Biology Unit Two: Homeostasis and Infectious Disease

Vocabulary flashcards covering the Nervous System, Homeostatic Regulation, the Endocrine System, Thermoregulation, and Infectious Diseases based on Biology Unit Two notes.

CNS

The Central Nervous System, which consists of the brain and spinal cord.

PNS

The Peripheral Nervous System, which consists of all other nerves in the body and sends signals from sense receptors to the CNS.

Cerebellum

Part of the brain that controls body movement, posture and balance.

Cerebrum

Part of the brain that controls memory, emotion and language, and sensory processing.

Thalamus

The relay centre for the brain.

Hypothalamus

Part of the brain that controls homeostatic functions such as appetite, thirst, body temperature and sleep.

Brainstem

Assists the hypothalamus in controlling homeostasis in automatic functions such as heart rate, breathing and cough/vomit reflexes.

Dendrites

Branches at the top of the neuron that recieve chemical signals secreted over the synaptic cleft.

Stoma

The cell body of a neuron that processes chemical signals into eletrical signals to create action potential.

Axon

A cable transmitting action potential down the neuron towards the axon terminals.

Myelin Sheath

A fatty substance coating the axon to protect the eletrical signal and ensure fast, clear communication.

Schwann Cell

A cell in the myelin sheath assisting in the proper flow of the signal down the axon.

Node of Ranvier

Connects the myelin sheath to the axon and each other, allowing the electrical signal to “jump” down the axon.

Sensory Neurons

Neurons that gather information from receptors to go to the CNS.

Interneurons

Neurons found in the CNS connecting sensory and motor neurons together.

Motor Neurons

Neurons that take messages from the CNS to the effector organ to cause a response in the muscle, organ, or gland.

Reflex Arc

A pathway in the brain allowing nerve impulses to have an immediate response through fast unconscious movements that bypass the brain.

Optimum Range

The range in which the human body is at its peak performance within its tolerance limits.

Homeostatic mechanisms

Processes that produce a stable internal environment by maintaining variables within a narrow limit, such as body temperature between $36.1-37.8\,^{\circ}C$.

Stimulus Response Model

The model all responses in the body follow: Stimulus \rightarrow Receptor \rightarrow Modulator/Control Centre \rightarrow Effector \rightarrow Response.

Negative Feedback Loops

Acts as a counteract to the original change to return the body to the normal levels.

Positive Feedback Loops

Mechanisms that increase normal values from the ideal ranges, such as in pregnancy and giving birth.

Osoregulation

The maintenance of water and electrolyte levels in the body, primarily involving the kidneys.

Exocrine Glands

Glands that secrete through ducts, such as sweat glands.

Endocrine Glands

Glands that secrete hormones directly into the blood stream, such as the adrenal gland.

Structural Mechanisms

Physical or body structures of an organism used to maintain ideal body temperature, such as elephants flapping their ears.

Hibernation

A prolonged time of reduced activity where metabolism slows to keep the animal warm.

Torpor

Reduced metabolic activity during sleep in colder months.

Astivation

A form of hibernation occurring in warm months to reduce energy and water loss.

Kleptothermy

A behavioral mechanism where animals share the metabolic thermogenesis of other animals, such as penguins huddling.

Pathogens

The overall category of harmful organisms that cause infectious disease, including bacteria, fungi, protozoa, and viruses.

Bacillus

Rod-shaped bacteria.

Coccus

Sphere-shaped bacteria.

Spirillus

Spiral-shaped bacteria.

Binary Fission

The process of DNA replication and division used by single-celled bacteria.

