IB Biology Past Paper - Human Physiology PDF

C3.1 Human Physiology IB Biology 12th Illustration by Smart-Servier Medical Art Unit guiding questions 1. What are the roles of nerves and hormones in integration of body systems? 2. What are the roles of feedback mechanisms i...

C3.1 Human Physiology IB Biology 12th Illustration by Smart-Servier Medical Art Unit guiding questions 1. What are the roles of nerves and hormones in integration of body systems? 2. What are the roles of feedback mechanisms in regulation of body systems?  C3.1.1—System integration. System Integration - When components communicate and coordinate. - Happens on multiple levels of organization: organelles, cells, tissue, organs… Watch the video Watch the video below then describe the process of differentiation and the emergence of new properties when many cells work together. These properties could not exist in a single celled organism like an amoeba. C3.1.2—Cells, tissues, organs and body systems as a hierarchy of subsystems that are integrated in a multicellular living organism. Illustration by Smart-Servier Medical Art C3.1.2—Cells, tissues, organs and body systems as a hierarchy of subsystems that are integrated in a multicellular living organism. Tissue Group of two or more different type of cells with specialised structures and functions working and communicating together. Example: type I and type II pneumocytes in alveolar tissue (lungs). Illustration by Smart-Servier Medical Art C3.1.2—Cells, tissues, organs and body systems as a hierarchy of subsystems that are integrated in a multicellular living organism. Organ Group of two or more types of tissues working together to perform a specific function. Example: spongy mesophyll tissue and palisade mesophyll tissue in a leaf. Example: lung (alveolar tissue, cartilage tissue, ciliated epithelium tissue). C3.1.2—Cells, tissues, organs and body systems as a hierarchy of subsystems that are integrated in a multicellular living organism. Organ system Group of organs working together to perform a function of life. Example: digestive system includes esophagus, stomach, intestines, pancreas, and other organs that all work together to digest and absorb nutrients. Illustration by Smart-Servier Medical Art  C3.1.2—Cells, tissues, organs and body systems as a hierarchy of subsystems that are integrated in a multicellular living organism. Organism A living thing made up of multiple integrated and interdependent systems at various levels of organization. Example: humans have 11 organ systems. Example of emergent properties. C3.1.3—Integration of organs in animal bodies by hormonal and nervous signalling and by transport of materials and energy. Integration requires coordination, which requires: Communication Transport of materials a. Hormones Blood, plant b. Nerves vessels. C3.1.3—Integration of organs in animal bodies by hormonal and nervous signalling and by transport of materials and energy. Hormones - Chemical substances, released by the endocrine system. - Travel through the bloodstream to the whole body. - Affect any cell with the proper receptor (target cell). - Slower. - Lasts until the hormone is broken down. C3.1.3—Integration of organs in animal bodies by hormonal and nervous signalling and by transport of materials and energy. Nervous signals - Electrical impulses: 100 m/s - Transmitted by neurons to a specific location. - Effects muscle or glands only - Rapid. - Very short. C3.1.4—The brain as a central information integration organ 1. Brain receives information. 2. Brain stores information. 3. Brain processes information. 4. Brain may send signals to effector organs (muscle, glands) if a response is required. C3.1.5—The spinal cord as an integrating centre for unconscious processes Two parts of the Nervous System: 1. Central Nervous System 2. Nerves CNS: Central nervous system, comprised of the brain and the spinal cord. C3.1.5—The spinal cord as an integrating centre for unconscious processes Spinal cord ha two main tissues: - White matter - Grey matter White Matter Transmit signals from: a. Sensory receptors to brain. b. brain to other organs. Grey Matter a. Contain cell bodies and synapses. b. Processing information c. Decision making d. Unconscious processes only e. Example: movement of food in the digestive tract. C3.1.3—Integration of organs in animal bodies by hormonal and nervous signalling and by transport of materials and energy. - Transport of materials and energy. - blood/circulatory system carries things from one part to the next. - Some systems also pass along intermediate products to the next organ in the line (digestive system). C3.1.6—Input to the spinal cord and cerebral hemispheres through sensory neurons. Sensory receptors Sensory Neurons CNS Type of receptors External Internal - Touch - Stretch - Heat receptors - Light - chemoreceptors Sensory receptors Sensory Neurons CNS Motor neurons Effector organs C3.1.7—Output from the cerebral hemispheres to muscles through motor neurons. C3.1.7—Output from the cerebral hemispheres to muscles through motor neurons. Motor cortex C3.1.8—Nerves as bundles of nerve fibres of both sensory and