6 human physiology Flashcards
what is chyme
food churned with acid
what enzymes does the pancreas excrete
amylase
lipase
protease
what does the liver secrete
bile to emulsify lipids
the gall bladder stores…
bile
what is bile
Bile is not an enzyme. Bile breaks large lipid globules into smaller lipid globules (this is what emulsify means). Bile does not facilitate hydrolysis reactions as enzymes do.
what is the serosa
the outermost layer consisting of connective tissue that is in contact with body cavities.
what is the longitudinal muscles
responsible for peristalsis.
what are the circular muscles
responsible for peristalsis.
what is the submucosa
connective tissue that supports the mucosa and that contains large veins and arteries which give rise to the capillary bed of the mucosa.
what is the mucosa
innermost layer forming the soft lining of the tube comprised of epithelium (which lines the lumen of the digestive track), connective tissue and smooth muscle (villi form part of this layer).
what does the pancreatic duct do
duct cells transport the enzymes produced by the acinar cells and secrete sodium hydrogen carbonate, which neutralises stomach acid
what do acinar cells do
secrete digestive enzymes
what do the islets of langerhoans do
produce the hormones insulin and glucagon
amylase:
breaks down starch into maltose
endopeptidase (trypsin) do
breaks down proteins into smaller polypeptides
lipases and phosopholipase
break down lipids and phospholipids, respectively, to glycerol and fatty acids. in case of the phospholipid, phosphate is also produced.
nucleases
break down dna into rna
maltase
breaks down maltose into glucose
lactase
breaks down lactose into galactose and glucose
exopeptidases
remove a single amino acid from the end of the small polypeptides
dipeptidases
break down a dipeptide into two amino acids.
stucture of a villus
where does absorption take place
epithelial cells
what do goblet cells produce
mucus
what carries nutrients away from the intestine
the capillary network and the lacteal
what is the lamina propria
connective tissue of the villus
absorption
the taking in of digested food substances as well as minerals and vitamins from the lumen of the small intestine into the blood.
what is directly absorbed by the villus
Bases and phosphates from nucleic acids
Fatty acids and glycerol
Amino acids
Monomeric carbohydrates, such as fructose, glucose, galactose and ribose.
what is assimilation
end products of digestion that are used by cells for anabolic processes or for respiration
methods of absorption
substances to be absorbed move from the lumen into the epithelial villi
Amino acids and monosaccharides move from the villi into the capillaries and monoglycerides move into the lacteals.
what mode of transport when molecules are small and hydrophobic
simple diffusion (they can pass through phospholipid bilayers)
facilitate diffusion
Fructose, glucose and other hydrophilic monomers are moved by protein channels. Be aware, this still requires a concentration gradient.
active transport
Is needed when the concentrations are lower in the lumen of the small intestine. Thus, the movement needs to occur against a concentration gradient. Glucose, amino acids and some mineral ions are transported out of the lumen in this way, which requires ATP. The cells of the epithelium have many mitochondria that can synthesise ATP for this process.
pinocytosis
Draws in small droplets of liquid surrounded by a small section of the phospholipid membrane, as shown in Figure 2. This is most likely to occur with fat droplets in the lumen of the small intestine.
describe the digestion of starch
Digestion of starch begins the moment you start chewing your food. Amylase is an enzyme present in saliva. Once the saliva and the food have been mixed, amylase starts breaking down the α-1,4 glycosidic bonds that connect the glucose monomers in amylose and amylopectin. The numbers 1 and 4 refer to specific carbon atoms within the two glucose molecules that are joined by the bond: refer to Figure 2 below. The end products are maltose, a dimer of glucose connected by α-1,4 bonds, and maltotriose, which is comprised of three glucose molecules also connected by α-1,4 bonds. Amylopectin also possesses a slightly different type of bond, called α-1,6 glycosidic bonds, however, these cannot be broken down by amylase.
amyolpctin vs amylose
what needs ot happen to the di- and tri-saccharides produced from the starch molecules
they are too large to pass through membranes, so they need to be broken down into monomers (monosaccharides) before they can be absorbed.
what enters the small intestine during the digestion of starch
a mixture of maltose, maltotriose and dextrins. Dextrins are very small polymers still containing the α-1,6 glycosidic bond.
what happens to the three enzymes that are immobilised in the epithelial cells of the small intestine
maltase, glucosidase and dextrinase, break down these molecules into glucose, which can then be absorbed by the villi.
