Human Bio - Body Systems and Metabolism (Ch 3, 4, 5, 6)

Structural organisation of the body

cells, tissues, organs, systems, organism

Tissue

cells with similar specialisation that carry out a common function

Types of tissue

epithelial, connective, muscular, nervous

Epithelial Tissue

• A body tissue that covers the surfaces of the body, inside and out.

• cells are very closely joined together.

• vary in shape: thin and flat (mouth), column shaped (intestines), cube shaped (kidney)

• e.g external covering of internal organs (heart, kidneys, intestines, lungs)

Connective Tissue

provides support for the body and holds all the parts together. Cells are not close together. Separated by large amounts of material that is not part of the cell - non cellular material (matrix). e.g bone, cartilage, tendon

Muscular Tissue

Long and thin muscle fibres that respond to stimuli and can contract to become shorter. Three types: skeletal, involuntary and cardiac

Skeletal Muscle (voluntary)

A muscle that is attached to the bones of the skeleton and provides the force that moves the bones. It is striated (has stripes when viewed under microscope)

Smooth Muscle

Involuntary muscle that we cannot control, found inside many internal organs of the body e.g walls of stomach, intestines, blood vessels, iris, uterus

Cardiac Muscle

Involuntary striated muscle tissue found only in the heart.

Nervous Tissue

- Made up of specialised nerve cells called neurons
- have long projections from the body of the cell
- electric impulses (messages) travel along projections
- found in the CNS (brain, spinal cord and nerves) and PNS

Organs

structures made up of two or more types of tissue. Work together to perform a specific task. Have distinct structures with recognisable shape, and organs may have organs within them, e.g skin and sweat glands.

System

A group of body organs or structures that together perform one or more specific functions within the body. e.g respiratory, digestive. Also have secondary functions. e.g circulatory system helps fight disease.

Organism

Body systems working together to form a functioning organism, do not work in isolation but rely on eachother.

Energy use within the body

Cells need chemical energy (from food and they need it all the time). Needed for:
- movement
- sending nerve messages
- building large molecules
- respiration
- heat
- growth
- reproduction

Metabolism

All the chemical processes that occur within the cells and the body. Two types: catabolism and anabolism. Chemical reactions require certain conditions. The reacting particles must collide in the correct orientation and with enough energy to break bonds (activation energy). At any given temperature there is a proportion of particles that have enough energy to start a chemical reaction. Proportion increases with temperature.

Catabolism

large molecules broken down into smaller molecules with the simultaneous release of energy. E.g cellular respiration.

Anabolism

Small molecules built up into larger substances. requires energy. E.g protein synthesis. The body must maintain a balance between energy release and energy utilisation.

Nutrients

Any substance in food that is used for growth, repair or maintaining the body. Classified into 6 groups: water, lipids, minerals, carbohydrates, proteins, vitamins.

Organic Compounds

Large molecules that contain carbon. Foods - carbohydrates, proteins and fats (lipids).

Inorganic Compounds

Small molecules not based on a carbon chain, e.g water, oxygen, vitamins and minerals. Lack of carbon and hydrogen bond. Water is the fluid of which all substances are dissolved, Vitamins, minerals act as co-factors that assist enzymes.

Carbohydrates

- contain atoms of carbon, hydrogen and oxygen.
- main source of energy for cells
- complex carbohydrates (starches) are broken down into simple sugars e.g glucose that are used in cellular respiration to release energy.
- 3 forms: monosaccharides, disaccharides, polysaccharides

Monosaccharides

Single sugar molecules. e.g glucose, fructose

Disaccharides

When two simple sugars are joined together. e.g maltose and lactose. Can be broken down into simpler sugars.

Polysaccharides

Large carbohydrate molecules formed when many simple sugars join together. e.g starch, cellulose.

Lipids

• Fats and oils that contain carbon, hydrogen and oxygen

• important energy source

• consists of a glycerol and fatty acids

• glycerol can enter glycolysis pathway of cellular respiration

• broken down to release energy.

• e.g phospholipids, steroid hormones and stored fats (triglycerides)

Proteins

• Always made up of carbon, hydrogen, oxygen and nitrogen

• Made up of amino acids (20 different types)

• Peptide bonds join amino acids together to make proteins

• Most proteins are enzymes (speed up chemical reactions)

• Can be used for energy if other supplies are inadequate.

• the type and order of amino acids is determined by the DNA that codes for the production of proteins.

• Dipeptides are made up of 2 amino acids, Polypeptides are made up of more then 10.

