Transport in Animals: Biology and Evolution

• Unit focuses on Functional Biology and Evolution

Transport in Animals

• Involves movement of nutrients and wastes
• Unicellular organisms use diffusion and active transport
• Multicellular organisms require a mass flow circulatory system due to a low surface area to volume ratio

Circulatory System

• This system uses blood vessels with a pump and valves
• These components facilitate one-way blood flow

Advantages of Circulatory Systems in Large Animals

• Supplies metabolites and removes waste faster than diffusion alone
• Enables separation of transported materials such as oxygenated and deoxygenated blood in different vessels
• Impermeability of external surfaces like the thick cuticle of insects limits water loss during transport
• Prevents utilization of materials along the way

Components of Animal Transport Systems

• Fluid medium, the blood, transports substances
• A pump, like the heart, propels the fluid
• Exchange surfaces, such as kidneys, are specialized
• Transport tubes are, for example, blood vessels
• Valves ensure unidirectional flow

Types of Circulatory Systems

• Single circulatory system: A single loop, exemplified by fish (Heart > Gills > Body > Heart)
• Double circulatory system: A double loop, exemplified by mammals (Heart > Lungs > Heart > Body > Heart)

Double Circulatory Systems

• Blood pressure is high/safe in the systemic/pulmonary circuit
• Organisms can be more active due to faster oxygen transport to respiring tissues
• Fish do not require such an efficient mechanism

Blood Flow in Mammals

• Deoxygenated blood enters the right atrium (RA)
• Deoxygenated blood then enters the right ventricle (RV)
• Blood is pumped to the lungs from the RV
• Oxygenated blood enters the left atrium (LA)
• Oxygenated blood enters the left ventricle (LV)
• Oxygenated blood is pumped to the rest of the body from the LV
• Body cells use the oxygen to produce deoxygenated blood
• Deoxygenated blood goes back to the heart and the cycle repeats

Heart Structure and Function

• Atria contract to pump blood into the right and left ventricles.

• Ventricles contract to pump blood to the lungs for oxygenation i.e. right ventricle. The left ventricle pumps blood to the rest of the body

• The left ventricle has a thicker wall for more force

• Atrioventricular valves separate atria/ventricles and prevent backflow, creating one-way flow

• Semilunar valves: Located in pulmonary arteries/aorta and prevent backflow, ensuring unidirectional flow

• Pulmonary artery: Transports blood from the right ventricle to the lungs

• Pulmonary vein: Carries blood from the lungs to the left atrium

• Aorta: Carries blood from the left ventricle to the rest of the body

• Vena cava: Large veins that carry deoxygenated blood from the body back to the right atrium

• Septum: Thick wall separating right and left sides of the heart to prevent mixing of oxygenated and deoxygenated blood

Blood Structure and Function

• Specialized tissue with cells suspended in plasma
• Soluble organic compounds are transported from the small intestine
• Soluble excretory matters are taken to organs of excretion
• Hormones are carried from glands to target organs
• Heat is distributed to maintain body temperature
• Defense against diseases via blood clotting, phagocytosis, and immunity
• Plasma protein activity maintains blood solute potential

Components of Blood

• Blood contains water, plasma, red blood cells, white blood cells, and platelets
• Water maintains blood pressure and volume, transporting dissolved materials, and important for glomerular filtration
• Plasma proteins include prothrombin, fibrinogen, serum albumen, globulin, enzymes, mineral salts, and dissolved nutrients etc
• Red blood cells transport oxygen due to their biconcave shape with haemoglobin

Red Blood Cells

• They lack a nucleus to maximize space for carrying oxygen
• They contain haemoglobin, a red pigment that binds to oxygen forming oxyhaemoglobin

White Blood Cells

• Immune system cells include:
  • Lymphocytes: Produce antibodies against microorganisms
  • Phagocytes: Engulf and digest pathogens
  • Cells that produce antitoxins to neutralize toxins from microorganisms

Platelets

• Facilitate clotting after injury
• Aid the formation of a scab, which is essential for new skin growth underneath while preventing microorganism entry
• They are small, enucleated cell fragments
• Platelet deficiency leads to excessive bleeding and bruising

Overview of the Immune System

• Vertebrate defense system with structures and processes that repel pathogens
• Protects the host from pathogens and tumor cells
• The immune system consists of cells and molecules that defend against pathogens
• Pathogens such as parasites, fungi, bacteria, viruses, and haptens, invade and cause disease

Pathogen Types and Disease Caused

• Bacteria: Single-celled organisms without a nucleus; cause strep throat, staph infections, tuberculosis, etc.
• Viruses: Reproduce by taking over cells; cause common cold, flu, AIDS, measles, etc.
• Fungi: Nucleated organisms growing as single cells or filaments; cause ringworm, athlete's foot, etc.
• Protozoa: Single-celled organisms with a nucleus; cause malaria, traveler's diarrhea, giardiasis, etc.

