Human Physiology:

DR BOOMINATHAN Ph.D. M.Sc.,(Med. Bio, JIPMER), M.Sc.,(FGS, Israel), Ph.D (NUS, SINGAPORE) PONDICHERRY UNIVERSITY

Source: Collected from different sources on the internet-http://koning.ecsu.ctstateu.edu/cell/cell.html

Anatomy, physiology, …

• • • • Anatomy is the science of the structure Physiology is the science of the function Anatomy and physiology are closely linked, in particular physiology cannot be understood without anatomy In many respects, both are ‘closed sciences’

Physiology

• • • • Some important moments: 17 th century: William Harvey first describes the closed circulation 19 th century: Claude Bernard formulates the modern version of homeostasis – the constancy of the internal milieu 19 th century: Johannes Muller formulates the ‘law of specific nerve energy’

Physiology

• • • • • Some important moments: 17 th century: William Harvey first describes the closed circulation 19 th century: Claude Bernard formulates the modern version of homeostasis – the constancy of the internal milieu 19 th century: Johannes Muller formulates the ‘law of specific nerve energy’ In general, a slow development of our modern view of the function of the body

Systems physiology:

Missing from the scheme: • • Structure and motion: Skeletal system Muscles • • Integratory systems: Nervous system Hormones

Cell Structure & Function

Source: http://koning.ecsu.ctstateu.edu/cell/cell.html

• • • • • • •

Unit-I Outline

Levels of Cellular Organization & function Organelles, tissues, organs & systems.

Cell theory Properties common to all cells Cell size and shape –

why are cells so small?

Prokaryotic cells Eukaryotic cells – Organelles and structure in all eukaryotic cell – Organelles in plant cells but not animal Cell junctions

History of Cell Theory

• mid 1600s – Anton van Leeuwenhoek – Improved microscope, observed many living cells • mid 1600s – Robert Hooke – Observed many cells •

1850 – Rudolf Virchow

– Proposed that all cells come from existing cells

Cell Theory

Cells were discovered in 1665 by Robert Hooke.

Early studies of cells were conducted by - Mathias Schleiden (1838) - Theodor Schwann (1839) Schleiden and Schwann proposed the Cell Theory.

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Cell Theory

1. All organisms consist of 1 or more cells.

2. Cell is the smallest unit of life.

3. All cells come from pre-existing cells.

Cell Theory

• • • All living things are made up of cells. Cells are the smallest working units of all living things. All cells come from preexisting cells through cell division.

Cell Theory

Cell Theory

1. All organisms are composed of cells.

2. Cells are the smallest living things.

3. Cells arise only from pre-existing cells.

All cells today represent a continuous line of descent from the first living cells.

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Cell Theory

Cell size is limited.

-As cell size increases, it takes longer for

material to diffuse from the cell membrane

to the interior of the cell.

Surface area-to-volume ratio

: as a cell increases in size, the volume increases

10x faster than the surface area

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Cell Theory

14

Cell Theory

Microscopes are required to visualize cells.

Light microscopes

are 200nm apart.

can resolve structures that

Electron microscopes

can resolve structures that are 0.2nm apart.

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Cell Theory

All cells have certain structures in common.

1. genetic material – in a nucleoid or nucleus 2. cytoplasm – a semifluid matrix 3. plasma membrane – a phospholipid bilayer 16

Definition of Cell

A cell is the smallest unit that is capable of performing life functions.

Observing Cells

(4.1) • Light microscope – Can observe living cells in true color – Magnification of up to ~1000x – Resolution ~ 0.2 microns – 0.5 microns

Observing Cells

(4.1) • Electron Microscopes – Images are black and white – may be colorized – Magnifcation up to ~100,000 • Transmission electron microscope (TEM) – 2-D image • Scanning electron microscope (SEM) – 3-D image

SEM TEM

Bacteria

Examples of Cells

Amoeba Proteus Plant Stem Red Blood Cell Nerve Cell

Two Types of Cells

•Prokaryotic •Eukaryotic

Prokaryotic

• • • Do not have structures surrounded by membranes Few internal structures One-celled organisms, Bacteria

http://library.thinkquest.org/C004535/prokaryotic_cells.html

Prokaryotic Cells

Prokaryotic cells

lack a membrane-bound nucleus.