Nucleic Acids

Large molecules containing carbon, hydrogen, oxygen, nitrogen and phosphorus. Two types are RNA and DNA. made up of nucleotides with a nitrogenous base, sugar and phosphate.

Catalysts

- decrease the amount of energy needed to break bonds
- decreases the activation energy
- more particles will have enough energy to react, making the reaction happen at a faster rate.
- not consumed during reactions

Enzymes

- Proteins that act as catalysts
- Allow chemical reactions to occur fast enough at body temperature for the body to function
- not used in the reaction
- without enzymes, metabolic reactions would be too slow to maintain life.

Features of Enzymes

1. all proteins

2. all speed up chemical reactions

3. not used up in reactions

4. susbtance that enzymes work on is called the substrate

5. enzymes and substrates have a specific shape and structure that allow them to fit together.

6. lowers activation energy

7. work on a lock-key principle

8. work with co-enzymes and co-factors

9. can be denatured by heating

Activation energy

the minimum amount of energy required to start a chemical reaction

Analogies of Enzyme Function

Lock-Key Model and Induced-Model Fit

Lock-Key Model

The analogy that enzymes and substrates fit together based on their specific shapes and sizes like a key fits a lock. The enzymes active site (key) attaches to a substrate (lock) forming an enzyme-substrate complex. The enzyme causes a weakening of chemical bonds, resulting in the substrate breaking down into smaller product molecules. The enzyme is unaltered during the reaction, free to catalyse breakdown of another substrate

Induced Model Fit

When the enzyme and substrate join, they form weak bonds that cause the shape of the substrate to change. This creates complementary shapes between the substrate and enzyme.

Factors Affecting Enzyme activity

Temperature, pH, enzyme concentration, substrate concentration, products of the reactions need to be removed, co-factors/co-enzymes, enzyme inhibitors
- Enzyme concentration: high concentration \= faster reaction
- Substrate concentration: more substrate \= more reactions
- Temperature: rate of reaction increases as temp increases (up to 45-50 degrees). Above this, enzymes are denatured (inactivated), change shape and no longer fits the substrate. Optimum temp is 30-40 degrees celsius
- pH: each enzymes have an optimum pH.
- Products of the reactions need to be removed: need to have space for the enzyme and substrate to come in contact with each other.
- Co-factors/Co-enzymes: many enzymes require other ions or substances to activate them. Co-factors are inorganic, co-enzymes are organic.
enzyme inhibitors: may slow or even stop enzyme activity. cells may control activity using inhibitors. e.g drugs.

Enzyme vs Sugar suffix

Enzymes often end in -ase. e.g lactase, Sugars often end in -ose. e.g lactose.

Cellular Respiration

Process that releases energy by breaking down glucose and other food molecules in the presence of oxygen. Glucose comes from the breakdown of complex carbohydrates, fatty acids and glycerol. Partly from breakdown of amino acids.

Cellular Respiration equation

glucose + oxygen --\> carbon dioxide + water + energy

Energy from cellular respiration

• a complex process where each step releases a small amount of energy. Slow process

• 60% produced is heat to maintain internal body temperature

• remaining 40% is used to form ATP

Adenosine Triphosphate

Formed when a phosphate is joined to ADP. The phosphates are joined by high energy chemical bonds between the second and third phoshphate group. removal of the 3rd phosphate group releases energy. ATP can be used to transfer energy into a cell that requires energy. ADP can be reused.

First stage of cellular respiration

Glycolysis: glucose is broken down into 2 molecules of pyruvate and 2 molecules of ATP. No oxygen is required (anaerobic). occurs in the cytosol of the cytoplasm.
Occurs when no oxygen is available.

Second stage of cellular respiration

Aerobic Respiration: involves the Krebs Cycle (Citric Acid Cycle) and electron transport system. Requires oxygen and produces up to 38 ATP. Occurs in the mitochondria which is made of a double membrane, with the inner membrane being folded to increase surface area for reactions to occur, so more energy is produced. The reaction involves enzymes, attached to the inner membrane. To complete the breakdown of glucose the pyruvate molecules must enter the mitochondrion. Pyruvate first converted to a co-enzyme, Acetyl CoA, which produces CO2 and no ATP.

Krebs Cycle (Citric Acid Cycle)

Acetyl CoA enters, and carbon dioxide is released. Produces 1 molecule of ATP per acetyl CoA that enters. Because two pyruvate molecules are produced in glycolosis, two ATP are produced per Kreb's Cycle

Electron Transport System

the final stage in cellular respiration, it uses oxygen. Electrons are passed between molecules, resulting in oxygen molecules forming water. Produces up to 34 ATP.

