Human Physiology Final

Capillary Hydrostatic Pressure

-pushes fluid out

-Force exerted by fluid against a wall

- 20L of fluid is pushed out each day

Colloid osmotic pressure

created by non-diffusible molecules that draw some fluid back.

Lymphatic system

A network of vessels that take up fluid from the interstitial space and return it to the blood.

Lymphatic capillary

a close-ended microscopic lymphatic vessel that begins in the interstitial spaces between cells, takes in interstitial fluid, and begins its transport through the lymphatic system

Lymph Vessels

vessels that receive lymph from the lymph capillaries and circulate it to the lymph nodes (everywhere)

Where Does Lymph Go?

Back to the blood to become plasma again (heart)

Lymph

is cleansed of debris and surveyed for pathogens.

Lymph Nodes

Solid spherical bodies that cluster along lymphatic vessels.

• Provide a meeting, surveillance, and proliferation site for immune cells

Lymphoid Organs

Lymphocytes, Antigen Presenting Cells

Lymphocytes (the soldiers)

T cells (T lymphocytes): manage response, can attack infected cells.

- B cells (B lymphocytes): produce antibodies

Antigen Presenting Cells (the intelligence)

Macrophages phagocytose foreign substances and present antigens

- Dendritic Cells capture antigens in tissues and bring them back to the lymph node

Cortex

-Dividing B cells (germinal centers)

- T cells in transit

Medulla

Draining sinuses that allow lymph efflux

Spleen

Immune surveillance of blood (- Removal of old RBCs (Red pulp)

Thymus

T Cell education/maturation

• No B cells

Atrophies with age

Tonsils

Trap and remove pathogens entering throat.

Produce memory cells for later.

Appendix

Off-shoot of large intestine

Thought to survey/store gut bacteria

Peyer's Patches

Nodules in small intestine

survey gut bacteri

First Line of Defense

Skin and Membranes are physical barriers.

Acid (skin, stomach = inhibit bacterial growth)

Enzymes (Lysozyme in saliva, tears = destroy bacteria)

Second Line of Defense

Innate Immune cells

Macrophages

Derived from blood monocytes • Search tissue and "eat" debris or foreign invader

What is the first step in phagocytosis?

Phagocyte adheres to pathogens or debris

What do phagocytes form to engulf particles during phagocytosis?

Pseudopods

What is formed when a phagocyte engulfs particles?

Phagosome

What fuses with the phagocytic vesicle to form a phagolysosome?

Lysosome

What do lysosomal enzymes do in the phagolysosome?

Digest the particles, leaving a residual body

What process removes indigestible and residual material from the phagocyte?

Exocytosis of the vesicle

What is inflammation?

Aggressive steps the body takes to fix a problem.

What triggers inflammation?

Tissue injury or infection.

What type of receptors do macrophages and dendritic cells use to detect problems?

Toll-like receptors (TLRs).

What do Toll-like receptors (TLRs) do?

They detect problems and 'sound the alarm'.

Why is edema beneficial?

Sweeps foreign material into lymphatics

Calling For Back up

Chemical "alarm" recruits immune cells to injured or infected area.

Neutrophils

A type of white blood cell that engulfs invading microbes and contributes to the nonspecific defenses of the body against disease.

Extravasation

escape of blood from the blood vessel into the tissue

- Blood vessels and immune cells upregulate adhesion molecules.

Diapedesis

Neutrophils enter tissue.

Chemotaxis

Movement up a chemical gradient (to injury/infection)

Interferons

"Interfere" with viral replication

Complement System

20 plasma proteins that circulate in blood.- Activation triggers cascade that lyses bacteria and cells.

T Cells

Cells created in the thymus that produce substances that attack infected cells in the body.

B Cells

produce antibodies

What are foreign antigens?

Foreign antigens originate from outside the body.

What are self antigens?

Self antigens are produced by the body and rarely initiate an immune response.

What can self antigens trigger in other people?

Self antigens can trigger an immune response in other people, as seen in the rejection of transplanted tissues and organs.

Bubble boy

Severe combined immunodeficiency (SCID)

What is required for T cell activation?

T cells require two signals.

What do Antigen Presenting Cells (APCs) do?

APCs present antigens to T cells.

Where do dendritic cells present antigens to T cells?

Dendritic cells present antigens to T cells in lymph nodes.

What happens to co-stimulation molecules on APCs when they encounter pathogens?

APCs upregulate co-stimulation molecules.

MHC Class II Proteins

present these antigens to Helper T Cells.