-genetic material is present in the

nucleoid

Two types of prokaryotes: -archaea -bacteria 24

Prokaryotic Cells

Prokaryotic cells possess -genetic material in the nucleoid -cytoplasm -plasma membrane -cell wall -ribosomes -no membrane-bound organelles 25

Prokaryotic Cells

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Prokaryotic Cells

Prokaryotic cell walls -protect the cell and maintain cell shape Bacterial cell walls -may be composed of peptidoglycan -may be

Gram positive

or

Gram negative

Archaean cell walls lack peptidoglycan.

27

Prokaryotic Cells

Flagella

-present in some prokaryotic cells -used for locomotion -rotary motion propels the cell 28

Prokaryotic Cell Structure

• Prokaryotic Cells are smaller and simpler in structure than eukaryotic cells.

– Typical prokaryotic cell is __________ – Prokaryotic cells do NOT have: • Nucleus • Membrane bound organelles

Prokaryotic Cell

TEM Prokaryotic Cell

Eukaryotic

• • Contain organelles surrounded by membranes Most living organisms

Plant Animal

http://library.thinkquest.org/C004535/eukaryotic_cells.html

“Typical” Animal Cell

http://web.jjay.cuny.edu

/~ acarpi/NSC/images/cell.gif

http://waynesword.palomar.edu/images/plant3.gif

Plant Cell

Eukaryotic Cells

Eukaryotic cells

-possess a membrane-bound nucleus -are more complex than prokaryotic cells -compartmentalize many cellular functions within

organelles

and the

endomembrane system

-possess a

cytoskeleton

for support and to maintain cellular structure 36

Eukaryotic Cells

37

Eukaryotic Cells

38

Eukaryotic Cells

Nucleus

-stores the genetic material of the cell in the form of multiple, linear chromosomes -surrounded by a

nuclear envelope

of 2 phospholipid bilayers composed -in chromosomes – DNA is organized with proteins to form

chromatin

39

Eukaryotic Cells

40

Eukaryotic Cells

Ribosomes

-the site of protein synthesis in the cell -composed of

ribosomal RNA

and proteins -found within the cytosol of the cytoplasm and attached to internal membranes 41

Cell Structure

•

All Cells have:

– an outermost plasma membrane – genetic material in the form of DNA – cytoplasm with ribosomes

Cell Parts Organelles

Surrounding the Cell

Cell Membrane

• • Outer membrane of cell that controls movement in and out of the cell Double layer

http://library.thinkquest.org/12413/structures.html

Cell Wall

• • Most commonly found in plant cells & bacteria Supports & protects cells

http://library.thinkquest.org/12413/structures.html

Inside the Cell

Nucleus

• • • Directs cell activities Separated from cytoplasm by nuclear membrane Contains genetic material - DNA

Nuclear Membrane

• • • Surrounds nucleus Made of two layers Openings allow material to enter and leave nucleus

http://library.thinkquest.org/12413/structures.html

Chromosomes

• • • In nucleus Made of DNA Contain instructions for traits & characteristics

http://library.thinkquest.org/12413/structures.html

Nucleolus

• • Inside nucleus Contains RNA to build proteins

http://library.thinkquest.org/12413/structures.html

Cytoplasm

• • • Gel-like mixture Surrounded by cell membrane Contains hereditary material

Endoplasmic Reticulum

• Moves materials around in cell • Smooth type: lacks ribosomes • Rough type (pictured): ribosomes embedded in surface

http://library.thinkquest.org/12413/structures.html

Ribosomes

• • • Each cell contains thousands Make proteins Found on ribosomes & floating throughout the cell

http://library.thinkquest.org/12413/structures.html

Mitochondria

• • • Produces energy through chemical reactions – breaking down fats & carbohydrates Controls level of water and other materials in cell Recycles and decomposes proteins, fats, and carbohydrates

http://library.thinkquest.org/12413/structures.html

Golgi Bodies

• • • Protein 'packaging plant ' Move materials within the cell Move materials out of the cell

http://library.thinkquest.org/12413/structures.html

Lysosome

• • • Digestive 'plant ' for proteins, fats, and carbohydrates Transports undigested material to cell membrane for removal Cell breaks down if lysosome structure is disrupted.

http://library.thinkquest.org/12413/structures.html

Vacuoles

• • • Membrane-bound sacs for storage, digestion, and waste removal Contains water solution Help plants maintain shape

http://library.thinkquest.org/12413/structures.html

Chloroplast

• • • Usually found in plant cells Contains green chlorophyll Where photosynthesis takes place

http://library.thinkquest.org/12413/structures.html

1. Plasma Membrane

• All membranes are phospholipid bilayers with embedded proteins • The outer plasma membrane – isolates cell contents – controls what gets in and out of the cell – receives signals

2. Genetic material in the form of DNA

– Prokaryotes – no membrane around the DNA (no nucleus) – Eukaryotes – DNA is within a membrane (there is nucleus)

3. Cytoplasm with ribosomes

– Cytoplasm – fluid area inside outer plasma membrane and outside DNA region – Ribosomes – make proteins

Cell Structure

•

All Cells have:

– an outermost plasma membrane – genetic material in the form of DNA – cytoplasm with ribosomes

Why Are Cells So Small?

