IB Bio - Human Physiology

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Subtopics 6.1-6.4

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81 Terms

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the digestive tract

complex tube that food goes through; has three roles: take in food, break down molecules and absorb nutrients, excrete waste

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peristalsis

involuntary action by longitudinal and circular muslces to move bolus through GI tract

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musoca

innermost layer of the SI lined with epithelium cells

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submucosa

connective tissue between the mucosa and serosa that contains large veins and arteries which give rise to the capillary bed of the mucosa

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serosa

the outermost layer of the SI consisting of connective tissue that is in contact with body cavities

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enzymes produced by the pancreas

amylase, endopeptidase (trypsin), lipases and phospholipases

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amylase produced by the pancreas…

breaks down starch into maltose

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endopeptidase (trypsin) produced by the pancreas…

breaks down proteins into smaller polypeptides

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lipases and phospholipases produced by the pancreas…

break down lipids and phospholipids to glucerol and fatty acids

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enzymes produced by the SI

nucleases, maltase, lactase, exopeptidase, dipeptidase

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nucleases…

break down DNA and RNA

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maltase…

breaks down maltose into glucose

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lactase…

breaks down lactose into galactose and glucose

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exopeptidase...

removes a single amino acid from the end of the small polypeptides

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dipeptidase…

breaks down a dipeptide into two amino acids

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villi and microvilli

increase surface area of the SI and absorb monomers produced by the digestive process

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monomers absorbed by the villi..

bases and phosphates from nucleic acids, fatty acids and glycerol, amino acids, monomeric carbohydrates (fructose, glucose, galactose)

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simple diffusion

absorbs small, hydrophobic molecules and occurs mostly with the products of lipid digestion

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facilitated diffusion

absorbs fructose, glucose and other hydrophilic monomers and are moved by protein channels; with concentration gradient

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active transport

needed when concentrations are lower in the lumen; goes against concentration gradient; glucose, amino acids, and some mineral ions are transported this way; ATP required

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pinocytosis

draws in small droplets of liquids surrounded by a small section of the phospholipid membrane; likely to occur with fat droplets in the SI

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systolic

part of the heartbeat when the muscle is contracting

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diastolic

part of the heartbeat when the muscle is relaxing; lower pressure than systolic

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what assists in maintains blood pressure in arteries?

muscle and elastic fibres

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tunica intima

  • innermost layer of arteries and veins

  • includes endothelium and lines the lumen of all vessels

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tunica media

  • middle coat that is mainly made of smooth (involuntary) muscle cells and elastic fibres arranged in roughly spiral layers

  • thick in arteries

  • thin in veins

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tunica adventitia

  • outermost coat

  • tough layer consisting largely of loosely woven collagen fibres

  • protect the blood vessel and anchor it to surrounding structures

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vasoconstriction

when the arteries experience the highest pressure: systolic blood pressure, and the circular muscles surrounding the arteries resist the outward pressure and constrict

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vasodilation

when the heart relaxes between beats, the pressure in the arteries is lowest: diastolic blood pressure, and the smooth muscles surrounding the arteries can also relax

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arterioles

smaller arteries that branch off in the body to supply blood to organs, limbs, etc

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stroke volume

the volume of blood pumped out of the left ventricle of the heart during each contraction (or heartbeat)

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cardiac output

the volume of blood the heart pumps through the circulatory system in a minute

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veins

blood vessels that transport blood back from the tissues of the body and return it to the atria of the heart

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vein walls

the blood pressure is much lower than in arteries and they do not need thick walls with lots of muscle fibres

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vein valves

periodic valves that close to prevent backflow

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skeletal muscles

muscles squeeze that squeeze the veins like a pump by exerting pressure

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composition of blood

  • plasma (liquid portion)

  • red blood cells

  • white blood cells

  • platelets (cell fragments)

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plasma

carries dissolved substances such as proteins, hormones, carbon dioxide, glucose, and vitamins and minerals

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RBC

contain hemoglobin proteins to transport oxygen

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WBC

part of the immune system and help to defend the body from disease

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platelets

help blood clot

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capillary network

connection between arteries and veins

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venules

small veins

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William Harvey

discovered that blood circulates around the body with the heart acting like a pump; he also found out about valves in veins and that the blood leaves the body via arteries and returns via veins

