Animal Physiology Flashcards
pathogen
any causative agent of diesease;
- certain virsues or bacteria
- certain fungi, protists and worms
fundamental body immune respnse
- immune system attempts to eradicate pathogen when it enters body
- self and not self recognition used; leucocytes are capable to detecting plasma memebrane proteins which don’t belong (not self); e.g. antigens
example of not self detection
- human blood plasma proteins on RBC
- Rh blood type based on presence or absence of Rh protein (+ or -)
- ABO blood types
steps of mammalian immune response
- B lymphocyte (plasma cells) can synthesize and secrete a specific antibody that binds to a specific antigen
- first type of leucocyte to encounter pathogen is macrophage; find ‘non self’ antigen and engulf phagocyte by phagotyosis and digest it
- helper t-cells recognize the antigen being presented and become activated; turn the immune response from non-specific to antigne-specific by chemically communicating and activating the specific B-Cell type that is able to produce the needed antibody
- activated B-Cell begins cells cloning so that there are many types of b cells to rpoduce antibodies
true immunity
- when there is a memory cell produced during primary infection still circulating in the bloodstream that can quickly respond to the pathogen
what are antibodies?
y-shaped protein molecules procued by plasma cell leucosytes in response to a specific pathogen
how do antibodies help destroy pathogens?
- at the end of the forks of the ‘Y’ there are 2 identical sequences of amino acids unique to that antibody that act as binding sites to the spefic antigen
types of cloned B-cells
- plasma cells; help secrete antibodies to help fight off the primary infection
- memory cells; don’t secrete antibodies but remain in bloodstream to prep for secondary infections
ANTIGENS;
ANTIGENS; unfamiliar surface molecules that can cause the production of antibodies (found on bacteria and viruses [pathogens])
Precipitation
– Solube pathogens become insoluble and precipitate
Mechanisms of AID IN PATHOGEN DESTRUCTION BY
• Precipitation • Agglutination • Neutralisation • Inflammation • Complement activation Mnemonic: PANIC
Agglutination
Cellular pathogens become clumped for easier removal
Neutralisation
Antibodies may occlude pathogenic regions (e.g. exotoxins)
Inflammation
Antibodies may trigger an inflammatory response within the body
Complement activation
Complement proteins perforate membranes (cell lysis
BLOOD GROUP INHERITANCE
ABO blood type classification system uses the presence of absence of antigens on red blood cells to categorize blood into four types
Distinct molecules called ‘agglutinogens’ (a type of antigen) are attached to the surface of red blood cells; there are two types called type “A’ and ‘B”
BLOOD TYPING:
Antibodies (immunoglobulins) are specific to antigens
The immune system recognizes ‘foreign’ antigens and produces antibodies in response
Blood type O is a universal donor, as it has no antigens which the recipient immune system can react to
AB is a universal recipient as the blood has no antibodies which will react to A or B antigens
Agglutination;
Agglutination; when your body has the wrong blood in it so it attacks itself (blood starts to clot as a reaction)
IMMUNITY
IMMUNITY: having sufficient biological defenses against infection
ACTIVE IMMUNITY
: is immunity due to the production of antibodies by the organism itself after the immune response has been stimulated by a pathogen
PASSIVE IMMUNITY
is the acquisition of antibodies from another organism; in which active immunity has been stimulated. This includes artificial sources as well as via the placenta,
colostrum or direct injection of antibodies
helper T-cells
Helper T-cells are the major driving force and regulators of the immune defense
Primary task; to activate B-cells and T-Cells (there are many different types of Helper T cells and B-Cells which respond to different antigens)
B LYMPHOCYTE ACTIVATION:
The B cells then search for the antigen matching its receptors, finds it + attaches to it
B cell however needs proteins produced by helper -T cells to become fully activated
how do phagocytes alert helper t cells?
- engulf phagocyte
- express the antigens of the phagocytes on their surface
- phagocytes present antigen to helper t-cells
- helper t cells become activated
PLASMA CELL AND ANTIBODY PRODUCTION
Plasma cells are specialized in production a specific antibody that matches the B-cell receptor
They can produce many tens of thousands of antibodies per second
PATHOGEN DESTRUCTION AND MEMORY CELL FORMATION
T-cells can also produce memory cells with an even longer lifespan than B memory cells.
Subsequent infections by the same pathogen therefore provoke a much more rapid immune response
If little or no symptoms are experienced, the organism is said to be immune!
ANTIBODY FUNCTIONS
Neutralization
Opsonization
Agglutination
Complement activation
Neutralization
attachment stops toxins from affecting/entering cells, viruses from invading cells and bacteria from efficiently functioning and therefore attacking cells
Opsonization
- through attachment antibodies mark the pathogens and make them easily identifiable by other immune cells. E.g. so macrophages can find + engulf + digest them
Agglutination
antibodies attach to each other causing a clumping of the pathogen (to enhance neutralization and opsonization)
Complement activation
antibodies ‘encourage’ other components to attach to the pathogen by attack it e.g. breaking the bacterial membrane and lysing the cell
Antigens can also cause inflammation in the affected area (this is an enhanced non-specific immune response to help combat the pathogen
HISTAMINE
is a small organic molecules produced by two types of leukocyte; basophils and mast cells
basophils
circulate and hence release histamine into the blood and cause symptoms at secondary sites
mast cells
found in connective tissues; if stimulated by an infection they release histamine in the infected area
effect of histamine
Key effect is the immune response in that it increases the permeability of the capillaries to white blood cells and some proteins (e.g. antibodies)
This allows the componenets of the immune system to engage with the pathogen early at the site of infection
Non specific immunity;
Non specific immunity; barriers, mucous membranes, clotting and phagocytosis
Specific immune response;
direct targetting of pathogen that has invade
If non specific immunnity fails, specific immunity must be produced by body
RESPONSE: (body to pathogen)
RESPONSE:
pathogen engulfed by macrophage
macrophage takes on antigen (Or epitope-cell surface protein)
Macrophage presents epitope to T-Cells
Complementary helper T-Cell is activated
Helper T-Cell stimulates appropiate B-Cell
B-Cell produces clones
Clones become either plasma cells or memory cells
Plasma cells produce antibodies
Memory cells remain as immunity to the pathogen
MONOCLONAL ANTIBODIES;
When an immune response occurs, antibodies specific to the pathogen are produced
are antibodies artificially derived from a single B cell clone (i.e. identical specific antibodies)
ADVANTAGE IN MEDICINE/BIOTECH of monoclonal antibodies
We can produce large numbers of antibodies in the lab to be used therapeutically and diagnostically
POLYCLONAL IMMUNE RESPONSE:
B-cells would respond to multiple epitoptes
what can monoclonal antibodies be used in?
