IPHY 3430 Exam 1

Which of the following is a teleological answer for the following: Why do the lungs expand during inspiration?

A. Because contraction of the diaphragm causes thoracic cavity volume to increase.

B. Because air needs to be brought into the lungs for gas exchange.

C. Because the pressure in the atmosphere exceeds thoracic pressure.

B - Because A and C tell you more of a mechanistic approach and they are not telling why. B tells us why - "I need the air for the gas exchange"

Physiology

Study of functions and processes of living organisms

Pathophysiology

Study of physiology gone awry

Themes in physiology

Homeostasis and control systems, structure-function relationships, compartmentation, and energy transformation within biological systems

What is the unit of life?

The cell

4 types of tissue

Epithelial, connective, muscle, nervous

Teleological Approach

Explains "why" (function/purpose)

Mechanistic approach

Describes "how" (process or mechanism)

Homeostasis

"Similar condition"; balancing act; affected by external or internal change; physiological attempt to correct; controlled by feedback loops; ex: body temperature, blood pressure, blood glucose

Physical requirements for membrane transport

Molecular size, solubility in lipids, and ionic charge/polarity

Energy requirements for membrane transport

Concentration gradient and ATP (direct or indirect)

What are the passive membrane transport processes?

Simple diffusion, facilitated diffusion, and osmosis

Simple diffusion

Moving from area of high concentration to area of low concentration

What does facilitated diffusion use/depend on?

Transmembrane proteins which bypass the phospholipids

Types of transmembrane proteins

Channel proteins and carrier proteins

Channel proteins

Continuous opening between intracellular and extracellular fluid

Carrier proteins

Bind to molecules and change shape to shuttle them across the membrane - only open to one side of the membrane at a time

Osmosis

Facilitated diffusion of water; depends on osmolarity, osmotic pressure, and hydrostatic pressure

Aquaporins

Channel proteins which transport water

Osmolarity

Number of particles dissolved in a unit of fluid

Osmotic pressure

Force that controls water entering/leaving a cell; is directly proportional to osmolarity

Water wants to move towards...

Higher osmolarity and higher osmotic pressure in order to create an equilibrium of these 2 factors

Hydrostatic pressure

Pressure exerted by a volume of fluid against a wall, membrane, or some other structure that encloses the fluid

Tonicity

Impact of osmotic pressure on the shape of cells

Hypertonic solution

Solution is very concentrated with solutes so the solution has high osmotic pressure and water is forced out of the cell

Hypotonic solution

Solution is very low in solutes so the osmotic pressure of the cell is high and water is forced into the cell

Which of the substances would be able to readily/easily cross the plasma membrane?

A. Glucose - polar

B. Na+ - polar

C. Water - polar

D. Oxygen - nonpolar

E. Proteins - polar

D. Oxygen - nonpolar

The following substances need to be able to enter into a cell. How will they do so? What will be the mechanism of diffusion? i.e. facilitated (carrier or channel) or simple diffusion. Based on physical requirements.

A. Glucose - polar

B. Na+ - polar

C. Water - polar

D. Oxygen - nonpolar

E. Proteins - polar

A. Facilitated diffusion; carrier protein (bc its too big to have a channel protein)

B. Facilitated diffusion; channel protein

C. Facilitated diffusion; channel protein

*We do not have any active transports for water or any gated transports - all water channels are porous.

D. Simple diffusion (no physical requirement)

E. Facilitated diffusion; either a channel or carrier protein, depends on size

Primary active transport

ATP binds to carrier and is directly used to move molecule

Secondary active transport

Uses concentration gradient which was created through expenditure of ATP

Uniporter

Carries a single substance

Symporter

Carries two substances, moves them in the same direction

Antiporter

Carries two substances, moves them in opposite directions

[Na+] is higher outside of the cell while [K+] is higher on the inside of the cell. The Na+/K+ ATPase is a channel protein that maintains this concentration. What type of carrier protein carries out this function?

A. Symporter

B. Antiporter

C. Uniporter

D. Gated Channel

B. Antiporter

[Na+] is higher outside of the cell while [K+] is higher on the inside of the cell. The Na+/K+ ATPase is a channel protein that maintains this concentration. What is the type of transport based on energy requirements?

A. Facilitated diffusion

B. Primary active transport

C. Secondary active transport

D. Simple diffusion

B. Primary active transport

Distribution of Na+

High concentration in extracellular fluid (plasma and interstitial fluid) and low concentration in intracellular fluid

Distribution of K+

Low concentration in extracellular fluid (plasma and interstitial fluid) and high concentration in intracellular fluid

Use the Distribution of Solutes table to answer the following. Suppose Cl- were able to cross the membrane, which way would it flow? What if we were to switch the concentration gradient?

A. In, out

B. Out, in

C. In, in

D. Out, out

A. In, out

Why do cells communicate?

To maintain homeostasis

Types of cellular communication

Electrical and chemical

Variable

Physiological aspect that can change in level/amount

Receptor/sensor

Sensitive to changes in the variable, usually a surface protein

What does the receptor/sensor do?

