in the blood?
As bicarbonate ions (HCO3-) (~70%), CO2 dissolved in the blood (~7%), and bound to hemoglobin (~23%)
What is the enzyme that causes CO2 and H2O to form carbonic acid (H2CO3)?
Carbonic anhydrase (CA) (carbonic acid dissociates into HCO3 and H+)
If the HCO3- builds up in the erythrocyte, what does the cell do?
Chloride ions will take its place in the chloride shift, exchanging one negative ion for another
What is the hemoglobin called when its bound to CO2?
Carbaminohemoglobin
What is the Haldane effect?
Partial pressures of oxygen affect the binding of CO2 to hemoglobin, high pO2 will favour releasing oxygen and low pO2 and no O2 bound will attach to CO2
What is hypernea?
Increase in depth of breathing to meet O2 demand
What is hyperventilation?
Increase in depth and breathing rate independent from O2 needs
What is hypoventilation?
A decrease in depth and rate of breathing
What happens below the VT1 threshold?
Increased ventilation meets our metabolic demands
What happens after the VT1 threshold?
Our bodies go into anaerobic metabolism and are producing more CO2 than the O2 we are consuming, we hyperventilate and try to expel that CO2
What happens when we hit the VT2 threshold?
Nearing the point of exhaustion and there is a further increase in ventilation as we try to get every bit of O2 we can
