Biological and Trace Evidence Analysis

class evidence

characteristics common to a group of objects or persons

individual evidence

characteristics linked to a specific source

purpose of class evidence

to refine pool of suspects and focus investigation

Fracture Patterns

example of individual evidence

integumentary system

Forms the external body, protects deeper tissues and Synthesizes vitamin D Used for hair, sweat and dermatoglyphics

skeletal system

protects organs, forms blood cells and stores minerals. Used for Anthropology and cause of death

Muscular System

manipulation of the environment maintains posture and produces heat. Useful for Time of Death and external temperature

nervous system

responds to internal and external changes by activating appropriate muscles and glands. Useful for Drug and Psychiatric Issues

endocrine system

controls glands and secretes hormones. Useful for unexplained deaths and insulin overdoses.

cardiovascular system

transports blood. Useful for DNA, mRNA and bruising

lymphatic system

Picks up fluid leaked, Disposes of debris and Houses white blood cells

respiratory system

keeps blood oxygenated and controls gas exchange. Useful for strangulation, fire and CO

digestive system

breaks down food and disposes of feces. Used for samples of teeth, saliva and vomit

urinary system

Eliminates nitrogenous wastes from the body and balances the blood. Used for urine samples

reproductive system

produces offspring. Used for rape cases and miscarriages/abortions

anatomical position (FAFP)

face forward, arms at the side, palms face forward and feet pointing forward

Superior

above

Inferior

below

Anterior

in front of

Posterior

in back of

medial

Toward the midline of the body

Lateral

Away from the midline of the body

Proximal

toward the trunk

Distal

further from the trunk

Crainal

skull

Cervical

neck

Cubital

elbow

Carpal

wrist

Patellar

kneecap

Orbital

eye

Thoracic

chest

Inguinal

groin

Metacrapals

backhand

Plantar

sole

Buccal

cheek

Axillary

armpit

Femoral

thigh

Gluteal

buttock

Tarsal

ankle

Digital

fingers, toes

dorsal body cavity

includes cranial and vertebral cavities

cranial cavity

contains the brain

vertebral cavity

contains the spinal cord

ventral body cavity

thoracic and abdominopelvic cavities (separated by diaphragm)

thoracic cavity

contains heart and lungs

abdominopelvic cavity

digestive and urinary organs

serous membrane

a thin membrane lining the closed cavities of the body

visceral layer

covers external surface of organs

Paterial layer

lines the cavity wall and doesn't touch organ

Prokaryotes

single-celled with no membrane bound organelles through binary fission

Eukaryotes

multi-celled with defined organelles and divide through meiosis/mitosis

Specialisation

different cells do different jobs

White Blood Cells

rough surface to distinguish bacteria and viruses

Histology

study of the structure of biological material

Cytology

examination of single cells

Biopsy

removal of living tissues for diagnostic purposes

Autopsy

examination of organs to determine cause of death

Acidic dyes

negatively charged (Na+) react with basic components

Basic dyes

positively charged (Cl-) react with acidic components

Metabolism

sum of catabolic and anabolic chemical processes

Homeostasis

maintenance of constant internal environment

Positive feedback systems

strengthen change in controlled condition

Negative feedback systems

reverse change in controlled condition

Hormones

chemical signals secreted by endocrine cells

Exocrine gland

secrete into specific compartments (ducts)

Endocrine gland

release hormones directly into interstitial fluid

Depolarization

When a stimulus binds to the axon, sodium ion channels open as the membrane becomes more permeable to sodium ions, allowing sodium ions to rapidly diffuse into the axon and increase the membrane potential - if the threshold is met, an all or nothing response is created and an action potential is generated

Repolarization

The sodium ion channels close and the potassium ion channels open, allowing potassium ions to rapidly diffuse out and lower the membrane potential - however, the potassium ion gates remain open for too long, and the membrane potential falls under the norm, so the sodium-potassium pump returns it to normal

Refractory Period

A period of inactivity an axon experiences after transmitting an action potential before it can transmit another - this limits the number of impulses transmitted by the neurone

Frontal plane

anterior-posterior axis

Sagittal plane

left and right halves

Transverse plane

divides body into superior/inferior

Agonist

muscle that causes action when it contracts

Antagonist

muscle working in opposition to agonist

Synergists

muscles that work together to cause movement

Tendons

bands of inelastic fibre tissue that connect the bones to the muscle

Epicardium

outer layer of heart wall

Myocardium

thick middle layer of cardiac muscle

Endocardium

simple squamous epithelium

Striations

parallel muscle proteins that slide along each other causing cell to contract

Vein

carries blood to the heart

Arteries

carries blood away from the heart

Pulmonary Circuit

right atrium and ventricle take blood from body to the lungs for oxygenation

Systematic circuit

left atrium and ventricle move oxygenated blood to the body from lungs

Myocardial infarction

blook in coronary arteries reduces oxygen supply to heart tissue

Darcy’s Law of Flow

Q= Change in pressure/Resistance

Atrioventricular (AV) valves

blood flow from atria to ventricles

Semilunar valves

blood flow from ventricle to outflow vessels

Diastole

relaxation of the heart

Systole

contraction of the heart

Cardiac cycle

Atrial systole, isovolumic contractions, ventricular ejection and isovolumic relaxation

Atrial systole

atria contracts and blood flows through to ventricles through AV valves

Isovolumic contraction

both ventricles contract closing AV valves with both ventricles closed

Ventricular ejection

rising pressure forces SL valves open and blood ejected from heart

Isovolumic relaxation

ventricles relax and pressure drops closing SL valves

Autorhythmic

heart doesn’t rely on CNS

Sinoatrial (SA) node

pacemaker and triggers initial signal

Atrioventricular (AV) node

delays action potentials between the atria and AC bundle

Cardiac Output

CO= Stroke Volume x Heart Rate

Systolic Blood Pressure

highest pressure measured during left ventricle systole when aortic valve is open