Name: human biology
Rating: 5 (1 reviews)

human biology - Details

Levels:

1) Chapter 1 View

Questions:

100 questions

🇬🇧		🇬🇧

Surrounds and form outer boundary of cell

Cell membrane

Cell structures that are specialised for particular function

Organelles

Thick fluid filling inside of cell and the suspended structures it contains

Cytoplasm

Liquid part of cytoplasm

Cytosol

- the internal scaffold of protein fibres within cytoplasm - the framework of protein fibres that gives the cell its shape - microtubes and microfilaments

Cytoskeleton

Chemical substance occurring as granules or liquid droplets in cytoplasm

Inclusions

- double layer: phospholipids, cholesteral and various proteins - semi-permeable membrane that allows some materials to pass

Cell structure

- separated from the cytoplasm by nuclear membrane - contains DNA, controls the type of proteins made and the chemical reactions that occur - DNA forms chromatin and chromosomes within the nucleus - largest organelle

Nucleus

- mainly composed of RNA - produces ribosomes which play a vital role in protein synthesis - both DNA and nucleolus are suspended in the nucleoplasm

Nucleolus

- small spherical organelle found free in the cytoplasm or bound to rough endoplasmic reticulum - make proteins via protein synthesis: amino acids are joined together to form proteins in a sequence determined by DNA

Ribosomes

- network of channels formed by parallel membranes - provides a surface for chemical reaction - the inner channels are for storing and transporting molecules - rough ER has ribosomes attached to the surface

Endoplasmic reticulum

- modifies proteins and packages them for secretion from the cell - proteins produce at ribosomes pass through ER to golgi body - form a vesicles to transport

Golgi body

- chemical reactions take place inside: site for cellular respiration where it produces energy (ATP) for the cell - double membrane: outer-sooth, inner-folded: increase surface area

Mitochondria

- small spheres, bound by a membrane, formed from golgi body - contains digestive enzymes that are able to break down large molecules - join with vesicles to break down material within - digest worn-out organelles

Lysosomes

- pair of cylindrial structures - plays a vital role in cell division (mitosis)

Centrioles

- moves materials past the cell or move the whole cell itself - cilia: tiny hairs, very fine and small - flagella: longer and only one or two are found

Cilia and flagella

- liquid surrounded by a membrane - acts as a storage compartment - rare in animal cells

Vacuole

- when diameter is doubled, volume is 8x bigger, surface area is 4x bigger - must be microscopic to function effectively - large cell cannot support itself as it does not have enough membrane surface to absorb all the nutrients required and remove waste

Small cells

- phospholipid bi-layer - proteins, cholesterol and other molecules are embedded in the membrane - semi-permeable: selectively permeable and only allows some substance to pass through and not other - hydrophilic head - hydrophobic tails - fatty, most water soluble substance cannot diffuse through it: exceptions include oxygen and carbon dioxide

Cell membrane

- embedded in the bi-layer - allows the movement of substances in and out of the cell - act as receptor sites for hormones - channel proteins: open channels that allow simple diffusion - carrier proteins: allow facilitated diffusion and active transport

Proteins

- physical barrier: separates cell cytoplasm form extracellular fluid - regulation of passage of materials: controls movement of materials in and out of the cells - maintains homeostasis

Functions

- passive process of movement from high to low concentration - spreads out particles so that they are evenly spread - gases and liquids

Diffusion

- diffusion of water across a permeable membrane form a region of higher water concentration to a region of lower water concentration

Osmosis

- requires special protein in membrane to carry substances across - can be active or passive - proteins in cell membrane bind to the molecule to be transported and help their passage across the membrane - are specific - become specific - activity is regulated by hormones

Carrier-mediated trransport

- active process where materials are move in membrane bound sacs - endocytosis: taking liquids and solids into cell by vesicular transport - pinocytosis: liquids - phagocytsis: solids - exocytosis: contents of a vesicle inside cell are passed to outside

Vesicular transport

- made up of cells - improve efficiency of operation - allow tasks to be shared amongst various specialised cells

