Chemical/Electrochemical Regulation: Homeostasis

Chemical and Electrochemical Regulation Systems

• Homeostasis maintains a stable internal physiological environment.
• Someone in good health will have a blood glucose level of ~100 mg\mL, a blood pH of ~7.4, an arterial pressure of 120\80 mm Hg and a body temperature of ~37°C.
• Interstitial fluid is the liquid between cells that has a constant salinity level + pH to maintain cell health.
• Dynamic equilibrium is a state of balance achieved in an environment through regulatory mechanisms that oppose external forces that try to modify the surroundings.

Mechanisms Against the Cold

• Goosebumps are when hairs stand on end.
• Shivering involves muscles creating heat.
• Vasoconstriction is when blood vessels near the skin decrease in diameter, concentrating circulation in the body's center to ensure proper function of main organs.
• Hypothermia occurs when the body runs out of energy to shiver, the extremities freeze, blood circulation in the brain decreases, causing drowsiness/fatigue, impaired judgement, loss of consciousness and possible death.

Mechanisms Against the Heat

• Sweat is when evaporated perspiration releases energy (heat).
• Vasodilation is when blood vessels near the skin dilate, transporting more blood to the skin's surface and releases energy (heat).
• Hyperthermia is heat exhaustion where body temperature becomes abnormally high, leading to death.

Negative Feedback Loops

• Negative Feedback Loops detect deviations in the body's constants and act in reverse by having three components:
• Receptor: Sensory receptors send nerve impulses to the brain based on environmental information and constantly monitor the body's internal conditions such as temprature, blood pH, blood glucose and tension.
  • Integrator: The brain sends messages to the effectors.
  • Effector: Effectors change internal conditions, the brain sends messages to different tissues or organs that can generate or retain heat.
• The message is transmitted by the nervous system or chemical messengers/hormones.
• Positive Feedback Loops depend on drugs and diseases like arterial hypertension.
• Increased stimuli forces that unbalance + destabilize the system which causes health problems.
• An exception is during childbirth when the baby tries to exit the uterus.

The Nervous System

• The nervous system consists of these parts: -Organ: Encephalon contains everything inside the cranium: brain, cerebellum, brainstem, and coordinates all the body's different systems and is the body's command center. -Cerebrum: Divided into 2 hemispheres: left and right. Hemispheres are made of gray matter (information processing) + white matter (information transmission). -Frontal Lobe: Divided into 4 lobes that each manage specific functions: -Functions: memory, logic, judgment, information received, analyzed, interpreted, center of consciousness
  • Controls muscles, integrates data from other parts of the encephalon, reasoning, critical reflection, planning and speaking.
  • Parietal Lobe: Sensory information from the skin + skeletal muscles, and taste.
  • Occipital Lobe: Information form the eyes
  • Temporal Lobe: Information form the ears, perception of language, feelings, voluntary movement, thinking processes. -Cerebral Cortex: Thin layer covering each hemisphere of the encephalon, containing more than a billion cells that transfers the flow from one hemisphere to the other. -Corpus Callosum: the 2 hemispheres of the brain are linked by the structure which is made of white matter formed of axons. -Cerebellum: is located under the brain and behind the cranium, divided into 2 hemispheres, made of gray+white matter, coordinates movements, analyzes information from eyes + ears for equilibrium. -Brainstem/Bulb rachidien: directly under the brain, links the brain and spinal cord, 7cm long + 1.5 - 2cm in diameter for adults. -Functions: information between the brain, cerebellum, and spinal cord, controls respiratory rhythm, heart rate, blood pressure, reflexes: cough, vomiting, sneeze, hiccup -Medulla Oblongata: is a long nervous cord + base of brainstem at the bottom of the back, transmits the flow of brain to nerves + nerves to brain, manages protection reflexes. -Thalamus Inside the center of the brain contains - sensorial transmission center: touch, pain, heat, cold, information form muscles.
  • Hypothalamus: Small mass of complex tissues under the thalamus + above hypophysis is the the command center for homeostasis; Links autonomous nervous and endocrine systems and controls hunger, thirst, sleep, body temp, and emotions, by secreting different hormones.

The Nervous System in Humans

• The nervous system has three functions: -Receptor: Information on alterations = occur inside + outside the body. Alteration = stimulus. Information gathered = sensory information
  • Integrator: Processes + interprets sensory information = determines action to undertake. -Effector: Supplies motor response = activates muscles or glands.
• The nervous system works with the endocrine system to react and maintain homeostasis.
• The nervous system emits rapid electric alerts and endocrine system secrets hormone in the blood.
• Subsystems: The nervous system divides into structure + specific functions: -Central Nervous System (CNS) consists of the encephalon + spinal cord that perceive + decide. -Peripheral Nervous System (PNS) has a set of nerves that are linked in 2 directions to the encephalon + spinal cord = Nerves that enter + exit the CNS. -Autonomous Nervous System: Transmits information to internal organs outside of the individual's control (involuntary) -Sympathetic System: Network of nerves that controls the involuntary muscles + organs during periods of stress = fight or flight reaction = prepares the body to handle imminent danger -Increased heart rate + respiratory rate. -Glucose is released form the liver = energy for the body -Pupils dilate -Parasympathetic System: Neutralizes affects of the sympathetic nervous system by slowing down the heart rate + respiratory rhythm = relaxing the muscles. -Opposite of sympathetic system -Slower heart/respiratory rates -Contracts pupils
• Somatic Nervous System: Transmits information to and from the skin + skeletal muscles. information from the eyes + ears is processed by the brain + associated so the decision can be made whether move muscles or not.
• Responsible for reflexes: Actions that start a certain reaction, formed of sensory nerves that transport infux of sensible nerves of body to the CNS: -Motor nerves transmit command form the CNS to the muscles and takes care of outside world and any changes that can happen.

