Biology Week 1 PDF

The Major Body Cavities The Abdominopelvic Cavity  Levels of Organisation The levels of organisation in the body is referred to as a cooperative hierarchy. Smaller parts come together to make bigger parts, be...

The Major Body Cavities The Abdominopelvic Cavity  Levels of Organisation The levels of organisation in the body is referred to as a cooperative hierarchy. Smaller parts come together to make bigger parts, becoming more complex as you go on. It’s cooperative in the sense that all of these levels need to work together for the organism to function as a healthy human body. Chemical/Molecular Level Atoms are the smallest chemical units of matter and when we start to join atoms together we make molecules. A molecule is two or more atoms joined together. Molecules can be very simple like carbon dioxide, which is one carbon and two oxygen or like water which is two hydrogen, one oxygen or they can be very large and complex and contain hundreds and thousands of atoms. Atoms come in a variety of different types and we call these different types, Elements. Each element has its own symbol. Some elements are measured in blood tests such as calcium or sodium levels. If the atom or molecule is what we call an Ion or an electrolyte, it will have either a positive or negative symbol after the element. (Sodium has Na+). If the atom or molecule is an Ion, It means that it is carrying a charge – if it is a positive charge you will see a plus, and if it is a negative charge, you will see a minus there. The charge will influence the way the atom or molecule behaves including what it’s attracted to as well as where it can or cannot move. A macro-molecule is a bigger molecules that has a lot of atoms joined together. They come in four classes that have a variety of functions. Proteins - Very diverse in terms of structure and function (can be hormones or enzymes. Some proteins are structural and help build parts of ourselves. Carbohydrates - One of the most important carbohydrates is glucose because it is our bodies favourite energy source. We use glucose to create ATP (our energy currency in our body). Some carbohydrates have structural roles or act as messengers on the surface of your cell. Lipids/Fats - Energy storage and a Structural Role (The cell membrane is made up of lipids). Nucleic Acid - Nucleic Acid is the building blocks of DNA (our genes and give us control over ourselves) Cellular Level Cells are the basic unit of life. The cell is the basic living, structural and functional unit of the human body. They carry out so many functions that help each system contribute to homeostasis of the entire body. At the cellular level we have a sack called the Cell Membrane. Inside, there are atoms and molecules working together to form organelles (like little factories that have specific jobs inside your cells). You have a nucleus inside most of the cells of your body which controls what the cell does and doesn’t do. All these cells have a structure that is related to their function, meaning that the way they are built enables them to fulfil their purpose – these are the organelles. Most cells have a nucleus which is where the DNA is found. It is important to note that cell numbers can vary in health and disease. For example, if you are Anaemic, you may expect to see decreased red blood cell counts. If you are experiencing an active infection, you may expect to see higher than normal levels of white blood cells which our body produces to help us fight infections.  An Animal Cell Tissue Level Tissue is a group of similar cells with a similar purpose working together to fulfil that purpose. An example is if we have lots of heart muscle cells which are built to contract and they come together and work cooperatively, this forms cardiac muscle tissue. There are four types of primary tissues: 1. Epithelial tissue 2. Connective tissue 3. Muscle tissue 4. Neural tissue The cells are arranged differently in each of those tissue types and this is related to the function of these tissue types. For example, Neural tissue is focused on communications, so these cells have a cell body and then they have got long processes going off them. That means these long processes can connect to another cell or another tissue in another part of the body or a little bit further away. If we get two or more tissues working together with a common purpose, this is where an organ is formed. An example is the Heart – The purpose is to pump blood around your body. There will be cardiac muscle cells in the heart but also Connective and Nervous tissue which is controlling things like heart rate and the force of which your heart can pump blood. Each of the organs are made up of different combinations of those four tissue types, some more and some less depending on what you are looking at. The brain is made up predominantly of neural tissue because there is a lot of nerves there.Some organs do more than one job, like skeletal muscle which is important for movement and thermoregulation. Other organs are more specific.  Organ systems We also need organs systems to fulfil functions on a whole body level. In terms of the heart, the heart is a great pump but cannot move blood around our body unless you have a set of tubes for it to move through (the blood vessels). Some of the organ systems may have more than one role, while others may be specific. The functions of the organs are to Control/direct, cool and warm, Digest, Move, Protect, Remove, Reproduce, Store, Support and transport. The Orgamism The entire human body is an organism. All of the 11 organ systems have been placed in essentially a skin sack and all work together to keep us alive.  The Body Cavities The Body Cavities are space that enclose internal organs. The organs are suspended within these body cavities, preventing movement. Our body cavities are separated by bones, muscles, ligaments and membranes. They function to protect, seperate and support our internal organs. The Trunk There are two major body cavities in our trunk. The Thoracic Cavity and the Abdominal-Pelvic Cavity. These two cavities are separated by an important skeletal muscle, the Diaphragm. Different organs are located in different cavities. You would expect to find the lungs in the Thoracic cavity and the majority of your gastrointestinal tract within your abdominal cavity. The functions of Body Cavities Body Cavities are closed sacks and are fully enclosed. They have fluid inside that is produced by a membrane tissue that surrounds them. This fluid and other packing tissues protect the organs from shocks and impacts. The second function of body cavities is to allow movement. When are organs are functioning, they often change in shape or size. The Lungs expand when breathing in air, and deflate when they exhale. The organs being suspended in body cavities means that they can change shape and move without impeding the function of any nearby organs. The Body Cavities  Anatomical Positioning What is the Anatomical Position and Why is it important? The Anatomical Position involves a person standing erect, Head level and eyes facing forward. The hands are at side and palms forward (anteriorly). The legs are parallel with feet flat on the floor. It is important as descriptions of any region or part of the human body assume that it is in a standard position of reference. The anatomical position provides a common world-wide reference point for describing the location of body parts and regions. Anatomical Planes and Sections Median (Median Sagittal) Plane - The vertical place passing longitudinally through the centre of the body, dividing it into left and right halves. Sagittal Plane - The vertical planes passing through the body parallel (side by side) to the median plane. (It is helpful to give a point of reference to indicate the position of a specific plane. I.e. A Sagittal plane through the midpoint of the clavicle. Paramedian Plane - A plane parallel to and near the median plane. Frontal (Coronal) Plane - Vertical planes passing through the body at right angles to the median plane, dividing it into front (anterior) and back (posterior). Transverse plane - Are planes passing through the body at right angles to the median and frontal planes. A transverse plane divides the body into superior (upper) and inferior (lower). It can also be referred to as transaxial or axial planes. Oblique Planes or Sections - Are planes or sections that do not align with any of the above planes (passing through the body or organ at any angle other than a 90 degree angle). Terms that can be combined to describe anatomical position Inferiomedial - means nearer to the feet and closer to the median plane. I.e. The anterior parts of the ribs run inferiomedially. Superiolateral - means nearer to the head and further from the median plane.  