BIOL1008 Ver 2 - Lecture notes All lectures PDF

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BIOL1008 Ver 2 Page 1L2 Body NormalFriday, 5June2020 9:52AMExplain the major themes organising the human body including scale, concept of surface area to volume ratio and examples of it in operation in the human body including the lungs, digestive tractLung alveoli 195 m 2 tennis courtVilli and micr...

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L2 Body Normal Friday, 5 June 2020

9:52 AM

Explain the major themes organising the human body including scale, concept of surface area to volume ratio and examples of it in operation in the human body including the lungs, digestive tract

Lung alveoli 195 m2 tennis court Villi and microvilli Increase surface area villi 30x microvilli 600x

Identify what is normal and abnormal range in some aspects of the human body.

BIOL1008 Ver 2 Page 1

L3: Let's Start With One Friday, 5 June 2020

9:52 AM

• Distinguish the main structures and functions of a cell and its main organelles. Parts of a Cell: Nucleus - control centre Nucleolus - site of RNA transcription and ribosome biogenesis Rough endoplasmic reticulum - ribosomes and protein synthesis - folding Smooth ER - lipid and steroid hormone production Golgi Complex - proteins from ER are processed and sorted ready for trafficking to correct destination Mitochondria : • Make ATP • replicate by fission and contain their own DNA • maternal Lysosome - acidic organelles for waste breakdown and disposal Cytoskeleton: • Filaments and tubules • Structure, support and transport "The cells are in effect a self-contained ecosystem..."

• Explain how cell membranes create compartmentalisation which regulate the flow of substances into and out of cells.

How are things transported in and out? The cell membrane is a phospholipid bi-layer ... The plasma membrane Hydrophobic: scared of water Hydrophilic: likes water Lipid bilayers are impermeable to most essential molecules and ions Permeable to water molecules and a few other small, uncharged, molecules like oxygen and carbon dioxide • Not permeable to: ions, small hydrophilic molecules like glucose, macromolecules like protein and RNA • • • • •

• Describe the passive diffusion of water across semipermeable cell membranes and the role of aquaporins Diffusion: with time - due to random motion molecules become equally distributed across concentration gradients Aquaporins, also called water channels Water also diffuses • The more solute in a given volume the higher the concentration of salt and the lower • • • •

amount of water Water will always flow to where concentration is lower Through semipermeable membrane Wants to be at equilibrium Plasma membrane is semipermeable

Tonicity Osmotic pressure Osmolarity - the measure of solute concentration Isotonic - the extracellular fluid has the same osmolarity as the cell, and there will be no net movement of water into or out of the cell. Hypotonic - the extracellular fluid has lower osmolarity than the fluid inside the cell and the net flow of water will be into the cell. Hypertonic - the extracellular fluid has a higher osmolarity than the cell’s cytoplasm and

water will move out of the cell to the region of higher solute concentration.

• Water will flow to the 1M side to equal concentration • More concentration inside, water escapes the cell • Less concentration inside, water enters the cell

Some of these form pores through the membrane of which there are two broad categories 1. Channels - facilitated diffusion 2. Transporters - facilitated diffusion or active transport Ions and nutrients can move through these pores

Transport of materials Passive = down a concentration gradient Active = against a concentration gradient • Active transport requires energy to proceed, while passive transport does not require the

input of extra energy to occur. • Active - solutes move from a region of low concentration to high concentration. In a biological system, a membrane is crossed using enzymes and energy (ATP). Ion channels conduct charge Moving charge across the membrane, develops a potential difference • Describe how the cell uses the Na-K ATPase to create the electrochemical gradient that provides the energy for life The sodium potassium pump is a plasma membrane transporter. It transports sodium out of the cell and potassium into the cell against their concentration gradients.