Aerobic Respiration Energy Summary

- Glucose (38 ADP) + oxygen (38 P) --\> carbon dioxide + water (38 ATP)
- one molecule of glucose can generate up to 38 ATP, 2 from glycolysis, 2 from Kreb's Cycle (Citric Acid Cycle) and up to 34 from electron transport. Will Rarely generate 38 ATP

Anaerobic Respiration

- Occurs when no oxygen is available.
- Pyruvate from glycolysis is converted into lactic acid (glucose -\> pyruvate -\> lactic acid)
- Lactic Acid is taken to the liver to recombine with oxygen to form glucose
- Build up of lactic acid made cause muscle pain

Oxygen Debt

Because the process for lactic acid to become glucose requires oxygen, our body will be in oxygen debt, Extra oxygen after exercise is called recovery oxygen, which is why we continue to breathe heavily,

cellular respiration classification

cellular respiration is catabolic. Energy is released from breaking down glucose can be used for anabolic reactions like protein synthesis

Nasal Cavity

- lined by mucous membranes
- filters, warms and moistens air
- hairs and mucus trap debris which prevent it from reaching the lungs

Pharynx

The throat, it is the region from the nasal cavity to the top of the trachea and oesophagus. Air travels through the pharynx before being diverted into the trachea by the epiglottis.

Epiglottis

a flap of elastic cartilage that, during inhalation, covers the oesophagus so the air goes into the trachea and when swallowing food closes off the larynx to prevent food from entering the lungs.

Larynx (voice box)

A cartilage structure that joins the pharynx and trachea. Contains the vocal cords which are mucous membranes that vibrate as air passes over them.

Trachea

Carries air in and out of the lungs. Made of C-shaped cartilage rings to ensure it always stays open. Lined with mucous membrane which traps dust and debris. Cillia push mucus with dust up to the pharynx to be swallowed.

Cilliated Lining Tissue

mucus secreting goblet cells.

Bronchi

Made of C shaped cartilage rings, lungs contain two primary bronchi, one for each lung. These split into secondary bronchi, which take air into each lobe. These divide into tertiary bronchi.

Bronchioles

Smaller tubes breaking off the tertiary bronchi, made of smooth muscle and elastin (not cartilage), which allow it to control the flow of air in the lungs. End in terminal bronchioles. Cilia and mucus are also present in the bronchioles, protecting the lungs from contaminants.

Alveoli

tiny air sacs which make up most of the lungs and are one cell thick. Surrounded by capillaries. Allow for good gas exchange

The Lung Lobes

2 on the left, 3 on the right

Pleura

covers the surface of the lungs and lines the inside of the chest

Pleural Fluid

thin layer of fluid between two layers of membrane that hold the lungs against the inside of the chest wall. Allow the lungs to slide when breathing.

Ribs

forms the framework of the chest. Consists of 12 pairs of bones.

Intercostal Muscles

Muscles between the ribs. Move rib cage up and outwards to increase volume of chest cavity

Diaphragm

Separates the chest/abdomen. Contracts/flattens downwards to increase chest cavity when breathing in.

Ventilation

Process where air is moved into and out of the lungs.

Respiration

transport of oxygen from the air to the tissues and the transport of CO2 in the opposite direction. Air moves from high to low pressure.

Inspiration

• Process of taking air into the lungs

• for air to flow into the lungs, the pressure of air in the lungs must be less then atmospheric pressure outside the body, which is achieved by increasing volume of lungs.

• to increase volume of the lungs, the diaphragm and external intercostal muscles contract.

• the diaphragm becomes flatter and the rib cage moves upwards and outwards, increasing the volume of the chest cavity.

• As pleura adheres to internal wall of the chest cavity, lungs expand with expanding chest cavity.

• a higher volume in the lungs means that air can flow into the lungs through the nasal cavity/mouth and trachea.

Expiration

- Process of expelling air out of body
- the diaphragm and external intercostal muscles relax.
- the diphragm bulges more into the chest cavity and the rib cage moves downwards
- Increase of the pressure of air in the lungs is achieved by decreasing the volume of the lungs
- Air flows out through the trachea and nose until pressures are equal.