motor neurons  C3.1.9—Pain reflex arcs as an example of involuntary responses with skeletal muscle as the effector. Reflex arc: an involuntary and rapid response to a specific stimulus. Receptor Sensory Neuron Interneuron (CNS) Motor neuron Effector organ C3.1.10—Role of the cerebellum in coordinating skeletal muscle contraction and balance Cerebellum is the coordination center. Illustration by Smart-Servier Medical Art Hormones and Feedback Illustration by Smart-Servier Medical Art  Homeostasis and Hormones Homeostasis = maintaining stability in the internal environment of the body between specific limits Maintain internal environment between limits – Blood pH, carbon dioxide concentration, blood glucose concentration, body temperature, water balance Endocrine system consists of glands that release hormones that are transported in blood  C3.1.11—Modulation of sleep patterns by melatonin secretion as a part of circadian rhythms Hormone: Melatonin Secreted by the pineal gland. Helps control circadian rhythms (pattern of sleep/wake cycles that organisms are adapted for). High levels of MELATONIN cause feeling of drowsiness and promote sleep. Falling melatonin levels encourage waking at the end of the night. Inhibited in light, produced in the dark. Integrated with a sensory neuron in the eye that senses light. Melatonin is sometimes advertised as a treatment for Jet Lag - why do you think it might work?  C3.1.12—Epinephrine (adrenaline) secretion by the adrenal glands to prepare the body for vigorous activity Hormone to prepare for vigorous activity (fight or flight). The goal is to increase glucose and oxygen supply to skeletal muscles. EFFECTS: - Hydrolysis of glycogen = glucose. - Increased diameter of bronchi and bronchioles. - Ventilation rate and tidal volume increase. - SA node increases heart rate. - Increase blood flow to liver and muscles (vasodilation). - Decrease blood flow to gut and Illustration by Smart-Servier Medical Art kidneys (vasoconstriction).  C3.1.13—Control of the endocrine system by the hypothalamus and pituitary gland. The Hypothalamus is attached to the Pituitary gland and connects the nervous system with the endocrine system. Receives input from many sources: - Other parts of the brain. - Sensors for temperature, blood glucose, solute concentrations.  C3.1.13—Control of the endocrine system by the hypothalamus and pituitary gland. OSMOREGULATION - Senses solute concentration/osmolarity. - Prompts Pituitary to release ADH (antidiuretic hormone). - Increases reabsorption in kidneys. PUBERTY - Hypothalamus release GnRH. - Prompts the Pituitary to release LH and FSH. - Initiate puberty.  C3.1.14—Feedback control of heart rate following sensory input from baroreceptors and chemoreceptors SA (Sinoatrial) node is connected to the medulla oblongata by the vagus and sympathetic system. Slow Increase Illustration by Smart-Servier Medical Art  C3.1.14—Feedback control of heart rate following sensory input from baroreceptors and chemoreceptors Illustration by Smart-Servier Medical Art C3.1.15—Feedback control of ventilation rate following sensory input from chemoreceptors.  C3.1.15—Feedback control of ventilation rate following sensory input from chemoreceptors. Spirometry to measure ventilation rate and tidal volume during exercise. C3.1.16—Control of peristalsis in the digestive system by the central nervous system and enteric nervous system C2.2.1 Neural Signaling Illustration by Smart-Servier Medical Art  C2.2.1—Neurons as cells within the nervous system that carry electrical impulses Nerve Impulse: electrical signal passed between two cells. Nerve impulses could be along the same neuron and between two neurons. C2.2.2—Generation of the resting potential by pumping to establish and maintain concentration gradients of sodium and potassium ions  NERVE IMPULSE Nerve impulses conducted along a neuron; Result of change in concentration of sodium and potassium ions across membrane of neuron Resting potential = electrical potential across a cell membrane when not propagating an impulse Action potential= reversal then restoration of electrical potential between inside and outside of neuron as impulse passes along it. 39 C2.2.3—Nerve impulses as action potentials that are propagated along nerve fibres.  C2.2.3—Nerve impulses as action potentials that are propagated along nerve fibres. Steps: 1. Voltage-gated sodium channels open. 2. Sodium ions diffuse into the cell (facilitated diffusion). 3. Depolarisation. - to + 4. Voltage-gated sodium ion channels close, and voltage-gated potassium ion channels open. 5. Potassium ions diffuse out of the cell (facilitated diffusion). 6. Repolarisation. 7. Sodium-potassium pump re-establishes resting potential by actively pumping sodium ions out and potassium ions in.  