Physiology Lecture Exam 2 – Flashcards

ADP and inorganic phosphate ATP provides energy for cellular processes via an exergonic reaction that is commonly coupled to an endergonic reaction of cellular metabolism.

d. and enzyme is versatile and able to catalyze many different types of reactions

b. enzymes lower the activation energy of the reaction

a. kinases

b. to the left

b. hydrolysis and dehydration reactions • Oxidation-reduction reactions involve energy extraction and transfer by the movement of electrons from one molecule to another. • Addition, subtraction and exchange reactions involve changes in the bonds between a molecule and functional group(s). • Hydrolysis and dehydration reactions build and break down biopolymers by the addition or removal of a molecule of water. • Ligation reactions join two molecules using enzymes called synthetases and energy from ATP.

a. hydrolysis of ATP to ADP and inorganic phosphate Endergonic reactions are often coupled to exergonic reactions so that the former can obtain the input of energy needed. A commonly coupled exergonic reaction is the hydrolysis of ATP to ADP and inorganic phosphate.

feedback inhibition

hydrolases These enzymes catalyze hydrolysis-dehydration reactions.

c. phenylalanine hydroxylase

exergonic reaction

The energy of motion; capacity to do work. Chemical bonds are a form of potential or stored energy.

Vitamin C

1. signal molecule (ligand or 1st messenger) binds to receptor 2. activates protein (tranduce) 3. creates second messenger (amplify) 4. creates a response

They are lipophilic and directly enters the cell and binds with intracellular receptors.

1. channel receptors (ion, G protein, Ca++) 2. enzyme receptors (activated by phosphorylation by kinase. eg. Tyrosine kinase phosphorylates tyrosine (amino acid) by adding phosphates 3. G protein receptors (adrenergic receptors). Adynyl cylclase and phospholipase C (amplifiers) common pathways 4. integrin receptors -blood clot and cell adhesion; binds to cytoskeleton

1st messengers are extracellular; 2nd messenger are intracellular.

amplifier enzyme, second messenger, protein kinase, phosphorylated protein, cell response

1.The nervous system has a rolein preserving the "fitness" of the internal environment. ie. blood pressure, blood volume 2. Some systems of the body are under tonic control. Tonic, like the radio's volume control. ie. neural regulation of certain blood vessels, if there is an increase in nervous system input, diameter decreases 3. Some systems of the body are under antagonistic control. ie. insulin and glucagon are antagonistic hormones; sympathetic and parasympathetic systems have opposing effect. 4. One chemical signal can have different effects in different tissues. ie. epinephrin can constrict or dilate blood vessels depending if the vessel has alpha or beta adrenergic receptors.

response where the body opposes or removes the signal.

response that sends the variable being regulated farther from the normal value. External intervention stops a positive feedback

response that anticipates change. ie. salivation reflex

chemicals that act on cells in the immediate vicinity

chemicals that act on the cell that secreted it

ligands that turn receptors on

ligands that block receptors

The cell is in electrical disequilibrium with the extracellular fluid. At rest, there is a negative electrical potential across the cell membrane. This requires a separation of charge, which is possible because the phospolipid bilayer acts as an insulator.

The Na+-K+-ATPase pump maintains the resting potential by restoring the ion concentrations on both sides.

[K] is higher in the cell so when channels are open, K will move out making the intracellular less positive, more negative which causes hyperpolarization.

phosphorylase

reductase

oxidase

deaminase

ligase or synthetase

dehydrogenase

aminase

kinase

transaminase

lipase

peptidase

phosphotase

protease

d. synthetase

b. dehydrogenase c. oxidase

feed-forward mechanism

antagonistic control

One chemical signal can have different effects in different tissues, due to the presence of different receptor types.

tonic control

a. Feedback loops are important part of reflexes. Feedback loops are response loops that have an effect on the initial stimulus, either enhancing it (positive feedback) or dampening it (negative feedback). They are an important part of reflexes. Negative feedback loops are homeostatic because they keep regulated variables within a narrow range of values around a setpoint. Positive feedback loops push regulated variables away from a setpoint. Negative feedback loops are more common than positive feedback loops.

feed-forward mechanism

negative feedback mechanism cAMP activates PK-A, which (among other effects) produces a phosphodiesterase which in turn reduces the amount of cAMP. With less cAMP available, the rate of production of PK-A will slow down. This is an example of a negative feedback loop.

positive feedback mechanism

feed-forward mechanism

negative feedback

negative feedback

insulator

a. The resting membrane potential for eukaryotic cells is usually negative.

b. potassium ion leak channels Because EqK+ is more strongly negative than EqNa+ is positive, potassium ion leak channels have a greater influence on the resting membrane potential. Physiologically, this is due to the much greater permeability of physiological membranes to potassium as compared to sodium.

b. hyperpolarization Chloride is at a higher concentration outside the cell than inside. When a chloride ion channel is opened, chloride will enter the cell. This adds negative charge, making the interior even more negative with respect to the outside, which is a hyperpolarizing change.