Terms of Laterality Bilateral - Are paired structures that have right or left members. (The Kidneys or Lungs) Unilateral - Structures occurring on only one side. (The Spleen) Ipsilateral - Means occurring on the same side of the body. (Right thumb and right thigh) Contralateral - Means occurring on the opposite side of the body (Right Hand and Left Hand) Terms of Relationship or Comparison Superficial - Near, towards or on the surface of the body (The ribs are superficial to the lungs) Intermediate - Between a superficial and deep structure (The bicep muscle is intermediate to the skin and the humerus) Deep - Far away from the surface of the body (The ribs are deep to the skin of the chest and back) Medial - Nearer to the midline/median plane (The ulnar is medial to the radius) Lateral - Farther from the midline/median plane (The lungs are lateral to the heart) Posterior/dorsal - Nearer to or at the back of the body (The heel is the posterior to the toes) Anterior - Nearer to or at the front of the body (The toes are anterior to the ankle) Inferior/Caudal- Nearer to feet, away from the head or a lower part of the structure (The stomach is inferior to the lungs) Superior/Cranial/Cephalic - Nearer or towards the head, or the upper part of a structure (The heart is superior to the liver) Proximal - Nearer to the attachment of a limb to trunk, nearer to the origination of a structure (The elbow is is proximal to the wrist) Distal - Farther from the attachment of a limb to the trunk, farther from the origination of a structure (The wrist is distal to the elbow) For the Hand - Palmar - Anterior hand (Palm) Dorsum - Superior foot surface (Dorsum) For the Foot - Plantar - Inferior foot surface (Sole) Dorsum - Superior foot surface (Dorsum) Dorsum refers to the superior or dorsal (back) surface of any part that protrudes anteriorly from the body such as the Dorsum of the foot, hand, penis or tongue.  Identifying Regions of the Body Posterior: Anterior: Calcaneal Perineal Abdominal Orbital Cephalic Plantar Acromial Palmar Gluteal Popiteal Antecubital Patellar Lumbar Sacral Axillary Pedal Occipital Scapular Cervical Pubic Olecranal Vertebral Coxal Digital Types of Movement Flexion - the motion tat reduces the angle between body parts (Flexion goes forward, an anterior motion) Extension - the motion that increases the angle between body parts (Extension goes backwards - posterior motion) Dorsiflexion - the action of raising the foot upward towards the shin Plantarflexion - the action of the foot in a downward motion away from the body (standing on tippy toes) Eversion - the act of turning inside out/rotated outwards (big toe rotates closer to the ground) Inversion - involves the sole of the feet moving inwards towards the midline of the body Supination - rotation of the hand so that the palm paces forwards or upwards Pronation - rotation of the hand so that the palm faces backwards or downwards Abduction - movement away from the midline Adduction - movement towards the midline (brings the limb closer to the midline) Elevation - movement in a superior direction (Shrugging the shoulders) Depression - movement in an inferior direction Circumduction - the movement of the limb, hand or fingers in a circular pattern using the sequential combination of Flexion, adduction, extension and abduction movements. Protraction - Placement that results in a baritone of the body being moved forward on a plane parallel to the ground. Retraction - Movement that results in the protracted part of the body being moved on a parallel plane back to the original position Retrusion - A movement going in a posterior or backwards direction. (Putting tongue back in mouth) Protrusion - A movement going straight ahead of forward (the jaw moving forward) Opposition - Thumb movement that brings the tip of the thumb in contact with the tip of the finger. Reposition - Restoring an object to a natural position (the thumb moves away from the finger tip) Lateral Bending - Involves bending any part of the body sideways Rotation - Where the limb or head moves in a circular movement around a fixed joint towards or away from the median plane Medial Rotation - Rotational movement towards the mid line (internal rotation)  Chemistry All substances are made of tiny particles called atoms. An element is a substance that is made of only one type of atom. The atoms of any element are different to the atoms of any other element. So nitrogen is made from a different type of atom to sodium, and carbon atoms are different to oxygen atoms. There are about 100 different elements. These are shown in the periodic table, which is a chart with all the elements arranged in a particular way. Each element has its own name and chemical symbol. Elements have their own characteristic physical and chemical properties. The horizontal rows in the periodic table are called periods and the vertical columns are called groups. The elements in a group have similar properties to each other, for example Group 0 (the column on the far right of the periodic table) are known as the noble gases, these elements include Helium (He), Neon (Ne) and Argon (Ar), they are all unreactive gases.The periodic table is divided into non-metals and metals. The atoms of each element are represented by a chemical symbol. This usually consists of one or two different letters, but sometimes three letters are used for newly discovered elements. For example, N represents a Nitrogen atom, and Na represents a sodium atom. The first letter in a chemical symbol is always an UPPERCASE letter, and the other letters are always lowercase. So, the symbol for a sodium atom is Na and not na, NA or nA.  Atomic Structure As shown in the diagram below, an atom has a small central nucleus made up of smaller sub-atomic particles called protons and neutrons. The nucleus is surrounded by even smaller sub-atomic particles called electrons. Protons and electrons have an electrical charge. Both have the same size of electrical charge, but the proton is positive and the electron negative. Neutrons are neutral. The number of electrons in an atom is equal to the number of protons in its nucleus. This means atoms are neutral with overall electrical charge. Each box in the periodic table provides the chemical symbol for an element, its atomic number and its mass number. You can use this information to calculate the number of each subatomic particle in an atom (i.e. you can work out how many protons, neutrons and electrons are in each atom of the element). Looking at the diagram below showing one box from a periodic table you can see that the symbol for a germanium atom is Ge.The atomic number tells you that the germanium atom has 32 protons in the nucleus. It will also have 32 electrons, because the number of protons and electrons in an atom is the same. The atomic mass number tells