Alveoli Structure for Gas exchange

- Extremely large internal surface area so large amounts of gases can be exchanged more efficiently
- each alveolus is supplied with blood vessels, so that as much blood as possible is close to air in the alveous. The continuous flow of blood helps maintain a concentration difference of oxygen and carbon dioxide between blood and air in the lungs.
- they are very thin so that gas molecules do not have to travel far when moving into or out of the blood
- very deep in the body so evaporation is reduced
- moist so that gases can diffuse into and out of the blood only when dissolved in fluid

Gas Exchange

- there must be a concentration gradient (difference in gas concentration (CO2 and O2) between air and alveoli and blood in the capillaries) for diffusion of gases in and out of the blood
- pulmonary artery brings deoxygenated blood to the capillaries around alveoli
- CO2 diffuses from higher concentration in the blood to lower concentration in the alveoli
- O2 diffuses from higher concentration in the alveoli to lower concentration in the deoxygenated blood
- air flows in and out of the alveoli as we breathe
- oxygenated blood taken back to the heart through pulmonary veins.

Concentration Gradient maintenance

- constant flow of blood through the capillaries
- movement of air into and out of the alveoli as we breathe in and out.

Emphysema (Causes, damage to alveoli, effects)

- Causes: long term exposure to irritating particles in the air. e.g smoke particles, dust, asbestos particles
- Damage to alveoli: loss of elasticity (which means that lungs are constantly inflated, so breathing is a voluntary effect (no longer passive)), break down, reducing internal surface area (loss efficiency)
- Effects: inadequate surface area for gas exchange, difficult in ventilating lungs, incurable

Lung Cancer (Causes, effects)

• Causes: irritating particles such as smoke or asbestos, inhaled particles constantly irritate mucus membrane that line the inside of air passages.

• Effects: mostly begins in the walls of the air passages, usually bronchi. cells at base divide uncontrollably and accumulating mucus can't be removed. trapped mucus causes rupture of alveoli (emphysema developed). Cancerous growth develops in the air passage and may spread to other parts of the body

Lung Infections (how it spreads, examples)

How it spreads: Most lung infections spread by droplets, when infected people cough, sneeze or spit, tiny droplets of moisture containing the infectious bacteria, virus or fungi may be inhaled by others, spreading the infection
Pneumonia: infection of the lungs caused by bacteria, viruses or fungi or other organisms. The surface area available for gas exchange reduces due to inflammation, causing fluids and mucus to be secreted into the alveoli
Tuberculosis (TB): infection by a bacterium Mycobacterium tuberculosis. Very low incidence in Australia.

Asthma (triggers, causes

Triggers: Allergic response to foreign substances that enter the body, e.g animal skins, feathers, pollen and even some foods.
Causes: Narrowing of the airways by the smooth muscles contracting, inflammation causing lining of the airways to thicken (reducing diameter) and mucus filling airway. Secretion of excessive mucus means reduced volume of air in and out of the lungs, and oxygen carrying capacity of blood decreases, meaning gas exchange is impaired.

Circulatory System

The bodys main internal transport system, it provides the cells with the substances they need to remove waste products. Consists of the heart, blood vessels and blood

Functions of Blood

• Transport: transport O2 and nutrients to all cells, CO2 and wastes away from cells and chemical messengers (hormones) to cells. Regulation: regulate pH, body temperature and water content and ion concentration Protection: protects against disease-causing micro-organisms, clotting when vessels are damaged.

Blood Composition

- Liquid part: Plasma. 55% blood volume
- Non liquid part: formed elements, makes up 45% of blood volume. Contains red blood cells (erythrocytes), white blood cells (leucocytes) and platelets (thrombocytes)

Plasma

A mixture of water (91% water) with dissolved substances (glucose and salts). Its function is to transport components of blood throughout the body.

Erythrocytes (Red Blood Cells)

Most abundant cell in the blood (40-45% volume). Biconcave discs that do not contain a nucleus. Lack of nucleus means they only live for around 120 days. Produced in the bone marrow and destroyed in the liver and spleen

How does the structure of red blood cells aid in achieving its purpose

• contain haemoglobin which readily combines with oxygen

• no nucleus means more room for haemoglobin (and therefore oxygen)

• biconcave discs increase surface area for oxygen exchange

• thicker edges create a larger volume that allows room for haemoglobin molecules

Leucocytes (White Blood Cells)

• Larger then RBC but fewer in volume (1% of blood). Protect the body from infection (if infection, WBC count increases) and remove dead or injured cells and invading microorganisms. Can live from few min to years.

