Biology Module 8 - Non-infectious Disease and Disorders PDF

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Syllabus notes for Biology Module 8 - Non-infectious Disease and Disorders...

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Module 8 – Non-infectious Disease and Disorders Contents 1.0 Homeostasis .......................................................................................................................... 3 1.1 Negative feedback loops ............................................................................................................... 3 1.1.1 Internal coordination systems ............................................................................................... 4 1.1.2 Temperature .......................................................................................................................... 4 1.1.3 Glucose................................................................................................................................... 5 1.1.4 Water ..................................................................................................................................... 5 1.2 Mechanisms used to maintain internal environment .................................................................. 6 1.2.1 Behavioural, structural, and psychological adaptions in endotherms................................... 6 1.2.2 Internal coordination systems ............................................................................................... 7 1.2.3 Mechanisms maintaining water balance in plants ..............................................................10 2.0 Causes and effects................................................................................................................ 11 2.1 Causes and effects of non-infectious diseases in humans.......................................................... 11 2.1.1 Genetic diseases................................................................................................................... 12 2.1.2 Diseases caused by environmental exposure ...................................................................... 13 2.1.3 Nutritional diseases ............................................................................................................. 14 2.1.4 Cancer .................................................................................................................................. 15 2.2 Incidence, prevalence, and mortality rates of non-infectious diseases ..................................... 16 2.2.1 Diseases caused by environmental exposure: melanoma ................................................... 17 3.0 Epidemiology ....................................................................................................................... 18 3.1 Analysing patterns of non-infectious diseases in populations ................................................... 20 3.2 Treatment and management for one example of non-infectious disease (melanoma) ............ 20 3.2.1 Future directions of treatment ............................................................................................ 21 3.3 Evaluation of method used in epidemiological study ................................................................. 21 3.4 Evaluation of benefits of epidemiological study......................................................................... 21 4.0 Prevention ........................................................................................................................... 22 4.1 Effectiveness of current disease-prevention methods ............................................................... 22 4.1.1 Educational programs and campaigns ................................................................................. 22 4.1.2 Genetic engineering ............................................................................................................. 24 5.0 Technologies and disorders .................................................................................................. 25 5.1 Structures and functions of organs............................................................................................. 25 5.1.1 Ears ...................................................................................................................................... 25 5.1.2 Eyes ...................................................................................................................................... 26 1

5.1.3 Kidneys ................................................................................................................................. 29 5.2 Technologies used for disorders ................................................................................................. 30 5.2.1 Hearing loss: cochlear implants, bone conduction implants, hearing aids ......................... 30 5.2.2 Visual disorder: spectacles, laser surgery/intraocular lens implantation, bionic eye ......... 31 5.2.3 Loss of kidney function: dialysis........................................................................................... 31

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1.0 Homeostasis Inquiry question: how is an organism’s internal environment maintained in response to a changing external environment?

Homeostasis: maintenance of a relatively constant internal state regardless of external environmental changes. Body able to function within ‘tolerance limits’, homeostatic mechanisms triggered when limits are exceeded Homeostatic mechanisms: nervous and endocrine systems maintain homeostasis Differences Form of signal Pathway of communication Speed (relative) Duration of effect Type of action/response (voluntary vs involuntary) Target (localised or entire body) Function Activation

Nervous Electrical impulses (action potentials) Transmission by neurons Fast Short-term Both

Endocrine system Chemical impulses Transmission in blood Slow Short or long-term Involuntary

Localised cells connected to a Many cells throughout body neuron Similarities Regulation of body systems to maintain homeostasis Response to stimuli

1.1 Negative feedback loops Negative feedback: reversal of stimulus change Detecting change Feedback loop Counteracting change 1. 2. 3. 4. 5. 6. 7. 8. 9.