you that the total number of protons and neutrons in the germanium atom is 74. You can work out the number of neutrons from the mass number and atomic number. In this example, it is 74 – 32 = 42 neutrons. The body and Elements Electronic Structure Four elements constitute about 96% of the The electrons in an atom are arranged in energy levels, body’s mass; hence oxygen, carbon, hydrogen, these are also called shells or orbits. Each electron in an and nitrogen are termed the major elements. A atom is found in a particular shell. The innermost shell further eight elements (the lesser elements; (lowest energy level) fills with electrons first. Each shell can calcium, phosphorus, potassium, sulphur, only hold a certain number of electrons before it becomes sodium, chlorine, magnesium, and iron) full. The first shell can hold a maximum of two electrons, the contribute about 3.6% of your body mass. The other shells are able to hold up to a maximum of 8 remainder of your body’s mass is made up of 14 electrons (only true for the first 20 elements). The outermost trace elements. Although very small amounts of shell is also known as the valence shell and electrons that trace elements are present in your body, they occupy the outermost shell are also known as valence often have very important functions in the body. electrons. Valence electrons are the electrons of an atom For example, iodine is needed to make thyroid that can participate in the formation of chemical bonds with hormones, that control metabolism, energy other atoms (see Chemical Reactions for more utilisation and growth. information).  Electronic Structure The electrons in an atom are arranged in energy levels, these are also called shells or orbits. Each electron in an atom is found in a particular shell. The innermost shell (lowest energy level) fills with electrons first. Each shell can only hold a certain number of electrons before it becomes full. The first shell can hold a maximum of two electrons, the other shells are able to hold up to a maximum of 8 electrons (only true for the first 20 elements). The outermost shell is also known as the valence shell and electrons that occupy the outermost shell are also known as valence electrons. Valence electrons are the electrons of an atom that can participate in the formation of chemical bonds with other atoms (see Chemical Reactions for more information). Writing an Electronic Structure The electronic structure of an atom is written using numbers to represent the electrons in each energy level. For example, for sodium the electronic structure is 2,8,1 – showing that there are: 2 electrons in the first energy level, 8 electrons in the second energy level, 1 electron in the third energy level. You can work out the electronic structure of an atom from its atomic number or its position in the periodic table. The number of occupied shells is the same as the period number (row in the table) and the number of electrons in the outermost shell (valence shell) is the same as the group number (column in the table). Drawing an Electronic Structure The electronic structure of an atom can be represented in a simple diagram with circles drawn around a central nucleus representing the shells and crosses or dots added to each circle to represent the electrons occupying each shell. Select an element in the periodic table, work out which period (row) it is in, and draw that number of circles around the nucleus then work out which group the element is in and draw that number of electrons in the outer circle – with eight for Group 0 elements (except helium). Fill the other circles with as many electrons as needed, two in the first circle, and eight in the second and third circles. Finally, check that the number of electrons is the same as the atomic number. Summary: Atoms are the building blocks of all matter. They consist of three sub-atomic particles: protons, neutrons and electrons. Protons and neutrons are found in the nucleus of an atom. Protons have a positive charge, neutrons have no charge. Electrons are found in energy levels called shells or orbits around the nucleus. Electrons have a negative charge. The charge on the proton and electron are the same size; because they have opposite charges they attract each other. Chemical reactions involve the rearrangement of electrons in the outermost shell. An element is a substance made up of atoms with the same number of protons. Elements are the simplest substances known. They can be metals or non-metals. The periodic table shows elements arranged by their atomic number. The atomic number of an atom tells us how many protons it has in the nucleus. Each element has its own name and chemical symbol, characteristic physical and chemical properties. Elements with similar properties are found in the same column of the periodic table. Molecules, Compounds and Ions A molecule is the general term used to describe two or more atoms joined together by chemical bonds. The molecule may be an element (a pure substance made up of only one type of atom) e.g. oxygen gas (O2) or a compound. Compounds are formed when atoms from two or more different elements react together and are bonded together e.g. water (H2O) or carbon dioxide (CO2). Compounds usually have different properties from the elements they contain. Some atoms are unlikely to react with other atoms, they exist as single atoms. These are the Noble Gases, which include helium, neon and argon, their atoms have a very stable electron structure because their outer shell (valence shell) is full. All other atoms react and bond together to become more stable, i.e. they try to create a full outer shell by gaining, losing or sharing electrons. The bonds that form between atoms usually involve only the electrons in the outer shell, the valence electrons. There are two main types of chemical bond that hold atoms together: covalent and ionic bonds. Ionic Bonds Atoms can gain or lose electrons from their outer shell (valence shell) in chemical reactions. When they do this they form charged particles called ions. When atoms lose electrons they form positively charged ions known as cations. When atoms gain electrons to form negatively charged ions known as anions. Remember that electrons carry a negative charge and protons (in the nucleus) carry a positive charge. The diagram below shows that when an atom loses (or donates) an electron it becomes a positively charged and when an atom gains (or accepts) an eletron it becomes a negatively charged. When sodium loses one electron it is losing one negative charge. The sodium atom then has 10 negatively charged electrons and 11 positively charged protons so overall it has a net charge of 1+, this is written as Na+. When a chlorine atom gains an electron it is gaining one negative charge. The chlorine atom then has 18 negatively charged electrons and 17 positively charged protons so overall it has a net charge of 1-, this is written as Cl-. An ionic bond is formed by one atom transferring electrons to another atom to form charged particles called ions. Oppositely charged ions attract each other, this force of attraction creates the ionic bond. For example positively charged sodium ions are attracted to negatively charged chloride ions, these ions bond together and form sodium chloride. Covalent Bond A covalent bond forms when two atoms share a pair of valence electrons. Hydrogen gas (H2) forms the simplest covalent bond - a molecule is formed by two individual hydrogen atoms joining together by sharing their single valence electron  Chemical Equations A chemical equation represents the total chemical change that occurs in a chemical reaction using words or symbols for the substances involved. Reactants are the substances that are changed and products are the substances that are produced in a chemical reaction. For