The Human Body- exam 1 (homeostasis and the muscoskletal system)

Chapter 1, 4, intro to muscoskleteal system slides, muscoskeletal system AUC all

homeostasis definition

the maintenance of a stable internal environment, state of dynamic constancy (may flux in the short term but is stable in the long term)

Physiology definition

study of the functions of the body parts

Pathophysiology definition

study of disease states (physiological dysfunction)

How many kinds of distinct cells are there in the body

about 200

Insertion point and origin of muscles how do they relate

during a muscle contraction the insertion point is pulled towards the origin

4 main categories of cells

muscle cells, neurons, epithelial cells, connective-tissue cells

tissue definition

an aggregate of a single type of specialized cell, general cellular fabric of any organ or structure

What does the extracellular matrix (ECM) consist of?

proteins, polysaccharides, minerals

Functions of the extracellular matrix (2)

provides a scaffold for cellular attachments, transmits info in the form of chemical messengers to the cells to help regulate their activity, migration, growth and differentiation

Organ composition (very general)

composed of 2 or more of the 4 kinds of tissue arranged in various proportions and patterns

Internal environment definition

body fluid that is present everywhere in the body

Types of body fluid compartments (2 + subtypes)

Intracellular fluid (in all the cells), Extracellular fluid- plasma (fluid portion of blood where blood cells are suspended), interstitial fluid (lies around and between cells)

Proportions of types of body fluid compartments of all the water in the body

intracellular fluid (67%), interstitial fluid (26%), plasma (7%)

Interstitium definition

the space around and between cells, eg between cell membranes and muscles

Silimarities/difference between composition of plasma and interstitial fluid

have the same concentration of dissolved substances but plasma has more proteins

What happens in homeostasis when it is disturbed for one variable?

other variables will compensate

stimulus definition

detectable change in the internal or external environment

negative feedback mechanism simple definition

action aimed at reducing the magnitude of the stimulus

reflex definition

a specific, involuntary, built in response to a particular stimulus, can involve muscular activity or internal homestatic responses

receptor definition

detects change (stimulus)

General components of a reflex arc (7 steps)

stimulus - receptor - afferent pathway - integrating center (compare to set point) - efferent pathway - effector - response

adaptation definition

aquiring characteristic(s) that favours survival or response in specific environments

acclimatization definition

improved function of an already existing homestatic system

effector (reflex arc) definition

last component of the system, its actions constitute the overall response of the system, most commonly muscle cells or glands but can be almost any body cells

local homeostatic response definition (3 points)

occurs only in area of the stimulus, induces an altercation of cell activity with the net effect of counteracting the stimulus, provides individual areas of the body with mechanisms for local self regulation

What do homeostatic control systems do?

Perform compensating mechanisms

steady state definition

a system in which a particular variable is not changing but in which energy must be added continuously to maintain a stable condition

equilibrium definition (bio)

particular variable is not changing but no input of energy is needed to maintain it

Set point homeostasis definition

variable in the steady state

positive feedback mechanism description

accelerates a process, an initial change in a particular variable subsequently leads to an even greater change in that variable eg. process of blood clotting

Examples of set points being reset (2)

short term- fever, rhythmic basis- temperature (lower at night)

Benefits of multiple systems controlling a single parameter (2)

provides greater fine-tuning and permits regulation to occur when one of the systems is not working

is it always possible for homeostatic control systems to maintain every variable within a normal range in response to an environmental challenge? How is that dealt with?

No, there is a hierarchy of importance, so that certain variables may be altered to maintain others

Feedforward regulation definition

changes in regulated variables are anticipated and prepared for before they actually occur

Example of feedforward regulation

Body temperature- compensatory thermoregulatory responses are activated before the colder outside temperature can cause the internal body temp to decrease

Benefits of feed forward regulation (3)

improves the speed of the body’s homeostatic responses, minimizes fluctuations in the level of the variable being regulated, fine-tunes homeostatic responses

Concentrations of Na+, K+ and glucose in ECF vs ICF (mM) (numbers)

ECF: Na²⁺ 145, K⁺ 5, Glucose 5.6
ICF: Na²⁺ 15, K⁺ 150, Glucose 1

How is homeostasis maintained in ECF and ICF?

Due to exchange of molecules between them

diffusion definition

movement of molecules/ions as a result of random thermal motion, always down a concentration gradient

4 categories of chemical messengers

hormones, neurotransmitters, paracrine substances, autocrine substances

Fick’s diffusion equation for biological membranes

J = PA(C₁-C₂)

Ficks diffusion equation definition of variables

J- net flux
P- permeability coefficient (inversely proportional to the (distance)²
A- surface area
C1, C2- the two compartments between which diffusion is happening

What does Fick’s diffusion equation tell us about diffusion times and distance?

Diffusion times increase in proportion to the square of the distance

What are membranes a barrier for and why?

charged/polar molecules, because they are apolar lipids

What things can go through membranes with diffusion and what cannot? (6 in total with examples)

Can: gasses (O_2, CO₂, N₂), small uncharged molecules (urea, ethanol)
Partially can: water
Cannot: large uncharged polar molecules (glucose), ions (H+, Na+, etc.), charged molecules (amino acid, ATP)

Ways that ions and polar/charged molecules can move across a membrane (4)

Facilitated diffusion, ion channels, primary active transport, secondary active transport

flux definition (diffusion)

amount of material crossing a surface in a unit of time

What does the magnitude of flux depend on (4)

Temperature, mass, surface area, medium

What sort of distances is diffusion for?

