Notes on ‘The Essential Ingredient’ and ‘Our Body in Balance’ PDF

Notes on ‘The Essential Ingredient’ and ‘Our Body in Balance’ DNA and its structure according to the Watson and Crick model - DNA contains the necessary instructions for life - The code within our DNA provides directions on how to make proteins that are vita...

Notes on ‘The Essential Ingredient’ and ‘Our Body in Balance’ DNA and its structure according to the Watson and Crick model - DNA contains the necessary instructions for life - The code within our DNA provides directions on how to make proteins that are vital for our growth, development and overall health - Our cells read this code three bases at a time to generate proteins essential for life - The DNA sequence that stores this code (information) is a gene - Proteins contain different combinations of amino acids - When placed together in the right order, each protein has a unique structure and function within our bodies - DNA stands for ‘deoxyribonucleic acid’, which contains nucleotides - DNA contains our hereditary material and our genes (which makes us unique) - A collection (strand) of nucleotides makes a DNA molecule. - A strand has millions of nucleotides - A strand is a polymer of nucleotides - Nucleotides comprise of a sugar, a phosphate group and a nitrogen base. - Sugar = 2-deoxyribose - makes up the backbone of the DNA strand and alternates with the phosphate groups - A nitrogen base is attached to a sugar. The teeth are nitrogen bases. - Nitrogen bases include: - Adenine (A) - Cytosine (C) - Guanine (G) - Thymine (T) - Cytosine (C) and Guanine (G) always join together - Adenine (A) and Thymine (T) always join together - Two strands of DNA form a double helix - Sugar-phosphate backbones are the legs of a ladder - Nitrogen base pairs are the rugs (footsteps) of a ladder - The bases attract because of hydrogen bonds  - Hydrogen bonds are weak, but there are millions of them in a single molecule of DNA Extra information (maybe) - The process from DNA to protein involves transcription and translation - Transcription: In the nucleus, the DNA strands split, and a special protein reads the DNA sequence to create a messenger known as RNA (mRNA) - an intermediary molecule. The RNA leaves the nucleus and carries the genetic code to the protein-making machinery - Translation: In the cytoplasm, the cell’s machinery reads the RNA in sets of three base pairs at a time (codons) to assemble a protein, adding amino acids in the right order - The genome contains roughly 3 billion DNA bases (20,000 genes) - Only 1% of the genome is made up of protein-coding genes, while the rest regulate gene expression - DNA is damaged daily due to replication errors, UV radiation and more - Cells have repair mechanisms, but mutations can lead to diseases or conditions like cystic fibrosis - Mutations contribute to genetic diversity, like different hair and eye colours - As we age, unrepaired DNA damage accumulates, potentially due to less efficient repair mechanisms after reproductive age - In eukaryotic cells (human cells), DNA is found in the nucleus and mitochondria - In prokaryotic cells (bacteria cells), DNA is found coiled in the nucleoid, without a membrane-bound nucleus - When cells divide, DNA replicates to ensure that each new cell gets a complete copy DNA, Chromosomes, and their role in the transfer of genetic information - DNA, genes and chromosomes cooperate to make up who we are and tell our cells how to behave. - Chromosomes carry DNA, DNA is responsible for building and maintaining our human structure, and genes are segments of our DNA that give us physical characteristics that make us unique - Chromosomes live in the nucleus of cells - They contain DNA and protein, coming in all shapes and sizes - Histones (proteins) allow them to shrink to fit in the nucleus. Without histones, chromosomes would be extra long - Chromosomes give your cells the instructions that make you unique - Humans have 23 pairs of chromosomes (46 altogether) - Divided into 22 numbered pairs (autosomes) and one pair of sex chromosomes (X and Y) - One chromosome is received from each parent to form a pair - Some people have trisomy (additional chromosome attached to the pair) or monosomy (one less chromosome on a pair) - Homologous chromosomes - Pairs of chromosomes in a diploid organism that have similar genes, although not necessarily identical - One maternal and one paternal chromosome that pair up with each other inside a cell during fertilisation - Genes and traits are passed down through chromosomes (offspring inherit the genes and traits from their parents) - Through DNA, genetic information is transmitted in the sequence of nucleotides to the next generations.  - Its twisted shape enables DNA to transfer biological instructions with great precision and accuracy - DNA is replicated or transferred via the opening of the double helix, separation of DNA strands, the priming of the template strand, and hence, the assembly of the new DNA segment - Genetic information is also transferred via the nucleus to the cytoplasm through messenger RNA (mRNA), aka ribonucleic acid - Chromosomes exchange genetic information during meiosis in a process called ‘crossing over’ - Meiosis: A process of cell division that produces non-identical daughter cells - Also the process of forming gametes (sperm and egg cells) where the chromosome number is halved to 23 - Produces cells that are genetically unique from the parent and contain half as much DNA - Because half of the genes are inherited from the mother and half from the father, sperm and eggs typically halve the amount of DNA (haploid). Their combination during fertilisation (23+23=46) produces enough genes to make a genetically unique child - Ensures genetic variation due to the random assortment of chromosomes and crossing over - Alternatively, during mitosis, cells divide to produce identical copies, ensuring that each new cell receives a full set of chromosomes (46) - Crucial for growth, repair and maintenance - The instructions encoded in DNA are transcribed into messenger RNA (mRNA) and translated into proteins. - Proteins are essential for cellular function and contribute to gene expression by determining an organism’s traits (phenotype). - DNA replication process - The two DNA strands (the double helix) are separated. The ‘unzipping’ (separation) is done by helicase (an enzyme). - This results in the formation of a replication fork - Primase (another enzyme) starts creating a new strand of DNA. - Primase makes a small piece of RNA (called primer) to mark the starting point for the construction of the strand - DNA polymerase (another enzyme) attaches to the primer and will make a new DNA strand - DNA polymerase only adds DNA bases from the 5’ end to the 3’ end (one direction) - The leading strand is made continuously, adding bases individually from the 5’ end to the 3’ end - The lagging strand is NOT made continuously, as it runs from the 3’ end to the 5’ end (opposite direction) - DNA polymerase creates the strand in Okazaki fragments (series of small chunks) - Fragments are first formulated using the RNA primer - DNA polymerase adds a short row of DNA bases, in the ‘5 to 3’ direction (direction of leading strand) - The next primer is added further down the lagging strand - Another Okazaki fragment is made, and the process is repeated  - After the DNA has been made, exonuclease (another enzyme) removes all RNA primer from the two DNA strands - Another DNA polymerase fills in the gaps left behind - DNA ligase seals up the fragments of DNA in the two strands to form a continuous double strand (double helix) DNA and mutation - Mutation is a process that changes the DNA sequence (or shape) of a cell - Genetic mutations prevent one’s body from developing and functioning normally - Factors that can change DNA - Random mutations, like errors in the DNA replication process during cell division - Exposure to mutagens, like UV radiation, x-ray gamma rays, harmful chemicals, etc - Carcinogens, which are chemical compounds that are bound to cause cancer - Viruses, like HPV which can cause cervical cancer - Inherited mutated DNA (DNA inherited from their parents) - Selective breeding involves selecting individuals of a species that have characteristics of interest in the hope that their offspring inherit those desirable characteristics - Responsible for the creation of certain pet breeds, foods (corn, papaya, tomatoes), and farm animals - Farmers have used this biotechnological technique for centuries - Used for an enhanced understanding of the pattern of inheritance - Transgenic species are produced from cells into which genes from another species have been added - Examples include transgenic rabbits, created by injecting jellyfish (gene for coding fluorescence) DNA into rabbits - Known as genetic engineering, used since the 1960s - Used to introduce new traits/features into existing species - Step 1: identifying target gene - the gene may code for a desired characteristic (like vigorous muscle growth) - Step 