Stimulus (change in external environment) Sensory cells (interoceptors) detect change Control centre analyses messages and initiates actions Effectors (muscles, organs, glands) Response (action carried out to return to original state)

Stimulus (e.g. boy tapped on back) Receptor activated (touch receptors simulated by information) Sensory neuron (information sent from receptor to spinal cord) Spinal cord (information sent to brain) Brain (processes info in appropriate location) Spinal cord (info from brain to motor neuron) Motor neuron (information sent from spinal cord to effector organs) Effector organ (information received by receptor organ e.g. muscle) Response

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1.1.1 Internal coordination systems Interceptors Thermoreceptors

Chemoreceptors Osmoreceptors

Systems Somatic/voluntary nervous system Automatic/involuntary system Parasympathetic system Sympathetic system

Detect changes in internal temperature. Located in thermoregulatory centre (hypothalamus), detects blood temperature in the brain Detect changes in chemical concentrations. Located in certain blood vessels, detect pH and chemical levels (e.g. Co2, O2) Detect changes in osmotic pressure, located in hypothalamus. Osmotic pressure is determined by substance concentration dissolved in blood plasma. Causes body response through regulating water levels Allows conscious control of skeletal muscles. Contains 12 cranial nerves and 31 spinal nerves Controls automatic body functions (heart, smooth muscle/organs, glands). Divided into ‘fight or flight’ system and ‘resting and digesting’ ‘Rest and digest’. Conserves energy by slowing heart rate, relaxing digestive muscles, decreasing gland activity ‘Fight or flight’. Increases energy by increasing heart rate, tightening digestive muscles, increasing gland activity

Action potentials: nerve impulse travelling is due to opening and closing of sodium/potassium/ion channels in fluid lipid bilayer via polarisation All or none principle: either the threshold potential is not reached, or a full action potential is fired Gland: any tissue structure that produces hormones

1.1.2 Temperature

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1.1.3 Glucose Pancreas is regulator of blood glucose Islets of Langerhans: endocrine section of pancreas, produce insulin and glucagon Beta cells: chemoreceptors. Detect high blood glucose, produce insulin to prevent hyperglycaemic shock Alpha cells: chemoreceptors. Detect low blood glucose, produce glucagon to prevent hypoglycaemic shock

1.1.4 Water Pituitary gland: produces antidiuretic hormone (ADH)

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1.2 Mechanisms used to maintain internal environment 1.2.1 Behavioural, structural, and psychological adaptions in endotherms Endotherms: organisms that maintain their body temperature within a range of tolerance limits despite variations in ambient temperature Adaptations in endotherms

Behavioural

Structural

Physiological

Changing body position

Body temperature

Shivering

Nocturnal activity

Surface area/volume ratio

Hibernation and torpor

Migration

Blubber (adipose tissue)

Evaporative cooling

Vasodilation, vasoconstriction

Non-shivering thermogenesis

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Behavioural adaptions Body position (alter surface area)

Nocturnal activity Migration

Structural adaptions Temperature control Body shape

Temperature too high – red kangaroo shades legs/tail with rest of body to reduce exposed area Temperature too low – mountain pygmy possum rolls into ball, reducing exposed surface area Typical where daytime temperatures are high Remain inactive during the day to avoid generating metabolic heat Grey plover breeds in northern hemisphere in May-August and migrates to Australia August-April to avoid severe winter Humpback whales migrate annually from southern feeding grounds to warmer water to mate Includes insulation e.g. fur, hair, feathers to trap air to reduce heat loss Penguins have small ears and legs and round body shape. Minimises exposure to cold through small surface area/volume ratio Blubber (adipose tissue) prevents heat less through low thermal conductivity