example, sodium and chlorine react together to form a compound called sodium chloride, in this example the reactants are sodium and chlorine and the product is sodium chloride, the word equation for this reaction would be written as shown below, Individual substances are separated by a plus sign, an arrow between the reactants and the products represents the reaction. Sodium + Chlorine → Sodium Chloride The chemical formula of a compound tells you how many atoms of each element the molecule contains. The table below shows the formula of some common compounds, with the number of atoms of each element in the molecule compound compound sodium hydrogen carbon sulphur oxyge name formula atoms atoms atoms atoms n atoms carbon CO 1 1 monoxide carbon CO2 1 2 dioxide water H 2O 2 1 sulphur SO2 1 2 dioxide sulphuric H2SO4 2 1 4 acid sodium NaCO3 1 1 3 carbonate This diagram below shows that one carbon atom and two oxygen atoms combine to make up the units of carbon dioxide. Its chemical formula is written as CO2. Sometimes you see more complex formulae such as Na2SO4 and C6H12O6: a unit of Na2SO4 (sodium sulphate) contains two sodium atoms, one sulphur atom and four oxygen atoms joined together a unit of C6H12O6 (glucose) contains six carbon atoms, twelve hydrogen atoms and six oxygen atoms  Organic Compounds The term organic compound comes from the fact that most of the original organic compounds studied by scientists came from living things, however now we are able to make some organic compounds in the laboratory. Organic compounds can be recognised from their formulae - they all contain the elements carbon and hydrogen. Examples of organic compounds are carbohydrates, lipids and proteins and nucleic acids. These may be classified as (a) small biological molecules and (b) large biological molecules and polymers. Proteins are organic compounds that contain the elements nitrogen and oxygen as well as carbon, hydrogen. Proteins are often considered to be the central compound necessary for life. There are many types of proteins, but they are all made from smaller units called amino acids. Proteins vary in length, complexity and shape is based on the number and type of amino acids they are built from. The specific shape of a protein determines its function, if the shape of a protein is altered it will not perform its function as expected (see Enzymes review). The diagram below shows the structure of one type of amino acid: Inorganic Compounds These are compounds that are not made by living things. They usually do not contain the element carbon but there are a few exceptions (e.g. carbon dioxide and carbon monoxide). Other examples of inorganic compounds are water (which exists as molecules) and salts (which contain ions such as potassium, calcium and chloride). Summary: Elements form compounds in chemical reactions. Atoms of elements combine in certain fixed ratios. The ratios are determined by the combining power of atoms. Each compound has its own: name, formula, characteristic physical properties and chemical properties. Atoms are held together in compounds by chemical bonds. In the formation of an ionic bond electrons are transferred between atoms, leaving some with fewer electrons and others with more electrons, these are ions. Positively charged ions are called cations and negatively charged ions are called anions. Cations and anions are attracted to one other because of their opposite charges, this force is called an ionic bond. In the formation of a covalent bond electrons are shared between atoms. They are always shared in pairs, so a covalent bond may consist of two, four or six electrons being shared. The compounds that make up living organisms fall into two types: organic and inorganic compounds. Organic compounds can be recognised from their formulae - they all contain the elements carbon (C) and hydrogen (H).  The PH Scale This is a scale from 0 – 14. The pH scale measures hydrogen ion (H+) concentration of a substance and therefore how acidic or basic/alkaline a substance is. It ranges from 0 (strongest acid) to 14 strongest base), a pH of 7 is neutral. An indicator is a chemical that changes colour when in contact with an acid or a base. Acids Acids have a pH lower than 7 (1 to 6), the lower the number the stronger the acid. Acidic solutions turn blue litmus paper red and turn universal indicator paper red if they are strongly acidic, and orange or yellow if they are weakly acidic. Acids are corrosive when they are strong, examples of strong acids include battery acid and hydrochloric acid which is found in the stomach. Weak acids are an irritant, examples of weak acids include tomato juice and black coffee. When acids dissolve in water they produce aqueous hydrogen ions (H+) Bases and Alkalis Neutral Solutions Substances that can react with acids and Neutral solutions have a pH of 7. They do not change neutralise them are called bases. Bases that the colour of litmus paper, but they turn universal dissolve in water Z are called alkalis. indicator paper green. Distilled water is an example of a neutral substance. Alkaline solutions have a pH greater than 7 (8 to 14). The higher the number the stronger the alkali. When the H+ ions from an acid react with the OH– Alkaline solutions turn red litmus paper blue and ions from an alkali, a neutralisation reaction occurs turn universal indicator paper dark blue or purple if to form water. they are strongly alkaline (e.g. bleach), and blue- green if they are weakly alkaline (e.g. Sea water). When alkalis dissolve in water they produce aqueous hydroxide ions (OH–) Acid-Base balance in the human body Cellular processes are generally restricted to the middle of the pH scale between pH6 and 8. A change in pH can cause proteins in the body to denature and alter the function of enzyme activity, it can alter hormone action and disrupt cell and tissue function. Therefore it is important to maintain acid-base balance in the body. The body has a buffer system to help neutralize the blood if excess hydrogen or hydroxide ions are produced. Buffers help to keep the pH in the normal range by combining with the excess hydrogen or hydroxide ions. The most common buffers in the body are bicarbonate (HCO3-) and carbonic acid (H2CO3). Bicarbonate is produced by the kidneys and released into the bloodstream. It can combine with excess hydrogen ions to keep the pH of the blood in the normal range. When bicarbonate combines with excess hydrogen ions, it forms carbonic acid, which keeps the pH of the blood from going too low. However, if the pH of the blood gets too high, carbonic acid breaks apart to release some hydrogen ions, which brings the pH back into balance. What you need to know about pH: The pH scale measures hydrogen ion (H+) concentration of a substance and therefore how acidic or basic/alkaline a substance is. Acids have a pH lower than 7, the lower the number the stronger the acid. When acids dissolve in water they produce hydrogen ions (H+). When bases are dissolved in water they are known as alkalis, they produce hydroxide ions (OH–). Alkalis have a pH greater than 7, the higher the number the stronger the alkali. Substances with a pH of exactly 7 are neutral. Cellular processes are generally restricted to the middle of the pH scale between pH6 and 8.  