2: After identifying this, the gene is removed from its DNA strand using certain enzymes - restriction enzymes - Step 3: Once the gene has been isolated, it is inserted into the host organism - the choice of host depends on the desired outcome. It can be inserted into the embryonic cells or bacteria - Benefits of mutations - It might result in a new or improved protein function, giving the organism an edge in survival or reproduction. - Over time, these beneficial mutations can spread through a population by natural selection and drive evolution. - Cons of mutations - It can lead to the production of nonfunctional or harmful proteins. These mutations can cause diseases or developmental issues, including - Genetic disorders: For example, sickle cell anemia results from a point mutation in the gene encoding hemoglobin, causing abnormal red blood cells. - Cancer: Mutations in certain genes (e.g., tumour suppressor genes, oncogenes) can lead to uncontrolled cell growth and cancer. - GMOs (genetically modified organisms) - Examples include  - GM papaya - transgene origin from the viral papaya ringspot virus (PRSV) - The transgene was formed to resist the ringspot virus, which severely threatened papaya crops in Hawaii. - The modification saved the papaya industry from collapse by making plants immune to the virus - Golden rice - transgene origin from daffodils and a bacterium - Was genetically engineered to produce beta-carotene, a precursor to vitamin A - The modification aimed to reduce vitamin A deficiency in developing countries, which can lead to blindness and other immune deficiencies (specifically in children) - There are concerns regarding the - Environmental impact of gmos - fears that transgenes from gmos will transfer to wild relatives and form weeds that are resistant to herbicides, which would make it harder to control weeds and contribute to increased herbicide usage - Could contribute to biodiversity loss - Impacts on health - Could introduce new allergies - Antibiotic resistance fears - Ethical impacts - Believed to be unnatural - we should nto interfere with the natural order of life. This concern often overlaps with religious or philosophical beliefs about the sanctity of life. - Doesn’t have to be advertised, which means that people may not be aware if the food their purchasing is genetically modified - consumers should have the right to know what their food contains - Long-term effects unknown - Benefits of gmos include - Increased crop yield - Reduction in pesticide use - Improved nutritional content - Disease resistance - Reduced food waste - Medical applications Relating the organs of the reproductive system to their function - Asexual reproduction - Involves one parent - Cells divide via mitosis - No mixing of genetic information = no variation in offspring - Gives rise to genetically identical offspring - clones - Genetic material identical to the parent and each other - Frequent in tiny animals and plants, bacteria and fungi - Bigger plants like strawberries, daffodils and brambles are also asexual - Cells in human bodies reproduce asexually all of the time - Cells divide into two identical cells for growth and to repair worn-out tissues  - Types of asexual reproduction include - Fission - A reaction in which the nucleus of an atom splits into two or more smaller nuclei - Releases a large amount of energy - Simple cell splitting (single cells or cell clusters) - Budding - When a new organism develops from an outgrowth or bud due to cell division at one particular site - Offspring which separates is smaller than the parent (eg. yeast or potatoes) - Vegetative propagation - When a new plant grows from a fragment or cutting of the parent plant or specialised reproductive structure - The process in which new plants are grown from the old parts of another plant like roots, shoots and leaves, without involving any reproductive organ - The formation of a miniaturised plant from specialised leaves or runners - Sexual reproduction (human reproduction) - Parents pass their genetic material onto their offspring - Offspring inherit genetic information from both parents - Will contain similar characteristics, but won’t be identical - Therefore, offspring are more genetically varied (unlike asexual offspring) - Variation is key for the long-term survival of a species. - This is why sexual reproduction takes place in living things ranging from single-celled organisms to humans - Goal of reproduction is to ensure the continuity of a species (achieved