science s2 exam Flashcards
First Line of Defence
Prevents pathogens from entering the body
Physically blocks, traps or removes pathogens
Chemically destroys pathogens with enzymes or acids before they enter the body
e.g skin, nose hair, eyebrows, lashes, earwax, tears, saliva, cilia, tears, mucus
Second Line of Defence
Innate and non-specific
Identifies a ‘non-self’ pathogen
Fever: increased core temperature that slows or kills pathogens
Inflammation: redness or swelling around infection site to bring white blood cells
Phagocytes: white blood cells that destroy pathogens
Destroys through phagocytosis (cell eating)
Third Line of Defence
Specific and Adaptive
Identifies and destroys specific pathogens
Builds long-term immunity against pathogen in case of reinfection
Lymphocytes: immune cell/white blood cell
Antibody: chemicals made by B-cells to fight pathogens
B-cell: type of immune cell that combats pathogens outside the cell
T-cell: type of immune cell that combats pathogens inside the cell
Memory Cells: B or T cells that stay om the body after infection
Antigens: non-self-markers on pathogens, B-cells produce matching antibodies
Describe the difference between chemical barriers and physical barriers
Physically blocks, traps or removes pathogens
e.g hairs, cilia, skin, mucus, tears, earwax, urine
Chemically destroys pathogens with enzymes or acids before they enter the body
e.g sweat, saliva, stomach acid
B-lymphocytes
get triggered by a specific invader’s antigen and duplicate themselves and produce millions of antibodies that match with the antigen
Agglutination
Antibodies make the pathogens clump together in a process called agglutination.
Phagocytosis
After the pathogens are all clumped together phagocytes kill them by engulfing them through phagocytosis
T-lymphocytes
attack your own cells that have been invaded to reduce the spread of infection to other healthy cells.
Memory cells
constantly search the body for the same pathogens and are created to make your immune system more efficient. The faster your body can identify the threat, the faster the lymphocytes can react accordingly.
Virus
Kill cells or disrupt cell function, causing disease. Treated with antivirals.
Bacteria
Single-celled organisms that can cause disease by multiplying and crowding host tissue, kills cells and tissues, or make toxins that paralyse and destroy metabolic machinery. Treated with antibiotics.
Fungi
Infect host tissues when spores are inhaled or traumatically implanted, disrupting their function. Treated with antifungal medications.
Protists
Enter a human body to feed, grow and reproduce, this can kill cells and tissues or disrupt their function. Treated with antimalarial drugs.
Parasites
Reproduce and invade the host, causing disease. Treated with antiparasitic drugs.
Active Immunity
Body produces its own antibodies (e.g., from vaccination or infection).
Passive Immunity
Receiving antibodies from another source (e.g., mother’s milk or antibody injections).
Natural Immunity
caused by exposure to the disease organism through infection with the actual disease.
Artificial immunity
caused by a man-made vaccination
Innate Immune System
you were born with, involves barriers to keep pathogens out of your body but cannot destroy them. First and Second line of defence.
Adaptive Immune System
defence system that builds up as you get exposed to different pathogens, naturally or through vaccination. Third line of defence.
Infectious
spreads, can be caught, transmits from human to human (malaria)
Non-Infectious
does not spread, can not be caught, through genetics/luck (diabetes)
Contagious
transmit from human to human (COVID)
Surgery in the past
no anaesthetic, antibiotics or antiseptic, performed by barber-surgeons
Parts of the stimulus-response model.
Stimulus -> receptor -> sensory neuron -> interneuron -> brain -> interneuron -> motor neuron -> effector
Brain
control centre of the nervous system
Spinal Cord
thick cord of nerves that run down your spine, pathway between brain and nerves
Nerves (neurons)
cells that transport information in the form of nerve impulses
Central Nervous System
Brain and spinal cord, performs majority of body’s functions
Processes and coordinates all sensory input and motor output
All conscious and unconscious activities (movement, sensation, perception etc)
Peripheral Nervous System
Nerves that connect CNS to the body’s organs, muscles and other tissue
Carries sensory information from sensory receptors to CNS
Carries motor information from CNS to body’s muscles and glands
Controls involuntary activities
Somatic: voluntary, communicates with sense organs and skeletal muscle
Autonomic: involuntary, communicates with internal organs and glands
-Sympathetic: fight or flight
-Parasympathetic: rest and digest
Different structures in a neuron with application to function
Dendrites (receive signals) -> cell body (with nucleus) -> axon (carry electrical signals quickly, covered by myelin sheath to ensure efficiency) -> axon terminals (pass signals to next neuron’s dendrites)
Structures of the brain
Cerebrum: higher order thinking
Frontal Lobe: decision making process
Parietal Lobe: functions relating to senses
Temporal Lobe: functions relating to hearing
Occipital Lobe: functions relating to sight
Cerebellum: coordination of movement
Brain stem: controls vital functions and is a motor/sensory pathway
Medulla: Regulates life support systems
Corpus callosum: links the left and right hemispheres of the brain
Hypothalamus: maintains homeostasis
Receptors
Chemoreceptors; detects chemicals; nose
Mechanoreceptors; detects pressure (touch); skin
Pain receptors; detects pain; skin
Thermoreceptors; detects temperature; hypothalamus
Photoreceptors; detects vision; eyes
Osmoreceptors; detects water balance; hypothalamus
Nociceptors; detects pain
Reflex
Stimulus -> receptor -> sensory neuron -> spinal reflex arc -> motor neuron -> effector
Does not get sent to brain.
Endocrine system
Consists of glands that produce chemical messengers called hormones
Hormones carry information around the blood stream to cells.
Main function is to regulate the hormones in the body.
Homeostasis
the body’s automatic response in maintaining a stable state in the body. The nervous system stimulates the ductless glands of the endocrine system to release hormones for homeostasis. The hormones carry signals to target cells to lower/raise internal temperature or blood sugar levels.
Forensic science
the application of science to criminal and civil laws. Includes advancements in crime-solving techniques like fingerprinting, DNA analysis, and digital forensics.
Types of evidence
Physical Evidence: Fingerprints, fibers, DNA.
Biological Evidence: Blood, hair, saliva.
Chemical Evidence: Gunshot residue, toxicology results.
Techniques
Fingerprinting: Generally reliable but not infallible.
Fibers: Can link individuals to scenes but often circumstantial.
Toxicology: Provides chemical data on substances, useful in overdose or poisoning cases.
Blood Spatter Analysis: Helps reconstruct events; requires expertise.
Ballistics: Matches bullets to firearms; reliable with proper technique.
Anthropometrics: Identifies individuals using body measurements; more accurate with advancements.
Witness Statements: Subject to human error; not as reliable as physical evidence.