Cells, Membranes and Tissues Combinations of many chemicals form our cells. Cells are the basic structural and functional units of the body. Each cell has a specific task and works with many other cells to help our body maintain homeostasis. A cell can be divided into three main parts: plasma (cell) membrane, cytoplasm, and nucleus. Organelles within the cytoplasm have specific functions related to cell structure, growth, maintenance, and metabolism. There are two different categories of cells; Eukaryotic cells (they have organelles including the nucleus and are more advanced cells which are those found in plants and animals) and Prokaryotic cells (they don’t have a nucleus or membrane closed organelles - they have genetic material that is not contained within a nucleus. They are always one-celled or unicellular organisms like bacteria). The Organelles and their Functions: Organelle means ‘little organ’ and are the specialised parts of the cell which have unique jobs to perform. Nucleus - The control centre of the cell. Contains DNA (genetic material) that dictates what the cell is going to do and how it is going to do it. Chromatin is the tangled form of DNA found inside the nuclear membrane. When the DNA is ready to divide, DNA condenses into structures called Chromosomes. The nucleus also contains a Nucleolus which is a structure where Ribsomes are made. The nucleus is the control centre of the cell, housing most of a cell's DNA. The nucleus contains the instructions (DNA) needed to build nearly all the body's proteins. It decides the types and amounts of proteins to be synthesised (made) at any one time in response to signals acting on the cell. Most cells are uninucleated i.e. have one nucleus. Some cells are multinucleate i.e. have more than one nucleus e.g. skeletal muscle. Some cells are anucleated i.e. have no nucleus e.g. mature red blood cells. Anucleated cells cannot make proteins or reproduce. Ribosomes - After the Ribosomes leave the Nucleus, they have the job of synthesising Proteins. Outside the Nucleus, the Ribosomes and the rest of the Organelles float around in the Cytoplasm. Ribosomes may move freely or attach to the endoplasmic reticulum. Ribosomes are the site of protein synthesis (production). Free ribosomes float freely in the cytosol. They make soluble proteins that function in the cytosol. Membrane-bound ribosomes are attached to membranes forming the rough endoplasmic reticulum. They make proteins destined for incorporation into cell membranes or lysosomes, or exportation from the cell. Rough Endoplasmic Reticulum - has ribosomes attached to it. The rough endoplasmic reticulum (RER) is an extensive membrane network of interconnected tubes and parallel sacs, with ribosomes (the site of protein synthesis) attached to the external surface. The RER is continuous with the outer nuclear membrane. The RER modifies and transports proteins. Cells that secrete proteins like liver cells (produce most blood proteins), and B-cells (produce antibodies) have lots of RER. Smooth Endoplasmic Reticulum - does not have Ribosomes attached to it. The Endoplasmic Reticulum - is a membrane closed passageway for transporting materials such as proteins synthesised by the ribosomes. Proteins and other materials emerge form the Endoplasmic reticulum in some Vesicles. The Golgi Apparatus (Golgi Body) - Receives the vesicles from the ER. As proteins move through the Golgi body, they are customised into forms that the cell can use. The Golgi body does this by folding the proteins into useable shapes or adding things on to them such as Lipids or carbohydrates.  Vacuoles - Are sac like structures that store different materials. In the plant cell, the Central Vacuoles stores water. Lysosomes - Are like the garbage collectors - they take in damaged or worn out cell parts. They contain enzymes that break down the cellular debris. Plasma Membrane - The plasma membrane provides a physical barrier that separates the intracellular fluid within the cell from the extracellular fluid outside the cell. The plasma (aka cell) membrane is selectively permeable; controlling movement across the membrane i.e., it controls the entry of ions and nutrients and the elimination of wastes. Receptors (specialised proteins) in the cell membrane allow the cells to recognise each other and respond to specific molecules. Mitochondria - Mitochondria are the 'powerhouses' of cells, generating most of its ATP. Active cells like sperm, kidney and liver cells have hundreds of mitochondria. Inactive cells like fat cells have few. Mitochondria contain two membranes and contain their own DNA, RNA and ribosomes and are able to reproduce themselves. - During a process called cellular respiration, the mitochondria make ATP molecules that provide the energy for all the cells activities. Cells that need more energy have more Mitochondria. Cytoplasm - The cytoplasm is the jelly like substance. The cytoplasm is the cellular material between the plasma membrane and the nucleus. The site of most cellular activity. The cytoplasm has two components: (1) Cytosol, which is also known as intracellular fluid. The cytosol contains water, dissolved solutes, and suspended particles. (2) Organelles (each of which have their own specific structure and function). Cytoskeleton - Is how the cell maintains its shape. It includes threadlike microfilaments that are made of protein and Microtubules which are thin, hollow tubes. Some cells that are Photoautotrophic meaning they capture sunlight for energy like plants, have organelles called the Chloroplast. This is where photosynthesis happens. It is green because it has a green ligament, Chlorophyll. Plant cells also have a cell wall outside of their cell membrane that shape, support and protect the plant cells. Animal cells never have a cell wall. The Plasma Membrane Functions: A physical barrier that maintains the composition/seperation of Intercellular fluid and Extracellular fluid from outside cells. Determines movement of substances into and out of cells Communicates with other cells and organs (receptors) Links adjacent cells Structural Features: Phospholipids bilayer with embedded proteins Selective Permeability: Hydrophilic phosphate heads (outside) Due to the structure of the membrane Hydrophobic lipid tails (inside) -> Lipid bilayer Proteins (peripheral or integral) It lets some substances in/out of the Channels, gates, or pumps cell, but stops others Carrier proteins Distinction based on Receptors Solubility Anchoring proteins Size Charge Plasma Membrane Lecture Notes: The plasma membrane is a physical barrier that separates the intracellular fluid within cells from the extra cellular fluids outside cells. Conditions inside and outside the cell are very different. Those differences maintain homeostasis cells are not self sufficient. Each day they require nutrients to provide energy to stay alive and function. They also generate waste products that must be removed. The plasma membrane acts as a gatekeeper, controlling the entry of eyes and nutrients. drug. In early clinical trials for cancer, embeds pause into the plasma membrane of only cancer cells. This results in free movement across the plasma membrane, disrupting homeostasis, and the cancer cells die while the non cancer cells survive. Maintaining homeostasis is vital for a cell and organism survival. The plasma membrane contains receptors that allow the sale to recognise and respond to specific molecules in its environment, and specialist connections between cells of the plasma membrane or between The plasma membrane is a phosphor lipid bi-layer with embedded proteins. The phosphate lipids form the basic structure of the membrane in each half of the bi-layer. The phosphor lipids lie with their hydrophilic, water loving prostate heads at the membrane surface and the water hating or hydrophobic lipid tails on the inside. In this arrangement, the hydrophilic phosphate heads of the two layers are in contact with the Aquarius environment on both sides of the membrane, so the extra cellular fluid on the outside of the cell and the intracellular fluid oth sides of the membrane, so the extra cellular fluid on the outside of the cell and the intracellular fluid on the inside of the cell. Some substances cannot cross the lipid portion of the plasma membrane because the lipid tails are hydrophobic and will not associate