through reproduction) - Involves a male sex cell and female sex cell from two parents - These two gametes (sex cells) merge to form a zygote - Zygotes develop new individuals - Gametes are formed via cell divison - meiosis - Results in 4 daughter cells that are haploid - Chromosome number of original cell is halved (haploid) - This is so the gametes can remerge, allowing the new cell to have the right number of chromosomes - Gametes in other domains - In plants, gametes are egg cells and pollen - In animals, gametes are the egg cells (ova) and sperm A. Process of fertilisation a. Sperm Production: Happens in the testicles of men or people assigned male at birth (AMAB) b. Ejaculation: Releases millions of sperm cells that swim through the vagina into the fallopian tubes to fertilise the egg c. Fertilisation: When one sperm breaks through the egg's outer layer; the fertilized egg is called a zygote. d. Zygote Development: The zygote divides into multiple cells, and fimbriae (Finger-like structures) guide the egg through the fallopian tubes toward the uterus. It forms a blastocyst (cluster of 100 cells) here after about a week. e. Implantation: The blastocyst attaches to the lining of the uterus (endometrium); if it doesn't, the fertilized egg passes during the next menstrual period. f. Successful Implantation: The blastocyst continues to divide, forming the baby and the placenta. g. Hormonal Changes: Hormones signal the body to maintain the uterine lining, preventing menstruation and indicating pregnancy. - Menstrual cycle process - Each month the lining of the uterus starts to thicken ready to receive a fertilised egg - At the same time an egg starts to mature in one of the ovaries - Approximately 14 days later, the egg is released from the ovary – ovulation  - The uterus lining remains thick - If the egg is fertilised it may implant on the uterus lining – here it is protected and received nutrients and oxygen from the mother. - The woman is now pregnant - If the egg is not fertilised, the uterus lining, and the egg are removed from the body – period/menstruation - Hormones involved in the menstrual cycle include - Follicle-stimulating hormone (FSH) - This is secreted by the pituitary gland. It travels to the ovaries where it causes an egg to mature and stimulates the production of oestrogen - Oestrogen - This is made and secreted by the ovaries. It causes the lining of the uterus to build up. It inhibits the production of FSH but stimulates the production of LH - Luteinising hormone (LH) - When it reaches a peak, ovulation is triggered - Progesterone - Maintains the uterus lining and inhibits LH - Levels of this hormone remain high during pregnancy - Organs involved in reproduction and their functions Female Reproductive Organs - Ovaries - Produce eggs (ova) and hormones such as estrogen and progesterone. - Fallopian Tubes - Transport eggs from the ovaries to the uterus; where fertilization by sperm typically occurs. - Uterus - A hollow organ where a fertilised egg implants and develops into a fetus; it also contracts during childbirth to deliver the baby. - Endometrium - The lining of the uterus that thickens each month in preparation for a fertilized egg; sheds during menstruation if no implantation occurs. - Cervix: - The lower part of the uterus that opens into the vagina; allows passage of sperm into the uterus and the baby out during childbirth. - Vagina - A muscular canal that serves as the birth canal, passage for menstrual flow, and where sperm is deposited during intercourse. - Vulva - External genital organs, including the labia, clitoris, and vaginal opening, which protect the internal reproductive organs and are involved in sexual arousal. - Clitoris - A small, sensitive organ that plays a significant role in sexual arousal and pleasure. Male Reproductive Organs - Testes  - Produce sperm and testosterone, the primary male sex hormone. - Scrotum - A sac that holds the testes and regulates their temperature to optimise sperm production. - Epididymis - Stores sperm as they mature and gain the ability to swim. - Vas Deferens - Transports mature sperm from the epididymis to the urethra in preparation for ejaculation. - Seminal Vesicles - Produce seminal fluid that mixes with sperm to form semen; this fluid contains nutrients that help nourish sperm. - Prostate Gland - Produces a fluid that makes up part of the semen, which helps to nourish and transport sperm during ejaculation. - Urethra - Carries semen out of the body during ejaculation and urine during