Tissues

- line the internal and external surfaces - blood vessels, ducts, gut lining - protects underlying structures from wear and tear - protect from infection and pressure - cells are very closely joined together - vary in shape depending on the tissue

Epithelial tissue

- major supporting tissue of the body - tendon, bone, cartilage and ligaments - helps hold the body part together - cells are not close together - separated by each other by large amounts of materials (semi-fluid extracellular matrix) - provides support against damage, infection and heat loss

Connective tissue

- long and thin (muscle fibres) - respond to stimulus by contracting and becoming shorter - skeletal muscle: muscle joined to bones, voluntary control, striated - smooth muscle: involuntary, in the walls of stomach and intestines, not striated - cardiac muscle: heart muscle, involuntary, striated, short cells

Muscle tissue

- made of nerve cells called neurons - specialised in transmitting electro-chemical impulse - found in the brain, spinal cord and nerves

Nervous tissue

- the higher level on one side of the membrane results in a pressure

Osmotic pressure

- the state of a solution in respect of osmatic pressure

Tonicity

- low concentration of solute than inside the cell - cell will swell up and burst

Hypotonic

- the concentration of solute is same on inside of cell as it is in solution - allows free movement of water across the membrane - equal movement of water in and out of cell

Isotonic

- high concentration of solute than inside the cell - cell will shrivel up and shrink in size (crenation)

Hypertonic

- cells require nutrients to supply energy and matter synthesis - organic or inorganic

Nutrients

- small molecules and only a few atoms - may contain carbon - sodium chloride, calcium carbonate

Inorganic

- carbohydrates, proteins, lipids and vitamins - large molecules and lots of them - always contain carbon - usually contains hydrogen and oxygen

Organic

- contain carbon, hydrogen and oxygen (CHO) - twice as many hydrogen and oxygen atoms - monosaccharide: a simple sugar or single unit sugar, glucose - disaccharide: two monosaccharide molecules joined together, sucrose - polysacchraride: a large number of monosaccharides joined together, starch, glycogen, cellulose

Carbohydrates

- contain carbon, hydrogen, oxygen and nitrogen (CHON) - many also contain sulphur and phosphorus - made up of 100 or more amino acids - peptide bond: a bond between two amino acids - dipeptide: two amino acids joined by a peptide bond - polypeptide: ten or more amino acids joined by peptide bonds

Protein

- contain carbon, hydrogen and little oxygen (CHO) - each fat molecule is made up of one molecule of glycerol and one-three molecules of fatty acid - most are insoluble in water - monoglyceride: glycerol and one molecule of fatty acid - diglyceride: glycerol and two molecules of fatty acid - triglyceride: glycerol and three molecules of fatty acid

Lipids

- large molecules containing carbon, hydrogen, oxygen, nitrogen and phosphorus (CHONP) - nucleotides: the units that make up nuclei acids - DNA and RNA

Nucleic acid

- proteins that allow chemical reactions to take place at normal body temperature - without enzymes, these reactions would be too slow to be of any use to the body

Enzymes

- chemical reaction requires energy to get started - enzymes reduce the activation energy needed to begin a reaction - enzymes allow reactions to occur at a rate suited to body's requirements

Activation energy

- substrate molecules on which an enzyme acts on - enzymes are specific - each enzyme will combine with only one particular substrate - enzyme and substrate have a shape and structure that allow them to fit together - lock and key model - active site: part of the enzyme that combines with the substrate

Enzyme-substrate complex

- increase the rate of chemical reaction - by regulating type and amount of enzyme present, the body is able to control which reactions occur and what rate they proceed

Higher concentration

- increases reaction rate - there will be more substrate coming into contact with enzyme molecules - beyond a certain concentration, the increasing substrate will cease to have an effect because all enzyme molecules will be fully occupied (saturation)

Increased substrate concentration

- otherwise rate of reaction will be slow because it becomes more difficult for substrate molecules to make contact with enzyme molecules

Products are continually removed

- rate of most chemical reactions increases as temperature increases - only within a limited temperature - enzymes are proteins, beyond 40 degrees, their structure changes and they are denatured - optimum temperature is around 37 or 38 degrees

