(1) homeostasis and cell physiology student

7/29/2019 (1) Homeostasis and Cell Physiology Student

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1) Organization - multicellular

2) Responsiveness

3) Growth - cell number, size, or amount of substances

(nutrients/fat deposition)4) Development and differentiation - shift fromgeneralized cells to specialized cells

5) Reproduction

6) Metabolism andExcretion (rid of waste products)

The Basic Functions of

Organisms


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Anatomy

Greek:

-ana (apart)

-tome (to cut/dissection)

The study of the structure of a livingorganism

Without knowledge of the anatomy of the body andcell structure, this course will be much more

difficult


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Gross Anatomy

Surface anatomy

Regional anatomy Systemic anatomy

Developmental anatomy

Microscopic anatomy

Cytology

Histology

The Specialties of Anatomy


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Anatomical Variation

No two humans are exactly alike 70% most common structure

30% anatomically variant

variable number of organs

missing muscles, extra vertebrae, renal arteries

variation in organ locations

situs solitus

situs inversus (things are flipped)

dextrocardia


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Physiology

The branch of knowledge which studies howstructures of a living organismfunction in order

to maintain life

function is an aspect ofstructure

Function is the how and whyof the system orevent


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Approaches to Physiology

Teleological approach

Is thinking about the why

Why do RBCs transport oxygen?

because cells need oxygen and RBCs bring it to them

Mechanistic approach

Thinking about physiological processes are

the how How do RBCs transport oxygen?

Oxygen binds to hemoglobin molecules contained in

RBCs


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Cell physiology

Special physiology

( e.g. cardio physiology )

Systemic physiology

(e.g. cardiovascularPhysiology)

Pathological physiology

The Specialties of Physiology


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Physiological Variation

Sex, age, diet, weight, physical activity

Typical physiological values

reference male 22 years old, 154 lbs, light physical activity

consumes 2800 kcal/day

reference female

same as male except 128 lbs and 2000kcal/day

Overmedication of eldery


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Organ systems

Systems ( 11 )

Integumentary, Nervous, Skeletal, Endocrine,

Muscular, Cardiovascular, Lymphatic, Urinary,Respiratory, Digestive, Reproductive

Organs

Heart, lung, pancreas, stomach, brain,etc.


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Chemical Molecules: Complex proteins comprised of atoms (DNA) Atoms

Cellular Comprised of many macromolecular complexes

The most basic functional unit of any multicellular organism Tissues

Comprised of various cell types Connective, muscle, nervous, epithelium

Organ Contain various tissue types

Organ systems Cardiovascular, respiratory, integumentary, etc.

Organism Homo sapiens

Organization of the Human

Body


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Levels of

Organization


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Homeostasis

The process of maintaining a relatively constant internalenvironment within an organism

(body temperature, heart rate , blood glucose levels, etc..)

Time

Normal

Range

Loss of homeostatic control

Set

Point


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Equilibrium

A state of rest or equalbalance All biologic phenomena act to adjust: there are no

biologic actions other than adjustments. Adjustment isanother name for equilibrium. Equilibrium is the

universal, or that which has nothing external to derangeit. Charles Fort

Homeostasis does not mean equilibrium whenconcerned with the entire body

i.e. the ECF and ICF usually exist in a state thatmight be best called adynamic disequilibrium


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Most cells are

in contact with

the ECF


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Homeostasis and Controls External or internal

Physiological attempt tocorrect occurs sensors detect

Integrating center process Response of cells and organs

occur

Successful compensation homeostasis reestablished

Failure to compensate Pathophysiology

illness/disease

death


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Mechanisms which maintain

systemclose to set point

Autoregulation (intrinsic regulation)

constant blood flow regardless of BP

Ex: renal system Extrinsic regulation - thermoregulation

(behavioral)

Mechanisms for Homeostasis


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A receptor ( input

signal)

A control center

An effector (output/efferent signal)

Homeostatic regulation

involves


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Homeostasis is mediated by the

Tonic

Activity

Control center


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Negative Feedback

Primarymechanismfor homeostasis!

Response

Decrease

stimulus


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Negative Feedback: The Control of Body

Temperature


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NOT homeostaticequilibrium, but instead

an Unstable equilibrium

Response

More

stimulus


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Positive Feedback: Blood Clotting

Positive feedback control- mechanisms which drive systems

farther from set point

usually leads away from homeostasis and can result in death

e.g. uterine contractions during childbirth

orgasm

blood clotting


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Harmful Positive Feedback Loop

Fever >140 degrees F metabolic rate increases

body produces heat even faster

body temperature continues to rise further increasing metabolic rate

Cycle continues to reinforce itself

Becomes fatal at 113 degrees F Damage to brain occurs around 107

degrees F


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Homeostatic Control

Body predicts that a change is about to occur and

starts the response in of the change

e.g. salivation


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Cytology scientific study of cells began when Robert Hooke coined the word,

cellulae to describe empty cell walls of cork

Theodore Schwannconcluded, about two

centuries later, that all animal tissues aremade of cells

Louis Pasteur established beyond anyreasonable doubt thatcells arise only fromother cells refuting the idea of spontaneous generation

living things arise from non-living matter

Modern Cell Theory emerges from this

Development of the Cell Theory


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1) Cells are the building blocks of all plants and

animals

2) Cells are produced by the division of pre-

existing cells3) Cells are thesmallest units that perform all

vital physiological functions

4) Each cell maintains homeostasis at thecellular level

The Cell Theory

- Homeostasis at higher levels reflects combined,

coordinated action of many cells


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The Cell

Rough ER

Secretory

vesicles

Microvilli

Smooth

ER

Golgi

apparatus

NucleusCytoskeleton

Cell membrane

Mitochondrion

Cytoplasm

Ciliacilia

cytoplasm

mitochondria

Rough ER

nucleus

Cell membrane

microvilli

Please review the function of organelles in Fig 3.4


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Is surrounded by extracellular fluid,

which is the interstitial fluid of the

tissue

Has an outer boundary called the

cell membrane, plasma membrane, or

plasmalemma

A typical cell


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Where does most physiology occur?

