Body Systems Integration PDF

## C 3.1 Integration of body systems: - System integration: Coordination between and within systems of the body. - Organism → multiple systems → within each system - Performing multiple functions - System integration depends on effective communication between components - Simple interaction eg posi...

## C 3.1 Integration of body systems: - System integration: Coordination between and within systems of the body. - Organism → multiple systems → within each system - Performing multiple functions - System integration depends on effective communication between components - Simple interaction eg positive/negative feedback - More complex and multifactorial with many loops and branches - Multicellular organisms have a hierarchy of subsystems that are integrated together - Cell → tissue → organ → organ system → organism ## Table 1 page 452 - Tissues: group of cells of the same type (specialized cells) that perform a specific function. - Tissues may contain 2 or more cell types, which specialize for different aspects of the function of the tissue. - eg alveoli in lungs (AT1 gas exchange, AT2 surfactant) - Cells in a tissue stick together - Plant cells: between cell walls (middle lamella) with pectin - Animal cells: trans membrane proteins that form links with neighbouring cells. - Cells within a tissue communicate with each other - Plant cells: use efflux pumps to transfer Auxin to coordinate growth - Animal cells: Heart muscles transmit electrical impulses which trigger contraction. ## Figure 4 page 453 - Organs: group of tissues that work together to carry out a specific function of life. - eg kidney for excretion, leaf for photosynthesis - Tissues within an organ are interdependent - Spongy mesophyll adapted for gas exchange - Palisade mesophyll adapted for Photosynthesis - Figure 5 and 6 on page 454 ## Organ systems - Groups of organs interact with each other to perform an overall function of life. - In humans, we have 11 organ systems: - circulatory - digestive - endocrine - gas exchange - lymphatic - muscular - nervous - reproduction - skeletal - urinary - integumentary - Most of the time, organs in an organ system are physically linked eg Digestive and nervous systems - In other cases, organs are dispersed around the body eg Endocrine system - See figure 8 page 454 - Organisms: made up of interconnected parts - Organ systems composed of organs - These parts are interdependent so failure of a single group of cells or tissues can cause an organism to die - Made up of tissues with constituent cells - To understand emergent properties of organisms, you must consider systems as a whole. - Integration of nervous and endocrine systems: - Study table 2 page 455 (very important) ## Circulatory system - Transports materials between organs - All tissues need a constant supply of energy/cell respiration - Removal of CO2 produced by respiration - Glucose + oxygen are supplied by bloodstream along with water and carbon compounds needed for growth and repair - Brain: Central integrating organ in the body - Receives information → processes it - Stores some of it - Sends instructions - (Coordinates life processes) - Brain receives information from sensory receptors - It can store information (short term/long term memory) - It can process information that leads to decision making and as a result, it may send signals to muscles/glands to carry out response (effectors) ## Spinal cord - Part of the CNS and located inside the vertebral column (backbone) - Spinal cord has 2 main tissues: - White matter: contains myelinated axons and other nerve fibres that convey signals from sensory receptors to the brain and from brain to organs of the body. - Grey matter: contains the cell bodies of motor neurons and relay (interneurons) with many synapses in between. - Spinal cord only coordinates unconscious processes/reflexes which can be quicker than conveying the information to and from the brain. - Study table 3 page 457 - Exceptions: actions that are non-binary - We may consciously choose to carry them out but the processing used in unconscious example: Striated muscles - We consciously choose to stand up and move in a certain direction - When we are sleeping we might turn over unconsciously using same muscles. ## Sensory receptors - In the skin and sense organs receive changes in the external environment as stimuli - Touch and heat receptors in skin - Other stimuli are received by specialized receptor cells eg light-sensitive rod and cone cells in the retina of the eye. - There are also receptors inside the body that monitor internal conditions. - Stretch receptors in striated muscles - Stretch receptors in the walls of arteries - All stimuli from all receptors and nerve endings are conveyed to the central nervous system by sensory neurons. - Brain → receives signals from head (eyes, ears, nose, tongue) - Spinal cord → receives signals from body organs (skin, muscles) - Visual cortex (brain) receives signals from rods and cones (eye) - Visual cortex is in the posterior part of the cerebrum. - *Exploring and designing: Two-point discrimination page 458 ## Striated muscles - And certain glands are controlled by the cerebral hemispheres of the brain. - Primary motor cortex send signals to striated muscles - Motor neurons - Cell body and dendrites are located in the grey matter of cerebral hemispheres - Attached to bones - 1 Axon leads from cell body of the brain to the spinal cord. Synapses... connect first a second motor leading to a specific muscle (can be one metre long or even more) - Study figure 15 page 459 - Nerve bundle (group of nerve fibres enclosed in protective sheath): - Widest: Sciatic nerve (20mm) - Optic