Animal Physiology Flashcards
What is the function of the immune system?
capacity to distinguish between body cells (‘self’) and foreign materials (‘non-self’). react to the presence of foreign materials with an immune response eliminating materials from the body.
What are MHC class I molecules and what is their function?
nucleated cells of the body possess unique and distinctive surface molecules that identify it as self. These self markers are called major histocompatibility complex molecules (MHC class I) and function as identification tags. Immune system wont react to them
What is an antigen and how are they recognised by lymphocytes?
A foreign substance triggers an immune response called an antigen. Antigens are recognised by lymphocytes which bind to and detect the characteristic shape of an exposed portion (epitope)
What are antigenic determinants and what are some examples?
specific sites on an antigen that are recognised by the immune system.
- surface markers - foreign bodies in the blood and tissue
- self-markers of cells
- proteins from food - rejected unless they are first broken down into component parts by the digestive system
What is the significance of self markers in the immune system?
Self markers prevent immune rejection of tissue from an individual’s own organism but limit transplant compatibility between different organisms.
Do red blood cells possess the same self markers as other nucleated cells?
Red blood cells are not nucleated and hence do not possess the same distinctive and unique self markers as other body cells.
What is the ABO blood system?
The ABO blood system is a classification system based on the presence of A and B antigens on the surface of red blood cells.
What are A and B antigens?
A and B antigens are surface glycoproteins present on red blood cells, either independently or in combination.
What does it mean if a person has type O blood?
If a person has type O blood, they possess neither A nor B antigens on their red blood cells
What is the significance of the Rhesus factor in blood transfusions?
The Rhesus factor is a glycoprotein present or absent on red blood cells that affects blood transfusion compatibility.
-Pathogens
- cause disease (disturbs the normal functioning of the body)
- generally species-specific in that their capacity to cause disease (pathogenesis) is limited to a particular species
zoonotic diseases
Diseases from animals that can be transmitted to humans
Disease Transmission
- Direct Contact - physical association
- Contamination - ingestion
- Airborne - air via coughing and sneezing
- Vectors - intermediary organisms that transfer without developing disease symptoms themselves
Non Specific VS Specific immune reaction
Non Specific - macrophages will engulf pathogens non-selectively and break them down internally
Specific - dendritic cells present antigens to lymphocytes. B and T lymphocytes recognize a specific antigen
Specific Immune response
- TH cells are activated by antigenic fragments presented by dendritic cells and release cytokines that stimulate specific B cells.
- Clonal selection occurs, resulting in the production of short-lived plasma cells and long-lived memory cells.
- Pathogens contain multiple distinct antigenic fragments that stimulate a variety of specific antibodies.
Specific B Lymphocytes
Activated then divides into plasma and memory cells. Plasma cells - Secretes high numbers of antibodies
Antibody function
- Precipitation – Soluble pathogens become insoluble and precipitate
- Agglutination – Cellular pathogens become clumped for easier removal
- Neutralisation – Antibodies may occlude pathogenic regions
- Inflammation – Antibodies may trigger an inflammatory response within the body
- Complement activation – Complement proteins perforate membranes
Clonal Expansion
An adaptive immune system is when plasma cells produce a lot of antibodies.
- Delay between initial exposure to a pathogen and the production of large quantities of antibodies. pathogens can reproduce rapidly during this delay period, they can impede normal body functioning and cause disease
what is produced to prevent delay during clonal expansion
Memory Cells
How do memory cells work
- B cell is activated which forms memory cells and some differentiate to form memory cells
- They live for a long time and produce low levels of antibodies that are constantly circulating
- So therefor when a pathogen re-enters the system the memory cells act more vigorously to produce more antibodies
- As the antibody is produced faster the pathogen cannot reproduce enough
Allergen
An environmental substance that triggers an immune response despite not being directly harmful
- severe allergic reaction is called anaphylaxis (can be fatal)
How an allergic reaction happens
- Specific B cell encounters the allergen it creates plasma cells hence antibodies (lgE)
- These specific lgE antibodies attach to mast cells which will prime them towards the allergen
- Once reexposed the lgE-primed mast cell will release a large amount of histamine causing inflammation
What can inflammation improve
Leukocyte mobility to infect regions by triggering vasodilation and permeability
Vasodilation - cause redness and heat as it increases circulation
Permeability - cause swelling more fluids leak from blood
Vaccination
The weakened pathogen is injected into blood stream unable to cause harm. This allows the body to detect it and create memory cells. Which will help to improve delay time.