CAN BE USED IN:
Therapeutic use of antibodies to treat rabies
Diagnostic use in pregnancy tests
Monoclonal antibodies are commonly used to provide immune protection for individuals who contract harmful diseases
PRODUCTION OF MONOCLONAL ANTIBODIES
- An animal (mouse) is injected with an antigen and in response produces specific plasma cells
- The plasma cells are harvested from the spleen of the animal
- Harvested plasma cells fuse with tumour cells (which are capable to endless division) forming hybridoma cell
- Hybridoma cells are screened to determine which ones are producing useful antibodies
- The selected hybridoma is allowed to divide to produce clones
- Hybridomas are then used to synthesise large quantities of a single (monoclonal) antibodies for use in diagnostic tests and treatments
how are monoclonal antibodies produced?
Monoclonal antibodies are produced by hybridoma cells;
Immune response is stimulated using the antigen;
specific B-Cells are harvested
B-Cell is fused with myeloma (tumor) cell
Hybridoma makes a large number of clones
Clones produce antibodies which are collected
how are monoclonal antibodies used to treat rabies?
Because the rabies virus can potentially be fatal, injecting purified antibodies functions as an effective emergency treatment
how are monoclonal antibodies used to treat cancer?
Monoclonal antibodies can be used to target cancer cells that the body’s own immune cells fail to recognise as harmful
how are monoclonal antibodies used to test for pregnancy?
Monoclonal antibodies can be used to test for pregnancy via the presence of human chorionic gonadotrophin (hCG) in urine
hCG is a hormone produced by women during foetal development and thus its presence in urine is indicative of pregnancy
Pregnancy tests use a process called ELISA (enzyme-linked immunosorbent assay) to identify a substance via a colour change
Free monoclonal antibodies specific to hCG are conjugated to an enzyme that changes the colour of a dye
A second set of monoclonal antibodies specific to hCG are immobilised to the dye substrate
If hCG is present in urine, it will interact with both sets of monoclonal antibody (forming an antibody ‘sandwich’)
When both sets of antibody are bound to hCG, the enzyme is brought into physicial proximity with the dye, changing its colour
A third set of monoclonal antibodies will bind any unattached enzyme-linked antibodies, functioning as a control
therapeutic monoclonal antibodies
Therapeutic monoclonal antibodies are named according to the source organism from which the antibodies were derived
Mice antibodies (‘-omab’) are easier to synthesise than human antibodies but are less likely to be tolerated by the patient
THE ELISA TEST
In the Elisa test, a tray is coated with antigens for a pathogen
Serum samples are taken from a patient, and if those samples contain the antibody; COLOR CHANGE occurs to show that he/she is carrying the pathogen and the body is trying to find it
EPIDEMIOLOGY
study of incidence, distrubtion and possible control of disease
Surveillance is critical to the control of MEASELES.
dentifying and confirming suspected measles cases allows;
Early detection of outbreaks
Analysis of transmission helps to create more effective vaccination measures
Estimation true measles incidence on reported data- reported incidence reflects a small proportion of the true number of incidences as many affected to not seek health care
what can epidemilogy be used for?
It can be used to compare the incidence of a disease over time (prior and following vaccination programme implementation)
It can be used to compare the incidence of a disease in different regions (both with and without vaccination programmes)
epidemic
substantially increased occurrence of a particular infection within a given region
pandemic
is an epidemic that has spread across a large geographical area (like a continent)
vaccinations
confers immunity to vaccinated individuals but also indirectly protects non-vaccinated individuals via herd immunity
herd immunity
Herd immunity is when individuals who are not immune to a pathogen are protected from exposure by the large amounts of immune individuals within the community
how can diseases be transmitted?