urination (although not at the same time). - Penis - The external organ used for delivering sperm into the female reproductive tract during intercourse; also expels urine from the body. Predicting the inheritance of dominant and recessive alleles - Each individual has two alleles for each gene, one inherited from each parent. - Dominant Allele (A) - An allele that expresses its trait even if only one copy is present - AA or Aa - Recessive Allele (a) - An allele that only expresses its trait if two copies are present - aa - Genotypes, the genetic makeup that determine a specific trait, can be - Homozygous Dominant (AA) - Two dominant alleles - Heterozygous (Aa) - One dominant and one recessive allele - Homozygous Recessive (aa) - Two recessive alleles - Phenotypes, the physical expression of a trait. - Dominant Phenotype - Expressed in both homozygous dominant (AA) and heterozygous (Aa) individuals - Recessive Phenotype - Expressed only in homozygous recessive (aa) individuals The relationship between genotype and phenotype - The genotype influences the phenotype by directing the production of proteins that shape an organism’s traits. However, environmental factors also play a role.  - eg. A plant’s height (phenotype) may depend on its genes (genotype) but can also be affected by sunlight or nutrients. - There can be more than one genotype for a given phenotype as dominant alleles mask the effect of recessive alleles, which is why dominant alleles are marked by the same uppercase letter, (AA), and recessive alleles are marked by the same lowercase letter (aa) - The genotype sets the potential, while the phenotype is the actual result, shaped by genetics and the environment - Genotype - The genetic makeup of an organism - The specific genes and alleles it possesses - Inherited from the organisms’ parents - each individual has two copies of most genes (one from each parent) - Resides in the DNA of its cells - Alleles - They are genes occupying the same position on a chromosome code for the same trait - Versions of the same gene - An individual can only have two alleles for a given gene - There may be more than two alleles in a population, like a blood group (A, B, O) - Heterozygous - Two different versions (alleles) of the same gene (eg, Aa) - Only the dominant allele (A) is expressed - Heterzygotes are carriers for a recessive allele - Homozygous - Both chromosomes (maternal and paternal) have identical copies of the dominant allele for a gene (eg, AA) - Both chromosomes (maternal and paternal) have identical copies of the recessive allele for that gene (eg, aa) - Phenotype - An organism’s observable features of traits - Influenced by the organisms’ genotype, as well as environmental factors - Examples include eye colour, hair tetxure, height, blood type, etc  Construction and interpretation of Punnett squares and pedigrees to explore inheritance - The Punnet square - Invented by Reginald Crundall Punnett - The punnet square is used to represent the outcome of crosses - The gametes of each parent are separated on each axis and recombined in the spaces within the 2x2 grid - Each parent provides two alleles for the grid - Heterozygous = recessive, Aa - Dominant homozygous = dominant, AA - Recessive homozygous = recessive, aa - Genetic crosses - The offspring are referred to by how many generations removed they are from the parental (P) generation - F1 = the heterzygous offspring of a cross between the two true breeding parents - F2 = offspring of a cross between two F1 offspring  - Pedigree charts - Shows inheritances of traits across generations in a family - Traces down how a gene/trait is passed down, specifically in genetic disorders - Circles represent females - Squares represent males - Horizontal lines between circles and squares indicate mating - Vertical lines show offspring - Rows represent different generations - squares/circles may have a dot to represent carriers of traits - squares/circles may be shaded to represent who has/doesn’t have a trait - Patterns of inheritance in pedrigree charts (USEFUL) - Autosomal dominant - If the trait appears in every generation, affected individuals have at least one affected parent - Autosomal recessive - The trait may skip generations, but individuals may still be carriers without showing the trait - Sex-linked inheritance - not needed - Traits linked to sex chromosomes are more common in one gender *hemophilia is the disease affecting generations The parts of the endocrine system and its role in the coordination and control - Consists of glands that secrete hormones  - Hormones are transported through the bloodstream - The hormones affect specific organs which have receptors for the hormones on the cell surface membranes Organ/Gland Hormone Produced Function of Hormone Pituitary Gland Growth hormone Influencing our height, and helping build our bones and muscles Pineal Gland Melatonin hormone It helps with the timing of your circadian rhythms (24-hour internal clock) and with sleep Hypothalamus Oxytocin and Vasopressin hormones Master regulator of thyroid gland growth and function Thyroid/Parathyroid Triiodothyronine, Controls calcium levels in your blood. Tetraiodothyronine, Calcitonin hormones Thymus Thymosin hormone Stimulates the production of T cells Adrenal Glands Cortisol, Aldosterone and Controls sex (androgens, estrogens), salt balance in Adrenaline hormones the blood (aldosterone), and sugar balance (cortisol) Pancreas Insulin and Glucagon hormones Glucagon keeps blood glucose from dropping too low, insulin is produced to keep blood glucose from rising too high. Ovaries Oestrogen and Progesterone Regulate the development and function of the uterus hormones Testes Testosterone hormone Regulate sex drive (libido), bone mass, fat distribution, muscle mass and strength, and the production of red blood cells and sperm - Adrenal Glands - Adrenaline - Activates the sympathetic nervous system (fight or flight mechanism) - Prepares the body for intensive action - Targets the heart, muscles, blood vessels, lungs  - When we feel threatened or scared, the brain signals the adrenal glands to secrete adrenaline - When stress stops, the adrenal glands are signalled to stop producing adrenaline - Body returns to homeostasis - The body responds by - Expands air passages in the lungs - respiring quicker - more energy is released - Increasing breathing rate - response to cope with the increased demand for oxygen - Increasing heart rate - Diverting blood away from trigger areas, like the digestive system to the muscles - Cortisol - Produced in the adrenal glands - Increases the amount of glucose (sugar) in the blood and increases the metabolism of fats, proteins and carbohydrates - Provides the energy for the ‘fight or flight’ response - Pancreas - Glucose - Glucose is an energy source - Chemical reactions transfer energy to ATP (a chemical energy storage molecule) which can be used by cells - Staying healthy = maintaining consistent glucose levels - After eating, glucose released via digestion passes into the blood - Blood sugar levels rise - If this is maintained for long periods of time, body systems can face severe damage - More glucose is needed during exercise as the body wants/needs more energy - This causes blood sugar levels to drop - Insulin - When blood sugar levels rise, the pancreas detects this and releases insulin to combat this - Travels to the liver via the blood - Stimulated the liver to turn glucose into glycogen, which is then stored in the liver - Cells are stimulated to remove glucose from the blood - Less glucose in blood = blood sugar levels falling - When blood sugar levels fall (after exercise), the pancreas detects this and releases glucagon - Triggers same process in reverse - Diabetes - A diabetic has constant high blood sugar levels - This can be harmful to bodily systems, like nerves and blood vessels - Type 1 diabetics - Cannot produce insulin  - Immune system destroyed pancreatic cells that make insulin - Usually stems from childhood - Control it by taking regular insulin injections - Balanced diet and regular exercise also helps - Type 2 diabetics - Cannot use insulin - Cells don’t produce enough insulin/cells don’t respond properly to insulin - Usually occurs later in life - Control it by regulating carbohydrate intake - Encouraged to lose weight - Drugs are sometimes given to stimulate insulin production or insulin injections are given - Role of endocrine system in coordination and control - Regulating growth and development - Hormones like growth hormone (GH) from the pituitary gland and thyroid hormones regulate physical growth and the development of tissues and organs - Metabolism control - Thyroid hormones (T3 and T4) from the thyroid gland control the rate of metabolism, influencing how quickly the body uses energy from food - Homeostasis and Balance - Hormones such as insulin and glucagon from the pancreas maintain blood sugar levels, while aldosterone from the adrenal glands controls sodium and water balance - Stress Response - The adrenal glands