with water molecules. Cholesterol stiffens the membrane and further decreases water soy ability of the membrane proteins in the membrane determine what functions the membrane can perform. Integral proteins span the plasma membrane. If removed, the plasma membrane will be destroyed. Some integral proteins are involved in transport and form channels. Small water soluble molecules or charged irons can move through these channels, bypassing the hydrophobic tails. Other integral proteins act as carriers that bind a substance and then move it through the membrane. Others act as receptors for chemical messengers. and relay messages to the cell interior. Peripheral proteins are not embedded in the lipid bi-layer. They are bound to the inner or outer surface of the membrane, like a post it note. They can't be separated from the plasma membrane. Peripheral proteins, maybe enzymes or filaments that helps support the membrane from its, um, cytoplasmic side. Others are motor proteins involved in mechanical functions, carbohydrates, actors, identity molecules allowing sale recognition. They can be attached to proteins forming a glycoprotein, although maybe attached to a lipid forming ag like a lipid. If a membrane was impermeable, nothing could cross. If freely permeable, anything can cross. Plasma membranes are selectively permeable due to the lipid bi-layer, and it will permit the passage of some molecules and restrict the passage of other molecules. The distinction can be based on soy ability, size and charge. The more lipid soluble, the more easily it can cross. The smaller the molecule, the more easily it can diffuse across molecules that are not sufficiently small or lipid soluble or, if they're charged, may still be able to diffuse across, but only if they are assisted by a carrier protein or a channel. But they cannot passively crossed through that lipid portion of bilayer.  Tissues Tissues are a group of cells that are similar in structure and perform a related function. Each tissue in one word: Epithelium - covers Connective - supports Muscle - moves Nervous - controls Epithelium Tissue Epithelium tissues cover exposed surfaces, Lines, internal passageways and chambers, and form glands. Epithelium forms boundaries between different environments and nearly all substances entering or leaving the body must pass through an epithelium. In its role as a boundary forming tissue, it provides physical protection from abrasion, dehydration, chemical or biological agents. It functions in absorption (I.e. oxygen entering the body must cross the epithelium of the alveoli in the lungs). It functions in filtration (I,e, waste cross the epithelium of the nephron in the kidney to enter the urine which is then excreted out of the body. It also secretes molecules or solutions such as enzymes, buffers and mucus. Epithelial cells that produce secretions either discharge them onto the surface of the epithelium or release them into the surrounding Interstitial fluid or blood. Epithelial cells are classed by their shape and size. Squamous cells are flat and scale like. Cuboidal cells are roughly as tall as they are wide, box like. Columnar cells are tall and column shaped. Simple consists of a single layer of cells. Stratified consists of two or more layers of cells. Pseudo means false, stratified means many, so psuedostratified means false many layers or one layer of cells. But this single layer of cells has cells that are uneven in size resulting in the appearance of many layers. Naming of epithelium tissue is in two parts; the number of layers and the shape. An example is simple squamous epithelium. A single layer of flat or Squamish cells are going to function in transport and in movement (I.e. simple squamous epithelium of the alveoli in the lungs allows for diffusion of oxygen and carbon dioxide. Multiple layers with the stratified epithelium are involved in protection (I.e. satisfied squamous Examples of Epithelium tissue include the lining of the GI tract epithelium of the skin). organs and other hollow organs, or the surface of the Skin (The Epidermis).  Connective Tissue Connective tissue has many functions, including establishing a structural framework for the body, transporting fluids and solve materials, supporting, surrounding and interconnecting other types of tissues, storing energy and protecting delicate organs, or defending them from invading microorganisms, Connective tissue is classified according to its physical properties. Examples include your areola, connective tissue, fat, tendons and ligaments, blood and lymph fluid, connective tissues, cartilage and bone supporting connective tissue. While connective tissues varies widely in appearance and function, all except fluid connective tissue share three basic components. These three components are specialised cells, extracellular protein fibres and a fluid known as ground substance. Muscle Tissue Muscle Tissue is specialist for contraction. To facilitate movement helps maintain joint stabilty, provide structural control and produces heat. There are three types of muscle - Skeletal muscle is attached to bone and it contracts to move the body. Smooth muscle forms the walls of hollow organs and it contracts to move substances or objects along internal passageways (I.e. Food) Cardiac muscle forms the walls of the heart, and contracts to pump blood into the circulation. Nervous Tissue Nervous tissue is the main component of the central nervous system which regulates and controls body functions. Neural tissue contains two basic cells; Glia and Neuronss. Neurons are specialist cells that generate and conduct electrical impulses from one region of the body to another neuron. Glia support and repair neural tissue and supply nutrients to neurons. Most neurons cannot divide under normal circumstances to they have a limited ability to repair themselves after injury. Membranes Membranes are physical barriers that lie in parts of the body. The Mucus, Cutaneous and Serous membranes are composed of at least two primary tissue types and epithelium bound to an underlying layer of connective tissue. The Cutaneous membrane is your skin, which covers the entire surface of your body. It is organ system consisting of the epidermis which is a superior layer of epithelium that is firmly attached to the dermis, a deeper, thick layer of connective tissue. The cutaneous membrane is exposed to air and it is a dry membrane. It has many structural and functional features. Mucous membranes line all body cavities that open to the outside of the body such as hollow organs of the digestive, respiratory and Urogenetial tract. The mucous membranes are moist membranes with varying types of epithelial tissue lying directly over a layer of connective tissue. Mucous membranes are adapted for absorption and secretion and has specialist cells in the epithelial layer that produce mucous, which prevents the cavity from drying out. It also helps tract particles and microbes. The connective tissue layer supports the epithelium and also helps bind it to the underlying structures. Serous membranes line organs that within cavities that do not open directly to the exterior. Serous membranes have a visceral layer which covers the organ and a parietal layer that lines the cavity. These layers are separated by a lubricating serous fluid. Each layer consists of an epithelium resting on a thin layer of connective tissue. The pleura is a serous membrane that lines the thoracic wall and covers the lungs, and the pericardium encloses the heart. The Synovial membranes lines the cavities of freely moveable joints. Unlike the other membranes, it lacks an epithelium and only consists of connective tissues and cells which secrete synovial fluid.  