Chapter 6- Human Physiology Flashcards
Name the structure of the small intestine from outward to inward.
Serosa
Longitudinal Muscle [SMOOTH MUSCLE] (Helps make it longer)
Circular Muscle [SMOOTH MUSCLE] (Helps squeeze it)
Submucosa
Mucosa
Lumen (lined with Villi)
Serosa
An outer coat = Tough/ Flexible/ Strong/ Surrounding outside (where pancreas is)
Submucosa
Tissue layer containing blood and lymph vessels.
Connective tissue betw. mucosa and muscle layer
Mucosa
The lining of the small intestine, w. epithelium that absorbs nutrients on its inner surface.
Mesentry
Hanging part of the small intestine = has the blood supply and nerve supply
What does the contraction of circular muscle behind the food do?
Constricts the gut = prevents it from being pushed back to the mouth.
What does the contraction of longitudinal muscle where the food is located do?
Moves food along the gut.
What is the main funct. of peristalsis in the intestine?
Churning of semi digested food to mix it w. enzymes and speeds up the digestion process.
Endocrine glands (in pancreas) what are they and what do they secrete?
Secretes Insulin and Glucagon (hormone) INTO THE BLOOD.
Exocrine glands (in pancreas) what are they and what do they secrete
Synthesis and secretes digestive enzymes INTO THE GUT in response to eating a meal.
What are contractions of muscles controlled by?
Enteric Nervous System
What is the name of the cell that secretes digestive enzymes?
Acinar cells
Enzymes secreted by the pancreas.
\+ Amylase \+ Lipase \+ Protease \+ Phospholipase \+ HCO3 (Hydrogen carbonate) Buffer
Why is the hydrogen carbonate an essential secretion from the pancreas?
The pH int he stomach = low cuz of the HCl
+ before it enters the intestine = needs to be made to abt pH 7 so it doesn’t corrode the cell lining of the small intestine.
Amylase digests?
Starch into Maltose
Lipase digests?
Triglycerides into:
+ Fatty acids and glycerol
+ Fatty acids and monoglycerides
Phospholipase digests?
Phospholipids into:
+ Fatty acids
+ Glycerol
+ Phosphate
Protease digests?
Proteins and Polypeptides into:
+ Shorter peptides
What form are most of the enzymes secreted by the small intestine in?
Immobilised in the plasma membrane of epithelium cells lining the intestine.
They are active there an continue to be active when epithelium cells = scraped away, off the lining and mixed w. semi digested food.
Nucleases digest? (Synthesised by small intestine)
DNA and RNA into Nucleotides
Maltase digests? (Synthesised by the small intestine)
Maltose into Glucose
Lactase digests? (Synthesised by the small intestine)
Lactose into Glucose and Galactose
Sucrase digests? (Synthesised by the small intestine)
Sucrose into Glucose and Fructose
Exopeptidase and proteases digests? (Synthesised by the small intestine)
peptides into dipeptides
Depeptidase digests? (Synthesised by the small intestine)
Dipeptides into amino acids
What does Villi do to the small intestine?
Increases the surface area of epithelium of which absorption = carried out.
Absorption
The process of taking substances into the cell and the body.
For nutrients to be absorbed into the body, what must it first be absorbed into?
The epithelium cells through the exposed part of a plasma membrane that has a surface area enlarged w. micro villi.
Once the nutrients pass into the epithelium cell from the lumen of intestine, where does it go?
Absorbed into the lacteal (part of lymphatic system)(fats) or into the blood capillaries.
What are the 4 different mechanisms that move nutrients into and out of the villus epithelium cell?
- Simple diffusion
- Facilitated diffusion
- Active transport
- Exocytosis
How are triglycerides absorbed into the body?
- They must be digested = fatty acids and monoglycerides
- 1 Monoglycerides can be absorbed into the villus epithelium cell by SIMPLE DIFFUSION
- 2 Fatty acids absorbed by FACILITATED DIFFUSION via Fatty acid transporters (protein channels)!