C2.2.3—Nerve impulses as action potentials that are propagated along nerve fibres. Self-propagating: depolarisation in one part triggers depolarisation in the next part due to the opening of voltage-gated channels. One-way C2.2.4—Variation in the speed of nerve impulses Myelinated and unmyelinated neurons - The average speed for nerve impulse is 1 m/s. - Ways to speed this up: Increase diameter Myelination C2.2.4—Variation in the speed of nerve impulses Myelination and saltatory conduction As myelin acts as an insulator myelinated axons only allow action potentials to occur at the unmyelinated nodes of Ranvier. This forces the the action potential to jump* from node to node (saltatory conduction). The result of this is that the impulse travels much more quickly (up to 100 m/s) along myelinated axons compared to unmyelinated axons *The jump along the axon is actually just (1 m/s). the very rapid conduction inside the myelinated portion of the axon. Saltatory conduction from node to node also reduces degradation of the impulse and hence allows the impulse to travel longer distances than impulses in unmyelinated axons. The myelin sheath also reduces energy expenditure over the axon as the quantity of sodium and potassium ions that need to be pumped to restore resting potential is less than that of a unmyelinated axon  How is information transmitted between neurons? Dendritic end to terminal end: synaptic gap Electrical impulse converted to chemical neurotransmitter. C2.2.5—Synapses as junctions between neurons and between neurons and effector cells. C2.2.6—Release of neurotransmitters from a presynaptic membrane Steps: 1. Action potential reaches the end Presynaptic of the presynaptic neuron. 2. Voltage-gated calcium ions channels open. 3. Calcium ions enter the presynaptic neuron (facilitated diffusion). 4. Calcium ions force vesicles with neurotransmitters to fuse with the membrane. 5. Neurotransmitters are released into the synapse (exocytosis). Postsynaptic  C2.2.7—Generation of an excitatory postsynaptic potential Steps: 1. Neurotransmitters diffuse across Presynaptic the synapse. 2. Binds to receptor to the postsynaptic membrane. 3. Ion channels open. 4. If enough ions enter the postsynaptic cell, that generates an action potential. 5. Neurotransmitter is removed from the synapse. Postsynaptic  C2.2.7—Generation of an excitatory postsynaptic potential Acetylcholine is a neurotransmitter found between neurons and muscle cells. 2 parts: – acetyl (from respiration) – choline (from diet) It travels across the synapse to bind its receptor However, the enzyme acetylcholinesterase rapidly breaks down acetylcholine in the synapse (into choline and acetate) Choline is absorbed by pre-synaptic neuron and re-used to make more acetylcholine. C2.2.8—Depolarization and repolarization during action potentials ONLY HL The threshold potential is the critical level to which the membrane potential must be depolarized in order to initiate an action potential. Threshold potentials are necessary in order to regulate and propagate signaling in both the central nervous system (CNS) and the peripheral nervous system (PNS). C2.2.8—Depolarization and repolarization during action potentials ONLY HL If the threshold potential is reached, the voltage-gated sodium ion channels open and sodium diffuses into the cell. This causes a wave of ion channels openings further down the axon. C2.2.9—Propagation of an action potential along a nerve fibre/axon as a result of local currents ONLY HL C2.2.10—Oscilloscope traces showing resting potentials and action potentials ONLY HL Oscilloscope measures membrane potentials using electrodes. ONLY HL C2.2.11—Saltatory conduction in myelinated fibres to achieve faster impulses ONLY HL C2.2.12—Effects of exogenous chemicals on synaptic transmission ONLY HL Exogenous chemical: something that enters the body through an external source (eating, inhaling, skin, injecting). Can affect synaptic transmission: block it, promote it. Neonicotinoids = an insecticide – synthetic chemical similar to nicotine Binds the acetylcholine receptor irreversibly Leads to paralysis and death in insects Neonicotinoids very widely in use (because safe for mammals) But it’s non-specific, so it also kills helpful insects (like bees). Pro: do not affect humans Con: effect on non-pest species (bees) C2.2.12—Effects of exogenous chemicals on synaptic transmission ONLY HL Cocaine: Blocks the reuptake mechanism for dopamine (brain). Dopamine builds up. Too many dopamine messages. Stimulant/feelings of euphoria. C2.2.13—Inhibitory neurotransmitters and generation of inhibitory postsynaptic potentials ONLY HL Inhibit=prevent Some neurotransmitters make the membrane even more negative, making it harder for nerve impulse to be sent. C2.2.14—Summation of the effects of excitatory and inhibitory neurotransmitters in a postsynaptic neuron ONLY HL Activity- Summation: The slides below explain the processes of summation. There are a number of scenarios posed. Explain what will happen in each one. C2.2.15—Perception of pain by neurons with free nerve endings in the skin. ONLY HL - Sensory neurons have endings in the skin. - An action potential is initiated in response to pain. - Carries the impulse to the spinal column, then to the brain. - Brain sends an impulse along motos neurons to affect behavior. C2.2.15—Perception of pain by neurons with free nerve endings in the skin. ONLY HL C2.2.16—Consciousness as a property that emerges from the interaction of individual neurons in the brain ONLY HL Consciousness: simultaneous awareness of many things. - Reduced consciousness: sleep - Unconsciousness: anesthesia - No agreement on how this works, but there is agreement that it is an emergent property (arises from the interaction between different neurons).  