Diffusion and Osmosis The plasma membrane is selectively permeable, it allows the passage of some ions or molecules but restricts the passage of others. This distinction is based on: Size and shape – larger molecules cannot directly cross through the phospholipid bilayer. Electrical change – changed molecules cannot directly cross through the phospholipid bilayer. Lipid solubility – water soluble molecules cannot directly cross through the phospholipid bilayer. Passage across the membrane is either: Passive – it results from the random motion and collisions of ions and molecules (kinetic energy). Active – energy expenditure, generally in the form of ATP, is required. Membrane Transport The Phospholipid bilayer separates the environment inside the cell from outside the cell. There is constant exchange across the membrane due to the removal of waste and the need for nutrients. These membranes are selectively permeable, so some things can cross but not everything can. Lipid Soluble and small and uncharged molecules: An example of something that is lipid, soluble, small and uncharged is a fatty acid or a steroid. There will be more of these lipid, soluble, small and uncharged molecules in the extra cellular fluid than there will be in the intracellular fluid so there is a gradient. Molecules if they’re moving through simple diffusion or passive diffusion will move down a concentration gradient, meaning they’re going to move from an area of high concentration to an area of low concentration. Any molecule that is water soluble, charged or large, cannot passively cross the membrane, it will need a channel or carrier protein (I.e. Amino Acid). It is going to move from an area of high concentration to an area of low concentration but will do it via a protein channel, which is called facilitated diffusion. Water also crosses the membrane through a channel called Aquaprorin which are intergalactic membrane proteins that function as water channels or by moving through neighbouring phospholipid molecules in the lipid bilayer via simple diffusion. Osmosis is a type of diffusion where water moves across a semi-permeable plasma membranes from an area of low solute concentration to an area of high solute concentration. Osmosis only occurs when a membrane is permeable to water but not permeable to certain solutions. Anything that is high in water and low in solute is hypotonic. Tonicity is the molecules in side of fluid, so the higher the concentration of molecules, the higher the Tonicity. The lower the concentration of molecules, the lower the Tonicity. Anything that is high in solvent and low in water is hypertonic. Active Transport is the movement from an area of low concentration to an area of high concentration (It is going against a concentration gradient). Because it is going against the concentration gradient, it cannot move via a passive process, it needs to move via an active process which means it needs ATP and to move through a membrane channel. Membrane transport is categorised according to the mechanism involved: Simple diffusion – the movement of a molecule directly through the phospholipid bilayer from an area of higher concentration to an area of lower concentration (until the concentration is the same on both sides of the membrane). Facilitated diffusion – the movement of an ion or molecule from an area of higher concentration to an area of lower concentration (until the concentration is the same on both sides of the membrane), via a channel or carrier protein. Osmosis – the movement of water molecules to an area of higher solute concentration, where the concentration of water is lower. Active transport – the movement of an ion or molecule from an area of lower concentration to an area of high concentration, via a channel or carrier protein. Diffusion rates are influenced by: Distance – the shorter the distance, the faster the diffusion. Molecular size – the smaller the molecule size, the faster the diffusion. Temperature – the higher the temperature, the faster the diffusion. Concentration gradient – the steeper the concentration gradient, the faster the diffusion. Electrical force – opposite electrical charges attract each other and like charges repel each other.  Tonicity The total solute concentration in an aqueous solution is the solutions osmolarity. Tonicity is based on how the solution affects the cell volume. Tonicity depends on the solute concentration outside the cell and solute permeability - can the solute cross the membrane? EXAMPLE USING RED BLOOD CELLS: Isotonic solutions have the same solute water concentration as inside the cells. When RBC are exposed to an isotonic solution, no osmotic flow takes place (that is the same amount of water leaving is entering, so there is no net gain of water or no net loss of water, therefore the cells retain their normal shape. The body’s extracellular fluids and most intravenous solutions are isotonic. Hypertonic solutions have a higher concentration of solutes compared to what is inside the cell. When RBC are exposed to a hypertonic solution, the cells lose water by osmosis and shrivels, which is also known as Crenation. The result is cell dehydration. Hypotonic solutions have a lower concentration of solute compared to what is inside the cell when RBC are exposed to a Hypotonic solution. The cells gain water by Osmosis and swell. Distilled water represents the most extreme example of Hypertonicity because it contains no solutes. Water will continue to enter the cell until it bursts or lies. Hemolysis is the scientific name for when a red blood cell bursts. A cell placed in an isotonic solution would experience net flow of water no net flow of water in or out of the cell A cell placed in a hypertonic solution would experience net flow of water out of the cell. A cell placed in a hypotonic solution would experience net flow of water into the cell.  Homeostasis Homeostasis is the body’s ability to maintain a stable (balanced) internal environment in the face of variable external conditions through constant interactions of the body’s many regulatory processes. In other words, homeostasis is your body’s ability to detect when something is out of balance, to process this information and to bring about changes that will restore balance. This is important because a constant state of balance (equilibrium) is required to keep us alive. Extended periods spent outside of homeostatic balances will lead to disease and eventually death if not corrected. For example, the normal levels of glucose in your blood sit somewhere between 70 – 110 mg/100 ml. This range is maintained through regulatory systems such as the interplay between insulin and glucagon. If for some reason, your body is not able maintain your blood glucose levels within this range, then you will become hypoglycaemic (not enough glucose in the blood) or hyperglycaemic (too much glucose in the blood). If not corrected, hypoglycaemia will mean that your body cells cannot receive the glucose they require to make energy and function properly, eventually leading to shut down of organs and death; think starvation. On the other hand, chronic hyperglycaemia can also lead to disease and eventually death, think diabetes mellitus. Our bodies are constantly facing homeostatic disruptions from both the internal (our cells; what’s inside them and what surrounds them) and external (outside of the body) environments and, our bodies must first be able to detect the change, then we must be able to interpret or process the change before we respond to the change. This brings us to the next topic of homeostatic control. (TLO T1D1) Our bodies maintain homeostasis through regulating systems, namely the nervous system and the endocrine system. The nervous system maintains homeostasis by sending electrical messages called nerve impulses along the nerves to organs that can act to counter the change whereas the endocrine system does this via sending