Direct contact – the transfer of pathogens via physical association or the exchange of body fluids
Contamination – ingestion of pathogens growing on, or in, edible food sources
Airborne – certain pathogens can be transferred in the air via coughing and sneezing
Vectors – intermediary organisms that transfer pathogens
without developing disease symptoms themselves
EDWARD JENNER + SMALLPOX VACCINE
1796; cowpox virus inserted into 8 year old boy; SUCCESS (he became immune to small pox)
Second line of defense; adaptive immunity (B cells and T cells; memory cells)
modern issues with edward jenner procedure
UNETHICAL;
No prior research done prior to human testing to measure effectiveness + side effects
Informed consent was not given (choice of a child who was to young to understand the dangers)
what do vccines do
Vaccines used to trigger adaptive immune system; allows an individual become immune without experiencing it (initiate primary immune response to motivate secondary response; memory cell creation remain in the body until actual infection happens so your secondary response is MUCH quicker)
Vaccines contain antigens; in various forms that shouldn’t cause symptoms in a healthy person
By initiating a primary immune reponse, resulting in the production of memory cells that can produce antibodies in response to the antigen
Can be given orally or injected
Vaccines contain antigens in various forms that should not cause symptoms in a healthy person
TYPES of vaccines
Life attenuated vaccines
Inactive/Weakened toxin vaccines
Subunit vaccine
DNA vaccine
Life attenuated vaccines
made of weak pathogen; can be difficult to make and are active
Inactive/Weakened toxin vaccines
dead pathogen
Subunit vaccine
made only of antigen or part of
pathogen carrying antigen; prompts responses
DNA vaccine
genes isolated of pathogen to create the
genes that make the immune response molecules (DNA encondes for antigens rather than the antigen itself)
SMALLPOX;
first infectious disease of humans to have been eradicated by vaccination
Caused by virus variola
WHO declared disease ‘dead’ in 1980
Cowpox is a mild viral infection of cows similar to small pox
other eradication programmes
Eradication programmes for other disease has reduced the number of cases, but has been less successful;
e.g. Polio and measles become contagious before symptoms are easily detected,
yellow fever has animal reservoir (also affects monkeys)
Immunity malaria not complete; can infect same person several times
species specific pathogens vs non. species specific
Some pathogens are species-specific (Polio, Measles and Syphilis are human specific)
Flu, Ebola and Salmonella can be transmitted between humans and other animals
Zoonosis is a diseases that is transmissible from vertebrate animals to humans
ALLERGEN:
environmental substance that triggers an immune reponse depite itself not being intrinsically harmful
Immune response tends to be localized on region of exposure (throat or eyes)
ANAPHYLAXIS
Severe systematic allergic reaction; ANAPHYLAXIS can be harmful if left untreated
allergen action
An allergic reaction requires a pre-sensitised immune state (i.e. prior exposure to the allergen)
When a specific B cell first encounters the allergen, it differentiates into plasma cells and makes large quantites of antibody (IgE)
The IgE antibodies attach to mast cells, effectively ‘priming’ them towards the allergen
Upon re-exposure to the allergen, the IgE-primed mast cells release large amounts of histamine which causes inflammation
WHAT CAUSES ALLERGIC REACTIONS?
The release of histamine from IgE-primed mast cells causes an inflammatory response that results in allergic symptoms
Inflammation
Vasodilation
Capillary permeability
symptoms of an allergic response
Redness, heat, swelling and localised pain
inflammation in allergy respone
improves leukocytes mobility to infected regions by triggering vasodilation and increasing capillary permeability
vasodilation in allergy reponse
is the widening of blood vessels to improve the circulation of blood to targeted regions
Vasodilation causes redness (as vessel expansion moves blood closer to the skin) and heat (which is transported in blood)
capillary permeability in allergy response
describes the capacity for leukocytes to leave the bloodstream and migrate into the body tissue
Increased permeability leads to swelling (more fluid leaks from the blood) and pain (swelling causes compression of nerves)
sensitization
(intial exposure to allergen)
1. allergen (e.g. pollen) enters bloodstream
- B Cells differentiate into plasma cells and make antibodies
- antibodies attach to mast cells
allergic reaction
(secondary exposure to same allergen)
- allergen binds to antibodies on mast cells
- histamine is released from mast cell
- alleric reaction ensues
lympathic system
Secondary transport system that protects and maintains the body by producing and filtering LYMPH
Absorbs fat from gut + other fluids (LIPID TRANSPORT + BLOOD PRESSURE)
LYMPTH:
a clear fluid that contains white blood cells + arises from the drainage of fluid from the blood and surrounding tissues
Filtered at points called lymph nodes (pathogens are removed before blood returns to circulation)
lymph organs
- spleen
- tonsils
- tymus
- adenoids
immune disorders
- hypersensitivity
- autoimmune disorders
- immunodefiency disorders
hypersenstivity
Refers to excess immune response to inherently unharmful substance (allergen)
Such reactions require a pre-sensitized immune state with excessive reaction occurring upon re-exposure
E.g. allergic reactions (localized hypersensitive conditions), anaphylaxic (severe, systemic)
autoimmune disorders
Autoimmunity occurs when the immune system fails to recognize body cells as ‘self’ and target its own cells and tissues
Some pathogens try to invade immune detection by producing antigens similar to host markers (results in production of antibodies that recognize and target markers on body cells)
E.g. diabetes I, rheumatoid arthritis, multiple sclerosis
immunodeficiency disorders
State in which the immune system’s capacity to fight infection is compromised/absent
Some inherited; SCIDS
Pathogen in origin (AIDS
Drug treatments (cytotoxic drugs cause
immunosuppression; usually used in organ transplant to avoid organ rejection)
TYPES OF IMMUNITY;
active immunity
passive immunity
active immunity
involves production of antibodies by the body itself + subsequent development of memory cells
Results in long term immunity
Natural; producing antibodies in response to pathogenic infection
Artificial; use of vaccines (producing antibodies in response to the controlled exposure to an attenuated pathogen)
passive immunity
Passive immunity: results from the acquisitions of antibodies from another source and hence memory cells aren’t developed
Natural; receiving antibodies from another organism (e.g. fetus via placenta from mum/breastmilk)
Artificial; receiving manufactured antibodies via external delivery (blood transfusion of monoclonal antibodies)
Humoral immunity
describes the pathway by which antibodies are produced by B-lymphocytes to target exogeneous antigens
humoral immunity action
When macrophages engulf pathogens; they digest them within lysosomes to release antigenic fragments
These fragments are present on special surface recetprs (DENOTE MATIERAL AS BEING FOREIGN)
Antigens are presented to helper T-Cells which in turn secrete cytokines to activate B-Lymphocytes
Specific B-Lymphocytes divide + differentiate to form antibody producing plasma cells
Cell-mediated immunity:
describes a pathway that doesn’t result in antigen production but instead targets endogenous antigens
cell mediated immunity action
Cancerous + virus-infected cells involve the body’s own cells (thus aren’t recognized as foreign and evade normal detection
These cells may instead present antigenic fragments as self markers
When helper T-Cells identify these cells; they stimulate a second type of T-lymphocyte (Tc Cells; cytotoxic cells)
Tc Cells show specificity to a particular antigen + will bind to the presented antigen and release perforating enzymes
These enzymes cause the infected/cancerous cells to be lysed + prevent further infection
Virus infected cells can also be destroyed by nonspecific NK cells (respond to interferon released by infected cells)
diseases that can cross over species?