Temperature

- each enzyme has an optimal pH at which it works most effectively

PH levels

- change the shape of the active site so the enzyme can combine with substrate

Co-factors

- substrates that slow or even stop enzyme activity - inhibitors may be used by cell to control reaction so that products are produced in specific amounts - many drugs are enzyme inhibitors

Enzyme inhibitors

- the total of all chemical processes that take place in the body - convert the food you eat into energy and material needed for all life processes - can be regarded as anabolic or catabolic

Metabolism

- large molecules are broken down into smaller ones - destructive metabolic processes during which substances are broken down into simpler ones - releases energy

Catabolic

- catabolic - takes place in the cytoplasm and the mitochondria - glycolysis: breaks down one molecule of glucose into two molecules of pyruvate, yields two molecules of ATP, takes place in the cytoplasm, doesn't require oxygen - Krebs cycle: pyruvate is broken down into carbon dioxide, yields 36 molecules of ATP, requires oxygen

Cellular respiration

- doesn't require oxygen - takes place in the cytoplasm - glycolysis - requires glucose - produces lactic acid - yields 2 ATP molecules - fast process - short and intense

Anaerobic

- requires oxygen - takes place in the mitochondria - Krebs cycle - requires pyruvate - produces water and carbon dioxide - yields 36 ATP - slow process - long and low intensity

Aerobic

- adenosine triphosphate - energy from the Krebs cycle is used to convert adenosine diphosphate (ADP) to the energy-rich compound, ATP - energy is stored in cells as ATP - when a phosphate molecule is stripped from ATP, energy is released and ATP becomes ADP again

ATP

- 60-80% of the energy produced by the breakdown on ATP is heat, which maintains our body temperature - muscle contractions - active transport across cell membrane - synthesis of large molecules needed for growth and repair - transmission of nerve impulses - cell division - cellular activities such as movement of substance in the cell

Uses of energy

- the construction of complex substances from simpler ones - requires energy

Anabolic

- proteins are long chains of amino acids - instructions for the assembly of proteins is carried by DNA in the cell nucleus - ribosomes are protein construction sites

Protein synthesis

- line the endoplasmic reticulum - made of RNA and consist of a large sub-unit and small sub-unit

Ribosomes

- the smallest amount of energy that can sustain life - amount of energy needed to keep the body function at rest

Basal metabolic rate

- air enters and leaves the body through the nose - air is cleaned, filtered, warmed and moistened before entering the body - nasal secretions also contain an enzyme (lysozyme) which can kill foreign microorganisms

Nasal cavity

- have a mucous lining - epithelial lining contains goblet cells which secrete a clear stick mucus - mucus traps dirt particles and microbes before entering the lungs - epithelial cells contain cilia which are microscopic hair-like structures that beat back and forth - cilia helps move mucus along and trap the particles, also sweeps dirty mucus up the trachea and into the throat

Nasal cavity and upper airways

- epiglottis: flaps of tissue which, when swallowing, close off the trachea to prevent food and liquid from entering the lungs - larynx: a passage way for air and organ of voice, air going to and from the lungs passes through the larynx, contains vocal cords which vibrate to make sound

Upper airways

- all passage ways for air - trachea and bronchi have a smooth muscle later but they are further reinforced with C-shaped rings of cartilage - prevent the tubes from collapsing during inhalation - bronchioles have smooth muscles without cartilage - bronchioles terminate in microscopic clusters of air sacs called alveoli

Trachea, bronchi and bronchioles

- takes up most of the lung - gas exchange takes place at the alveoli - well supplied with blood capillaries increasing efficiency of gas exchange

Alveoli

- double layered: visceral and parietal pleural membranes - between the layers is a pleural cavity containing pleural fluid - membranes lubricate the surfaces: allows the layers to slide easily over each other - help keep lungs in position

Pleural membrane

- muscles are involved in contracting and relaxing during inspiration and expiration to change the volume of thoratic cavity and therefore changes the volume of the lungs