• • • •

Uses ATP to transport Sodium out of the cell and potassium into the cell Happens tens of thousands of times a second 3 Sodiums. 2 Potassiums. 3 positively charged out, 2 in. Electrical difference. Inside is more negative than the outside

Consequences of NA-K ATPase action • • • • •

Opposite movement of key ions Unequal movement of charge 3+ out and only 2+ in All cells have a negative membrane potential This is the electrochemical driving force

Facilitated Diffusion

• Regulated movement of nutrients across the membrane • Glucose and amino acids • Often use Na+ gradient as driving force

• Explain how larger molecules and particles get in and out of cells Other ways of transport in and out of the cell Endo and Exocytosis Endo - in Exo - out Endocytosis- Receptors signal cells to open and engulf a molecule Exocytosis -Expansion of membrane and expulsion of material before reclosing

Phagocytosis • Cell recognises a target • Engulfs and destroys it

L4: Powering It All Up Friday, 5 June 2020

10:34 AM

• Outline the major uses of energy in humans Some of the nutrients you eat are used to build bits and pieces of you • You use 80-90% of the nutrients to provide energy • Nutrients absorbed from meals supply energy for ~ 4 hours. • In the 4 hours after a meal, you store nutrients as glycogen and fat to give you energy till the next meal Glucose- key energy source for cells • Glucose and fatty acids are important when you are not starving • Most tissues use glucose • Brain mainly uses glucose • Heart muscle only uses fatty acids and lactate • Skeletal muscle uses both • When you are starving, your cells can use • Ketone bodies (more about these later) • Glucose made by the liver from amino acids (proteins) and lactate Amino acids coming from proteins

• Describe the role of ATP as the common intracellular energy source for human cells ATP = Adenosine Triphosphate Burn food to make energy ATP • Found in all known forms of life, ATP is often referred to as the "molecular unit of currency" of intracellular energy transfer. • ATP is the energy sources >95% of cellular activity: • Contractility and motility (actin and myosin in muscles), Ion pumping, signalling. biosynthesis Regular exercise increases the capacity of muscle to generate ATP • Exercise causes calcium to increase in muscle which triggers contraction • The contraction increases ATP usage in muscles and then increases AMP in muscle(produced from ATP during contraction) • The increase in calcium and AMP leads to the production of new (growing) mitochondria

• Compare and contrast the role of glucose and fatty acids as substrates for ATP production • There is more energy available per gram of fatty acid than per gram of glucose (106 ATP vs 32 ATP) • Aerobic metabolism (using O2) of glucose produces much more energy than anaerobic metabolism (without using O2) (32 ATP vs 2 ATP) •

Fatty acids are not used to produce ATP in the absence of O2

• Distinguish between aerobic and anaerobic metabolism as mechanisms to produce ATP from glucose and fatty acids With oxygen

Glucose goes through glycolysis converts to pyruvate produces ATP Without using oxygen

• Describe the differences in preferences for metabolic substrates between skeletal muscle, heart muscle and brain and the implications for these of starvation From fed to fasting to starving First 4 hours after a meal • All tissues use glucose from the meal From 4-30 hours • Tissues other than brain reduce glucose usage • Liver produces glucose from glycogen and amino acids After 30 hours • Brain starts using ketone bodies rather than glucose

• Other tissues stop using glucose • Liver makes ketone bodies from fatty acids (Acetyl Coenzyme A) • Liver and kidney make glucose from amino acids Ketone bodies • Are produced in liver from Acetyl Coenzyme A during starvation • They are acetone and small organic acids • They can be used by other tissues, including brain, to produce energy • In people with uncontrolled diabetes they can reach very high levels, causing diabetic ketoacidosis

L5 Let it flow Friday, 5 June 2020

10:34 AM

– Explain why blood flows continuously around the body. Humans have a closed circulatory system – Physically separated from the rest of the body – Consists of vessels and pump Humans have a “double” circulatory system as our heart is divided completely into right and left sides Heart divided into 4 chamber Left and right side so blood isn't mixed

Pulmonary circuit going to lungs and lungs alone Systemic circulation everywhere else except lungs

– List the key differences between the three main types of blood vessels. Different types of blood vessels Artery: contains elastic tissue (aorta to stretch for heavy loads), large amount of smooth muscle (able to contract - alter the dilation of our vessels) Arterioles: predominantly smooth muscle and endothelial layer (resistance vessels - allow us to alter blood flow to the tissues)

Vein: contains elastic tissue and smooth muscle Capillaries: only contain a single layer of endothelium (allows exchange)

Endothelium is a single layer thick important for exchange • Capillary only contain a single layer of endothelium • Important to let it exchange rapidly and across a small surface area • Allows to exchange to happen rapid Artery and veins have elastic tissue, allows it to stretch Smooth muscle can contract and alter vessel alter contraction or dilation of vessel Change in arteriole would constrict Skeletal muscle dilate to allow blood to reach – Trace a red blood cell arriving at the right atrium through the heart, listing each chamber and structure that it passes on its way to the aorta. -Generates a pressure to force blood to continuously around the body -Composed predominantly of cardiac muscle