- HIV/Aids
- ebola
- SARS
- H1N1
two problems in moncolonal antibody procedure?
- keeping B-cells alive for extended period of time
2. identifying B-cell type that produces the antibody that recognizes desired antigen
endoskeleton
internal skeleton (internal bones)
exoskeleton
an external skeleton that surrounds and protects most of the body surface of an animal e.g. crustaceans and insects
- made up of chitin instead of bone
species with good leverage potential
- asian weaver ant (Oceophylla smaragdina)
2. flea (Ctenocephalides felis)
how do bones and exoskeletons facilitate movements?
providing an anchorage for muscles and by acting as levers
levers
change the size and direction of forces; relative of these positions determine class of lever;
Effort force
Pivot Point (Fulcrum)
Resultant Force
Muscles are attached to the insides of exoskeletons but to the outside of bones
Movement of the body requires muscles to work in antagonistic pairs
Skeletal muscles occur in pairs; one contracts as the other relaxes (Antagonistic)
Antagonistic muscles; produce opposite movements at a joint
E.g. elbow; triceps extends the forearm while the biceps flex the forearm
insect leg antagonistic muscles
Grasshopper has three pairs of appendages; the hindlimb is specialized for jumping
Below the joint; tibia
At the base of the tibia another joint below is found called the tarsus
Above the joint; femur relatively massive muscles found there
grasshoper jumps;
When a grasshopper jumps;
Flexor muscles will contract bringing the tibia and tarsus into a position where they resemble the letter Z and the femur and tibia are brought closer together (FLEXING);
extensor muscles relax at this phase
When extensor muscles contract; the tibia extends= powerful propelling force
humerus bone
to which biceps and triceps are attached
example of synovial joint?
human elbow
triceps
extends the joint
biceps
flexes the join
joint capsule
seals the joint and helps to prevent disolocation
synovial fluid
lubriates the joint and prevents friction
- provides nutrients to cells of cartilage
ulna bone
to which triceps are attached; acts as a leveer for triceps muslce
cartilage
covers the bones and prevents friction and absorbs compression
radius bone
to which the biceps are attached; acts as alever for biceps muscle
what do synovial joints alllow?
for certain movements but not others
knee joint
acts as a hinge joint to allow only two movements;
1. flexion (bending)
- extension (straightening)
- can act as a pivot point when flexed
when does the knee have the greatest movement range?
when flex and extedned
structure of a joint
The structure of a joint (including joint capsule + ligaments) determines possible movements
hip joint
between pelvis and femur; is a BALL AND SOCKET joint
-has great range of movmenet than kneed joint in that it can flex, extend, rotate and move sideways and back (abduction and adduction)
skeletal muscle fibres
- are multinucleate
- contain specialised endoplasmic reticulum
skeletal muslces
used to move the body and attached to bones
striated muscles
- there are clear trips (other muscles are smooth and cardiac)
- composed of muscle cells called muscle fibres surrounded by plasma membrnae (SACROLEMMA)
muscle fibres
Many nuclei present + muscle fibres are longer than typical cells; these features are due to the fact that embryonic muscle cells fuse together to form muscle fibres
- contain sacropaslmic reticulum
- contain many mitchondria for ATP for contraction etween myofibrils
sacroplasmic retriculum
- muscle fibres contain a modified endoplasmic reticulum
- extends through muscle fibre and wraps around every myofirbril conveying the signal to contract to all parts of muscle fibre
- also store calcium
myofibrils
parallel, elongated structured
- have alternating light/dark bands (gives striated muslce its stripes)
- centre of each light band is disce shapped and called Z-line
- muscle fibres contain many
contracticle sacromeres
- make up myofibrils
- centre of light area called Z line
- repeating units of light and dark bands due to arrangement of two types of proteins (thin actin and thick myosin)
sacromere
(the part of the myofbiril between one Z line and next is called the sacromere; functional unit of myofibril)
actin
- thin
- attached to Z line at one end
myosin
- interdigitate diwth actin filaments at both ends
- occupy qcenter of sacromere
- thick
how is the contraction of skeletal muscles achieved?
- by the sliding of actin and myosin filaments
mechanism of skeletal muscle contraction
- Myosin filaments pull actin filaments inwards towards centre of sarcomere; shortening the sarcomere + overall length of muscle fibre
2 Contraction occurs by the sliding actin and myosin filaments
- Myosin filaments cause this sliding; have heads that can bind to special sites on actin filaments creating cross bridges through which they exert force using ATP
- Heads are regularly spaced along myosin filaments
- Binding sites spaced regularly along the actin filaments; many cross bridges can form at once
how is skeletal muscle contrcation controlled?