Short distances

How do membranes interact with diffusion

They slow it down

Are most of the organic molecules that make up the intermediate stages of the various metabolic pathways polar or non polar? Where are they normally?

Polar, usually retained in the cell

electrochemical gradient definition

combines concentration difference and electrical differences

Channel gating definition

process of opening or closing ion channels

What unit is used for membrane potentials?

milivolts

How do ions diffuse through membranes

Through ion channels- because polar but easier, they are also acted on by electrical forces

What type of transport is the Na+ gradient used in?

Secondary active transport

ligand definition

substance that forms a complex with a biomolecule to serve a biological purpose

ligand-gated channel description

a group of transmembrane ion-channel proteins which open to allow ions such as Na⁺, K⁺, Ca²⁺, and/or Cl⁻ to pass through the membrane in response to the binding of a chemical messenger (i.e. a ligand), such as a neurotransmitter

Example of ligand-gated + 5 steps

Nicotinic acetylcholine (nACh) receptor: binding of ACh to nAChR, conformational change receptor, channel opens, net flux of Na+ into the cell, action potential

General principles of physiology (6) (HICTSL)

homeostasis, information flow, coordination between the functions of different organ systems, transfer of matter and energy, structure determines function, physiological processes follow the laws of chemistry and physics

Example of primary active transport

Na+/K+ - ATPase

How does water cross membranes

Osmosis

What does movement of water across a semipermeable membrane lead to?

The compartment with less non-penetrating solute shrinks as the water leaves it to achieve equilibrium

Osmolarity definition

total solute concentration of a solution (osmoles/L, Osm), refers to all solutes

How do the osmolarities of ICF and ECF compare?

Normally they are the same (~300 mOsm) but changes in them result in movement of water

Primary active transport description

driven by ATP, can go against a concentration gradient

Secondary active transport description

two molecules being moved, one has to move down a concentration gradient, the other can move up

tonicity definition

measure of the ability of a solution to add or remove water from cells due to osmosis, refers to nonpenetrating solutes only, predicts the effect of the solution on cell volume

facilitated diffusion definition

process of spontaneous passive transport of molecules or ions across a biological membrane via specific transmembrane integral proteins, only one side can be open at a time

aquaporin description

Water channel, open most of the time

3 options for tonicity (+ amounts compared to base level of 300mOsm, all nonpenetrating solutes)

hypertonic- swell in volume (400mOsm)
isotonic- no change in volume (300mOsm)
hypotonic- shrink in volume (200mOsm)

Are changes in cell volume due to changes in concentration of membrane-penetrating solute in the ECF permanent?

Nope

What level of mOsmol/L does an idealized cell have?

Internal concentration of 300 mOsmol/L of nonpenetrating solute

What is nonpenetrating solute

Solute that cannot leave the cell

Osmolarity vs tonicity

Osmolarity just refers to the mOsmol/L in the cell, tonicity tells us the amount of nonpenetrating solutes and whether it will swell or shrink

What happens when there is excessive sweating on the level of compartments and internal fluid? (2 steps)

1)water loss from ECF- reduces volume, ECF hypertonic with respect to ICF, 2) an osmotic water shift from the ICF into the ECF restores osmotic equilibrium but reduces the ICF volume

Different types of solution with regards to osmolarity

Isoosmotic: 300 mOsm/L
Hypoosmotic: < 300 mOsm/L
Hyperosmotic: > 300 mOsmol/L

most abundant cation/anions in the ECF

Na+ and Cl-

What are the determinants of ion channel specificity?

charged surfaces of the proteins that form the channel wall

First anatomist + when

16th Century, Andrea Vesalius

Anatomy terminology- what does it consist of?

Location, shape and/or structure

Some (3) anatomy acronyms

m. = muscle (musculus)
a. = artery (arteria)
n. = nerve (nervus)

In anatomical position: plane that splits the body in half vertically (into left and right)

Sagittal/median plane

In anatomical position: plane parallel to the sagittal plane but off to one side

Parasagittal plane

In anatomical position: plane that splits everything vertically into front and back

Coronal/frontal plane

In anatomical position: plane that divides the body into top and bottom

transverse/horizontal plane

Axial skeleton- main bones, percentage of all bones, characteristic

skull, spine and thorax, 40% of all bones, immobile but firm

What are the appendicular parts

Appendages- arms and legs, attached to the axis

Axial bones: how many and how are they divided

80 bones, divided into skull, vertebral column, thoracic cage region

Functions of the axial bones (3)

carry other body parts, provide skeletal support, organ protection

4 types of bone shapes + brief descriptions

Long bones (longer than wide), short bones (short cube like), flat bones (thin ones), irregular bones

Front of body in anatomical terms

anterior/ventral

Back of body in anatomical terms

posterior/dorsal

Towards the top in anatomical terms

Superior/cranial

Towards the bottom in anatomical terms

inferior/caudial

Medial defnition

Structures towards the midline of the body

Lateral definition

Structures away from the midline of the body

Closer to the trunk in anatomical terms

Proximal

Further to the trunk in anatomical terms

Distal

How do body movements happen on a very basic, bone level?

muscles contract across joints, moving one bone towards another