produce cortisol and adrenaline, which help the body respond to stress by increasing heart rate, blood pressure, and energy supply - Reproductive Control - Gonadal hormones (testosterone, estrogen, progesterone) regulate sexual development, reproductive cycles, and fertility - Immune System Regulation - The thymus and hormones like thymosin contribute to the development of immune cells (T-cells), especially in childhood, ensuring a strong immune system - Sleep and Circadian Rhythms - Melatonin from the pineal gland helps regulate sleep patterns and daily rhythms Examples of hormones, the glands they are secreted from, their targets and effects - Thyroxine (T4) and Triiodothyronine (T3) - Gland: Thyroid Gland - Target: Most cells in the body - Effect: - Increases the metabolic rate of cells. - Regulates growth and development. - Controls energy production and oxygen consumption. - Growth Hormone (GH) - Gland: Pituitary Gland (Anterior) - Target: Liver, bones, muscles, and tissues  - Effect: - Stimulates growth and cell reproduction. - Increases muscle mass and bone strength. - Promotes protein synthesis and fat metabolism. - Oxytocin - Gland: Pituitary Gland (Posterior) - Target: Uterus, mammary glands - Effect: - Triggers contractions during childbirth. - Promotes the release of breast milk in lactating women. - Associated with bonding and social behaviors. - Vasopressin - Gland: Pituitary Gland (Posterior) - Target: Kidneys - Effect: - Promotes water reabsorption in the kidneys. - Reduces urine production to maintain the body's water balance. - Testosterone - Gland: Testes (in males), Adrenal glands (small amounts in females) - Target: Male reproductive organs, muscle, bones - Effect: - Promotes development of male secondary sexual characteristics (facial hair, deep voice). - Increases muscle mass, bone density, and stimulates sperm production. - Estrogen - Gland: Ovaries (in females), Adrenal glands (small amounts in males) - Target: Uterus, breasts, bones - Effect: - Promotes the development of female secondary sexual characteristics (breast development, menstrual cycle regulation). - Supports the growth of the uterine lining during the menstrual cycle. - Maintains bone health. - Progesterone - Gland: Ovaries (mainly produced by the corpus luteum) - Target: Uterus, mammary glands - Effect: - Prepares the uterus for implantation of a fertilised egg. - Maintains the uterine lining during pregnancy. - Helps prepare the breasts for milk production. - Parathyroid Hormone (PTH) - Gland: Parathyroid Glands - Target: Bones, kidneys - Effect: - Increases blood calcium levels by promoting the release of calcium from bones. - Enhances calcium reabsorption in the kidneys and increases the activation of Vitamin D.  - Melatonin - Gland: Pineal Gland - Target: Brain - Effect: - Regulates sleep-wake cycles (circadian rhythms). - Promotes sleepiness as it responds to darkness. - Thymosin - Gland: Thymus - Target: T-cells (a type of white blood cell) - Effect: - Promotes the development and maturation of T-cells, which are essential for the immune response. The parts of the nervous system and its role in coordination and control - Stimulates a response by activating muscles or glands - Homeostasis - Maintenance of a constant internal environment - If homeostasis fails, it can lead to cellular and tissue toxicity, which eventually causes organ failure. It can also result in death and disability in severe circumstances. - Healthy body temp = 37.5° - To keep the temperature the same it must balance the heat lost and heat gained - Bodies use behavioural and physiological methods to control body temperature - Behavioural = actions you decide to take - Psychological = actions your body takes that you can’t control - Negative feedback systems - Counteract a change, bringing the value of a parameter—such as temperature or blood sugar—back towards it set point - Examples include body temperature regulation and control of blood glucose - Positive feedback systems - Amplify their initiating stimuli - move the system away from its starting state - Examples include clot formation, childbirth, fruit ripening, and menstrual cycle - Automatic control systems: - Receptor → processing centre → effector - Neurons - Individual cells found in the nervous system - They transmit information in the form of impulses (a type of electrical signal) - Travels along neurons, from one end of the axon to the other - Synapse - Site where a neuron connects to another cell - Pre-synaptic terminal → synaptic cleft (via