- by calcium ions
- by proteins; tropomyosin and troponin
tropomyosin
- regulatory protein that blocks binding sites of actin in relaxed muscle
calcium ion action in movement
- motor neuron sends signal ot muscle fibre to contract
- causes sacropaslmic reticulum to release calcium ions
- calcium ions bind to protein (troponin) which causes tropomyoson to move and for the ACTIN filament binding sites to be exposed
- myosin heads then and bind to the centre of the sacromere moving the actin filaments a smal distance
role of ATP in sliding filaments
ATP hydrolysis and cross bridge formation needed for filaments to slide
Sequence of stages of ATP role in sliding filanents
- ATP causes the breaking of the cross-bridges by attaching the myosin heads causing them to detach from the binding sites on actin
- Hydrolysis of ATP to ADP from phosphate; provides energy for the myosin heads to swivel outwards away from the centre of the sacromere; ‘cocking of the myosin head’
- New cross bridges are formed by the binding of myosin heads to actin at binding sites adjacent to the ones previously occupied (each head binds to a site one position further from the centre of the sarcomere)
- Energy stored in the myosin head when it was cocked causes it to swivel inwards towards the centre of the sarcomere moving the actin filament a small distance.
- This sequence of stages continues until the motor neuron stops ending signals to the muscle fibre
- Calcium ions are then pumped back into the sarcoplasmic reticulum so the regulatory protein movs and covers the actin binding sites= MUSCLE FIBRE RELAXES
USE OF FLUORESCENCE TO STUDY CONTRACTION
Fluorescence has been used to study the cyclic interactions in muscle contractions.
- Fluocorscene can be detected by a light microscope and capture on film for analysis
what does fluorenscne use portray?
ATP depedence of myostin-actin interaction
nisella axillaris cells
- researches cut open Nisella axillariss cells; unique in that they have a network of actin filaments underlying their membranes; researches attached fluorescent dye to the myosin muscles to show how myosin can ‘walk along’ actin
acorn barnacles
- Scientists have studied the contraction of the giant single muscle gibres on the acorn barnacle by injecting samples of the muscle with aeqourin (calcium sensitive protein ); bioluminscene resulted from the release of the calcium ions
synovial joint
bone to bone joints where there is self contained capsule area that contains a lubricant called synovial fluid
tendons
attach muscle to bone
ligaments
connect bone to bone
types of muscle tissue
smooth muscle
cardiac muscle
skeletela striated muscle
sacroplasm
- cytoplasm of muscle fibres
- contain glycogen as energy reserve
- contains myoglobin which provides and stores oxygen
sliding filament theory of muscle contraction
- myosin heads are activated by splitting ATP; this causes a chane in the positions of the heads
- myosin heads are attracted to and attach to exposed binding sites of actin to form cross bridges
- as myosin forms cross brdiges, ADP is released and tme myosin bends tue to loss of energy; bending towards centre of sacromere and actin is moved inwards
- myosin binds to ATP and this allows for detachment of myosin heads from the actin attachement sites
steps of muscle contraction
- motor neurone carries action potential unit it reaches the neuromuscular junction
- neurotransmitter (acetylecholine) released into synaptic gap between neurone end buttons and sacrolemma of muscle fibre
- acetylcholine binds to receptors on sacrolemma
- sacrolemma ions channels opens and sodium ions move through membrane
- resulting action potential moves through the T-Tubules causing teh release of caclium ions from sacropaslm
- released calcium ions flood onto sacroplasm
- myosin heads then attach to binding sites on actin
- myosin heads all flex towards sacromere centre
- entire sacromere shortens as Z lines move towards each other
- ATp binds to myosin head resulting in detachment of myosin from actin and awaiting new action potential from motor neurone
excretion
removal of bodies waste products of metaolism
-carried out by kidney
diuretic
caffiene and alcohol; increase passing of urine
metabolic waste; nigrogen
fish and amphibians; constant access to water their flush their nitrogeneious waste as ammonia
mammalas; metabolize ammonia into molecules called urea
reptiles and birds;
package their nitrogenous waste as uric acid
osmoregulators
tightly regulate their body osmolarity which always stays constant, irrespectve of their environment
- much more common in animal kingon
kidney role in osmoregulation
- regulating amount of water reabsorved
- a disadvantage as osmoregulation costs animals ATP
osmoregulation in freshwater fish
- food enters fishs mouth along with ions (Na+, K+ Cl-) and water
- water absorved by skin too
- active ion uptake through gills
- dilute urine is expelled at end of fish
osmoregulators
- needs ATP
- cost animals ATP
- use kidney
- tightly regulate their body osmolarity to keep it constant irrespective of environemnt
- homeostasis
- found in fish and other marine invertabres
- ion control
osmoconformers
- no ATP
- disadvatange as internal conditions must be sub optimal
- maintain an internal conditions taht are equalt o the osmolarity of their environemnt
- -homeostasis
- found in fish and other marine invertabres
- ion control
ammonia
- fish
- requires little energy to produce
- very toxic in blood and tissues; must be diluted and removed quickly by a lot of water
urea
- mammals
- requires less enerty to produce compared with uric acid
- toxic in blood and tissues
- requires more energy than ammonia, only some water for dilution and removal from body
uric acid
- birds
- relatively insoluble in aqueous solutions such as blood and cyoplasm
- stored in specialized structures within animal eggs
- little to not water for dilution and removal ob body
- complex structure requires a great deal of eneryg ot produce
nitrogenous waste execretion in insects
- insecst have open circulatorysystem; so their blood is sometimes outside veseels
- body cavities of insects have Malpighian tubules; tubes connecteed by distal and proximal ends
- selective reabsorbtion occurs here
- nitrogenous waste and excess water move thourgh Malpighian tubules to proximal end that empties into the gut so waste eliminated along with feacus
how is the kidney like a dirty fridge?