(4.2) • • Cells need sufficient surface area to allow adequate transport of nutrients in and wastes out.

As cell volume increases, so does the need for the transporting of nutrients and wastes.

Why Are Cells So Small?

• • However, as cell volume increases the surface area of the cell does not expand as quickly.

– If the cell’s volume gets too large it cannot transport enough wastes out or nutrients in. Thus, surface area limits cell volume/size.

Why Are Cells So Small?

• Strategies for increasing surface area, so cell can be larger: – “Frilly” edged…….

– Long and narrow…..

• Round cells will always be small.

Eukaryotic Cells

•

Structures in all eukaryotic cells

– Nucleus – Ribosomes – Endomembrane System • Endoplasmic reticulum – smooth and rough • Golgi apparatus • Vesicles – Mitochondria – Cytoskeleton

CYTOSKELETON MITOCHONDRION

CYTOPLASM

CENTRIOLES PLASMA MEMBRANE NUCLEUS RIBOSOMES ROUGH ER SMOOTH ER GOLGI BODY

VESICLE

LYSOSOME Fig. 4-15b, p.59

Nucleus

(4.5) • Function – isolates the cell’s genetic material, DNA – DNA directs/controls the activities of the cell • DNA determines which types of RNA are made • The RNA leaves the nucleus and directs the synthesis of proteins in the cytoplasm at a ______________

Nucleus

•

Structure

– Nuclear envelope • Two Phospholipid bilayers with protein lined pores – Each pore is a ring of 8 proteins with an opening in the center of the ring – Nucleoplasm – fluid of the nucleus

Nuclear pore bilayer facing cytoplasm Nuclear envelope bilayer facing nucleoplasm Fig. 4-17, p.61

Nucleus

• DNA is arranged in chromosomes – Chromosome – fiber of DNA with proteins attached – Chromatin – all of the cell’s DNA and the associated proteins

Nucleus

•

Structure,

continued

– Nucleolus • Area of condensed DNA • Where ribosomal subunits are made – Subunits exit the nucleus via nuclear pores

ADD THE LABELS

Endomembrane System

(4.6 – 4.9) • Series of organelles responsible for: – Modifying protein chains into their final form – Synthesizing of lipids – Packaging of fully modified proteins and lipids into vesicles for export or use in the cell – And more that we will not cover!

Structures of the Endomembrane System • • • Endoplasmic Reticulum (ER) – Continuous with the outer membrane of the nuclear envelope – Two forms - smooth and rough Transport vesicles Golgi apparatus

Endoplasmic Reticulum (ER)

– The ER is continuous with the outer membrane of the nuclear envelope – There are 2 types of ER: • Rough ER – has ribosomes attached • Smooth ER – no ribosomes attached

Endoplasmic Reticulum

• Rough Endoplasmic Reticulum (RER) • Network of flattened membrane sacs create a “maze” – RER contains enzymes that recognize and modify proteins • Ribosomes are attached to the outside of the RER and make it appear rough

Endoplasmic Reticulum

• Function RER • Proteins are modified as they move through the RER • Once modified, the proteins are packaged in transport vesicles for transport to the Golgi body

Endomembrane System

• • Smooth ER (SER) – Tubular membrane structure – Continuous with RER – No ribosomes attached Function SER – Lipids are made inside the SER • fatty acids, phospholipids, sterols..