Physiological adaptions Functions within the Metabolic activity (main source of internal heat) body Shivering Increases metabolic rate, increasing internal body temperature Hibernation Extended period of inactivity in response to cold where heart rate and oxygen drop considerably but body temperature remains normal Mountain pygmy possum hibernates during cold winters to reduce energy expended on maintaining internal body heat Torpor Short-term hibernation where body temperature, metabolism, heart rate, and respiratory rate decrease Wombat slows its metabolism to a third of its normal rate on hot days Hibernation and torpor are physiological rather than behavioural because of the changes in body function (i.e. Humans can’t go into torpor) Evaporative cooling Sweat Vasodilation or Bilby ears regulate internal temperature through countercurrent vasoconstriction exchange (warm arterial blood heats cooler blood in veins so organs are not cooled by returning blood from appendages) Non-shivering Fat in brown adipose tissue is broken down to produce heat, instead of thermogenesis below usual carbs/sugars. Fats (lipids) are used for cellular metabolism, 36° producing heat as a biproduct

1.2.2 Internal coordination systems Nervous and endocrine system coordinate and provide pathways of communication for negative feedback systems Receptors



Control centres

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Effectors

Via nerves or hormones Receptors: detect stimuli – any changes outside homeostasis tolerance limits. Contain sensory cells Complex forms of concentrated receptors form sense organs (e.g. eyes, mouth, nose) 7

Sense organs: Detect changes in external environment

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Interoceptors: Detect changes in internal environment

Thermoreceptors: detect changes in temperature Chemoreceptors: detect changes in chemical concentration and pH Osmoreceptors: detect changes in osmotic pressure

1.2.2.1 Hormones Endocrine system regulates body activity. Hormones are transported via bloodstream to target cells with receptors for specific hormones -

Influences activity/concentration of enzymes in target cells Causes cells to change activity to maintain homeostasis

Glands are stimulated to secrete hormones by the nervous system, other hormones, or receptors in glands

Pituitary gland

Thyroid and parathyroid glands Adrenal glands (adrenal cortex and medulla)

Pancreas

Releases hormones to regulate/coordinate other glands Anterior: controlled by hormones Posterior: controlled by nerve impulses Produce thyroxine – transfers message to cells to increase metabolic rate Maintains calcium in blood via parathyroid hormone (PTH) Adrenal cortex stimulates production of hydrocortisone (cortisol) and corticosterone – manages stress, regulates cardiovascular function and blood pressure, regulates immune response Also secretes aldosterone, increasing reabsorption of sodium ions and decreasing reabsorption of potassium ions in kidneys Islets of Langerhans produce insulin and glucagon (see maintenance of blood glucose)

1.2.2.2 Neural pathways Nervous system comprised of: Central Nervous System: Brain, spinal cord

Peripheral Nervous System: All other nerves

Via ‘messages’ – electrochemical impulses Neurons have unique, individual structures and functions. Contain 3 main structural features: -

Cell body (nucleus, common organelles) Dendrite (receive and conduct messages towards cell body) Axon (conduct messages away from cell body)

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Neurons are classified according the function and direction of message carried: -

Sensory: from sensory cells to CNS Motor: from CNS to effectors (muscles, glands) Interneurons: between sensory and motor neurons

Synapse: junction between two neurons across which electrical signals pass. Human body contains up to 500 trillion synapsis Action potential: temporary change in electrical potential of cell membrane of axon. Change in chemical concentration by movement across cell membrane causes electrical impulse Resting membrane potential (while not transmitting message) = -70mV (membrane is polarised)

1. Electrical nerve impulse travels along first axon (presynaptic neuron) 2. Nerve impulse reaches dendrites at the end of the axon, causing synaptic vessels containing neurotransmitter to move and fuse to cell membrane 3. Neurotransmitters are released into the synapse. Due to the concentration difference they diffuse across the synaptic cleft 4. Chemicals bind with receptor molecules on the membrane of the second neuron. The receptor molecules can only bind to the specific neurotransmitters released from the first neuron (cocaine accelerates diffusion, alcohol inhibits diffusion)

Central nervous system Brain Grey matter: neuron cell bodies White matter: nerve fibres + myelin sheaths Hypothalamus is control centre for homeostasis, maintaining heart rate, body temp, blood pressure, and O/CO blood concentrations

Spinal cord Conduction pathway for nerve impulses Coordinate reflex actions

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1.2.3 Mechanisms maintaining water balance in plants Mechanisms

Reducing plant internal temperature

Reducing transpiring structures to sunlight

Water storage

Shiny leaf cuticle

Leaf orientation

Dry fruits

Covering of hairs on leaf

Leaf size

Succulents

Stomata regulation

Flower size

Sunken stomata

Curled leaves

Phyllodes

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2.0 Causes and effects Inquiry question: do non-infectious diseases cause more deaths than infectious diseases?