- Inside the epithelium cell = fatty acids and monoglycerides combine = triglyceride = can’t diffuse back into lumen.
- Triglycerides = combine w. cholesterol to form droplets = become coated in phsopholipids and proteins = LIPOPROTEIN.
- Lipoprotein = released by exocytosis through plasma membrane on inner side of villus
- Either enter lacteal OR enter blood capillaries
Why can’t glucose enter the plasma membrane by ‘simple diffusion’?
Its POLAR = its hydrophilic!
How is glucose absorbed into the body?
- Sodium-Potassium pumps (on the inwards facing parts of the plasma membrane) = PUMPS 3Na+ ions by ACTIVE TRANSPORT from cytoplasm to the interstitial spaces inside the villus and 2K+ ions the opposite way!
- Sodium-Glucose co-transporter proteins in the (micro villi) = transfer a Na+ ion and a glucose molecule together from the intestinal lumen to the cytoplasm of epithelium cells
THIS is a passive FACILITATED DIFFUSION that depends on the conc. grad of Na+ ions created by active transport. - Glucose channels allow FACILITATED DIFFUSION of glucose from cytoplasm into the interstitial spaces inside the villus then into the blood capillaries.
Pinocytic vesicles contain?
Liquid
Phagocytic vesicles contain?
Solid
What does starch digestion in the small intestine illustrate?
+ Catalysis
+ Enzyme specificity
+ Membrane permeability
Properties of arteries (2)
1) Elastic Tissues in the wall
→ elastin fibres = store energy that stretches them at peak of each pumping cycle = recoil helps propel blood down artery
2) Smooth muscles contractions in artery walls determine diameter of lumen
List artery walls from outside in (3)
1) Tunica Externa = tough outer layer of connective tissue
2) Tunica Media = thick layer containing smooth muscles and elastic fibres
3) Tunica intima = Smooth endothelium forming the lining of artery
Peak pressure in the arteries
+ Systolic pressure = pushes the walls of the arteries outwards = widening the lumen and stretching the elastic fibres int he wall = stores potential energy
At the end of each heartbeat what happens to the pressure in the arteries?
+ Falls sufficiently for the stretched elastic fibres to squeeze blood in the lumen
→ Mech. saves energy and prevents the min. pressure in the artery = diastolic pressure in being too low
Vasoconstriction
When circular muscles in wall of artery contracts
How wide are capillaries?
10μm smallest blood vessel
Features of capillaries
+ Endothelium cell = 1 cell thick
+ Walls v. permeable
+ Fenestrations allow plasma to leak out
What is blood flow in veins assisted by? (2)
1) Gravity
2) Pressure exerted by other surrounding tissues
Why are there valves in the veins?
Because bp is too low = danger of backflow
→ valves = prevent backflow
How many flaps does a vein have and what shape?
3 cup-shaped
2 circulations of the heart
1) Pulmonery circulation = to and from the lungs (RHS)
→ blood capillaries in lungs can’t withstand high pressure = blood pumped from heart at low pressure
2) Systemic circulation = to every else in the body
(LHS)
→ high pressure system
Consequence of coronary occlusion (2)
+ Lack of oxygen = causes pain = Angina
→ impairs ability of heart to contract = heart beats faster to maintain blood circulation around body
+ Fibrous cap of arthroma = sometimes ruptures!
→ stimulates the formation of blood clots = block arteries to heart
How to fix Coronary Occlusion (3)
1) Warfarin (Rat Poison!) = med. that prevents vlood clot from forming
2) Diet controlling = reducing LDL’s
3) Heart bypass surgery
Medulla oblongata contains what that monitors the sinoatrial node
Cardiovascular centre
→ with sympathetic and parasympathetic nerves stemming out from it
What does the cardiovascular centre receive?