Left ventricle is more thicker and muscular as it pumps blood to rest of blood Right side only pumps to lungs Backflow of blood stopped via valves 4 valves located in the heart

Tricuspid valve and bicuspid valve: open and close based on the pressure within the heart. • When the atria contract, the value is forced open and forces blood down to the ventricles, as the ventricles contract, the valve closes. Tricuspid right side of heart Bicuspid left side of heart 2 valves located in entry to circulatory Semilunar valve: open and close based on pressure changes within the heart

One on the pulmonary One on entry to aorta is also semi lunar valve Movement of blood 1. Deoxygenated blood enters the right atrium via the superior and inferior vena cava 2. From the right atrium, the deoxygenated blood moves down to the right ventricle 3. From the right ventricle, deoxygenated blood is pumped through the pulmonary arteries to the lungs 4. Gas exchange occur in the alveoli 5. Oxygenated blood re-enters the heart through the pulmonary veins into the left atrium 6. From the left atrium, the oxygenated blood is pumped into the left ventricle 7. From the left ventricle, the oxygenated blood is pumped out through the aorta to the rest of the body

– Explain physiologically why you can feel a pulse when pressing your fingers to an artery. -Heart generates its own electrical activity Heart will beat independently of input from our nervous system Can alter our heart contractibility and rate in which it fire by having input from our nervous system – Specialised cells within the heart generate an electrical signal to coordinate contraction – Autorhythmic cells – Depolarises the membrane, spreading rapidly through conducting pathway SA node are autorhythmic fluctuate membrane potential allows ion to move across plasma membrane Never at rest When it reaches a threshold it will cause action potential This electrical activity must proceed the mechanical event of the heart Electrical activity is not heart contracting

When SA node fires Trigger cardiac muscle cells of the atrial to begin contracting Force blood into subsequent chambers Electrical signal travels to bottom to heart up then spread back up Ventricle begin to contract and force blood out through large blood vessel closing of Tricuspid and bicuspid close Why u feel pulse when the heart contracts, your arteries will 'stretch', allowing blood to flow from a high pressure to low pressure gradient. When the heart relaxes, arteries will 'snap back' into position, forcing the blood flow forward (instead of back into the heart). It is essentially this motion that translates to a pulse. Also, interestingly, you can feel a pulse in your arteries, but not in your veins. This is because your veins have a lot less muscular tissue and withstand far less pressure. They actually predominantly rely on the contraction and relaxation of surrounding skeletal muscles to deliver blood back to the heart.

Alterations to our heart rate • heart rarely contracts to its maximum force • At rest, after each beat blood remains in the heart (65mL) • For each contraction of the heart, the volume ejected is known as the stroke volume (SV) • Changing SV directly correlates to alterations in heart rate (HR), therefore altering the performance of the heart • Performance is measured by cardiac output – (CO) CO = SV x HR • CO = 70 mL/beat x 72 bpm = 5.4 L/min – HR is altered by the autonomic nervous system by changes to the depolarisation of the autorhythmic cells Systemic

Blood flow around the body Blood flows from an area of low pressure to an area of high pressure

Arterial system is under high pressure Venous system is under low pressure

Blood should flow high to low Creates gradient for blood to move from aorta to venae cavae high to low Move away from heart Closed system causes friction, slow down flow Pressure drops from friction from walls causes blood to slow Blood pressure – Blood pressure is often recorded as: – 120/80 mmHg Measure in millimetres of mercury – What do these numbers actually mean? – As the heart oscillates between contraction and relaxation, measurements are taken at these points: – 120 mmHg is the systolic pressure – 80 mm Hg is the diastolic pressure Systole = contract Diastole = relaxed – Systole is the pressure in the arteries when the heart has contracted – Diastole is the pressure in the arteries when the heart is fully relaxed Postural hypotension Not moving leg doesn’t allow blood to return to the heart Fainting soldier Standing at attention can cause fainting after a period of time Blood and gravity build at feet Unique physiological response Caused by postural hypotension Hypo = low Tension = pressure

Our vein rely on contraction of skeletal muscle in order to drive blood back up yo heart called skeletal pump When you not moving it isn't causing veins to constrict Feet got hot or swell up as blood is stuck blood pressure gets to low so we Fainting in an attempt to remove effects of gravity

