Introduction to Human Physiology - Unit 1 Flashcards by Shirley To

Physiology

Study of the normal functioning of a living organism and its component parts.

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Key concepts and themes in Physiology

-Structure and function
-Biological energy (How does opening of the channel impact the neuron function?)
-Information flow
-Homeostasis

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6 Levels of Organization

-Chemical - atoms and molecules
-Cellular - neuron, lymphocyte
-Tissue - a collection of cells (e.g. connective)
-Organ - structural unit made of tissues (e.g. heart)
-Organ system - integrated group of organs
-Organism - individual form of life (G. Community, Ecosystem, Biosphere)

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Physiology is an Integrative Science

-Physiology considers many different levels of organization
-most questions at the organ level are already answered
-therefore, most current research focuses on the molecular or cellular level
-researchers attempt to understand how events within a single cell influence neighboring cells, tissues, organs, and organ systems

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Tissue Types

Cells in the body assemble into larger units called tissues

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How are cells held together?

By cell junctions, including anchoring junctions, gap junctions, and tight junctions

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Anchoring junctions that are between cells

Desmosomes and Adherens

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Anchoring junctions that hold cells down to the basal lamina

Hemidesmosomes

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What do tight junctions do?

Help with nutrient absorption, control in the cell, and regulation, and keep things from flowing into unwanted places in the body

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What do gap junctions do?

-Allow transfer of information between cells
-direct communication

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Between Cells

The extracellular matrix

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Extracellular matrix is synthesized and secreted by

cells in the tissue

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4 primary tissue types in the human body

-epithelial
-connective
-muscle
-neural

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Nervous tissue Components

Brain, spinal cord, and nerves

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3 Types of Muscle Tissue

Cardiac, Smooth, Skeletal

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Epithelial Tissue can be found

-lining the GI tract organs and other hollow organs
-skin surface (epidermis)

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Connective Tissue Types

-Fat and other soft padding tissue
-bone
-tendon

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Epithelia function

-protect the internal environment of the individual
-regulate the exchange of material between the external environment and internal environment - any material that moves between these two environments must cross an epithelium

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Epithelia consists of

one or more layers of cells connected to one another and to a basal lamina (basement membrane)

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5 types of epithelia

-Exchange
-Ciliated
-Secretory
-Transporting
-Protective

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Epithelia that involves the rapid exchange of material
-In the lungs

Exchange

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Epithelia that involves line airways and female reproductive tract
-in respiratory tract

Ciliated

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Epithelia that synthesize and release products into the external environment
(e.g. mucus membrane in the respiratory tract)

Secretory

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Epithelia that involves the selective transport of material
(e.g. hormones, nutrient absorption, kidney reabsorption)

Transporting

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Epithelia found on the surface of the body (skin)

protective

Squamous epithelium looks like, and can be found in

-thin -blood vessels, alveoli, lungs

Cuboidal epithelium looks like, and can be found in

-cubes -Ducts, glands

Columnar epithelium looks like, and can be found in

-long, column-like -Digestive Tract

Simple Vs. Stratified Epithelium

-Simple is one layer -Stratified is multiple layers stacked

Ciliated Epithelia

Columnar

3 shapes of epithelial cells

-Squamous -Cuboidal -Columnar

Stratified columnar epithelium vs. pseudostratified columnar epithelium

pseudostratified columnar epithelium is ciliated

Connective tissue function

-provides structural support and barriers

Connective tissue has an extensive

extracellular matrix

Extracellular Matrix in the connective tissue contains

proteoglycans, collagen, elastin, fibronectin

5 types of connective tissue

-loose - elastic tissue (tissue underlying the skin) -dense - strength is the primary function (tendons) -adipose - contains adipocytes (e.g. white fat (storage) and brown fat (helps in thermoregulation)) -blood - watery matrix lacking insoluble protein fibers -supporting - dense substances (e.g. cartilage and bone)

Muscle tissue function

Ability to contract to produce force and movement

3 types of muscle

-skeletal -smooth -cardiac

type of muscle responsible for gross body movement

skeletal

type of muscle responsible for influencing the movement of substances into and out of or within the body -e.g. intestine sphincters, are between the esophagus and stomach - outside of organs to prevent things from going from one place to another

smooth

type of muscle found only in the heart, contraction moves blood through the body

cardiac

Neural tissue function

-Carry information from one part of the body to another -There is very little extracellular matrix in neural tissue

2 types of cells in the neural tissue

-neurons - carry information as electrical or chemical signals -glial cells - supporting cells for neurons

Neural cells that carry information as electrical or chemical signals

neurons

Supporting cells for neurons

Glial cells

Function Vs. Mechanism

-Function: the function of a system is the "why" -Mechanism: the process of a system is the "how"

Psychologists study - to understand -

Mechanism, function - how cellular and molecular changes affect the organism as a whole

The central organizing principle of physiology

Homeostasis

Homeostasis?