out chemical messages called hormones from the glands into the blood. Because the nervous system uses electrical impulses that travel directly to the effector organ(s) via the nerves, targeted and rapid responses are achieved but are typically short in duration. The endocrine system generally brings about a slower, more widespread and long- lasting response. Both systems work to ultimately maintain homeostasis, usually via negative feedback systems. Feedback Systems A feedback system is a cycle of events in which body conditions (parameters that need to be maintained) are first monitored, and then evaluated to see if change has occurred. If a change has occurred, they’re assessed to see whether that change can be maintained or it should be changed (so whether or not a response needs to be initiated, and once that change or response has been initiated we need to reevaluate that change and see if the Homeostatic ranges poor balance has been restored). This constant monitoring, evaluating, maintaining, changing or reevaluating is why it is called a feedback loop/cycle or system. Cycle of Events: 1. Monitored 2. Evaluated 3. Maintained/Changed 4. Re-evaluated The components that make up the feedback system/loop: The controlled condition - the thing or body parameter that needs to be monitored (I.e. Body Temperature, Blood Sugar, Blood Pressure, PH) The Stimulus - Any disruption to the controlled condition, anything that changes the control condition or deviates from the set point. The Receptor - Typically a nerve ending whose job is to constantly monitor change, and when change is detected to report it to the control centre via nerve impulses or chemical signals on the Afferent pathway (towards the brain) The Control Centre - The brain sets the range (upper and lower limits of the controlled condition) and receives the information from the receptor and evaluates and interprets that information. If something needs to be done, it will send that command or output to the effector again bia nerve impulses and chemical signals on the Efferent Pathway (away from the brain). The Effector - The effector produces the result and alters the controlled condition and tries to return the body to Homeostasis (or normal). Once the response is carried out and the receptors no longer pick up that change causing them to send messages to the control centre, the control centre stops commanding and the effector stops their response.  Negative Feedback: Negative Feedback is a feedback loop in which the response opposes the initial stimulus to reverse the change (If something is going up & we want it to go back down). We always want to maintain the body condition within a homeostatic range and that is normally done by negative feedback. Most of the homeostatic mechanisms operate via negative feedback. Negative feedback is used in situations where we need to frequently adjust and this is constant adjusting. The body controlled condition is constantly monitored and if change has occurred, the response is produced. If no change has occurred, the response is not needed. Body Temperature is a classic example. Thermoregulation: Hot Day: It is a hot day, the body temp goes up a bit. This is pick up the thermoreceptors located in your skin (they detect the temperature of the skin and outside the body). They then feedback to the Hypothalamus (this is the part of your brain responsible for temperature) which acts as the control centre. The Hypothalamus receives this information and processes it, and then once it has decided what to do, it will put out that information to the effectors which are in this case, the sweat glands and blood vessels. The hypothalamus will tell the sweat glands to start produces sweet and the blood vessels to dilate a little to allow more blood to run through them and move to the surface of the skin where more heat can be released. This creates what is known as evaporative cooling, where the heat is taken away from the skin as your sweat evaporates and cools the body temperature. Then the body will return to normal temperature. The receptors will report the controlled condition, and if it still hot, the receptors will alert the hypothalamus to continue to send the effectors but if the effectors work the receptors will then pick that up and alert the hypothalamus which will stop the response. This is a negative feedback because the arrows are pointing in different directions, they are working opposite to each other. The stimulus goes up and the response is to go down. The response is ALWAYS the opposite direction to the stimulus. Regulation of Blood Calcium levels: Calcium needs to be at around 10milligrams per 100mil. If something has caused the blood calcium levels to go up, the Thyroid gland will release a hormone called Calcitonin which will act on the bones to ask them to deposit some calcium, and the kidneys as well to ask them to release some calcium into the urine. This will hopefully cause your blood calcium to go back to the normal level. If calcium levels are too low, another hormone called Parathyroid hormone (from the parathyroid gland) will tell the bones to release some calcium that was stored back into the blood. Parathyroid hormone also works on the kidneys and stimulates them to reuptake Calcium and not let it into the urine, as well as activate vitamin D which makes it possible for the gut to absorb more calcium in the diet.  Positive Feedback: In Positive Feedback, the response strengthens or enhances the stimulus to produce an even bigger response or change. In positive feedback, we want to amplify the stimulus and make the change bigger. The response works in the same direction as the stimulus. Positive feedback loops are when you want a large, rapid change. The release of Oxytocin during childbirth, during breastfeeding. When the mother is lactating and producing milk and we want to feed the baby so more milk comes - that is an example of positive feedback. Childbirth Example: The controlled stimulus is the stretching of the cervix for when the child is ready to be born. The baby’s head starts to push on the cervix which will cause a stretch. The baby’s head pushing is a stimulus. The stretch is detected by the receptors in the cervix which sends the information to the control centre. The brain responds by releasing Oxytocin which is a hormone that travels in the blood to land on target receptors. The target receptors happen to be on the Uterus’ muscle cells so oxytocin stimulates the uterine muscle cells to contract which is the effectors. When the uterus contracts, it will push the baby further down onto the cervix causing it to stretch more. The receptors will continue to feed that information to the brain which produces more oxytocin continuing the contraction. The contractions and oxytocin release will continue until the baby is born. This is the example of the stimulus starting small and then becoming bigger and bugger and more frequent because of the feedback link. Once the baby is born, the brain realises the cervix is not stretched anymore and the brain ceases the production of oxytocin. Platelet Plug Formation in blood clotting: A tear in the blood vessels will activate the circulating platelets. The platelets aggregate or congregate at the injured site. They are attracted to the injured site and they become sticky and release chemicals. Those chemicals attract more platelets to the area. So new platelets come to the area and in turn become sticky and release their chemicals which then attracts more platelets. This cycle continues until you get a big plug called the platelet plug which seals of the hole so that you don’t bleed anymore. The platelets stick together to form the platelet plug so coagulation can begin and you stop bleeding. Without positive feedback, you would continue bleeding for longer.