nerve contains 770,000 to 1.7 million nerve fibres ## Reflex arc - A reflex action that is rapid and involuntary response to a specific stimulus. - Reflexes are simple responses involving the smallest number of neurons. - Reflexes are fast, which is an advantage preventing harm to the body. - Some reflexes are coordinated by the spinal cord eg moving hand away from a hot object. - While other reflexes are coordinated by the brain eg pupil in the eye constriction in response to bright light (protecting the retina from damage) - Reflexes depend on: - Receptors - Sensory neurons - Interneurons - Motor neurons - Effectors (muscles, glands) - *Figure 17 page 462 (Shows reflex are very important) - Role of cerebellum: - Cerebellum is important for controlling skeletal muscle contraction and balance. - See figure 19 page 463 - Cerebellum works on the timing of contractions (Not which muscles contract) - It allows coordination of movements and helps us to maintain posture and also helps with activities such as riding a bike or typing on a keyboard. - Circadian rhythms: Sleep cycles in humans that depend on 2 groups: - Hypothalamus - SCN (suprachiasmatic nuclei) - They control the secretion of the hormone Melatonin by pineal gland. - Melatonin secretion increases in the evening and decreases (drops) at dawn. ## Melatonin - (sleep-wake cycle) - Evening time: special cells in the retina (ganglion cells) detect the change in light wavelength and causes impulses to pass to cells in the SCN to allow secretion of melatonin by pineal gland (high melatonin). - At dawn: the same cells detect changes in wavelengths (light) and accordingly response by dropping the levels of melatonin (wake up). - High melatonin: - Cause feelings of drowsiness. - Promote sleep - Receptors of melatonin in the kidneys result in decreased urine production at night. - If melatonin levels fall during the night (to prevent drop of core temperature) and encourage waking up at the end of the night. ## Regression analysis - page 464 (very important to read for all students) - If you sleep better (longer hours) you will get better grades in assessments - Epinephrine (adrenaline): a hormone secreted by adrenal glands to prepare the body for vigorous activity. - Epinephrine binds to adrenergic receptors in plasma membrane of target cells where the supply of oxygen and glucose to (skeletal muscles) increases, maximizing production of ATP by respiration. - Effects of secreting epinephrine: - Muscle cells break down glycogen → glucose - Liver cells break down glycogen as well to release more glucose to the bloodstream - Bronchi and bronchioles dilate to have wider airways and easier ventilation. - Increasing ventilation rate and volume of air. - SA node speeds up the heart rate. - Arterioles carrying blood to muscles and liver widen (vasodilation) so more blood flows to them. - Arterioles carrying blood to gut, kidneys, skin, and extremities become narrower (vasoconstriction) so less blood flows to them. - Epinephrine is known as “fight and flight” hormone. ## Control of endocrine system - by the hypothalamus and pituitary gland: * - Hypothalamus is situated in the 3d ventricle of the brain (on both right and left side) - Ventricles are spaces inside the brain with cerebrospinal fluid inside them. - Hypothalamus links the nervous system to the endocrine system via the pituitary gland. - Receive signals from sense organs via cerebral hemispheres - Also from hippocampus, medulla oblongata, amygdala - Hypothalamus contains specialized areas called Nuclei - Each nucleus operates one or more control systems: - Blood temperature - Blood glucose - Osmolarity - Pituitary gland is located directly below the hypothalamus and is made from 2 main parts: - Anterior lobe - Posterior lobe - They operate in different ways - Anterior lobe: - HGH (human growth hormone) - TSH (thyroid stimulating hormone) - LH (luteinizing hormone) - FSH (follicle stimulating hormone) - Prolactin - Posterior lobe: - ADH (antidiuretic hormone) - Oxytocin - Osmoregulation and puberty are 2 processes based on system integration by hypothalamus and pituitary gland. - Osmoregulation: Using ADH (antidiuretic hormone) - Puberty: secreting GnRH (gonadotropin releasing hormone) - Stimulates FSH and LH secreted by pituitary gland ## Figure 23 page 467 - Feedback control of heart rate: - SAN (sinoatrial node) is made up of special cardiac muscle cells in the right atrium. - Acts as a pacemaker for the heart beat - Pace maker receives signals from Cardiovascular centre (in the medulla oblongata of the brain). - Signals reach pacemaker via 2 nerves: - Sympathetic nerve: Increase the frequency of heart beats. - Vagus nerve: Decrease the frequency of the heart rate - See figure 24 page 468 - Cardiovascular centre in the brain receives sensory inputs from: - Baroreceptors - Chemoreceptors - Baroreceptors: found in the walls of the aorta and carotid arteries which monitor blood pressure. - Control blood pressure by negative feedback: - ↓ blood pressure response increase in heart rate (will increase blood pressure) - Chemoreceptors: found in the aorta and carotid arteries which monitor blood oxygen concentration and blood pH (control method: negative feedback): - ↓ oxygen concentration ↓ blood pH response increase in heart rate (more oxygen is delivered, and more CO2 is removed) - SA node responds to epinephrine as well by increasing the heart rate. - Figure 25 page 468 ## Feedback control of ventilation rate: - Normal range of blood pH is 7.35 to 7.45 - If the blood pH decrease (due to rise in CO2) there will be harmful consequences (acidosis) - Changes in the ventilation rate are the main method to regulate blood pH. - Ventilation rate is regulated by the respiratory centres in the brainstem - Nerves carry signals from respiratory centres to the muscles: - Diaphragm - External intercostal muscles - Contracting these muscles cause lungs to expand - See figure 26 page 469 - Chemoreceptors in the aorta and carotid arteries monitor blood pH using acid-sensing ion channels: - ↑CO2, ↓ blood pH - Chemoreceptors detect and send signals to respiratory centres - ↑ ventilation rate - There is also a back-up mechanism for oxygen supply. - Chemoreceptors in carotid arteries monitor oxygen concentration of blood flowing to head. - Signals are sent to respiratory centres leading to an increase in ventilation rate if lack of oxygen (hypoxia) - Read practical work (ventilation rates) pages 470 and 471 - *Control of Peristalsis in the digestive system:* - Gut: tube that extends from the mouth to the anus. (see figure 31 page 472) - Digestive system - Wall of the gut contains 2 layers of muscles (smooth muscles): - Longitudinal (outer layer) - Circular (inner layer) - Peristalsis: waves of vigorous contractions that pass along the intestine. After swallowing food, food passes quickly down the esophagus to the stomach in one continuous peristaltic waves that move in one direction only (away from the mouth). - In the intestines, food moves in a slower progression that allows food to be digested. - Main function of peristalsis in the intestine is to mix semi-digested food with enzymes to speed up the process of digestion. - Peristaltic muscle contractions are controlled (unconsciously) by the ENS (enteric nervous system). - Intrinsic microcircuits that control stomach and intestines without inputs from CNS - There are two gut movements that are not involuntary, controlled by CNS: - Swallowing - Defecation ## HL: Tropic responses in seedlings - Plants control the direction of growth of their roots and shoots. - If one side of the root/shoot grows more quickly than the other side, then root/shoot will become curved. - This type of growth happens due to external stimuli such as gravity and sunlight. - Tropisms: Differential growth responses to directional stimuli. - Positive tropism: growth towards the stimulus - Negative tropism: growth away from the stimulus - Study figure 34 page 474 - Roots are positively gravitropic: grow downwards with the direction of gravity - Shoots are positively phototrophic: grow towards the source of light. ## Positive phototropism - As a directional growth response to lateral light in plant shoots: - Growth hormones IAA (auxin) is responsible for controlling growth in seedlings. - Unilateral light in shoots causes the shoot to grow towards the light, because aurins accumulate at the shadier region which causes more growth on that side. - Study figure 36 page 476. ## Hormones - Are chemical messages that are produced and released in one part of an organism to have an effect in another part of the organism. - Plant hormones (phytohormones) help control growth, development, and responses to stimuli in plants. - Examples for the main types of phytohormones: - Ethylene - Auxin - Cytokinins - Jasmonic acid - Brassinosteroids - Gibberellins - Abscisic acid ## Growth - Phyto hormones can either promote or inhibit growth by affecting rates of cell division and cell enlargement. - Eg Gibberellin promotes stem growth - Development: Phyto hormones can promote or inhibit development for example: - When/if bud starts to grow to produce a side shoot. - When/if apex of a stem produces more leaves. - Ripening in the fruits (promoted by phytohormone: ethylene) - Responses to stimuli: - Examples: - Tendrils of climbing plants respond to touch stimuli by coiling around a potential support. - Capturing of an insect by a Venus flytrap plant. (Jasmonic acid triggers the secretion of enzymes to digest the fly). ## Auxin - Is a phytohormone that promotes stem growth. - Auxin can enter cells by passive transport (diffusion) as long a carboxyl group (COOH) remains undissociated. - Once auxin enters the cytoplasm (which is slightly alkaline) the carboxyl group dissociates (losing a proton) leaving it as (COO-) - Membrane proteins called auxin efflux carries pump charged auxin across the plasma membrane into the surrounding cell wall (which is acidic) - Reverts auxin to uncharged state - Resulting in diffusing auxin to adjacent cells. - Study figure 38 page 477 ## Growth of cell walls - Cellulose microfibrils including pectin are crosslinked to become strong (influenced by pH) -+pH weakens the links. - Auxin promotes the synthesis of proton pumps that transport H+ ions from inside the cell to the cell wall (acidifying the apoplast) - This allows the wall to expand so that the cell can elongate - Auxin interacts with cytokinin to regulate root and shoot growth: - Auxin produced in shoot tips are transported to root by phloem, while cytokinin is produced in root tips and transported to shoots by xylem. - Amounts of auxins and cytokinins balance the growth between shoots and roots - Study table 6 page 478 ## Auxin and cytokinin - In some cases, auxin and cytokinin work together to stimulate a process (synergism): - Eg if main shoot in a plant is eaten by an animal → + auxin produced to slow down growth of roots and allows growth of one or more lateral buds to replace the main shoot. - In other cases, auxin and cytokinin have opposing effects (antagonism) - *When fruits start ripening and seeds become ready to disperse, ethylene is secreted which stimulates ripening. (positive feedback) - Ethylene is volatile (released as vapor) which helps to synchronize the ripening of fruits on a plant ensuring that plenty of ripe fruits are available at the same time.