Input from receptors that monitor:
+ bp
+ pH which shows CO2 conc.
+ O2 conc.
What does ventilation do?
Maintains the conc. grad of oxygen and carbon dioxide betw/ air in the alveoli and blood flowing in adjacent capillaries
Gas only diffuses when?
There’s a conc. grad
What has to be done to maintain the conc. grad?
fresh air must be pumped in and stale air pumped out
For gas exchange to be efficient what has to happen?
A conc. grad needs to be maintained in the alveoli
Breathing in (conc. grad)
increases the conc. grad of the oxygen betw/ the alveoli and the blood
→ O2 diffuses into blood
Breathing out (conc. grad)
decreases the conc. grad of CO2 betw/ the blood and alveoli
→ CO2 diffuses out
Why are there rings of cartilage in the trachea?
To stop the tubes from collapsing when you turn your head
What does the plural fluid do?
Stops the ribcage and lungs rubbing against e.o
Adaptations to aid gas exchange (5)
1) Large surface area of lungs → alveoli
2) Thin cell wall of alveoli = allows fast rate of gas exchange
3) Good blood supply → maintains a high conc. grad
4) Warm
5) Moist/damp = allows gas to dissolve
→ and evaporated and be exhaled
Type 1 pneumocytes
+ Extremely thin alveolar cells
→ adapted to carry out gas exchange
+ Lungs contain a huge # of alveoli w/ v. large s.a for diffusion
What does the wall of the alveolus consist of ?
a single layer and cells = epithelium cells
→ most of them are type 1 pneumocytes
= flattened cells w/ thickness of 0.15μm of cytoplasm!
Type II pneumocytes
+ round cells that occupy abt 5% of the alveolar s.a
→ secretes fluid containing SURFACTANTS that coat the inner surface of alveoli
What does the fluid do to help gas exchange?
+ Allows for O2 in alveoli to dissolve then diffuse into the blood in alveolar capillaries
+ Provide area for CO2 to evaporate into air and be exhaled
What is the structure of surfactants?
Similar to phospholipids in cell membranes
+ forms a MONOlayer on surface of moisture lining the alveoli
→ Hydrophilic heads facing water
→ Hydrophobic tails facing air
What does surfactants do in the alveoli?
+ reduces surface tension and prevents water from causing the sides of the alveoli to adhere to e.o when air = exhaled
prevents collapsing of lungs
Causes of lung cancer (5)
1) Smoking/tabacco/tar → caruses abt 87% of cases
2) Passive smoking → causes abt 3% of cases
3) Air pollution → causes abt 5% of lung cancer
→ most sig = diesel exhaust fumes/nitrogen oxides/smoke from burning coal, wood, organic matter
4) Radon gas → radioactive gas = leaks out of certain rocks s.a granite = accumulates in badly ventilates buildings and ppl inhale
5) Asbestos ,silica, other solids → cause lung cancer if dust/ other particles and them inhaled
→ usually in construction sites/ quarries/ mines/ factories etc.
Consequences of lung cancer (7)
\+ difficulty breathing \+ persistent coughing \+ coughing up blood \+ chest pain \+ loss of appetite \+ weight loss \+ general fatigue
What are the characteristics of the lungs of people w/ Emphysema?
→ smaller # of alveoli + larger air sacs w/ much thicker walls!
→ totals s.a for gas exchange reduced
→ dist. over which diffusion of gases occur increases
→ Gas exchange = less effective + lungs become less elastic and harder to ventilate
What happens in the lungs of people that have Emphysema? (3)
+ Phagocytes inside the alveoli = normally prevent lung infections by engulfing bacteria and producing elastase (Protein digesting enzymes)
→ to kill them inside the vesicles formed by endocytosis
+ Enzyme inhibitor = alpha - 1 antitrypsin (A1AT)
→ usually prevents elastase and other proteases from digesting lung tissue
+ In smokers = the # of phagocytes in the lungs increase = produces more elastase
+ Genetic factors affect the quantity and effectiveness of A1AT made in the lungs
+ in abt 30% of smokers → digestion of proteins in alveolus wall by increase quantity of protease = not prevented by A1AT
→ walls are weakened and destroyed!