All absorbed monomers from food are
transported via the hepatic portal vein from the small intestine to the liver, from there it enters the general circulation.
what happens to excess glucose
taken up by the liver and converted into glycogen, the animal equivalent of starch. resembles amylopectin but has moe alpha-1,6, glycosidic bonds
dialysis
the separation of smaller molecules from larger molecules in solution by selective diffusion through a partially permeable (also known as selectively permeable or semipermeable) membrane.
use of dialysis tubing to model absorption?
Mucous membranes are made up of
a surface layer of epithelial cells over a deeper layer of connective tissue. They produce mucus for protection and lubrication.
what do the skin and mucous membarnes act as
physical barries forming a primary defence against pathogens that cause infectious disease
how does blood clotting occur
Platelets release chemicals to start these reactions.
The first reaction triggers the second reaction by producing a chemical required for the second reaction.
This continues through a series of several reactions including up to 12 factors.
People who have the most common form of hemophilia are missing clotting factor VIII.
Each reaction takes an inactive protein in the blood called a clotting factor and activates it.
The last step of this cascade of reactions is the conversion of fibrinogen, a soluble and inactive clotting factor in blood, to insoluble fibrin.
This reaction is catalysed by an enzyme called thrombin which itself had to be activated by the cascade of reactions.
The result is a network of fibers that traps red blood cells and platelets to form a scab,
what is a thrombus
a blood clot that forms in a vessel and remains in the place where it was formed.
what is a coronary thrombus
a blood clot in the coronary arteries
what is atherosclerosis
narrows the lumen of arteries and slows down blood flow; thus increasing the chance of a clot occluding (blocking) a coronary artery. This will lead to certain parts of the heart not receiving any oxygen and nutrients, causing that part of the heart to die, resulting in a heart attack.
what happens as a result of blood clots
When a blood clot reduces the amount of blood reaching the heart muscles rather than stopping it completely, it causes angina or chest pain due to heart muscles not getting enough oxygen-rich blood.
Thrombosis of coronary arteries or formation of a clot within the coronary artery starts when the fatty deposit (plaque) in artery walls rupture the lining of the vessel. The clot that began at the site of the rupture can grow larger with time and completely block the artery.
what contributes to blood clots
atherosclerosis
obesity
smoking
hypertension
divide the immune system
Non-specific immune system involving phagocytes.
Specific immune system made up of lymphocytes and antibodies.
how many types of leukocyte are there
5
macrophages are often called
phagocytes because one of their main functions is phagocytosis
what can phagocytes do
Phagocytes can squeeze past the leaky endothelial cells of the capillaries and invade the tissue where an infection has occurred, for example, in a small wound in your skin. This is an example of non-specific immunity to diseases as the phagocytes can respond equally well to a variety of organisms.
pathogen
a disease-causing virus or microorganism. Examples of pathogens are: viruses, bacteria, protozoans, prions and fungi.
label parts of the antibody
what do lymphocytes have the capbability for
they have the capability to recognise millions of different antigens through receptors on their surfaces. These receptors are essentially an antibody that is attached to its cell surface as an integral protein so that the antigen binding site points outwards. An antibody is a protein molecule made by lymphocytes with a specific structure (as shown in Figure 2 ) and the function of recognising antigens
when a b cell encounters an antigen…
Firstly, the B cell divides repeatedly through mitosis to create many copies of the B cell that can recognise the antigen. This process is called clonal selection: ‘clonal’ comes from the fact that mitosis exactly duplicates, or clones, the B cells, and ‘selection’ comes from the idea that only one type of B cell, the one matching the antigen, has been ‘chosen’ to divide.