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double circulatory system

that is the blood flows through the heart twice before it is distributed to tissues

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pulmonary circulation

the circulation of blood from the heart to the lungs and back

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systemic circulation

the circulation of blood from the heart to the body tissues and back

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sinoatrial node

a group of specialised muscle cells in the wall of the right atrium that fires at regular intervals to cause the heart to beat with a rhythm

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atrioventricular node

recieves signals from the SA node relayed via the bundle of His located in the interventricular septum to the top of each ventricle

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purkinje fibres

fibres that spread signals to the ventricles

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cardiac accelerator nerve

the nerve that stimulates the heart to beat faster

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vagus nerve

the nerve that reduces the heart rate

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epinephrine

increases the heart rate by stimulating the SA node to emit electrical signals at a faster rate as well as by increasing the conduction speed of impulses generated by both the SA and AV nodes

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atheromas

fatty deposits caused by high blood concentrations of low density lipoprotein (LDL) in the arterial walls next to the endothelial cells

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thrombosis

the forming of a clot in the blood vessel that can block the blood vessel entirely

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primary defense

non-specific defence that prevents the entry of organisms and viruses that cause disease

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skin pores

for sweating, hair follicles and sebaceous glands that produce oils (called sebum) to keep the skin supple and at a slightly lower pH

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mucous membrane

membranes that produce a sticky mucus that contains glycoproteins and lysozymes, enzymes that attack bacterial cell walls

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blood clotting

  1. exposure to collagen (fibrous protein)

  2. collagen exposure attracted platelets to the site

  3. platelets get activated and change shape

  4. platelets cross link – activation of ADP: binds to receptors, induces aggregation, and recruits further platelets to the site

  5. snowball effect (positive feedback): accumulation of platelets; chemicals release -> platelet activation = amplification 

  6. thrombin turns fribinogen to firbrin fibres 

  7. fibrin form a mesh that catches platelets and RBC to form a clot

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leukocytes

white blood cells

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macrophages

phagocytes; non-specific; moving by a process called amoeboid motion, these cells engulf a pathogen that has entered the body and is found in the lymph nodes or the blood, and once inside the phagocyte, enzymes secreted by the lysosome will digest the pathogen

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pathogen

a disease-causing virus or microorganism

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antigen

any molecule that enters the body and triggers an immune response

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lymphocyte

the type of white blood cell responsible for specific immune responses

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B lymphocyte

recognize antigens through antibody receptors on its surface, they then divide and some become plasma cells and some become memory cells

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plasma cells

can bind to the antigen, which allows phagocytes to recognise and then destroy the pathogen, and can bind to proteins in the coat of a virus, which will prevent the virus from entering other (human) cells

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memory cells

long-lived pool of cells capable of responding quickly to the same antigen in case you encounter it again

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T helper cells

activate B cells

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HIV

a retrovirus that infects and stops T helper cells; it has RNA as its genetic material

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antibiotics

any substance produced by a microorganism (usually fungi) that block processes that occur in prokaryotic cells but not in eukaryotic cells

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antibiotic resistance

if a mutation causing resistance to an antibiotic occurs in a bacterium, after several generations a strain of bacteria will evolve with genes that confer resistance to that antibiotic

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ventilation

actively moving air into and out of lungs in order to bring fresh air into the alveoli and get rid of stale air

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properties that aid in diffusion

  • thin membrane

  • large surface area

  • concentration gradient

  • permeability

  • moisture

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oxygen concentrations

high in alveoli, lower in blood

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carbon dioxide concentrations

high in blood, lower in alveoli

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type i pneumocytes

extremely thin alveolar cells that are adapted to carry out gas exchange; flat and thin to increase surface area

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type ii pneumocytes

secrete a solution containing surfactant, a water-based solution containing phospho-lipoproteins

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inspiration

  • external intercostals contract

  • internal intercostals relax

  • diaphragm contracts

  • high volume, low pressure

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expiration

  • external intercostals relax

  • internal intercostals contract

  • diaphragm relaxes

  • low volume, high pressure

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external intercostals

can only lift ribs and move them out

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internal intercostals

can only move ribs down and in