Herd immunity
Individuals who are not immune to a pathogen are protected from exposure by the large amounts of immune individuals within the community
monoclonal antibodies
artificially derived from a single B cell clone (identical specific antibodies)
How monoclonal antibodies work
- An animal is injected with an antigen which is able to produce antigen-specific plasma cells
- Cells are removed and fused with tumour cells that allow for division
- This allows for a large synthesis of monoclonal antibodies
Where can monoclonal antibodies be used
- Treatment
- Diagnostic (pregnancy test)
Movement Systems
skeletal system - bones
muscular system - muscles to deliver force
nervous system - delivers signals to the muscles
Movement Systems
skeletal system - bones
muscular system - muscles to deliver force
nervous system - delivers signals to the muscles
Skeletal system
the skeleton can be internal or external depending on the organism.
- endoskeleton - consists of numerous bones
- exoskeleton - compromised of connected segments. Acts as levers moving in response to muscular contractions.
- bones connected to other bones by ligaments and muscles by tendons
Synovial joints
capsules that surround the articulating surfaces of two bones. only allow certain movements
- Joint capsule - seals the joint spaces and provides stability by restricting the range of motion
- Cartilage - Lines the bone surface and facilitates smoother movement
- Synovial Fluid - Provides oxygen and nutrition to the cartilage
Joints in order of mobility least to most
Plane joints, hinge joints, pivot joints, condyloid joints, saddle joints, ball and socket joints
Hinge joint
capable of angular movement in one direction
What is a static bone
what the muscle connects to as a point of origin
Antagonistic pairs
When skeletal muscles have one contract and the other relaxes
Insect exoskeleton
hind legs are specialized for jumping. They are divided into 3 (femur, tibia, and tarsus).
Connected through two antagonistic muscles: flexor tibiae muscle, extensor tibiae muscle
The organisation of Skeletal Muscles
- Skeletal muscles have tightly packaged muscular bundles (fascicles) surrounded by connective tissue (perimysium)
- Each bundle has multiple muscle fibres formed by the fusion of individual muscle cells
- Muscle fibres contain tubular myofibrils that run the length of the fibre
- Myofibrils are divided into repeating sections called sarcomeres
- Sarcomeres represent a single contractile unit responsible for muscular contraction
Muscle Fibre Structure
- Multinucleated
- A large number of mitochondria (muscles require ATP hydrolysis)
- Specialised endoplasmic reticulum
- contain tubular myofibrils made up of two different myofilaments – thin filament (actin) and thick filament (myosin)
- the continuous membrane surrounding the muscle fibre is called the sarcolemma and contains invaginations called T tubules
Myofibrils
Muscle fibre
Sarcomeres
fibre inside the myofibrils that are made of two protein myofilaments. Repeating unit of the two overlap
Myosin - Thick filament
Actin - Thin filament
Actin and Myosin
Actin has a tropomyosin that coils around it the overlaps between the two are called troponin and binding sites
Myosin has heads which allow a cross bridge to be formed
Color of bands
Dark bands are where the two overlap
Light bands re the actin
Medium bands are the myosin
Muscle Contraction
- motor neuron triggers a response which depolarizes sarcolemma causing the sarcoplasmic reticulum to release calcium ions (Ca2+)
- The flood of calcium ion takes the troponin away and exposes the binding sites to the myosin head forming a cross-bridge with the actin
- ATP hydrolysis will cause the myosin head to change directions moving the actin and therefore more overlap and a contraction. (shortening the sarcomere)
- Then Ca Ions will flood back into the reticulum and the myosin head will return to its original position. Causing relaxation in the muscle
Removing Nitrogen Waste
Excess nitrogen levels are toxic and are produced from the breakdown of compounds like amino acids and nucleotides.
What is nitrogen waste excreted as in aquatic animal
Ammonia (NH3). However, it is very soluble so its typically easily flushed out by animals in aquatic habitats.
How do mammals eliminate nitrogen waste
Urea. Less toxic and can be stored in high concentrations when compared to ammonia
How do Reptiles and birds eliminate nitrogen waste
Uric Acid. Requires more energy to produce but is pretty non-toxic and requires less water.