– Describe the composition of blood and how red blood cells are produced during hypoxia. What is Blood? It is a connective tissue made up of cellular elements, suspended in a fluid matrix – Plasma fluid component – Makes up a quarter of the ECF – Acts as buffer between the cells and the external environment – Circulating portion Takes away waste bring oxygen removing CO2 etc Difference between plasma and interstitial fluid is plasma Blood composition

92% Water – 7% Protein – 1% Dissolved organic molecules

Cellular Constituents of Blood – Red Blood Cells (RBCs) – aka Erythrocytes (erythos = red) – O2 and CO2 transport – No nuclei – White Blood Cells (WBCs) – aka Leukocytes (leukos = white) – Key role in immune response – Circulate in blood, but act on/in tissues – Five types – Platelets – aka Thrombocytes (thrombo = clot/lump)

– Important in coagulation – Cell fragments that split off from Megakaryocytes Erythropoiesis (production of RBC) – Controlled by the glycoprotein erythropoietin (EPO) + some cytokines – Produced by the kidneys – The trigger for EPO release is hypoxia Hypo = low Reduced oxygen carrying capacity within blood triggers kidney to secrete EPO into bloodstream This acts on our bone marrow and matures blood cells which are secreted out into our normal circulation which triggers the decrease in production of EPO

– Describe why fluid is lost from the blood to the interstitium when exchange takes place at the capillaries. Capillary transport – Three mechanisms of exchange – Movement between endothelium – Transcytosis – Bulk flow driven by pressure change Lymphatic System Fluid that is filtering into the interstitial space → we don't want to lose the fluid because our pressure will drop too low, we need to maintain volume to maintain pressure. So the lymphatic system is what's in place. They have fingerlike projections that intertwine between capillary beds to pick up filtered fluid to transport back into our system. – Three key functions: – Return filtered fluid to circulatory system – Fat reabsorption from gut into circulation – Destroy foreign pathogens

L6 Take My Breath Away Friday, 5 June 2020

10:34 AM

– Understand what the partial pressure of a gas is. Gas exchange (respiration): uptake of O2 from the atmosphere and discharge of CO2 back into the environment. Partial pressure: a particular gas within a mixture of gases exerts a specific pressure Atmospheric pressure: 760mL of mercury Knowing the partial pressure of a gas allows us to predict its movement • Gases always diffuse from a region of high partial pressure to a low partial pressure – Trace the flow of air into the body beginning at the nose and ending at the alveoli.

1. 2. 3. 4. 5.

Air is drawn in by the nose or mouth and is warmed in these structures Air moves through the pharynx and past the larynx (voice box) Air moves down the trachea (windpipe) Trachea divides into two chronchiai tubes, one bronchus in each lung Bronchus divides into small bronchioles and eventually ends in small air sacs called alveoli 6. Alveoli have thin walls and are covered in capillaries carrying blood. Oxygen passes through the thin walls of the alveoli to the blood and CO2 moves in the opposite direction (from the blood into the alveoli) 7. The air in the lungs which is now high in CO2 is exhaled

Bronchi diverge many times Bronchiole have similar function to arteriole control resistance to airway. Wrapped with smooth muscle can contract or dilate. Functional unit :Alveoli covered in capillary beds catch large surface area for exchange

– Describe why expansion of the thoracic cavity also expands the lungs. Negative pressure breathing – To move O2 from the atmosphere into our lungs, the pressure must be lower in the lungs – Pulling, rather than pushing air into our lungs Mouth and nose are connected to lung exposed to environment. If you weren't breathing at all we were just at equilibrium lung would be same pressure as atmosphere, equilibrate as open to the environment. To achieve a lower pressure in our lungs we have to expand our chest to increase volume in our lung so we have a greater space for gas molecules to move around Increase in volume -> low pressure Suction in lung – Achieved by expansion of the chest wall by muscle contraction

When volume is increased, pressure is decreased air is pulled into airway Active because muscles need to contract we require energy Why do our lungs expand when our chest contracts? – A double membrane surrounds the lungs Blue strip is pleural cavity Fluid filled hence will exert pressure Pressure inside pleural cavity is lower than atmospheric pressure Lung are not directly connected to ribs or diaphragm Fluid form very strong hydrogen bonds, sticks walls of the pleural cavity to the ribcage Stick because every time muscle contract lung will stick and move with it – One side adheres to the outside...