Most of these B cells become plasma cells which make and secrete large quantities of the antibody to circulate in the blood. Some of the B cells become memory cells: a long-lived pool of cells capable of responding quickly to the same antigen in case you encounter it again.
what do antibodies do (that are produced by plasma cells)
They can bind to the antigen, which allows phagocytes to recognise and then destroy the pathogen.
They can bind to proteins in the coat of a virus, which will prevent the virus from entering other (human) cells.
Where do memory cells remain
Bloodstream and lymph nodes
Antigens to antibodies pathway
Where are B cells produced
Bone marrow
What is a leukocyte
A leukocyte is any type of white blood cell. A lymphocyte is a particular type of white blood cell that produces antibodies.
What is a t cell
A type of lymphocyte
What is an apc
Antigen presenting cell
Once the antigen has been recognised by the T helper cell, the immune system is
activated to fight against the antigen. It triggers the production of antibodies and activates macrophages and killer T cells, which will engulf and destroy the antigen.
What does HIV do
The infected T helper cells are destroyed leading to a reduced number in the body. Since T helper cells are needed to activate B cells to produce antibodies, infection with HIV causes a loss in the ability to produce antibodies which can lead to the development of AIDS (acquired immune deficiency syndrome). It should be noted that HIV causes an overall reduction of active lymphocytes in the body, including both T and B cells: activated T cells decrease as infected T helper cells are destroyed and activated B cells decrease because there are fewer T helper cells to cause their activation.
HIV diagram
What is a retrovirus
HIV is a retrovirus that has RNA as its genetic material. Once HIV infects a cell through the proteins on the surface of its envelope, it makes a DNA copy from its RNA, with the help of an enzyme called reverse transcriptase. The cDNA that is produced is inserted into the host cell’s genome. These days the infection can be slowed down, or even stopped, with the use of antiviral drugs specifically targeting reverse transcriptase activity.
HIV symptoms
High fever
Headaches
Mood swings
Cough
Joint pain
High heart rate
Clammy skin
Nausea
Fatigue
When untreated aids develops into
AIDS
HIV can be transmitted via
Sexual intercourse
Transfusion of infected blood
Sharing of hypodermic needles by drug users
From mother to child during pregnancy, birth or breastfeeding.
HIV cannot be transmitted through ordinary day-to-day contact such as shaking hands, hugging and kissing or via sharing food, drink or personal items.
What do antibiotics do
Antibiotics block processes that occur in prokaryotic cells but not in eukaryotic cells. Thus, antibiotics can be used to treat bacterial infections in humans and animals (because they are eukaryotes) without harming their body cells.
What do antibiotics target
A ntibiotics do not have an effect on human cellular processes. The drugs target bacterial cell wall and membrane formation, ribosome function or DNA replication, transcription and translation. None of these may directly kill the bacteria, but it will slow down or stop growth and prevent cellular division.
Fungi and bacteria can compete for the same food resources so
fungi often secrete antibiotics to inhibit the growth of the competing bacteria. The best known example of an antibiotic is penicillin.
Florey and chain and streptococcus
Florey and Chain infected eight mice with Streptococcus . This bacterium causes pneumonia in mice. Eight mice were kept under identical conditions, but four of the eight were given an injection of penicillin. The four mice that were not treated with penicillin died within 24 hours, but the treated mice stayed alive. This experiment does not prove a causal relationship but gives a very strong indication that penicillin may have played a role in the recovery of the mice.
The next step was to test the drug on humans. Florey and Chain proceeded to test penicillin on very sick patients with infections. Most survived, and the commercial production of the drug in the 1940s allowed testing on more and more patients; eventually confirming it as a very effective weapon against infections.