Cell membrane

Cell membrane composition Lipids

phospholipid bilayer

Cholesterol

Carbohydrates (sugars)

Proteins

Cell Membrane


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Cell membrane


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Cell membrane functions1.Forms physical boundary of the cell

2. Selectively permeableregulates transport across the

membrane

3. Structural support

4. Motilityfacilitated by the presence of cilia (moves EC

fluid, flagellum (moves cell), etc.

5. Signal Transduction- movement of a stimulus from oneform to another

6.Cellular recognition- autoimmune conditions


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Components of the plasma

membrane

1) Lipids - not very soluble in H20 Fats and oils

Phospholipids

Phosopholipid bilayer contains: Hydrophillic , polar head

Hydrophobic, non-polar tail

Glycerol + Phosphate group

Fluid mosaic modelphospholipids swim aboutthe bilayers of the cell membrane


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choline

PO4-

glycerol

Head

Polar

Hydrophilic(water-loving)

Tail Non-polar

Hydrophobic(water-repelling)

Phospholipid Molecule


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membrane

1) Lipids

Phospholipid bilayer

Cholesterol and other lipids

Glycolipidssugar attached to a fay

Lipoproteins- (HDL and LDL)

Steroids

These all influences membrane fluidity


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Structure of phospholipids and glycolipids

C,H,O


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Glycolipids

Carbohydrate-attached lipids.

Function:

Provide energy

Serve as markers for marker for cellular

recognition (markers that can tell if a cell

belongs or not)


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membrane

1) Lipids

2) Carbohydrates- most abundant biomolecules,yet only 5% of the membrane

Glycoproteins


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Membrane components:

carbohydrates

Carbohydrates

Simple sugars

fructose,glucose , galactose (monosaccharides or oligosaccarides)

Sucrose, maltose, lactose (disaccharides)

Complex sugars chitin, glycogen,cellulose , starch, dextrin (polysaccharides -

high in energy)

Membrane carbohydrates form the Glycocalyx

Glycocalyx (sugar coat on the outside of the cell)- located on

extracellular surface

Sperm have a sweet tooth


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Function:

orient andanchor membrane proteins

serve as a type of recognition particles

ABO bloodgroups determined by

oligosaccharides on surface of RBC

(antigens)

Glycoproteins


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membrane1) Lipids

2) Carbohydrates

3) Proteins (at least50% of membrane) What are proteins?

Proteins are a linear chain of amino acids

Primary structure (amino acids sequence)

Secondary structure (amino acid interactions)

Tertiary structure (complex forming) Quaternary structure (protein complexes)


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Primary structure (amino acids

sequence)

Secondary structure (amino acid

Tertiary structure

structure (protein

complexes)

Four levels of protein structure


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1) Integral proteins

2) Peripheralproteins

3) Anchoring/structureal proteins

4) Enzymatic proteins5) Receptor proteins

6) Carrier proteins

7) Channelsa) Non-gated Ion

b) Gated

Membrane protein classes

include:


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Membrane Proteins

1) Integral membrane protein

normally spans membrane - transmembrane protein

Crosses the membrane

2) Peripheral membrane protein

- bound to the inner or outer surface (two com together tomake tight junctions

3) Anchoring proteins (junction proteins)

attach cell membrane tostructures : cytoskeleton

attach cell membrane to other membranes: intercalated discs

These proteins can degrade when metabolized

4) Enzymatic Proteins (help break down other substances)- Binds enzymes to catalyze intracellular or extracellular reactions

Example: peptidases

M b i


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Membrane proteins5) Receptor proteins

Bind to ligands , causes cells to respond

Ex: Insulin, antigen, glucose, neurotransmitters, serotonin,epinephrine, ect.

6) Carrier proteinstransport solutes across membranes

- Includes uniport, symport, andantiport

ATP dependent - Na+ K- exchange protein

ATP independent- neurotransmitter transporters

NEVER FORMS AND OPEN CHANNEL7a) Non gated ion channel proteins

Non-gated- always open Leak Channel or pores (Cl- channel, K+ channel, etc.)

Selectivity determined by channel diameter and electrical

charge of amino acids

7b) Gated ion channels

gated = opening/closing

gated by voltage change (Na+, K+, Ca2+ channels)

gated by chemical ligand (chemical binds to receptor) (acetylcholine

receptor)

gated by physical change (physical distortion of membrane) ( temperature,

force)


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Channel Protein Structure

Selectivity is determined by channel

of amino acids that line the channel


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Types of gating:

Gated Channel Proteins

(1) homeostasis and cell physiology student

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