Emphysema and the results of the damage
Chronic damage to the alveoli = usually irreversible
+ Causes Low O2 sat. in blood and higher than normal CO2 conc.
Result:
+ patients lacks energy
+ ventilation = labored and tends to be more rapid than normal
What are the region of endocrine tissues in the pancreas called?
Islet of Langerhans
What happens to Leptin in Obese ppl?
+ Have HIGH blood Leptin conc.
What happens to target cells in the hypothalamus to leptin in obese ppl?
+ May become resistant to Leptin = fail to respond to it
Where is Melatonin secreted?
Pineal gland
What does Melatonin control?
Circadian rhythms
What group of cells does the Circadian Rhythm depend on? (located in Hypothalamus)
Suprachiasmatic nuclei (SCN)
When is Melatonin secretion elevated?
In the evening before bed = arouses sleepiness
When does Melatonin levels fall?
At the end of the night = at dawn
→ The hormone is rapidly removed from the blood by liver
How does melatonin contribute to body temp at night?
Causes the core body temp to fall
What does melatonin receptors in the kidney suggest?
Decrease urine production at night = affected by melatonin
What are the names of the special cells in the retina that is involved w/ regulating circadian rhythms?
Ganglion cells
What do the Ganglion cells do?
They detect light at 460-480 nm = pass impulse to cells in the SCN
→ indicates to the SCN the timing of dusk and dawn = allows it to adjust the Melatonin secretion to correspond w/ day-night cycle
The cause of Jetlag
+ The SCN and pineal gland = continuing to set the circadian rhythm to correspond to the timing of day-night at the time of departure rather than the time of destination
If what gene is present on the Y chromosome then the embryonic gonads will develop to testes?
SRY
→ Codes for a DNA binding protein = TDF (Testes determining factor)
What does TDF (Testes Determining Factor)do?
Stimulate the expression if other genes that cause Testis development
The process of IVF ()
1) Down Regulation
→ women takes drugs everyday (nasal spray)
= stops pituitary glands from secreting FSH or LH
= secretion of Oestrogen and Progesterone stops
→ Suspends the normal menstrual cycle so doctors can control timing and amt of eggs made in ovaries
2) Artificial Hormone
→ intramuscular injections of FSH and LH = given daily for 10 days = stimulates follicle dev.
FSH given at higher conc. than Normal menstrual cycle = SUPRAOVULATION
3) When the follicles 18mm in diameter = stimulated to mature = injection of HCG
4) Micropipette mounted on an ultrasound scanner →
→ passed through uterus wall to wash out eggs out of follicles
5) Each egg = mixed w/ 50,000-100,000 sperm cells in sterile conditions in shallow dish
→ incubated at 37°C the next day
6) If fertilisation successful
→ one/more embryos = placed in the uterus when they are 48hrs old
→ Cuz women = not go through normal cycle = tablet of progesterone = placed in vagina to ensure endometrium maintained!
Where does MOST starch breakdown happen?
In the small intestine w/ pancreatic amylase
Which bond in starch can amylase break down?
1,4 bond (Amylose)
→ as long as there are at lease 4 glucose monomers
Amylose is digested in how many glucose fragments and their names?
2-3 glucose fragments
Maltose and Maltotriose
Why can’t Amylose breakdown 1,6 bond in Amylopectin?
Because of the specificity of the active site
What are the segments of 1,6 bonds in amylopectin called?
Dextrin
What are the 3 enzymes that complete the digestion of starch and what do they digest?
1) Maltase digests maltose
2) Glucosidase digests maltotriose
3) Dextrinase digests dextrins