Diaphragm and intercostal muscles

- a primary role of the respiratory system - concentration gradients are required for gas exchange to occur - when air is breathed in, it is high in oxygen concentration - the blood in the capillaries around the alveoli has a low oxygen concentration - oxygen will make more via diffusion from high to low concentration - oxygen dissolves in the moisture on the inside of the alveolus and diffuses through the membrane, through the walls of the capillaries and into the blood - the blood in capillaries around the alveoli are high in carbon dioxide - carbon dioxide diffuses out of the blood and into the air in the alveolus

Gas exchange and concentration gradient

- have a very large internal surface area due to many alveoli: more surface are for gas exchange - alveolis are supplied with close blood vessels/capillaries - concentration gradients are maintained: blood is continuously moved through blood vessels , air is continuously moved in and out of lungs - alveolis are one cell thick: decrease distance for easier diffusion - thin layer of moisture in alveoli for easier gas diffusion - lungs are deep in the body to prevent excess evaportaion

Lungs and alveoli

- the process of moving air into and out of the lungs - the exchange of oxygen and carbon dioxide between lungs and air

Breathing

- transport of oxygen from the air to tissues/cells and carbon dioxide in the opposite direction

Respiration

- thoracic: the space the lungs occupy - volume and pressure changes are important in allowing ventilation to occur - increase thoracic volume decreases the pressure in lungs

Thoracic volume

- the pressure of air in the lungs is less than outside - low pressure inside is achieved by increasing the volume of lungs - the diaphragm and intercostal muscles contract - the diaphragm moves down - the rib cage moves out and up - air flows in until pressure is equal - rib cage becomes important in heavier breathing

Inspiration

- pressure of air in the lungs is greater than outside - high pressure inside is achieved by decreasing the volume of lungs - diaphragm and intercostal muscles relax - diaphragm moves up - rib cage move down and in - lung volume decreases and air is greater inside, air flows out until pressure is equal - passive process

Expiration

- internal: the exchange of oxygen and carbon dioxide between the blood and the tissues that need it - external: the movement of oxygen and carbon dioxide between the lungs and the bloodstream

Internal and external respiration

- oxygen enters the body and is delivered via blood to cells - carbon dioxide is removed from cells, delivered to the lungs via blood and is excreted

Systems

- causes mucus lining to produce excess mucus - can destroy/slow the action of cilia: unable to clear mucus - congestion in airways: become prone to secondary infections - alveoli are destroyed: loss of gas exchange surface area - contains carcinogenic increasing the risk of lung cancer

Smoking

- inspired air: 21% oxygen, 0.04 carbon dioxide - expired air: 16% oxygen. 4% carbon dioxide - other % made up of nitrogen and water vapour

Percentage of gas

- maintained by constant flow of blood through the capillaries, always replaces by more blood pumping around the body, the new blood is low in oxygen and high in carbon dioxide - maintained by the continual movement of air in and out of the alveoli as we breath in and out, new air is low in carbon dioxide and high in oxygen

Concentration gradient

- oxygen is carried: 3% dissolved in blood plasma, 96% as oxyghaemoglobin - Hb + O2 <-> HbO2: oxygen combines with haemoglobin where oxygen concentration is high - oxygenated blood is blood with a high proportion of oxyhaemoglobin - oxyhaemoglobin breaks down into oxygen and haemoglobin where oxygen concentrations are low - oxygenhaemoglobin is bright red in colour, so the blood in the arteries is bright red - haemoglobin is dark red or purplin in colour, the deoxygenated blood in veins is therefore dark red

Oxygen gas

- carbon dioxide is carried: 7-8% dissolved in plasma, 22% coined withe the globin part of haemoglobin (forms carbaminohaemoglobin), 70% carried in plasma in bicarbonate ions - blood in the capillaries: most carbon dioxide reacts with water to form carbonic acid (H2CO3) - carbonic acid then dissolves into hydrogen ions and bicarbonate ions - CO2 + H20 <-> H2CO3 <-> H + HCO3