- take out all contents in blood and filter them into water and non waste
where are kidneys in the body?
Dark red, bean shaped on each side of the spine along the posterior wall, between the dorsal wall and the peritoneum (not in abdominal cavity where digestive system is)
how do kidneys work?
Continuously filter blood; hold 20% of total blood volume
Branching into capillaries, each with filtering units (NEPHRONS)
- Filtration, reabsorption and excretion
renal/bowmans capsule
ultrafiltration
glomerus
delivers blood
proximal convulated tubule
selective reabsorbtion
distal convulated tube
secretion of toxins into urine
loop of henle
osmoregulations
collecting duct
delivers urine to pelvis
nephrons
carry out ultrafiltractions, reabosrbtion and secretion in the production of urine
ultrafiltrations
- nearly all the substances (water and other molecules such as drugs and glucose) are filtered out of the blood exept blood cells and proteins
- enter through pailiary wall to bowmans capsule from glomerus
capilary wall
-has
fenestrated pores
-basement membrane has these pores to allow passage of small molecules and block large molecules from leaving plasma
-passive process
podocytes
provide support to capillaries
basement membrane
act as filter to only allow certain sized molecules into bowmans capsule
capillary endothelium
pores found in capillary endothelium which allow certain size molecules to pass through
process of ultrafiltration
Ultrafiltration occurs in the renal artery, in the cortex of the kidney
- Blood enters through the afferent arteriole and leaves the efferent arteriole
- The afferent arteriole is much larger than the efferent arteriole; this causes high pressure in the renal artery
- Water, glucose, amino acids and solutes are forced out of blood (including metabolic wastes) through fenestrated capillaries and basement membrane
- Podocytes acts as filters; plasma proteins and blood are large so they remain in blood stream
- Glomerular filtrate is carried through the nephron where selective reabsorption takes places in the proximal convoluted tubule
What is the difference between an osmoconformer and an osmoregulator?
Osmoregulators need ATP and use kidneys, whereas osmoconformers are passive
glomerulus
Glomerulus; network of capillaries at beginning of nephron in bowman’s capsule
Aids in filtering process of blood
what does the bowmans capsule do?
filters the glomerular filtrate into the proximal tube
kidney renal corpuslce
composed of tangled clusters of blood capillaries, called a glomerulus, and a thin-walled, saclike structure called the Bowman’s capsule, which surrounds the glomerulus.
bowmans capsule structure
The Bowman’s capsule is composed of two layers of cells:
an inner layer that closely covers the glomerulus, and an
outer layer that is continuous with the inner layer and with the wall of the renal tubule
Proximal convoluted tubule:
The swirly one; the one that joins the bowman’s capsule to the loop of henle
Main job is reabsorption of ions, glucose and water
Contains microvilli for larger surface area
Pulls sodium ions back into blood stream
loop of henle function
recovery of water and sodium chloride from urine
firest segement of loop
descending limb; permeable to water so liquid reaches the bend of the blpoop is much richer than blood plasma in salt and urine
-liquid returns through ascending limb; sodium chlroide diffuses out of tubue into surrounding tissue where concentration is lower
third segement of loop
tubuel wall, if needed, removes further salt against concentration gradient
(NEEDS ATP)
strucutre of loops of hendle
- long curly shape for max time for reabsorbtion
- starts in cortex, dips into medulla, back to cortex
loops of henle primary task
-creates hypertonic environment in the medulle oaf th ekidneuy
drive reabsrobtion of water by creating salt concentration gradient
collecting duct task
reasbortion of water; balacne water concentraiton in blood
ADH in collecting duct
- body uses negative feedback when body is dehydrated
- hormone ADH causes aquaparines in channels in wall to factiliate osmosis
- ADH released by pituitary gland increases permataiblity of walls in distal convulated tubule to increase body water amount
homeostasis
the body’s ability to maintain a stable internal environment
factors that affect osmoregulation
- total volume of water ingested
- pesperiation rate (influence by environmental tempearture and excersize)
- ventilation rate
proximal convulated tubule structure
- one cell thick
- ring of cells
- intertior is called lumen where the filtrate flows through
- tubule cells have microvilli to increase surface area for reabosrbtion
what happens when ADh is present?
= collecting duct becomes permeable to water and water moves by osmosis out of collecting duct and into medulla intersittial fluid
what happens when adh is NOT present
- colelcting duct is impermeable to water
- so water stays in collecting duct and urine is more dilute
adaptions to water consevation
- longer loop of henle
- wate rintake of kangaroo rats comes from foods they eat; only venture out at night when water is cooler to reduce water loss
what changes to the kidneys make to the blood?
