This unit covers chapters: 7,11,43,44,45

Evolution

• Pathway similarities suggest that ancestral signaling molecules evolved in prokaryotes and were modified later in eukaryotes

• The concentration of signaling molecules allows bacteria to sense local population density

Cell Membrane structures that aid in communication Ch. 7• Animal and plant cells have cell junctions

that directly connect the cytoplasm of adjacent cells

a.Tight Junctionsb.Desmosomesc.Gap Junctions

• Tight Junctions-prevent leakage of extra cellular fluid by making a tight seal around adjacent cells. Ex: skin cells

• Desmosomes-acts like a rivet, attaching cells together. Ex: muscle cells, if a muscle tears then a desmosome has ruptured.

• Gap Junctions- in animals and Plasmodesmata in plants allows ions, amino acids, and sugars to transport between cells

Membrane Protein functions

• Transport• Signal Transduction• Cell to Cell recognition• Intercellular joining• Attachment to cytoskeleton

Feedback

• Positive Feedback Negative Feedback

Which is an example is each:a.Temperature regulation _______________b.Lactation in mammals _________________c.Blood Clotting ______________________d.Secretion of Insulin __________________

SOOOO……

• How would you describe Positive Feedback?

• How would you describe Negative Feedback?

Chapter 11

Cell Communication

Signal-Transduction Pathway

• Signal on a cell’s surface is converted into Signal on a cell’s surface is converted into a specific cellular responsea specific cellular response

• Local signalingLocal signaling (short distance) - Paracrine (growth factors); SynapticSynaptic (neurotransmitters)

• Long distanceLong distance - hormones

Stages of Cell Signaling3 steps:3 steps:• Reception: target cell detectionReception: target cell detection• Transduction: single-step or series of Transduction: single-step or series of

changeschanges• Response: triggering of a specific Response: triggering of a specific

cellular responsecellular response

Immunity and Cell CommunicationCh 43

Types of immune responses

• Humoral immunity• B cell activation• Production of antibodies• Defend against bacteria, toxins, and

viruses free in the lymph and blood plasma

• Cell-mediated immunity• T cell activation• Binds to and/or lyses cells• Defend against cells infected with

bacteria, viruses, fungi, protozoa, and parasites; nonself interaction

Immunity in Health & Disease

• Active immunity/natural: conferred immunity by recovering from disease

• Active immunity/artificial: immunization and vaccination; produces a primary response

• Passive immunity: transfer of immunity from one individual to another

• natural: mother to fetus; breast milk• artificial: rabies antibodies

The Inflammatory Response

1- Tissue injury; release of chemical signals~ • histamine (basophils/mast cells):

causes Step 2... • prostaglandins: increases blood flow & vessel permeability

2/3- Dilation and increased permeability of capillary4- Phagocytosis of pathogens~ • fever- leukocyte-released molecules increase body temperature

Nervous System and cell communicationCh 48

Parts of Neuron-Nervous System Cell• Neuron~ structural and functional unit• Cell body~ nucelus and organelles• Dendrites~ impulses from tips to neuron• Axons~ impulses toward tips• Myelin sheath~ supporting, insulating layer• Schwann cells~PNS support cells• Synaptic terminals~ neurotransmitter releaser• Synapse~ neuron junction• Neurotransmitters- chemical messengers that pass

information from transmitting to receiving neurons

• Sensory Receptors~ dendrites receive stimulus and send to CNS which will relay to Effector cells

• Effector cells~ muscle or gland cells that will produce a desired response

• Nerves~ bundles of neurons wrapped in connective tissue

• Central nervous system (CNS)~ brain and spinal cord

• Peripheral nervous system (PNS)~ sensory and motor neurons

• Sensory neuron: convey information to spinal cord

• Motor neurons: convey signals to effector cell (muscle or gland)

• Reflex: simple response; sensory to motor neurons.

Is typically -60 to -80 millivolts

Endocrine and cell communicationCh 45

Regulatory systems• Hormone~ chemical signal secreted into body

fluids (blood) communicating regulatory messages

• Target cells~ body cells that respond to hormones

• Endocrine system/glands~ hormone secreting system/glands (ductless);

• Exocrine glands~ secrete chemicals (sweat, mucus, enzymes) through ducts

• Neurosecretory cells~ actual cells that secrete hormones

• Feedback mechanisms ~ negative and positive

Mode of Action: Chemical Signaling1- Plasma membrane reception • signal-transduction pathways (neurotransmitters, growth factors, most hormones) 2- Cell nucleus reception • steroid hormones, thyroid hormones, some local regulators

Hypothalamus~regulates the pituitary gland

Pituitary glandPineal glandThyroid glandParathyroid glandsThymusAdrenal glandsPancreasGonads -ovary, testis

• Pineal-secretes serotonin which regulates the sleep/wake cycles

• Thyroid- regulates metabolism • Parathyroid- control calcium level in bones and blood• Thymus-secretes hormones that produce antibodies• Adrenal- secretes aldosterone and cortisol which

creates a fight or flight response • Gonads-secrete testosterone, esterogen, or

progesterone• Pancreas- secretes Insulin and Glucagon to regulate

blood sugar levels

Examples of Hormone Regulation

• Pituitary: Regulates other glands

• Oxytocin: uterine and mammary gland cell contraction

• Antidiuretic (ADH):retention of water by kidneys

Pituitary Gland regulates• Growth (GH)~bones • Disorder: gigantism/dwarfism• • Prolactin (PRL)~mammary glands; milk

production • Follicle-stimulating (FSH) – this causes the sex

cells to finish meiosis and prepare for sexual reproduction

• Luteinizing (LH)~ovaries/testes- helps maintain levels of sex hormones in the body

• Thyroid-stimulating (TSH)~ regulates metabolism

• Adrenocorticotropic (ACTH)~ aids in body’s response to stress

• • Melanocyte-stimulating (MSH) has effects on skin

pigmentation

• Endorphins~natural ‘opiates’; brain pain receptors

MSH

• Interesting fact about MSH : However, in many red headed people, and other people who do not tan well, there are variations in their hormone receptors, causing them to not respond to MSH in the blood.

The pancreas (organ)

Hormones secretes by the pancreas to regulate Blood Sugar•glucagon~ raises blood glucose levels• insulin~ lowers blood glucose levels

Ch 44 Excretory

• With focus on the Kidneys, Ureter, Bladder, and Urethrea

• Other organs involved in excretory would be skin and lungs

The Kidneys (organ)

Role of ADH

• When the brain detects dehydration it will secrete ADH.

• ADH will reduce amt of water in urine.• Secretion stops when the blood volume

returns to homeostasis.