B3.2.1 Transport  B3.2.1—Adaptations of capillaries for exchange of materials between blood and the internal or external environment. Site of diffusion into/out of the blood. Large surface area. Tissues that need lots of oxygen or nutrients have a high-density capillary network.  B3.2.1—Adaptations of capillaries for exchange of materials between blood and the internal or external environment. Pores to increase permeability. Fluids that comes out of capillaries are called tissue fluid. - Water - Oxygen - Glucose - Ions Tissue fluids leaves capillaries and flows between tissues. Materials diffuse into tissues, waste diffuses into tissue fluid. Fluid return to capillaries. B3.2.2—Structure of arteries and veins  B3.2.3—Adaptations of arteries for the transport of blood away from the heart. The function of arteries is to convey blood at high pressure away from the heart - to accomplish this task, arteries have a specialised structure: - They have a narrow lumen (relative to wall thickness) to maintaining a high blood pressure (80-120 mmHg). - They have a tick wall containing an outer layer of collagen to prevent the artery from rupturing under the high pressure. - The arterial wall also contains a inner layer of muscle and elastic fibres to help maintain pulse flow (it can contract and stretch). B3.2.3—Adaptations of arteries for the transport of blood away from the heart. Maintain high pressure Can expand, contract and withstand high pressure without bursting Help provide Less energy recoil to required push blood than a full through contraction Contract to push blood through B3.2.4—Measurement of pulse rates  B3.2.5—Adaptations of veins for the return of blood to the heart - Low pressure - Towards the heart - Relies on contraction of skeletal muscles - Valves veins prevent backflow B3.2.5—Adaptations of veins for the return of blood to the heart B3.2.5—Adaptations of veins for the return of blood to the heart Prevent backflow Easier for muscles to squeeze Low pressure, easier for muscles to squeeze B3.2.6—Causes and consequences of occlusion of the coronary arteries Blood pumped through the heart is at high pressure and cannot be used to supply the heart muscle with oxygen and nutrients. Coronary arteries are the blood vessels that surround the heart and nourish the cardiac tissue to keep the heart working. If coronary arteries become occluded, the region of heart tissue nourished by the blocked artery will die and cease to function. B3.2.6—Causes and consequences of occlusion of the coronary arteries Risk Factors: Smoking Obesity Lack of exercise Genetics High blood pressure (hypertension) Diet high in saturated fats and salt Age B3.2.6—Causes and consequences of occlusion of the coronary arteries B3.2.6—Causes and consequences of occlusion of the coronary arteries Heart Structure Transport in Plants  B3.2.7—Transport of water from roots to leaves during transpiration Transpiration begins with the conversion of water into vapour within the spongy mesophyll of the leaf. - Some of the light energy absorbed by leaves is converted into heat, which evaporates the water within the leaf tissue - This vapour diffuses out of the leaf via stomata, creating a negative pressure gradient within the leaf - This negative pressure causes water to be drawn out of xylem vessels and through cell walls by capillary action, generating tension - This tension draws water up the xylem vessels in opposition to gravity – moving in a continuous stream via mass flow.  B3.2.7—Transport of water from roots to leaves during transpiration The water vapour lost from the leaf is replaced by water taken up from the soil by the roots (maintaining a pressure gradient). Water will then be absorbed into the roots via osmosis – moving towards the region with the higher solute concentration The rate of water uptake will be regulated by specialised water channels (aquaporins) on the root cell membrane. The epidermis of roots may have cellular extensions called root hairs, which further increases the surface area for absorption. B3.2.8—Adaptations of xylem vessels for transport of water  B3.2.8—Adaptations of xylem vessels for transport of water Complete the following table: Structure Function Dead, hollow cells Lignin Pits  B3.2.9— Skill: Distribution of tissues in a transverse section of the stem of a dicotyledonous plant Pith (medulla) B3.2.10—Skill: Distribution of tissues in a transverse section of the root of a dicotyledonous plant  To Do Cut out the hexagons and do one of the following: draw an outline diagram of a plant and label it using the hexagons. annotate each hexagon to make it's meaning more clear. arrange groups of hexagons which are about the same part of a plant. link the hexagons to each other and use these linked cards to create your own written explanations of how water flows in the transpiration stream.