- lower urea
- lower salt ion
- lower water amount
- nearly identical amount og fluocse and proteins
- no change to blood cells
kidney failure
- two options abailbe; kidney dialysis/ haemodulais
Kidney transplamt
testing urine for chemical composition
- glucose needs to be completly reabsrobed
- no blood cells should by in urine
- no proteins should not be in urine
- no drugs should be in urine
dehydration
sleepiness
contipation
dry mouth and skin
dizzines and headache
overhydration
change in bheaviour/confusion
blurred vision
muscle cramps
nausea and vomitting
haemodialysis
- patients blood pumped into device with large surface area of a membrane
- patiens blood on one side, dialysate solution on other
- urea is small enough molecuel to diffuse out of membrane
- basically balances water, salt, glucose and urea balancein body
- repeated sessions needed every 1-3 days
kidney transplant
- transplated organs need to have matching donor-patient tissues in order to minimize rejection
- usually family member used
- after recieving transplated kidney; person must need immune suprresing drugs
follicle cells
provide nutrients to support the early development of a fertilize d egg
zone pellucida
conssits of a glycoprotein that protects the egg and prevents sperm entry
1st polar body nucleus
not required; will break down
nucleolus
haploid (n) contains 23 chromosomes to be passed from mother to child
cytoplasm
contains nutrients to support early developments of fertilized egg
cortical granules
make the zone pellcuidea impenetrable to sperm post-fertlization to prevent polyspermy
spermatogensis
- production of male gametes by meiosis
- occurs in testes; in seminiferous tubules
- each spermatogonium capable of mitosis/meisosis (germinal epithelial cells)
mitosis and spermatogenia
- to replish their numbers
- spermatozoa production starts at puberty and continues throughout life; mitosis replaces cells that become spermtozoa
meiosis and spermatogenia
- produce spermtazoa
- reduction division of diploid to haploid number of chromosomes
- spermatognia replicate DNA in diploid nucleus and then undergo cell growth in prep for cell division
single chromosome
a pair of chromatids connected by a centromere
steps of spermatogensis
interphase:
- DNA replication so each of the 46 chromosomes now exsit as a pair of chromatis
Meiosis I:
-two cells result weach with haploid number of chromosomes (each chromosome stile xists as a pir of chromatids)
Meisosis II;
- chromatids are seprate two produce four halpod cells created from original diploid
what happens after meisosis in spertmagotenesis
- each cell must differentiate into functioning, motile spermtazoon
- cells remain in seminiferious tubule untill they form the cellulcular structural characteristics of sterm
characteristic structures of spermtazoon
- flagellum for mobility
2. acrosome with enzymes for fertliziation
what happens when spermatazoon have matured?
- detach from the sertoli cell and move towards the lumen to the storage area of testis called epididmis
oogensis
production of female gametes by mitosis
produces 4 cells as end products, but three aren’t used (polar bodies)
-fourth haploid cell produced is large and is the ovum
events occuring before birth
- cells called oognoia undergo mitosis to build up number of oogonia in ovaries
0oocongia grow into primary oocytes
–both oogonia and primary oocytes are idploid cells (undergo meisosis)
-process of meisosis stops during prophase I - cells called follicle cells undergo mitosis to surround the primary oocyte (forming primary folliciles); remain unchange duntil girl in puberty
oogensis process
- During fetal development large numbers of oogonia are formed by mitosis
- Oogonia enlarge and undergo meiosis, but stop in prophase I (until puberty). They are now termed primary oocytes and are held in primary follicles
(AT PUBERTY) some follicles develop each month in response to FSH - The oocyte completes the first meiotic division
- Division of the cytoplasm is unequal creating a polar body
- The secondary oocyte continues into meiosis II and halts at prophase II
- Secondary ooctyes develop along with the follicle. When the foolicle is masture it ruptures to release the secondary oocture with a small number of cells (the mature egg) into the fallipian tube. The reamining follicle cells remain in the ovary to form the CORPUS LUTEUM (which secretes progresterone)
- The oocyte completes meiosis II (forming the ovum) if the cell is fertilized and another polar body
spermatogensiss contrast
- occurs in testes
- millions produced daily
- released during ejactulation
- beings at puberty
- continues throughout life
- 4 sperm made per meiosis
- polar bodies not produced (equal division)
- cytoplasm reduced in sperm
- sperm are motile
oogensiss contrast
- occurs in ovaries
- one/few produced monthly
- released during ovultion
- egg production beings before birth
- production stops at menopause
- only one egg produced per meiosis
- polar bodies produced/uneven distribution of cytoplasm
- cytoplasm not ehnahnced in eggs
- eggs not motile
spermatogensisis + oogensis compare
- both start with germ gells
- both start with mitosis to produce many cells
- both involve cell growth before mitosis
- both involve mieosis to produce haploid cells
internal fertilization
most mammals; prevents dehydration of gametes
- parents must care for animals; childbirth and raising the child
external fertilization
awuatic species ferlization (fish and amphibians); sucestible to environmental variation; large quantities of eggs produced to compensate loss;
parents dont provide parental care
gestation period
period pf pregnancy
- humans have 9 month period
fertliization producess
- sperm pushes through follicular celsl and bind to receptors in zona pellucida
- enzmes are relased from acrosome and digest glycoprotein based zona pellucida
- membranes of sperm and ova fuse
- exosytosis cortical granules release protease enzymes into zona pellucida to harden it and become impnetrable to sperm (prevent polyspermy)
- influx of calcium 2+ ions into ova to prompt meiosis II completion
- nucleus of sperm cell is deposited into ova’s cytoplasm to fuse wiht ova nucleus and form diploid zygote cell
simple fertlization overview
- many sperm cell needed to achieve fertilization
- sperm cells push thorugh follicle cells
- first sperm to reach zona pellcudia uses acrosome enzymes
- acrosome enzymes allow for cell membranes of sperm and ovum to meet and fuse
- fusion of membranes result in cortical reaction
- haploid nucleus of sperm enters ovum; restores diploid number
polyspermy prevention in sea urchings
- revesr electrical charge upon first fertilization
- sea urchin ova have negative charge inside, when first spermatazoon fertilizes ovum charge is made positive to repell further spermtazoa
matierals exchaged between maternal and foetal blood in placenta
maternal blood to fetal blood:
- oxygen, glucose, lipids, water, amino acids, antibodies, hormones, drugs
foetul bloo to maternal blood;
carbon dioxide, urea, waste, water, hormones
early development
- implantation into endometrium by blastocystes
- fertilization stimulates zyogte to being mititoci division to create blastocyst
blastocyte charactersitics
- surrounding layer of cells called the trophoblast which help the foetal portion of the placenta
- group of cells called inner cell mass which become the body of teh embryo
- bluid filled cavity
why is the human ovum so large?