diffusion) → post-synaptic terminal - Neurotransmitter - Small chemical which transfers a nerve impulse from one neuron to another - Stored in the presynaptic neuron, in sacs called vesicles - Parts of a neuron:  - Three types of neurons - Sensory - Connect Brain/receptors and neural pathway - Transfer information from receptors to the CNS - Relay - Pass messages between sensor and motor neurons along the neural pathway - Motor - Connect the muscles/effector organs to the neural pathway - Transfer information from the CNS to the effector organs Point of Comparison Nervous System Endocrine System Components - Brain - Hypothalamus - Spinal Cord - Pituitary - Complex network of - Thyroid nerves - Parathyroids - neurons - Adrenals - Pineal body - The ovaries - The testes - (basically hormones and glands, important gland is the pituitary gland) Rate of Response - Really fast - Really slow - fractions of a - 5 seconds+ second Response Locality - Very localised - Systemic response - - specific tissues hormones go everywhere and organs for a nervous response Response Duration - Incredibly quick - over - Last 30 secs to a min before within a second it is flushed out Signal Transmission - electrical - chemical - Endocrine System vs Nervous System - The nervous system transmits electrical impulses along neurones. - The endocrine system delivers hormones using the lymphatic and circulatory systems. - Some key differences between the two systems include: - The nervous system creates faster and more localised responses compared to the endocrine system. - Responses created by the nervous system are short-lasting, whereas the endocrine system creates permanent or long-lasting effects. - Sensory organs - Eye - Nose - Ear - Skin - Tongue Type of Receptor Stimulus these receptors Example of places where respond to these are found Chemoreceptors Chemicals Tongue Photoreceptors Light Eye Mechanoreceptors Pressure or distortion Skin, inner ear Thermoreceptors Heat Skin - Central Nervous System (CNS) - Information about sensory stimuli is integrated - Responses are coordinated - Brain - The control center of the body, responsible for processing sensory information, managing emotions, thoughts, and motor control. - It coordinates voluntary and involuntary activities - Spinal Cord - A bundle of nerve fibers that connects the brain to the rest of the body, transmitting signals to and from the brain. - It also handles reflex actions independently of the brain - Peripheral Nervous System (PNS) - Categorised by all of the neurons found outside of the brain and spinal cord - Some neurons also carry information to glands - Somatic Nervous System (SNS) - Manages voluntary movements by controlling skeletal muscles. It transmits sensory information from the body to the CNS and motor signals from the CNS to muscles - Autonomic Nervous System (ANS) - Regulates involuntary bodily functions like heart rate, digestion, and breathing. It has two branches - Sympathetic Nervous System - Prepares the body for stressful or emergency situations (fight-or-flight response), increasing heart rate, dilating pupils, and redirecting blood flow to muscles - Parasympathetic Nervous System - Supports rest and recovery, slowing down heart rate, aiding digestion, and conserving energy - The nervous system processes external stimuli (like light, sound, or touch) and internal signals (like hunger or fatigue) - Sensory neurons detect changes, relay this information to the CNS, which interprets it, and sends commands to the body via motor neurons to respond appropriately - Sensory neurons carry information towards the CNS - Motor neurons carry information away from the CNS - The nervous system maintains homeostasis by controlling bodily functions and behaviours - It regulates vital processes (like heartbeat, respiration, and temperature), as well as complex behaviours (like speaking or walking) - Reflexes - Automatic responses managed by the spinal cord to protect the body from harm - Performed without conscious thought, in response to a particular stimulus - Reflex arc - A neural pathway that controls a reflex action - Carries impulses from a receptor to an effector without involving the conscious regions of the brain - Allows for a quick response - Reflex examples include - Blinking - Receptors in the cornea sense touch - Triggers muscles in the eyelid to contract and cover the eye - Knee-jerking - Receptors in the quadriceps muscle detect stretching - Causes the quadriceps muscle to contract in order to maintain balance