Neurons

• Neurons are the nervous cells that construct the structural + functional unit of the nervous system and consists of interlinked neurons.
• They don't go through cellular division after adolescence, don't renew and live ~100 years.
• Cellular Components: -Cell body: Large nucleus (large nucleolus) containing cytoplasm, MITOCHONDRIA - that gives energy, lysosomes eliminate waste, golgi apparatus that stores fats + proteins, rough reticulum endoplasmtic for protein syntheisis. -Dendrites: Reception sites of the signals from other neurons, single neurons contains thousands of them.
• Axon is the elongation of the cellular body, where waves are transmitted on for the production of product.
  • Myelin sheath is coating around axon that protects the axon and helps it function, a greasy and white substance that feeds the axon
• Node of Ranvier: Section between myelin sheaths through which the nervous influx can "jump" form "node to node", accelerating acceleration.
• Three Neuron Types:
  • Sensory sensory requires a strong trigger to be activated + transmits signals to INERNEURONS.
  • INTERNEURON is a connector between sensory and motor nurones to trigger the contraction of the activity of the voluntary motor.
  • Synapse is point of contact between a neurone and another neurone or a muscular fiber where the nerve has to move to space to continue the transmission of influx

The Functioning of Neurons

• Neuron at Rest: The membrane at rest is 50x more permeable for K+ than Na+.
• On the exterior = has a positive charge + strong in Na+/ interior = negative charge + strong in K+.
• Depolarization Waves: -Influx of the axon sends message form on side of or organism to the other which are formed by positives ions Na and K at the other side of the axons.
  • At a resting stage in a nerve of a difference cellular is at -70mv
• **Electric load variation during axon when canals K+ close and Na + open, start after beginning.
• Of a depolarization wave neutralize negative charge for a constant power.

Principle of All or None

• When an axon is stimulated over stimulation treshold an influxis signaled on the whole surface that happens or not
• Neurotransmitters are chemical products secreted by the neuron's, example. Acetylcholine is the main one of the somatique, decreases ryhtm of heart rhythm + respiration nor adrenaline does the opposite, augmente ryhtm of heart rhythm + respiration more than others.
• Glutamate (75% of excitatory transmissions in the encephalon, memorize, and learning).
• Gamma-aminobutyrique acid (GABA) is inhibitor of the most known (fear and anxiety)Dopamine and stimulates commends the muscular esquelettiques (reward and motivation) and serotonine humeur Thermoregulation
• Schumann Cells is insulator that surround the axon and allows the neuron to regenerate and if the demmages are not to big can only repair axon if they came in central nervous syndrom
• Synapses are contact between neurons and muscles, and trasport polarisation where you recive the polarisation

The Eye and the Receptors

• Protected by: eyelashes, eyelids, eyebrows and bony cranium crests
• Three-dimensional vision enables estimation distances whereas binocular vision uses both eyes at the same time
• 3 eye layers: Opaque ≠ light goes through

External Eye

• The sclera (outer white layer) Thick, give form to the eye, protection The the is bome transperant light
• The conjonctive, covers the light thanks to liquid/ lacrimal glands: which small canals that drive the nose.
• Intermediate: a coloïde (Color membrane) which is the light and also the Iris (open and close light modification many vessel body behind the like the muscles with modifications

Retina

• Structures the clairs flexible modifies from close and from afar attached muscles form images.
• Formed 2 of lights sensitive to neuron light cells as well as more de 150 cells.
  • Ganglian receives visual information
  • Bipolar connex or transport to.

Battonnets = with is the repartitions uniformes and the centre des Cristallin point and clairs

• -Sensitives light or night vision and don't differentiate plus until that vision plus violet (chemique) two prot

• **Cônes: stimulates in red+green and need lights/ and is a image plus that we get and more clairs

Other Information

• The 2 corners separate the chrystals

1. Anterior: In liquid aqueaus the lights from the Cristal
2. Forme: like the transparent gelatine forms that is more small

Funcionamiento de l'oeil

• Fonctionnement de l'oeil
• Fonctionnement de l'oeil:
• Pas assez lumière = yeux dilatent
• Trop de lumière = yeux contractent
• Pupilles contractent = mise au point d'objet rapproché = réduit distortion
• Forme du cristallin:
• Objets éloingés:
• Muscles ciliaires relâchent
• Ligaments suspenseurs deviennent tendu
• Cristallin s'aplatit
• Objets approchés:
• Muscles ciliaires contractent
• Cristallin devient arrondi
• Ajustement = appelés des accommodation
• Vision de loin Parcours pris par la lumière à travers de l'oeil jusqu'au moment où 'influx nerveux se
• Vision de près

Ear Anatomy and Mechano Receptors

• The parts of the :
• *Outside cartligion cover with pole and a capter and protect insect
• • Middle : transmission to light and the time
• *Three smaller form
• • Base to receive light
• *Transmition of son light the and to the to receive vibrations and transform
• • And send to light.
• *Middle and with the light also from in
• *Also close light also the pressure. And the end
• • Vestibles light nerve in the cerverlet to and give the equilibrium
• • Cochie = with the liquid the the base cerverlets the the .
• Endicorne: with light.

Explore homeostasis and dynamic equilibrium in maintaining internal physiological balance. Learn about mechanisms like goosebumps, shivering, and vasoconstriction that help the body regulate against the cold. Understand how these processes ensure stable blood glucose, pH, pressure, and temperature.