Removing excess water
Osmoconformers - maintain internal conditions that are equal to the osmolarity in the environment. (minimizes water loss)
Osmoregulators - Keep body osmolarity consistent regardless of the environment. (maintain optimal internal conditions)
Malpighian Tubules
An insect’s excretory system. Connects to the digestive system of an animal.
How do the Malpighian tubules work?
- The epithelial cells from the tubules have narrow intercellular channels that allow for water and small solutes to pass through but not proteins or big solutes
- Sodium or potassium are pumped into the lumen and change the difference chloride follows passively.
- So then Na, Cl, K will enter from the extracellular fluid. Creating a high concentration gradient.
- Due to this H20 and small solutes (waste) enter through intercellular channels.
- And move down to the gut where material combines with digested food.
- Solutes, water and salts are reabsorbed into the hemolymph at the hindgut, whereas nitrogenous wastes (as uric acid) and undigested food materials are excreted via the anus
What does the kidney do?
Filter your blood (through the nephron) to remove metabolic waste which helps to maintain osmoregulation.
How does blood flow in the kidney?
- Blood enters through the renal artery and exits through the renal vein
- Blood is filtered through structures called nephrons which produce urine. Which is then transported to the ureter to be stored and excreted
Difference between blood in the renal vein (after kidney)
- Less urea and it is removed by the nephrons
- Less water and solutes
- Less glucose and oxygen as it is used to generate energy for metabolic reactions
- More carbon dioxide as a byproduct of metabolic reactions
Parts of a nephron and their functions
Bowmans Capsule - blood initially filtered
Proximal convoluted tubule - Folded structure
connected to the bowman capsule where selective reabsorption happens
Loop of Henle - A selectively permeable loop that descends into the medulla to establish a gradient
Distal convoluted tubule - folded structure connected to the loop where more selective reabsorption happens
How does blood flow in the Bowmans Capsule
blood enters through afferent arteriole and leaves via the afferent arteriole
Glomerulus
Where the blood is filtered at the capillary tuft. Knot of blood vessels where blood is at high pressure as the arterioles are thinner
Vasa recta
Blood network by the afferent arteriole that reabsorbs components of the filtrate from the nephron
How does the nephron function
Filters blood at then reabsorbs useful material before eliminating the rest as urine
- Untrafiltration - Blood is filtered out of the glomerulus at the Bowman’s capsule to form filtrate
- Selective reabsorption - Usable materials are reabsorbed in convoluted tubules
- Osmoregulation – The loop of Henle establishes a salt gradient, which draws water out of the collecting duct
Ultrafiltration
In the glomerulus, there are pores where (salt, waste products, glucose and water) can be squeezed out. Gaps are known as fenestrations and basement membrane. The filtrate is collected in the renal (Bowmans capsule)
2. The filtrate is then transported through the rest of the nephron
Selective reabsorption
Reupatke of useful substances such as glucose, amino acids, vitamins etc. Where the substances are actively transported across the apical membrane and then passively diffused across the basolateral membrane into the blood.
How are things adapted for selective reabsorption
- Prociman convoluted tubule has microvilli to increase SA for absorption
- Lots of mitochondria as reabsorption involves active transport
Osmoregulation
Control of water balance of the blood that occurs in the medulla.
- Loop of henle established the salt gradient
- ADH (anti-diuretic hormone) regulated level of water reabsorption in collecting duct
How is a salt gradient established in Osmoregulation
- arriving into the loop of Henle is the filtrate
- the descending limb is permeable to water and the ascending limb is to salts. So as it moves down it gets saltier as water moves out into tissue and blood.
- counter current as blood moves one way and the filtrate moves the other. Helps to maintain a concentration gradient
- Bottom of the loop is very salty
- In the ascending salts are pumped out through sodium pumps
- This means the filtrate that enters the distilled convoluted tubule is balanced.
How is water reabsorbed in osmogreulation
- In the Collecting duct water moves out to be retained by the body
- The amount that is released is dependent of the levels of ADH (more ADH more water being released)
- ADH is released from the posterior pituitary in response to dehydration (detected by osmoreceptors in the hypothalamus)
- ADH will increase the permeability of the collecting ducts by upregulating the production of aquaporins (water channels)
- This means that there is less water in the filtrate and urine is more concentrated
