Studied by 106 people
the digestive tract
complex tube that food goes through; has three roles: take in food, break down molecules and absorb nutrients, excrete waste
peristalsis
involuntary action by longitudinal and circular muslces to move bolus through GI tract
musoca
innermost layer of the SI lined with epithelium cells
submucosa
connective tissue between the mucosa and serosa that contains large veins and arteries which give rise to the capillary bed of the mucosa
serosa
the outermost layer of the SI consisting of connective tissue that is in contact with body cavities
enzymes produced by the pancreas
amylase, endopeptidase (trypsin), lipases and phospholipases
amylase produced by the pancreas…
breaks down starch into maltose
endopeptidase (trypsin) produced by the pancreas…
breaks down proteins into smaller polypeptides
lipases and phospholipases produced by the pancreas…
break down lipids and phospholipids to glucerol and fatty acids
enzymes produced by the SI
nucleases, maltase, lactase, exopeptidase, dipeptidase
nucleases…
break down DNA and RNA
maltase…
breaks down maltose into glucose
lactase…
breaks down lactose into galactose and glucose
exopeptidase...
removes a single amino acid from the end of the small polypeptides
dipeptidase…
breaks down a dipeptide into two amino acids
villi and microvilli
increase surface area of the SI and absorb monomers produced by the digestive process
monomers absorbed by the villi..
bases and phosphates from nucleic acids, fatty acids and glycerol, amino acids, monomeric carbohydrates (fructose, glucose, galactose)
simple diffusion
absorbs small, hydrophobic molecules and occurs mostly with the products of lipid digestion
facilitated diffusion
absorbs fructose, glucose and other hydrophilic monomers and are moved by protein channels; with concentration gradient
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
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
systolic
part of the heartbeat when the muscle is contracting
diastolic
part of the heartbeat when the muscle is relaxing; lower pressure than systolic
what assists in maintains blood pressure in arteries?
muscle and elastic fibres
tunica intima
innermost layer of arteries and veins
includes endothelium and lines the lumen of all vessels
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
tunica adventitia
outermost coat
tough layer consisting largely of loosely woven collagen fibres
protect the blood vessel and anchor it to surrounding structures
vasoconstriction
when the arteries experience the highest pressure: systolic blood pressure, and the circular muscles surrounding the arteries resist the outward pressure and constrict
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
arterioles
smaller arteries that branch off in the body to supply blood to organs, limbs, etc
stroke volume
the volume of blood pumped out of the left ventricle of the heart during each contraction (or heartbeat)
cardiac output
the volume of blood the heart pumps through the circulatory system in a minute
veins
blood vessels that transport blood back from the tissues of the body and return it to the atria of the heart
vein walls
the blood pressure is much lower than in arteries and they do not need thick walls with lots of muscle fibres
vein valves
periodic valves that close to prevent backflow
skeletal muscles
muscles squeeze that squeeze the veins like a pump by exerting pressure
composition of blood
plasma (liquid portion)
red blood cells
white blood cells
platelets (cell fragments)
plasma
carries dissolved substances such as proteins, hormones, carbon dioxide, glucose, and vitamins and minerals
RBC
contain hemoglobin proteins to transport oxygen
WBC
part of the immune system and help to defend the body from disease
platelets
help blood clot
capillary network
connection between arteries and veins
venules
small veins
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
double circulatory system
that is the blood flows through the heart twice before it is distributed to tissues
pulmonary circulation
the circulation of blood from the heart to the lungs and back
systemic circulation
the circulation of blood from the heart to the body tissues and back
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
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
purkinje fibres
fibres that spread signals to the ventricles
cardiac accelerator nerve
the nerve that stimulates the heart to beat faster
vagus nerve
the nerve that reduces the heart rate
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
atheromas
fatty deposits caused by high blood concentrations of low density lipoprotein (LDL) in the arterial walls next to the endothelial cells
thrombosis
the forming of a clot in the blood vessel that can block the blood vessel entirely
primary defense
non-specific defence that prevents the entry of organisms and viruses that cause disease
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
mucous membrane
membranes that produce a sticky mucus that contains glycoproteins and lysozymes, enzymes that attack bacterial cell walls
blood clotting
exposure to collagen (fibrous protein)
collagen exposure attracted platelets to the site
platelets get activated and change shape
platelets cross link – activation of ADP: binds to receptors, induces aggregation, and recruits further platelets to the site
snowball effect (positive feedback): accumulation of platelets; chemicals release -> platelet activation = amplification
thrombin turns fribinogen to firbrin fibres
fibrin form a mesh that catches platelets and RBC to form a clot
leukocytes
white blood cells
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
pathogen
a disease-causing virus or microorganism
antigen
any molecule that enters the body and triggers an immune response
lymphocyte
the type of white blood cell responsible for specific immune responses
B lymphocyte
recognize antigens through antibody receptors on its surface, they then divide and some become plasma cells and some become memory cells
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
memory cells
long-lived pool of cells capable of responding quickly to the same antigen in case you encounter it again
T helper cells
activate B cells
HIV
a retrovirus that infects and stops T helper cells; it has RNA as its genetic material
antibiotics
any substance produced by a microorganism (usually fungi) that block processes that occur in prokaryotic cells but not in eukaryotic cells
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
ventilation
actively moving air into and out of lungs in order to bring fresh air into the alveoli and get rid of stale air
properties that aid in diffusion
thin membrane
large surface area
concentration gradient
permeability
moisture
oxygen concentrations
high in alveoli, lower in blood
carbon dioxide concentrations
high in blood, lower in alveoli
type i pneumocytes
extremely thin alveolar cells that are adapted to carry out gas exchange; flat and thin to increase surface area
type ii pneumocytes
secrete a solution containing surfactant, a water-based solution containing phospho-lipoproteins
inspiration
external intercostals contract
internal intercostals relax
diaphragm contracts
high volume, low pressure
expiration
external intercostals relax
internal intercostals contract
diaphragm relaxes
low volume, high pressure
external intercostals
can only lift ribs and move them out
internal intercostals
can only move ribs down and in
Note 
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