contains nutrients needed for early embryonic devvelopment that will be sued for metabolism
placenta structure
The placenta is a disk shaped structure that nourishes the developing embryo
It is formed from the development of the TROPHOBLAST upon implantation and eventually invades the uterine wall
Umbilical Cord; connects the foetus to the placenta and maternal blood pools via open ended arterioles into intervillous spaces
Chorionic villi; extend into these spaces and facilitate the exchange of materials between the maternal blood and fetal capillaries
Nutrients, oxygen and antibodies will be taken up by the fetus, while carbon dioxide and waste products will be removed
The placenta is expelled from the uterus after childbirth
functions of placenta
- production of estrogen and progesterone
- exchange of molecules between maternal and foetal blood
- maintaining pregnancy
what do progesterone and estrogen do?
prevent menstratuion by building up the endometrium
progestrone
- helps maintain the highly bascular tissue characteristic of the uterus/placenta
- suppresses contractions of smooth muscle of the uterus
oestrogen
- encourages muscle growth of the uterus
- antagonizes action of progestrone to suppress urine contractions
- stimulates mammary glad devvelopment late in pregnancy in prep for milk production
- induces production of oxytocin receptors in uterine muscle late in pregnanacy
placenta formation
The placenta begins to form when the fetus develops a villus, a finger-like growth into the uterus.
The number of villi increases steadily to meet the needs of the growing fetus.
Maternal blood flows out of capillaries into inter-villous spaces surrounding each villus.
Fetal capillaries are very close to the surface of each villus (within 5 µm of the maternal blood).
The cells separating fetal and maternal blood form a selectively permeable barrier known as the placental barrier.
Microvilli project from each villus to increase surface area, which allows rapid diffusion of molecules.
Nutrients and O2 diffuse from maternal blood to fetal blood, and carbon dioxide diffuses from fetal blood to maternal blood.
Fetal blood flows toward the placenta in the umbilical artery, and away from the placenta in the umbilical vein.
ib response of placenta strcuture and function
During the first 2-4 weeks of development, the embryo obtains nutrients directly from the endometrium (the uterus lining).
Tissues grow out of the developing embryo and mingle with the endometrium to form the placenta.
Diffusion of material between the maternal and embryonic circulatory systems via the placenta provides nutrients, exchanges respiratory gases, and disposes of metabolic wastes from the embryo.
Blood from the embryo travels to the placenta through the arteries of the umbilical cord and returns through the umbilical vein.
The embryo secretes hormones that signal its presence and controls the mother’s reproductive system.
HCG acts like luteinizing hormone to maintain secretion of progesterone and estrogen.
Placenta is expelled from the uterus after childbirth
oxytocin
- postive feedback mechanism
- hormone produced in hypothalmus and secreted by pituitary gland
- when birth time ahs come, oxytocin will stimulate contractions in uterus to cause birth
HCG role in early pregnancy
The endometrium is a blood rich environment in which an implanted zygote can grow and it is sustained by the hormone progesterone
If progesterone levels aren’t maintained then the endometrium will be sloughed away (menstruation)
A fertilized zygote develops into a blastocyst that secretes human chorionic gonadotrophin (hCG)
hCG maintains the corpus luteum post-ovulation so that the blastocyst can remain embedded in the endometrium and continue to develop
Gradually the placenta develops and produces progesterone (at around 8-10 weeks), at which point the corpus luteum is no longer needed
HOW THE FETUS IS SUPPORTED + PROTECTED BY THE AMNIOTIC SAC/FLUID:
The fetus develops in a fluid-filled space called the amniotic sac
Amniotic fluid is largely incompressible and good at absorbing pressure; and so protects the child from impacts to the uterine wall
The fluid also creates buoyancy so that the fetus dos not have to support its own body weight while the skeletal system develops
Amniotic fluid prevents dehydration of the tissues, while the amniotic sac provides an effective barrier against infection
Interstitial cells
Interstitial cells: produce testosterone
Spermatogonia
Spermatogonia; divide to produce spermatocytes
Sertoli cells
Sertoli cells: nourish developing spermatozoa
Developing spermatozoa
Developing spermatozoa; almost complete sperm cells
Germinal epithelium
Germinal epithelium: outer layer of cells in the ovary
Primary follicle:
Primary follicle: contain the primary oocyte surrounded by a single layer of supporting follicle cells
Mature follicle
Mature follicle: contains the secondary oocyte ready for ovulation
Secondary oocyte
Secondary oocyte: haploid gamete; final stage of meiosis occurs after fertilization
Medulla:
Medulla: central main body of ovary (blood vessels, lymph and nerves)
Zona pellucida:
Zona pellucida: outer layer of ovum
Troponin
Troponin: molecules are bound to tropomyosin and contain calcium ion binding sites
Tropomyosin:
Tropomyosin: is wound around the actin
Actin
at edge; form a helix of actin-subunits with a binding site for myosin heads
- has tropomyosin wrapped around it attached to troponin
Myosin
Myosin thick and internal
Each ends in a myosin head contains ATPase; for muscle contraction ATP use
sacromere muscle contraction
Ca2+ released from sarcoplasmic reticulum
Bind to troponin; cause tropomyosin to move
Actin filament myosin binding sites now free; Myosin cross bridge attaches the actin myofilament using ATPase
Power stroke; myosin head pivots and pulls on the actin filament sliding down the M line
New ATP attaches to myosin head and cross bridge detaches
ATP split back into ADP and Pi; cocking of myosin head occurs