The maintenance of a relatively stable internal environment

Homeostasis involves a series of

Automatic control mechanisms

What: -maintains a similar condition for all cells of the body -achieved through the effects of different organ systems working together

Homeostasis

Result of homeostatic control

-Oscillation around a set point (can change) -set points can change with time

-Environmentally induced change in physiological function with no genetic change

Acclimatization -e.g. acclimatization to altitude

Failure to maintain - may result in a disease state and disrupt function, as well as lead to pathophysiology

Homeostasis

Example of temperature acclimatization

Body adapts to high or low temperatures to adapt to surroundings. Body shifts to a new set point to adapt to the needs of the body

4 basic mechanisms of cell to cell communication

-gap junctions -contact-dependant signal -local communication -long distance communication

Known as direct cell to cell communication

Gap junctions

Communication between cells via protein channels (connexons) between adjacent cells

Gap junctions

Mechanism of cell communication capable of closing and opening and are found in many cell types like the heart

Gap junction

This type of communication is from the interaction between membrane molecules on two cells

Contact dependant signal

Type of communication found in immune cells and during development

Contact dependant signal

Communication with neighbouring cells

Local communication

Occurs via paracrine and autocrine signals

Local communication

Chemicals secreted by cells which act on neighbouring cells and act on immediate vicinity are known as

Paracrine signals

Chemicals that act on the cell that produces them

Autocrines

Histamine is an example of a

Paracrine signalling molecule - vasodilator

Type of communication that is the responsibility of the nervous and endocrine systems

Long distance communication

Uses combination of chemical and electrical signals -e.g neurohormones and neurotransmitters

Nervous system

Uses chemical signals only and these signals are known as hormones

Endocrine system

Why do some cells respond to a chemical signal and others do not?

-target cells have various receptor proteins -only respond to a chemical signal if they have the appropriate receptor

Receptors are usually which type of protein?

Usually transmembrane proteins or glycoproteins

Where receptors are usually found

Plasma membrane but can be intracellular (cytosolic or nuclear)

3 main domains (regions) of membrane spanning receptors

-extracellular domain -transmembrane domain -intercellular (cytoplasmic) domain

Domain of receptors involved in binding the ligand (chemical signal)

Extra cellular domain

Domain of receptors that is hydrophobic

Transmembrane domain

Domain of receptors involved in activating the cellular response

Intracellular (cytoplasmic) domain

Receptors vs. Chemical signals

-it is the receptor not just the signal that determines the type of response -any molecules that can bind with the receptor and induce activity with elicit the response

Both of these 2 chemical signals illicit the same response when attached to the same type of receptor

Primary ligand and Agonist

Competitive to a ligand or an agonist and stops the response when binded to the receptor

Antagonist

Responses to chemical signals (4 steps)

-signaling molecule binds to a receptor -activated receptor interacts with molecules inside the cell to start a signal -signal is carried to appropriate place in the cell like the nucleus - this is signal transduction -response occurs

Homeostasis can be maintained by both - and - pathways

-local or long-distance -local control or reflex control

What type of control: the effects are exerted on neighboring cells

local control

-e.g. paracrine control of blood vessel diameter in response to low oxygen is an example of

local control

What type of control: the reaction in one or more organs controlled from elsewhere in the body. Can be any long-distance path of the nervous and/or endocrine systems

reflex control

Points of remember on homeostatic control systems (6)

-stability is the result of a balance between input and output -negative feedback returns variable to original condition -homeostatic systems maintain similarity not constancy -setpoints can be reset -some variables are controlled more closely than others -most control systems require communication between cells

-3 types of reflex control -feedback control systems/pathways that control and regulate the response loops

-negative feedback -positive feedback -feedforward control

-Response loops start with a - and result in a -

stimulus, response

results in a change that opposes or removes the signal thus returning the variable to its original state

negative feedback

feedback pathway that allows for homeostatic control

negative feedback

feedback pathway that keeps a system near or at a set point. Results in oscillation around the setpoint. E.g. blood pressure

negative feedback

Put in order: response, control, sensor, effector, stimulus

stimulus, sensor, control, effector, response

Negative feedback control example: Put in order to cool down body: 1. nerve cells in skin and brain 2. sweat glands throughout body 3. increased heat loss 4. body temperature exceeds 37 degrees celsius 5. temperature in regulatory center in the brain

-4, 1, 5, 2, 3

Put in order: -stimulus, integrating center, response, output signal, input signal, sensor, target

-stimulus, sensor, input signal, integrating center, output signal, target, response

Response sends a signal, which reinforces stimulus and sends the variable further from the setpoint until an external signal turns the response off

positive feedback

Feedback control that is not homeostatic and response reinforces the stimulus

positive feedback

feedback control that sense system temporarily out of control. E.g. labour

positive feedback

Anticipatory control: predicts that change is about to happen, starts the response loop, prevent change -e.g. sight, smell or though of food

Feedforward control