Carbon dioxide gas

- main system of internal transport

Cardiovascular system

- made up of 55% plasma and 45% formed elements

Blood

- transport of oxygen and nutrients to cells - transports carbon dioxide and other wastes away from cells - transports hormones to cells - distributes hear and maintain body temperatures - maintains water content and ion concentration in the body fluids - protects against foreign micro-organisms - clotting when vessels are damaged, preventing blood loss

Functions of blood

- 91% water - 9% dissolved substances: nutrients, ions, gases, hormones, antibodies, plasma proteins and wastes

Plasma

- transports oxygen and some carbon dioxide - no nucleus: more room for haemoglobin - contains a haemoglobin protein: able to combine with oxygen - circular biconcave disc: increases surface are for oxygen exchange, thicker edges give large volume allowing more room for haemoglobin - number per mm3: 4.8-5.4 million - site of production: red bone marrow - lifespan: 120 days

Red blood cells (erythrocytes)

- protects against foreign micro-organisms (phagocytosis) - removes dead cells and cell debris - granular: have granules and loved nucleus - agranular: no granules and spherical nucleus - number per mm3: 5000-10000, increased count when infected - site of production: red bone marrow - lifespan: a few days

White blood cells (leucocytes)

- blood clotting - very small and no nucleus - number per mm3: 250000-400000 - site of production: red bone marrow - lifespan: around a week

Platelets (thrombocytes)

- nutrients and wastes are transported dissolved in plasma - nutrients: essential elements we obtain from the food we eat - inorganic nutrients transport as ions: Na, Ca, K, Cl, I - organic nutrients dissolved in the blood plasma: glucose, vitamins, amino acids, fatty acids, glycerol - metabolic wastes: urea, creatinine and uric acid

Transports of other substances

- located in the middle of chest cavity between the lungs (mediastinum space) - approximately the size of a human fist - pericardium: membrane enclosing heart, hold hear in place but also allows it to beat, prevents overstretching - made up of cardiac muscular tissue - heart is a double pump: left pumps from lungs to body, right pumps from body to lungs

Heart structure

- the heart consts of 4 muscular chambers - the left 2 are separated from the right by the septum - atria: upper chambers, receive blood, thin walls as it only pumps blood to ventricles - ventricles: lower/pumping chambers, thicker walls as it pumps to lungs and body, left ventricle is thicker than right

Heart chambers

- direction of the blood flow is controlled by four valves, small flaps of tissue that function to prevent the backflow of blood - atrioventricular valves: between atria and ventricle, held in position by strong tendons, the chordae tendinae - semi-lunar valves: prevent backflow of blood from arteries to ventricles - the heart sounds "lubb-dubb" result from the valves snapping shut

Heart valves

- aorta - pulmonary trunk which branches into pulmonary arteries - pulmonary veins - inferior and superior vena cava

Blood vessels of the heart

- vena cava carries deoxygentaed blood from body to right atrium - pulmonary arteries carry deoxygenated blood from right ventricle to lungs - pulmonary veins carry oxygenated blood from the lungs to the left atrium - aorta carries oxygenated blood from the left ventricle to the body

Major blood vessels

- LORD: left-oxygenated, right-deoxygenated - left: pulmonary vein -> left atrium -> left atrioventricular valve -> left ventricle -> aortic semi lunar valve -> aorta -> body - right: pulmonary artery -> right atrium -> right atrioventricular valve -> right ventricle -> pulmonary semi lunar valve -> pulmonary trunk/arteries -> lungs

Circulation of blood

- arteries - arterioles - capillaries - veins - venules

Blood vessels

- carry blood away from the hear - walls contain thick smooth muscle and thick elastic fibres - walls of arteries can stretch to accommodate extra blood from ventricles - elastic recoil keeps blood moving and maintaining high pressure - form arterioles - vasoconstriction: muscle of walls contracts to reduce diameter of vessel and therefore reduce blood flow through artery - vasodilation: muscle of wall relaxes to increase diameter of vessel and therefore increase blood flow

Arteries

human biology

cells, cell membrane, tissues, tonicity, nutrients, enzymes, metabolism

Practice Known Questions

Exams

Learn New Questions

human biology - Leaderboard

human biology - Details

Levels:

Questions: