L1 - Human Physiology

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🧠 Concepts Introduced

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Definitions

Anatomy ​definition: study of structures associated with human body (organelle, cells, tissues, organs & organisms)

Physiology ​definition: study of functionality of living organisms at the cellular, organ & systemic level ​- relating structure & function

Levels of organisation:

  1. subatomic particle - proton, neutron, electron

  2. atomic

  3. molecule

  4. macromolecule - carbohydrate, protein, nucleic acid, lipid

  5. organelle

  6. cell

  7. tissue

  8. organ

  9. system

  10. organism

Organ systems:

  1. Integumentary system ​skin: acts as a barrier against the external environment as 1st line of barrier ​sweat glands

  2. Skeletal system & Muscular system ​movement, structure support

  3. Nervous system & Endocrine system ​control responses ( brain & spinal cord) ​action potential ​important for regulation ​ ​C2 hormones

  4. Cardiovascular system & Lymphatic system

  5. Digestive system & Respiratory system & Urinary system

  6. Male & Female reproductive system ​hormones

(L1-HP)-Organ-systems-of-the-human-body-and-their-integration

Internal & External Environment

External environment ​ - temperature, humdity etc.

Internal environment ​- body temperature, blood pH, water balance, CO2

Intracellular fluid

  • ​inside cells
  • ​not part of internal environment

Extracellular fluid

  • fluid surrounds cells ​
  • part of internal environment ​
  • plasma & interstitial fluid

Homeostasis

the process of maintaning a relatively stable internal environment regardless of changing external environment ​- it's not a static state of balance but a continuous dynamic response ​ ​receptor -> integrator -> effector

  1. Stimulus produces change in variable

  2. change is detected by receptor

  3. information is sent along afferent pathway to control centre

  4. Information is sent along efferent patheay to effector

  5. response of effector feeds back to influence magnitude of stimulus and returns variable to homeostasis

negative feedback - opposes stimulus to stabilise the regulated variable

positive feedback - reinforces stimulus and sends the regulated variable even farther from its normal value

Basic Unit of life - cells & Organelles

characteristics of cells:

  • general cell structure & components

  • general mechanisms for changing nutrients to energy

  • deliver end products into their surrounding fluid

  • almost all have the ability to reproduce

cell structure:

  • plasma (cell) membrane

  • cytoplasm & organelles ​

    1. cytosol ​

    2. ​membranous organelles: ​ mitochondria ​ endoplasmic reticulum ​ golgi complex ​ lysosomes ​ peroxisomes ​

    3. inclusions ​- lipid droplets ​- glycogen granules ​- ribosomes ​- caults ​- proteasomes ​- cytoskeleton ​- centrioles ​- centrosome ​- cilia ​- flagella

  • nucleus

(L1-HP)-Componenets-of-a-cell

4 Classes of Biomolecules + Functions

  • carbohydrates -glucose fructose galactose ​- sucrose lactose maltose ​- starch cellulose glycogen
(L1-HP)-Carbohydrates-function

  • proteins ​- has 4 levels of protein structure ​ structural protein ​storage proteins ​ contractile proteins ​transport proteins

  • lipids ​- carbon & hydrogen ​ -tryglycerides (glycerol, fatty acid chains for energy storage) ​- phospholipids (membranes) ​- steroids (membranes / hormones) ​- eicosanoids (signaling molecules)

(L1-HP)-Lipid-types-&-functions
  • nucleotides ​DNA & RNA store genetic material ​tranmit & store energy ​- composition of base, sugar (carbohydrate) & phosphate groups

Energy in biological systems

energy - defined as the ability to do work

types of work in biological systems: ​- chemical (forming & breaking chemical bonds - storing & releasing energy) ​- transport (movement of substances across a concentration gradient - plasma membrane) ​- mechanical (movement of organelles, cells changing shape, muscle contractions, etc.)

kinetic energy - energy of motion (chemical, transport, mechanical)

potential energy - stored energy (concentration gradient, chemical bonds)

energy converted from one form to another is never a 100% efficiet conversion

Activation Energy

initial input of energy into reactants to initiate a chemical reaction

endergonic reaction - exergonic reaction

anabolic pathway: ​

  • synthesizing large molecules ​
  • require input of energy

catabolic pathway:

  • large molecules broke down to smaller molecules
  • release energy that can be used for work

Function of enzymes

biological catalysts

lower activation energy

specific enzyme bind to specific targets ​form enzyme - substrate complex

(L1-HP)-Different-enzymes-and-their-functions

Factors that influence enzyme activity

  1. Temperature & pH

  2. Substrate concentration

  3. competitive inhibitors ​another molecule mimics the substrate & binds to active site which blocks the active site and prevents substrate from binding

  4. allosteric modulators

    (L1-HP-Allosteric-modulators

  5. cofactor ​inorganic metal ions ​conformational changes of active site

  6. coenzymes ​small organic molecules (vitamins, NAD+, FAD+) ​act as receptor or carries for atoms or functional group that are removed from substrate

Links to this page:

  1. allosteric modulators
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