Infectious Disease Illness caused by the invasion of a harmful organism in the body Causes: Pathogens (overall category) Bacteria Fungi Protozoa Viruses All living organisms are suseptible to pathogens) Bacteria and Disease Very few kinds of bacteria are pathogenic Most bacteria form normal microflora are found in healthy humans (they feed off of a well living host) Bacteria exploit the host → use host as food, home, growth etc Bacteria Microbe = bacteria Classed into 3 groups: bacillus (rods), coccus (spheres), spirillus (spirals) Single celled organisms that undergo binary fission DNA replication Genetic material not contained in the neuclus Viruses Not classified as living; need a host in order to live Intracellular parasite → found inbetween cells Host range = spectrum of host cells the virus can invade Structure of Virus: Contain DNA or RNA Have a protective capsid Infection of a Virus: Receptor-Mediated Fusion Bonds to a specific receptor on a cell so a virus can inject itʼs DNA. Cell with replicate the DNA and then explode Endocytosis Pathway Whole virus will be engulfed through a vesicle so it can pass through the plasma membrane and enter a cell Viral Infection Process Attachment → viral particle will attach to a cell recpetor sites on the plasma membrane Penetration → engulfed via endocytosis so cell can begin foreign particple response Uncoating → caspid desinigrates and DNA is released into the cell. The host cell will replicate the viral DNA to then pass onto other cells. Protozoa and Disease Protazoa = protist can cause a disease produce a protective capsule called a cyst unicellular organisms Multicellular Parasites Endoparasites are specialsed to live in the host and cause disease directly (e.g. tapeworm) Ectoparasites act as a vector (host) by carrying the disease to pass on (e.g. blackdeath carried by fleas to pass on to humans) Some insects carry the disease and are known as insect parasites Prion Proteins Proteins that when they touch other proteins, will cause them to unfold and become unusable Prions are abnormal forms of a normal cell protein, that have a mutation for for the protein to fold incorrectly Virulence Factor Characteristics of pathogens enhancing their ability to cause a disease Adherence Factor → Ability to attach to a hostʼs cell receptors (e.g. pili in bacteria) Invasion Factor → How it getʼs inside your body or a cell (e.g. enzymes breaking down tissue) Capsules → Protective outer layer surrounding bacteria Toxin → Substances produced that damage host tissue (e.g. mosquito venom that dirupt platelets that causes you to bleed more) Life Cycle → Adaptations in a pathogens life cycle that enhance speed and survival (e.g. Paradite reproduction is fast) Portals of Entry Eyes Nose Mouth Skin if cut UTI Repiratory Tract → inhalation of pathogens Gastrointestinal Tract → contaminated food pathogens Urinogential Openings → opending for pathogens in reproductive areas Transmission of Disease Contact Transmission → transmission by touch Vechile Transmission → Needs something to hold onto Vector Transmission → Needs a living organism Immune System Types of Defence Microbiota Job is to out compete the pathogen Microbiota is found on skin, nose, mouth, gut, reproductive regions Non-Specific 1st Line of Defence → the external stopping of harmful pathogens from invading the body. This is a type of physical defence that prevents the entry of pathogens. 2nd Line of Defence → white blood cells in the body to initate a phisological response. This is a type of chemical defence that kills or harms the pathogens Specific 3rd Line of Defence → specialised lymphocytes and antiobodies 1st Line of Defence Stopping of harmful pathogens from entering Needs to recognise itʼs own tissues when they are growing correctly Recognise microflora → gut bacteria, mouth bacteria 2nd Line of Defence Non-specific process occurs Esoinophils → produce toxins against certain pathogens Basophil → release of heparin/histamine to cause inflamation Neutrophil → cells engulf and destory foreign material Engages natural killer cells NK cells) and white blood cells that are specific for killing infected and disease cells Phacocytes White blood cells that ingest microbes by phagocytosis: Detection → detects microbes by the chemicals they give off Ingestion → phagocyte wraps pseudopodia around the microbe engulfing it Phagosmome forms → phagosome is formed enclosing microbe in a membrane Fusion with lysosome → phagosome fuses with lysosome for acids and chemicals to digest DiDigestion → microbe is broken down by enzymes Discharge → material is discharged from phagocytes Pseudopdia = membrane forming a vesicle Phagosome = what the vesicle is called when engulfed Inflammation increase of blood flow to damaged area inflammation surrounds pathogens to keep it from spreading white blood cells destroy cause of infection red blood cells (for oxygen) and platlets (for clotting) repair tissue The Complement System group of proteins in the blood to defend against infection Causes a cascade: chain reaction where proteins are activiated leading to the formation of membrane attack complex Activation of cascade occurs 3 ways: Classical - triggered to antibodies binding to pathogens Lectin - proteins recognise specific sugars on bacteria or virus surface Alternative - sponanteous activation but is enhanced by presence of pathogen Fever Known as pyrexia is a temperature above 37 degree celcius Fevers push bacteria and viruses out of their optimum temperature killing it Fevers set off the complement cascade causing an interferon Interferon → chemical stopping the replication of bacteria Third Line of Defence Adapts and becomes specific to the pathogen Lymph Fluid Tissue fluid Bathes the tissue supplying it with nutirients, oxygen and waste removal Lymphatic System Network of vessles that drains the fluid Lymph nodes actively fight off pathogens by recognising the pathogen Nodes become swollen and hard as lymph cells reproduce rapidly to increase numbers Lymphocytes BCell → Create antibodies to target antigens TCells → Target pathogens directly Antigens → protein mark identifiers on the outside of cells and pathogens Antibody → folded proteins that are specific to an antigen in a lock-and-key method to destroy the antigen