– Lipids are packaged in transport vesicles and sent to the Golgi

Endomembrane System

Vacuoles

-membrane-bound structures with various functions depending on the cell type There are different types of vacuoles: -

central vacuole

in plant cells -contractile vacuole of some protists -vacuoles for storage 82

Endomembrane System

Endomembrane system

-a series of membranes throughout the cytoplasm -divides cell into compartments where different cellular functions occur 1. endoplasmic reticulum 2. Golgi apparatus 3. lysosomes 83

Endomembrane System

Rough endoplasmic reticulum (RER)

-membranes that create a network of channels throughout the cytoplasm -attachment of ribosomes to the membrane gives a rough appearance -synthesis of proteins to be secreted, sent to lysosomes or plasma membrane 84

Endomembrane System

Smooth endoplasmic reticulum (SER)

-relatively few ribosomes attached -functions: -synthesis of membrane lipids -calcium storage -detoxification of foreign substances 85

Endomembrane System

Endomembrane System

Golgi apparatus

-flattened stacks of interconnected membranes -packaging and distribution of materials to different parts of the cell -synthesis of cell wall components 87

88

Endomembrane System

Lysosomes

-membrane bound vesicles containing digestive enzymes to break down macromolecules -destroy cells or foreign matter that the cell has engulfed by phagocytosis 89

90

Endomembrane System

Microbodies

-membrane bound vesicles -contain enzymes -not part of the endomembrane system -

glyoxysomes

in plants contain enzymes for converting fats to carbohydrates -

peroxisomes

catalase contain oxidative enzymes and 91

Golgi Apparatus

• • Golgi Apparatus – Stack of flattened membrane sacs Function Golgi apparatus – Completes the processing substances received from the ER – Sorts, tags and packages fully processed proteins and lipids in vesicles

Golgi Apparatus

• Golgi apparatus receives transport vesicles from the ER on one side of the organelle – Vesicle binds to the first layer of the Golgi and its contents enter the Golgi

Golgi Apparatus

– The proteins and lipids are modified as they pass through layers of the Golgi – Molecular tags are added to the fully modified substances • These tags allow the substances to be sorted and packaged appropriately.

• Tags also indicate where the substance is to be shipped.

Golgi Apparatus

Transport Vesicles

• Transport Vesicles – Vesicle = small membrane bound sac – Transport modified proteins and lipids from the ER to the Golgi apparatus (and from Golgi to final destination)

Endomembrane System

• Putting it all together – DNA directs RNA synthesis  RNA exits nucleus through a nuclear pore  ribosome  protein is made  proteins with proper code enter RER RER and lipids  proteins are made in are modified in SER  vesicles containing the proteins and lipids bud off from the ER

Endomembrane System

• Putting it all together  ER vesicles merge with Golgi body  proteins and lipids enter Golgi  each is fully modified as it passes through layers of Golgi  modified products are tagged, sorted and bud off in Golgi vesicles  …

Endomembrane System

• Putting it all together  Golgi vesicles either merge with the plasma membrane and release their contents OR remain in the cell and serve a purpose

Vesicles

• Vesicles - small membrane bound sacs – Examples • Golgi and ER transport vesicles • Peroxisome – Where fatty acids are metabolized – Where hydrogen peroxide is detoxified • Lysosome – contains digestive enzymes – Digests unwanted cell parts and other wastes

Lysosomes

(4.10) • The lysosome is an example of an organelle made at the Golgi apparatus.

– Golgi packages digestive enzymes in a vesicle. The vesicle remains in the cell and: • Digests unwanted or damaged cell parts • Merges with food vacuoles and digest the contents • Figure 4.10A

Lysosomes

(4.11) • Tay-Sachs disease occurs when the lysosome is missing the enzyme needed to digest a lipid found in nerve cells.

– As a result the lipid accumulates and nerve cells are damaged as the lysosome swells with undigested lipid.

Mitochondria

(4.15) • – Function – synthesis of ATP 3 major pathways involved in ATP production 1. Glycolysis 2. Krebs Cycle 3. Electron transport system (ETS)

Mitochondria

• Structure: – ~1-5 microns – Two membranes • Outer membrane • Inner membrane - Highly folded – Folds called cristae – Intermembrane space (or outer compartment) – Matrix • DNA and ribosomes in matrix

Mitochondria

Mitochondria

(4.15) • – Function – synthesis of ATP 3 major pathways involved in ATP production 1. Glycolysis - cytoplasm 2. Krebs Cycle - matrix 3. Electron transport system (ETS) - intermembrane space

TEM

Mitochondria

Mitochondria

Mitochondria

-organelles present in all types of eukaryotic cells -contain oxidative metabolism enzymes for transferring the energy within macromolecules to ATP -found in all types of eukaryotic cells 110

Mitochondria

-surrounded by 2 membranes -smooth outer membrane -folded inner membrane with layers called

cristae

-

matrix

is within the inner membrane -

intermembrane space

two membranes is located between the -contain their own DNA 111

Mitochondria

112