Immune System Subsystems

• Innate immune system: Present from birth
• Adaptive immune system: Develops over time

Types of Immunity

• Innate immunity: Present from birth
• Adaptive/Active immunity: Acquired after birth

Innate Immunity

• Innate immunity provides nonspecific protection via: Antimicrobial proteins fight invaders Physical barriers

Antimicrobial Proteins

• They harm invaders and cells that attack foreign/infected cells
• Innate response: The response is initiated by physical barriers that prevent pathogen entry

Acquired Immunity

• Natural protection, like skin, prevents pathogen entry

Adaptive (Active) Immunity

• Adaptive Active immunity develops, and occurs when a host contacts a pathogen/antigen
• Occurs after primary contact with diseases, allergies, or immunization
• Active immunity results from antibody production
• Natural active immunity occurs following primary response, preparing antibodies for reinfection

Passive Immunity

• Passive immunity develops from antibodies produced outside the body
• Passive immunity provides short-term protection. Breast milk provides temporary immunity in babies

Main Parts of the Immune System

• Spleen
• Thymus
• Antibodies
• Bone marrow
• White blood cells
• Lymphatic system
• Complement system

Disorders of the Immune System

• Allergic diseases: Hay fever, sinus disease, asthma, hives, dermatitis, eczema
• Autoimmune diseases: Multiple sclerosis, autoimmune thyroid disease, type 1 diabetes, systemic lupus erythematosus
• Immunodeficiency: Inherited conditions like X-linked severe combined immunodeficiency (SCID), complement deficiencies

Infectious Diseases

• These are disorders caused by microscopic parasitic organisms like bacteria, viruses, fungi, or parasites

Cholera

• Cholera causative agent: Vibrio cholera
• Cholera spreads by:
• Contaminated water supply
• Consumption of contaminated food and drink
• Vegetables grown in water with human waste
• Contaminated seafood polluted by water with sewage

Cholera Symptoms

• High fever, weight loss, and increased thirst
• Nausea symptoms, bloating, and low blood pressure
• Skin elasticity is reduced, cramps, increased heart rate, dryness in mouth
• Presence of blood/mucus/undigested stool

Cholera Prevention

• Cholera is prevented by:
• Drinking Boiled water
• Avoiding raw foods/dairy
• Practicing better hygiene
• Washing hands, fruits, vegetables before eating

Tuberculosis (TB)

• Tuberculosis causative agent: Mycobacterium tuberculosis
• Tuberculosis has three stages:
• Primary infection
• Latent TB infection
• Active TB
• Types: Pulmonary Tuberculosis (TB) and Extrapulmonary Tuberculosis

Tuberculosis Symptoms

• Coughing up blood in mucus
• Bad cough for 3 weeks or longer
• Sweating/weakness/fatigue with chest pain
• Loss of appetite and chilly fever

Tuberculosis Spread

• Spreads through the air by coughing, sneezing, talking, singing, or laughing
• Contagious in people with active pulmonary infection
• Disease can be active if the immune system weakens
• High-risk carriers include;
• Infants
• Senile
• Individuals with a weak immune system
• Metabolic diseases like diabetes may also increase risk
• Four other types of TB-causing bacteria are - Mycobacterium bovis, Mycobacterium canetti, Mycobacterium microti, Mycobacterium africanum

HIV/AIDS

• Caused by Human Immunodeficiency Virus (HIV)
• HIV-1 (90% of AIDS cases) is the most common type and it consists of groups M, N, O, and P.
• HIV-2 is found in West Africa and closely related to simian immunodeficiency virus in sooty mangabeys

HIV General Symptoms

• Symptoms vary
• Some may experience no symptoms at all
• Fever, chills, and headache may occur
• Swollen enlarged glands
• Upset Stomach/ sore throat/ joint pains/ muscle aches, tiredness

Malaria

• Malaria is caused by protozoan parasite; Plasmodium, which are spread be mosquitoes
• Spread of Malaria:
• Infected Anopheles mosquito bites
• Shared syringes
• Organ transplants
• Transfusions from infected mother

Malaria General Symptoms

• Fatigue, Fever, and chills
• Headaches and profuse sweating
• Muscle pain, anemia, and Diarrhoea. In severe circumstances malaria can cause;
• Seizures, Coma, and eventually death
• Bloody Stools