Label the heart
Pulmonary circulation
From the heart to the lungs and back
Systemic circulation
From the heart to the body tissues and back
Which side is responsible for pulmonary circulation
Right
What side is responsible for systemic circukatuon
Left
The heart is myogenic which means
that the heart muscle can generate its own contractions. There is a group of specialised muscle cells in the wall of the right atrium called the sinoatrial (SA) node. This SA node initiates (starts) each heartbeat and it sets the heart rate, so it is often called the pacemaker. The SA node ‘fires’ (sends electrical signals) at regular intervals to cause the heart to beat with a rhythm of about 60 to 70 beats per minute for a healthy, resting heart.
Summary of the propagation through the heart of the electrical signal initiated in the SA node
The SA node sends out an electrical signal that stimulates contraction as it is propagated through the walls of the atria.
The signal then passes via interatrial septum to reach the atrioventricular (AV) node.
From the AV node, the signal is relayed via the bundle of His located in the interventricular septum to the top of each ventricle (confusingly, the top of the heart, or apex, is the bottom-most part where the two ventricles meet in a shape somewhat like a point).
At the top of the ventricles, the signal spreads from the bundle of His (also called the atrioventricular (AV) bundle), to the ventricles via the Purkinje fibres located in its wall.
Order of valves in the cardiac cycle
Left AV closes
Aortic valve opens
Aortic valve closes
Left AV valve opens
what controls the SA node to speed up the heart or slow it down
Two nerves that originate in the medulla oblongata of your brain
The nerve that stimulates the heart to beat faster is called the
cardiac accelerator nerve
the nerve that stimulates the heart to beat faster is called the
cardiac accelerator nerve
the nerve that reduces heart rate is called
the vagus nerve
what is monitored by the cv centre to determine whether impulses should be sent along the cardiac accelerator nerve or vagus nerve to the heart
Blood pressure, pH and carbon dioxide concentration of the blood
what is epinephrine
adrenalin, the fight or flight hormone. 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 SA and AV nodes.
epinephrine also increases
muscle strength, blood pressure, sugar metabolism
infection response
central role of a t cell diagram
alveolus diagram
blood glucose cycle
menustration cycle
steps of IVF
Step 1a: The woman is given a drug (or drugs) to suppress her natural cycle by suspending her normal secretion of hormones. She can administer them herself in the form of a daily injection or a nasal spray. The drug treatment continues for about 2 weeks.
Step 1b: FSH and LH are injected at a higher dose than normal for around 12 days to stimulate the production of a number of ova (egg cells), called superovulation. The clinic monitors progress throughout the drug treatment through vaginal ultrasound scans and, possibly, blood tests.
Step 2: Between 34 and 38 hours before the eggs are due to be collected, the woman will be given a hormone injection to help the eggs mature (this is likely to be human chorionic gonadotrophin). Eggs are then usually collected from the ovaries by using ultrasound guidance while the person is sedated. A hollow needle is attached to the ultrasound probe and is used to collect the eggs from the follicles in each ovary.
Step 3: A sperm sample is collected from the woman’s partner and checked for viability.
Step 4: The eggs are mixed with the partner’s or the donor’s sperm and cultured in the laboratory for 16–20 hours after which they are checked for signs of fertilisation. (Sperm can also be injected directly into the egg, as shown in the alternate picture on the right at number 4 in the diagram.) Eggs that are fertilised (now called embryos) are grown in the laboratory incubator for up to 6 days. The embryologist will monitor the development of the embryos and the best will then be chosen for transfer. The remaining embryos of suitable quality are frozen for future use.
Step 5: If the woman is under the age of 40, one or two embryos are implanted in the uterus at the appropriate time in her menstrual cycle. But, if she is older than 40 years, a maximum of three may be used. The number of embryos transferred is restricted because of the risks associated with multiple births.
structure of the digestive system
transvesr section of small intestine with villi lining the small intestine
different tissue layers of the wall of thes mall intestine as seen under the light microscope
mucosa
submucosa
longitudinal muscle