2.1 Causes and effects of non-infectious diseases in humans

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The top 4 causes of death in 2015 (ischaemic heart disease, dementia/Alzheimer’s, cerebrovascular disease (stroke), trachea, bronchus, and lung cancer) are all non-infectious diseases. Environmental and genetic factors may affect the likelihood of developing a non-infectious disease (e.g. diet, radiation exposure, lifestyle)

2.1.1 Genetic diseases Caused by mutation in genes or chromosomes of an individual. Can be harmful, beneficial, or have no effect. Can also arise during cell division (abnormal mitosis or meiosis) causing aneuploidy (incorrect number of chromosomes) or abnormal chromosomes. Affects the protein, causing phenotypic symptoms

Cystic fibrosis

PKU (phenylketonuria)

2.1.1.1 Single gene Causes Mutation of cystic fibrosis transmembrane conductance regulator (CFTR) gene on chromosome 7 (recessive). Changes the protein which regulates normal movement of sodium chloride in and out of cells

Mutation of gene on chromosome 12 coding for production of phenylalanine hydroxylase (PAH). Produces enzyme required for breakdown of amino acid phenylalanine

Effects Mucus-secreting organs secrete abnormally thick mucus. Affects respiratory, digestive, reproductive systems, and sweat glands. Mucus is thick and blocks passageways in lungs and digestive tracts. Symptoms include chest infections, malabsorption of nutrients, diabetes, excess salt in sweat, liver failure, infertility. Average life expectancy 30-40 years Leads to build-up of phenylalanine in blood and tissues. Build-up causes intellectual disabilities, delayed development, social, emotional, behavioural problems, psychiatric disorders, hyperactivity, seizures. Disease is managed by diet low in protein-rich foods e.g. nuts, eggs, milk, meat to prevent amino acid build-up. Must avoid sugar-free products with artificial sweeteners

2.1.1.2 Chromosomal abnormalities Aneuploidy or deletion/addition/substitution mutations occur due to: -

Non-disjunction: incorrect chromosome separation Trisomy: extra chromosome causing chromosomes in excess of diploid number Monosomy: one member of chromosome pair is missing causing less than diploid number

Syndrome: group of symptoms that occur together and characterise a disease. The chromosome determining the mutation determines the syndrome

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Down syndrome

Klinefelter syndrome

Causes Presence in zygote of additional chromosome 21 (trisomy 21) Affects 1 in 800 births

Trisomy involving sex chromosomes – males have XXY Individual chromosomes can be changed or mutated. Genes on deleted sections are lost

Effects Characteristic facial features (small flattened skull, short flat-bridged nose, wide set, almond-shaped eyes, skin folds on eyes), protruding tongue, small, folded ears, intellectual disability, infertility, susceptibility to infection Lower testosterone and sterility Feminine fat distribution and breast growth. Young boys often have learning disabilities

2.1.2 Diseases caused by environmental exposure Caused by the interaction of humans with their environment throughout their lives

2.1.2.1 Lifestyle factors Arise as a direct result of the way in which individuals lead their lives Cardiovascular disease

Skin cancer

Causes Effects Atherosclerosis: hardening of the Hinders blood flow and increases arteries. Occurs due to insufficient blood pressure (hypertension). activity, alcohol consumption, stress, Deposited plaque reduces elasticity smoking, imbalanced diet. Occurs and blood flow, can cause cerebral via deposition of lipids in inner haemorrhage. Occlusion can occur arterial walls, causing artery walls to in blood vessels, causing cardiac become rough ...