Human Biology ATAR Year 12 (Units 3 & 4)

Endocrine Gland Secretion

Directly into the bloodstream.

Recombinant DNA Technology

Produces synthetic hormones to treat disorders like diabetes mellitus.

Cerebrum Function

Conscious thought, sensory processing, memory, and voluntary movement.

Cerebellum Function

Coordination, balance, and fine motor control.

Medulla Oblongata Function

Involuntary functions like breathing and heart rate.

Hypothalamus Function

Homeostasis, temperature, water balance, and endocrine control.

Corpus Callosum Function

Communication between cerebral hemispheres.

CNS Protection

Protected by skull/vertebrae, meninges, and cerebrospinal fluid.

Sensory Receptor Types

Thermoreceptors, osmoreceptors, chemoreceptors, touch receptors, and pain receptors.

Reflex Arc Pathway

Receptor → sensory neuron → interneuron → motor neuron → effector.

Depolarisation

Occurs when sodium ions enter the neuron.

Repolarisation

Occurs as potassium ions leave the neuron.

Myelin Function

Increases conduction speed of nerve impulses along axons.

Synaptic Signal Transmission

Neurotransmitters cross the synapse and bind to postsynaptic membrane receptors.

Homeostasis

Maintaining internal body conditions within tolerance limits using negative feedback.

Physiological Responses to Cold

Vasoconstriction, shivering, and increased metabolic activity.

Physiological Responses to Heat

Vasodilation, sweating, and reduced metabolic heat production.

Insulin

Lowers blood glucose by promoting cellular glucose uptake and glycogen synthesis.

Glucagon

Raises blood glucose by promoting glycogen breakdown and glucose release.

ADH

Increases water reabsorption in kidney nephrons, concentrating urine.

Aldosterone

Increases sodium reabsorption in kidneys, causing water to follow by osmosis.

Respiratory Control of Elevated CO₂

Medulla oblongata triggers increased ventilation via the autonomic nervous system.

First Line of Defence Mechanisms

Physical/chemical barriers of the skin, digestive tract, urogenital tract, and respiratory tract.

Non-Specific Defences

Inflammation (isolates pathogens/recruits cells) and fever (raises body temperature).

Vaccination Purpose

Exposes immune system to safe pathogen forms to produce memory cells.

Polygenic Inheritance

Multiple genes contributing to a single phenotypic characteristic.

Gene Flow

Movement of alleles between populations through migration and interbreeding.

Genetic Drift

Random changes in allele frequencies affecting small populations purely by chance.

Natural Selection

Acts on phenotypes to favour advantageous traits, altering population allele frequencies over generations.

Speciation

Reproductive isolation prevents gene flow, leading to divergence into distinct species.

Stratigraphy

Relative dating method where deeper rock layers are older than upper layers.

Homologous Structures

Similar underlying structure from common ancestry, adapted for different functions.

Comparative Biochemistry

Compares DNA and protein sequences using PCR, gel electrophoresis, and DNA sequencing.

Phylogenetic Tree Branch Points

Represent common ancestors of divergent evolutionary lines.

Key Hominid Trends

Increased brain size, decreased prognathism, bipedalism adaptations, and refined tool manufacture.

Homo habilis tool culture

Oldowan. choppers, flakes

Homo erectus tool culture

Acheulian. bi facial teardrop hand axe

Homo neanderthalensis tool culture

Mousterian. spear points, arrows

Homo sapiens tool culture

Aurignacian, Solutrian, Magdelanian. ivory, antlers, bones

Sub unit vaccine

Fragment of organism

Live attenuated vaccine

Weakened live virus

Toxoid vaccine

inactivated toxins

inactivated vaccine

inactivated virus/dead bacteria

Process of Action potential

Depolarisation (Na+ in), Repolarisation (K+ out), Refractory period (no change)

Hyperventilation

increased rate and depth of breathing. More O2, removes more CO2

Thirst reflex

When osmotic pressure is high, osmoreceptors in hypothalamus triggered

Water intoxication

Loss of Na+ in fluid after mass water loss

Vasodilation

Increased diameter of blood vessels to increase blood flow

Vasoconstriction

Decreased diameter of blood vessels which increases blood pressure

Shivering

Rhythmic muscle contractions, due to increase in skeletal muscle tone.

Sweating

Secretion of fluid by sweat glands, evaporation= cooling effect

Thyroid hormones

Thyroxine, calcitonin

Parathyroid hormones

parathyroid hormone (PTH)

Thymus hormones

Thymosins

Pineal gland hormones

Melatonin

Adrenal cortex hormones

aldosterone, cortisol

Adrenal medulla hormones

Adrenaline, noradrenaline

Pancreatic hormones

Insulin, glucagon

Phagocytotic response

Phagocytes engulf and destroy dead cells, waste & foreign particles

Inflammatory response

Mast cells= destroy & reduce spread of pathogen, Histamine= increases blood flow, Heparin= prevents clotting, slows spread

Fever response

release of pyrogens, kills pathogen

Protective reflexes

vomiting, sneezing, diarrhoea, coughing

Recombinant DNA process

Restriction enzymes to isolate gene, Insert isolated gene into plasmid, Splice with ligase, treat until it multiplies

Posterior pituitary hormones

ADH, oxytocin

Anterior pituitary hormones

FSH, LH, TSH, GH, ACTH, and prolactin

Lipid soluble hormones

bind to intracellular receptors

Water soluble hormones

bind to membrane receptors using secondary messengers

CNS composition

brain, spinal cord

PNS composition

31 pairs spinal nerves, 12 pairs cranial

Afferent pathway

carries sensory input to CNS

Efferent pathway

carries motor input away from CNS

Somatic NS

controls voluntary skeletal muscle response

Autonomic NS

regulates involuntary function

T lymphocytes

mediate cell-mediated immunity

B lymphocytes

produce antibodies

Gene pool

all alleles in a population

Allele frequency

the proportion of a specific allele

founder effect

a new small group colonising

bottleneck effect

drastic population size reduction

Radiocarbon dating

dates recent organic material

potassium-argon dating

dates older rocks/materials