CD4 Helper T Cells (2 signals)

T Cell receptor (TCR) binds antigen in MHC-II complex

Alveoli

tiny sacs of lung tissue specialized for the movement of gases between air and blood

Pleurae

Double layered membrane

- Fluid between laye

Parietal

covers chest wall and diaphragm

Visceral

covers lung surface

Lung Expansion

Increase in lung volume during inhalation.

Boyle's Law- Volume changes lead to pressure changes

Recoil

Recoil expels air • Lungs sticking to chest wall prevents collapse

Pneumothorax

Presence of air pleural cavity.-

Seal broken.

- Can't breathe!

collapsed lung

Diaphragm

Parachute-shaped muscle

• Contraction (Down) increases chest volume

Intercostal muscles

Muscles between ribs

• Raises rib cage

. • "Bucket Handle" movement.

Intercostal muscles + Diaphragm =

Inspiration

Lung Recoil

Expiration

Passive proces

Muscles relax...- Major driving forces Lung elasticity and Surface tension

Forced Expiration

Contract abdominal muscles

CD4 Helper T Cells

Promote B Cell Activation and Antibody Synthesis

MHC-I Presents Intracellular Proteins

Random sampling of recycled proteins sent to ER. • Peptides bind MHC-I and present what is being made.

MHC-I

is expressed by ALL cells.

Cytotoxic CD8 T cells Scan MHC-I Molecules

CD8 cells recognize foreign antigens presented by MHC-I. • Release toxic enzymes killing target cell.

Natural Killer (NK) Cells:

a Back-up plan for those Sneaky Viruses

CAR T-Cell Therapy for Cancer

CAR (Chimeric Antigen Receptor)- Synthetic receptor- Allows T cells to recognize and attack cancer cells

What is the role of MHC in organ transplantation?

MHC must match between donor and recipient to reduce rejection.

What types of cells are involved in rejecting mismatched tissue?

CD8 and NK cells.

What is the effect of immunosuppressive drugs on transplant rejection?

They can reduce the rate of rejection.

What percentage of patients reject a transplant within 10 years under the best conditions?

50%.

Acquired Immune Deficiency Syndrome

Caused by Human Immunodeficiency Virus (HIV)

• Infects and kills CD4 T cells

• Virus always X mutating ("new" molecules/antigens)

Autoimmunity

Immune system destroys own cells

- Antibodies or CD8 T Cells

• Most prevalent in women.

Rheumatoid Arthritis

(joints)

Multiple Sclerosis

myelin sheath destruction. disruptions in nerve impulse conduction

Grave's Disease

thyroid gland stimulation

Diabetes Mellitus

destroys insulin producing cells

Molecular mimicry

Pathogen antigens look like our own

treatments of autoimmune diseases

metabolic control therapy

immunosuppressive therapy

targeted treatments

oral tolerance

What is the first step in the activation of CD4 Helper T Cells?

An APC encounters and ingests a microorganism, processing the antigen into short peptides that combine with MHC class II molecules.

What happens after the MHC-antigen complex is formed on the APC?

A receptor on the surface of the CD4 T cell binds to the MHC-antigen complex, providing two signals that activate the Th cell.

What do activated CD4 Helper T Cells produce?

Cytokines.

What is the result of cytokine production by activated CD4 Helper T Cells?

The Th cell proliferates and develops its effector functions.

What is required for a T cell to become activated by a dendritic cell?

The T cell must recognize a dendritic cell that is producing costimulatory molecules.

FAB Region (2 Ends)

Binds antigens

FC Region (Tail)

Binds macrophage receptors

Active immunity (Induce)

Vaccines

weakened or attenuated pathogen

mRNA vaccines

Plasma Cells

Short-lived "Antibody factories

Helper T Cells promote B Cell activation

by providing cytokines

cytokines

Chemicals released by the immune system communicate with the brain.

Guardians of the Nostrils

Lined with hair follicles- Filter large particles (dust, pollen)

Respiratory System Lined with

mucus membranes and ciliated cells

When Large Particles Sneak Through

Nasal mucosa lined with sensory nerve endings.

• Contact with particles triggers reflex

Cold air

makes nose engorged with blood.

- Blood circulation provides heat

• Moisture = humidity

thin-walled air sacs in lungs

Alveoli

Asthma

Inflammation triggers muscle contraction

• Epinephrine relaxes muscle

Inside Alveoli

Thin epithelium

- Fuses with vessels

- Diffusion of gase