Bio 1A- Systems (i currently have a C-)

physiological structural organization

correlation between STRUCTURE and FUNCTION

necessary functions of life

MRS. NERG

• movement, respiration, sensitivity (to the environment), nutrition, excretion, reproduction, growth

7 requirements for life

• maintain boundaries

• movement

• responsiveness

• digestion

• metabolism

• excretion

• reproduction

• growth

maintains boundaries

integumentary systems

• skin and such cover external body to protect from injury

movement

skeletal/muscular systems

• support body organs, allows locomotion

responsiveness

• nervous system: fast acting control to respond to changes

• endocrine system: slow acting control to secrete hormones to regulate growth/reproduction/nutrient use

metabolism

• respiratory system: keeps blood supplied w oxygen and removes CO2

• cardiovascular system: transportts blood 

• digestion and excretion

digestion

digestive system: breaks down food

excretion

urinary system: eliminates nitrogenous waste from body

reproduction

reproductive systems: function to produce offspring

homeostasis

maintenance of stable internal environment despite changes in external environment

homeostatic system components

1- set point: physiological value or range around which the system fluctuates

2- receptor: mechanism to detect when conditions deviate from the set point

3- control center: structure that both interprets input from receptor and initiates effector change

4- structure that brings change to alter stimulus

negative feedback loop

response moves variable OPPOSITE from initial stimulus

• variable fluctuates back toward set point (ex: body temp)

positive feedback loop

response move variable in SAME DIRECTION as initial stimulus

• stimulus is reinforced until a climactic event is reached, then the body returns to homeostasis (ex: childbirth)

• hint: if the system includes the brain, its likely positive

levels of organization in the human body

atom —> molecule —> macromolecule —> cell —> tissue —> organ —> organ system —> organism

core concepts of physiology

homeostasis, structure/function, interdependency of cells, gradients/permeability, cell membrane, levels of organization, systems integration

signals used in feedback loop

ligands (signaling molecules) + receptor on cell

ligand

a molecule that binds to uaually a larger molecule (receptor)

receptor

chemical structure made of protein that receive and transduce signals

cell signaling/communication steps

• signal reception: chemical signal detected when ligand binds to receptor

• signal transduction: receptor protein conformational change initiates signal transduction within the cell

• cell response: transduced signal is converted to a response

different types of signaling

direct, synaptic, paracrine, endocrine

direct contact cell signaling

molecules on plasma membrane of one cell recognized by receptors on plasma membrane of neighboring cell

synaptic cell signaling

neurotransmitters released from neuron travels across synapse to neighboring neuron

paracrine cell signaling

specific cell secretes signaling molecules which affect nearby cells

endocrine signaline

hormones travel via the circulatory (blood) system to affect distant target cells (Ex: insulin production from pancreas) 

membrane receptor types

• cell surface receptors (GPCR, Channel linked, enzyme linked)

• intracellular receptors

GPCR (G protein coupled receptors)

• include 7 transmembrane domains

• rely on G proteins

• when ligands bind to GPCR, it activates G protein

• activated G protein leads to cellular response (ex: taste signal transduction)

G protein

• “active” when bound to GTP; “inactive” when bound to GDP

• composed of ɑβ𝛾 subunits

channel linked receptor

ligand binds to channel, allowing it to open for ions to pass through membrane

• Ex: nervous system neurotransmitter

Enzyme linked receptors

• ligand binds to the protein which is situated in the bilayer

• protein morphs to have enzymatic function inside cell

• Ex: insulin receptor phosphorylates the insulin response protein

intracellular receptors

• ligands (hormones) cross plasma membrane to bind to receptor

• receptor protein no longer binds to inhibitor

• hormone-receptor protein moves to nucleus where it binds to DNA, turning transcription on/off

• Ex: estrogen receptor in mammalian cells

protein kinases

phosphorylate proteins from the phosphate groups of ATP; categorized by the amino acids they modify

phosphatases

remove phosphate groups from proteins for the kinase to do its thing

signal transduction pathway

use phosphorylation/dephosphorylation to control activities

• phosphorylation cascade (relay proteins/protein kinases)

• multiplies a tiny signal into something much larger

second messengers

small molecules and ions which relay signals recieved by cell surface receptors to effector proteins

• participate in pathway initiations by B protein-coupled receptors

• Ex: cyclic AMP and calcium ions are common second messangers

Ca² as a second messenger

binds to Calmodulin (cytoplasmic protein)

GPCR second messangers

cAMP, IP, Ca

Receptor Tyrosine kinases (RTKs)

type of enzyme receptor

• ex: insulin receptor

cellular responses to signals

transcription or cytoplasmic activities