Serves as a monitor of variable and sends information to control center

Control center

Determines a set value for the variable, analyzes input from receptor and acts/adjusts accordingly

Effector

Receives information from control center and produces a response

Autoregulation of homeostasis

Local stimulus elicits local response; response may involve positive or negative feedback and is usually independent of neural or endocrine involvement.

Regulation of homeostasis by nervous system

Initiation, control, and coordination of rapid responses designed to restore homeostasis

Regulation of homeostasis by endocrine system

Produces more diffuse action than nervous system effects

The ONLY system that can integrate a sensation is the nervous system:

A. True

B. False

B. False

Feedback mechanism

Cycle of events in which status of variable is constantly monitored and reported to control center

What is the most common type of feedback?

Negative feedback

Negative feedback

Response reverses original stimulus, maintains variable in narrow range; ex: body temperature, blood pressure, blood glucose levels

Positive feedback

Response enhances original stimulus

Feedforward mechanism

Stimulus produces physiological response in anticipation of a change or need before the variable has been altered; ex: prepping the body for digestion when you smell food

What is the purpose of feedforward mechanisms?

Ensure that body is prepared to function best when the variable is eventually altered

Ligand

Substance released by a cell that can bind to a receptor; ex: hormone, neurotransmitter

Receptor (in relation to ligand)

Has a binding site for the ligand which allows them to interact; can be membrane bound or inside the cell

Types of local cell to cell communication

Gap junctions, juxtacrine, autocrine, and paracrine

Gap junction

Forms direct cytoplasmic connections, transfers chemical and electrical signals

Juxtacrine

Contact-dependent signals which require interaction between membrane molecules on 2 cells; uses cell adhesion molecules

Cell adhesion molecules (CAMs)

Transfer signals in both directions between cells

Autocrine signals

Act on the same cell that secreted them

Paracrine signals

Are secreted by one cell and diffuse to adjacent cells; ligand is released into interstitial fluid space and reaches receptors on adjacent target cells

Types of long distance signals

Hormones and neurohormones

Hormones

Secreted into blood by endocrine cells

Neurohormones

Released by neurons into the blood

What determines cellular response to a signal?

Receptor specificity, type of internal signal which is mediated by secondary messengers

Signal transduction

Process by which a cell converts one kind of signal or stimulus to another

Ligand-gated channel

Ligand binding opens or closes the channel

Receptor-enzyme

Ligand binding to a receptor-enzyme activates an intracellular enzyme

G-protein coupled receptor

Ligand binding to a G protein-coupled receptor opens an ion channel or alters enzyme activity

Integrin receptor

Ligand binding to integrin receptors alters the cytoskeleton

Second messengers

Converts the ligand's signal from the receptor to an intracellular process

Most common second messengers

Ca2+ (ion), cAMP and cGMP (nucleotides), IP3 and DAG (lipid derived)

How are signals terminated?

By stopping stimulation of the receptor through removal of ligand (degradation), reuptake, or stopping release

Competitive inhibitor

Blocks ligand binding at the binding site

Upregulation

More receptors are synthesized and exported in response to stimulus of receptors

Downregulation

Amount of receptors is decreased in response to stimulus of receptors

Agonist

A ligand which is not the primary ligand but also activates the receptor

Antagonist

Blocks receptor activity

Tonic control

Regulates physiological parameters in an up-down fashion

What does the endocrine system do?

Allows for communication and regulation of bodily processes through hormones; uses the blood as a means for transportation

Hormone functions

Rates of enzymatic reactions, transport of ions or molecules across cell membranes, gene expression and protein synthesis

Amine hormones

Derived from tryptophan or tyrosine

What type of hormones can be synthesized in advance?

Peptide/protein

Hormone release (peptide/protein)

Hormone and pieces stay in vesicle until release signal is received; when a signal is received, vesicles can move to the membrane and all contents (hormone and inactive fragments) are released by Ca+2-dependent exocytosis

Hormone travel (peptide/protein)

Upon release the hormone enters the blood, travels and spreads until it reaches the target organ

Target organ

Has receptors which can interact with the hormone to produce the intended physiological effect

Characteristics of steroid hormones

Cholesterol-derived, lipophilic and can enter target cell, cytoplasmic or nuclear receptors, slower acting, longer half-life, cannot be synthesized ahead of time - only made on command

Which type of hormone requires lower concentrations?

Steroid bc they last longer in the blood

Most hydrophobic steroids are...

Bound to plasma protein carriers

Only _____ hormones can diffuse into the target cell

Unbound steroid

Where are steroid hormone receptors typically found?

In the cytoplasm or the nucleus

Infundibulum

The stalk that connects the pituitary to the brain

Where is the pituitary gland located?

Sits inferior to the hypothalamus and is encased by the sphenoid bone

What neurohormones does the posterior pituitary release?

Vasopressin and oxytocin

Anterior pituitary

True endocrine gland of epithelial origin

What types of hormones does the hypothalamus release?

Releasing and inhibiting hormones

Trophic hormones

Are released and stimulate an endocrine gland to release another hormone

Releasing hormones are also...

Trophic hormones - bc they stimulate the anterior pituitary gland to release other hormones