Autonomic: • controls smooth muscles, cardiac muscles and many glands, lymphoid and some adipose • 2 neurons in efferent pathway (preganglionic and postganglionic neurons) • neurotransmitter/receptor at target synapse (Sympathetic & Parasympathetic: ACh/nicotinic receptors@ preganlionic axon terminals; Parasympathetic: ACh/muscarinic @ postganglionic axon terminals (cholinergic); Sympathetic: NE/alpha or beta (adrenergic) • neurotransmitters are released from axon terminals or varicosities • exhitatory or inhibitory effects of neurotransmitters • peripheral components found outside CNS: preganglionic axons, ganglia, postganglionic axons • controls metabolism, visceral functions (internal organs) Somatic: • controls posture and movement (motor) • 1 neuron in efferent pathway • neurotransmitter/receptor -- ACh/nicotinic receptor (cholinergic) • targets skeletal muscles • neurotransmitter released from axon terminals • exhitatory effects • peripheral components found outside CNS: axons only

• arterioles and veins -- constricts/dilates • adrenal medulla -- secretes catecholamines • kidney -- increase renin secretion • adipose tissues -- fat breakdown • lymphoid tissue -- generally inhibitory

ciliary muscle

swollen regions along the autonomic axons that store neurotransmitters

cholinergic -- nicotinic and muscarinic

adrenergic -- alpha and beta

synapse between postganglionic autonomic neuron and its target cell • varicosities that contain neurotransmitters • released into interstitial fluid and diffuse where receptors are located • contains cholinergic muscarinic (parasympathetic), adrenergic alpha or adrinergic beta receptors (sympathetic)

synapse of somatic motor neuron on a muscle fiber • axon terminal filled with synaptic vesicle (like neuroeffector junction) • includes extension of Schwann cells that cover axon terminals • at synaptic cleft matrix hold axon terminal and motor end plate in alignment • contains cholinergic nicotinic receptors

preganglionic neurons originate from spinal cord. no postganglions but instead have chromaffin cells that sevrete neurohormone epinephrine into the blood

Agonists: Muscarinic and Nicotinic Antagonists: Atrophine and TEA

drugs that block the specific receptors eg of alpha blocker is Flomax, muscle relaxant, eg of beta blockers are blood pressure drugs

• contractability • irritability/excitability - carry electrical impulse; ability to respond rapidly • extensibility/compliance • elasticity - ability to recoil from stretch

Excitation-contraction coupling is a sequence of events that converts action potential in a muscle fiber to a contraction. 1. ACh is released from somatic motor neuron 2. ACh initiates action potential in muscle fiber 3. Action potential triggers Ca release from sarcoplasmic reticulum DHP receptors opened manually to release Ca 4. Ca combines with troponin

1. Action potential travels length of the axon of a motor neuron to an axon terminal. 2. Voltage gated Ca channels open and diffuse into the terminal 3. Ca ions causes release of ACh via exocytosis 4. ACh diffuses into the synaptic cleft and binds with ligand-gated channels 5. Ligand-gated channels open 6. Na++ enter muscle fiber, K+ exit muscle fiber 7. Once membrane reach threshold value, action potential propagates sarcolemma

muscle contracts but doesn't shorten. Force cannot move a load

muscle contracts and shortens. Force moves a load.

reversible condition when muscle unable to sustain expected power output. ACh is not synthesized in the axon terminal fast enough to keep up with neuron firing rate.

• inactivation by enzymes: ACh by acetycholinesterase • transported back to into presynaptic terminal: Choline reuptake • removed by transport

phenomena that action potential needs to achieve threshold value or it doesn't occur at all

Na+ = +60 K+ = -90

variable-strength signals that travel short distance as they lose their strength

forward fast transport of vesicles and mitochondria from cell body to axon terminal

backward fast axonal transport that returns old cellular components from axon terminal to cell body for recycling