Leucocyte Types

• Granulocytes (Neutrophils): most common. Contain digestive enzymes. Engulf pathogens and/or damaged cells by phagocytosis

Agranulocytes

- Monocytes: form other cells (macrophages) that engulf pathogen and aged/damaged cells by phagocytosis
- Lymphocytes: Immune Response

Platelets (Thrombocytes)

• small cell fragments that do not contain a nucleus. Formed in red bone marrow and live for around 7 days. When blood vessels are injured, platelets help form clots.

Transport of Oxygen

3% dissolved in blood plasma (not very soluble in water), 97% carried with haemoglobins such as oxyhaemoglobin.
- Hb + O2 \= HbO2 or HbO2 can break into Hb + O2
- Oxygenated blood/oxyhaemoglobin is red (so blood in arteries are red)
- Deoxygenated blood/haemoglobin is dark red

Transport of Carbon Dioxide

• diffuses into the plasma due to concentration difference.

• around 7-8% dissolved in plasma, 22% combines with haemoglobin to form carbaminohaemoglobin

• 70% reacts with water to form carbonic acid which then breaks down into hydrogen and bicarbonate ions

• CO2 + H2O = H2CO3 which breaks down into H+ and HCO3-

• this can also start from H+ and HCO3-

Carbon Dioxide at the Lungs

carbaminohaemoglobin breaks down and released CO2. CO2 in plasma diffuses out of the blood into the alveoli. Hydrogen and bicarbonate ions recombine (carbonic acid), which breaks down into water and CO2

Transport of Nutrients and Waste

organic and inorganic wastes. e.g urea and creatinine are transported in the plasma.

Blood Clotting

- When blood vessels are damaged, the body must repair itself to prevent blood loss and infections from microorganisms
- Step 1: Vasoconstriction: muscles in the walls of damaged arteries constrict to reduce blood flow/blood loss
- Step 2: Platelet Plug: damage to internal walls of blood vessels cause them to become rough, which allow platelets to stick to the rough surface. Platelets release substances that attract other platelets (and so a plug is built up at site of injury, which helps reduce blood loss), sufficient for small injuries.
- Step 3: Coagulation: for more serious injuries, blood clotting (coagulation) is necessary. The formation of a clot is a complex series of reactions. Clotting factors stimulate the production of fibrin (fibrous mesh), which traps blood cells, platelets, and plasma to form a clot (thrombus). Threads stick to the damaged blood vessels and hold the clot in position. The clot dries, forms a scab and prevents entry of infectious microorganisms.

Pericardium

membrane which encloses the heart and holds it in place and prevents overstretching with a wall made up of cardiac muscles. The septum separates the right and left sides.

Heart Structure

4 chambers: 2 atria at the top (right and left) and 2 ventricles (right and left) at the bottom. Atria pump blood to ventricles and ventricles pump blood to the body/lungs.
- Right side - deoxygenated blood from body pumps to the lungs.
- Left side - oxygenated blood from the lungs is pumped around the body
Left is thicker then right side as it pumps blood further

Right Atrium

Receives deoxygenated blood from the body and passes it to right ventricle

Right Ventricle

Pumps blood to the lungs

Left Atrium

receives blood from the lungs and passes it to the left ventricle.

Left ventricle

Pumps blood to the body

Valves in the heart

• ensure that blood flows in only one direction

• anchored by the chordae tendinea and papillary muscles

• between atria and ventricle are atrioventricular valves

• Between ventricles and arteries are semilunar valves

Arteries

Blood vessels that carry blood away from the heart. walls contain smooth muscles and elastic fibres. Elastic walls as blood entering arteries is under high pressure. When ventricles relax, elastic artery walls recoil (elastic recoil) to keep blood moving and maintain high pressure. Arterioles (small arteries) in blood tissue

• Vasoconstriction: reduces the diameter of arteries to reduce blood flow

• Vasodilation: increases the diameter of arteries to increase blood flow.

Capillaries

Link between arteries and veins. Microscopic vessels that carry blood to the cells. Walls are single celled thick which allow substances to pass between blood and surrounding cells.

Veins

Carry blood back to the heart. Capillaries join to the venules (small veins) which then join up to make larger veins. Blood is under relatively low pressure so walls are inelastic, not muscular and thin. Unable to change diameter. Have valves to prevent blood flowing the wrong way.

The right ventricle pumps blood to the

pulmonary vein (deoxygenated blood), then to the lungs, then the pulmonary vein (oxygenated blood) and then the left atrium