Physiology 1 Final Flashcards
What are the three types of muscle tissue
Skeletal, smooth, and cardiac
Functions of muscle
Movement, Stabilization, Thermogenesis
General Characteristics of muscle
Irritability, Contractility, Extensibility, and Elasticity. Composed of elongated cells
Voluntary or Striated muscle is aka
Skeletal M.
Where is skeletal m. located
Somatic/skeletal m., upper esophagus, diaphragm
Origin of the skeletal m. cells
Long, multinucleated, and come from the fusion of numerous myoblasts
Dense connective tissue surrounding m.
Epimysium
Bundles of m. cells
Fascicles
What dense connective tissue covers fasicles
Perimysium
What make up fascicles
M. cells/”fibers”
What covers the m. cells/”fibers”
Endomysium (made of basal lamina)
What occurs at the myotendinous junction
Endo, peri, and epimysium become continuous with m. tendon which attaches the m. to bone
What is a sarcolemma
Cell membrane of a m. fiber
Location of Transverse (T) Tubules
Continuous with sarcolemma, and extend to interior of fiber surrounding myofibrils
What is the Sarcoplasmic Reticulum
Specialized ER that forms a tubular network around the myofibrils
What are Cisternae
Large Chamers of SR around myofibril on either side of T tubule. STORES CA++ ions
What is a Triad
Unit of T Tubule and flanking cisternae encircling a myofibril
What is a Myofibril
Micro(Myo)filaments arranged into sarcomeres
What makes up thin filaments
Contractile protein Actin
Regulatory proteins found with thin filaments
Troponin and Tropomyosin
What structural protein attaches the thin filament to the Z disc
Nebulin
What primarily makes up thick filaments
The protein Myosin
What structural protein attaches thick filaments to Z disc and M line
Titin
What structural protein makes up the M line
Myomesin
What is Dystrophin, and what does it do
Structural protein that connects thin filaments to the sarcolemma to transmit m. tension to m. tendon
What is the sarcomere
Functional unit of a m. contraction
What makes up the A band
Dark band, primarily thick filaments
Where is the M line located
Center of the A band
Where is the H zone
Lighter zone on either side of M line. ONLY HAS THICK FILAMENTS
What is the zone of overlap
Overlapping zone of thin and thick filaments
What makes up the I band
Light band, ENTIRELY THIN FILAMENTS
What is the Z disc/line
Boundary between 2 sarcomeres
What makes up the Z disc/line
Structural protein Alpha-Actinin which holds thick and thin filaments in place
When the sarcolemma is stimulated by signals from the nervous system, what happens
Generates an AP (electrical impulse) which travels down the sarcolemma
How does the AP get to the myofibrils
Through the T tubules
What does an AP trigger
The release of Ca++ ions from the cisternae
What do the Ca++ ions cause
Exposure of binding sites on the Actin molecules of thin filaments
What does Ca++ bind to
Troponin. Causes Tropomyosin to move away and uncover binding sites
Myosin binding to Actin and causes what to happen
Thin filaments to slide past thick filaments toward M line. ie: Contraction of m. fiber
Before contraction of sarcomere begins, adenosine triphosphate (ATP) binds to the myosin head and immediately hydrolyzes into what
ADP, phosphate group (Pi), and stored energy
What causes the release of the Pi
Mysoin heads binding to an actin molecule on thin filament
What does the release of Pi initiate
The “Power Stroke”. Pulls thin filament toward center of sarcomere
What happens at the end of the power stroke
ADP molecule is released from the myosin head
What causes the myosin head to detach from the Actin molecule post contraction
Another ATP molecule
How often do the steps of a m. traction occur
Until there is either no more Ca++, ATP, or sarcomere is maximally shortened
What causes Rigor Mortis
Permanent cross-bridging between actin and myosin because there is no ATP available to break the bond
What are the energy sources for skeletal m. contraction
Creatine phosphate stored in m. (anaerobic), Glycolysis of glycogen stored within the muscle and in the liver (anaerobic), and Oxidativemetabolism of lipids, carbohydrates, and proteins(aerobic)
Phase 1 of Energy Utilization
Creatine Phosphate and glycogen (Anaerobic)
Phase 2 of Energy Utilization
Breakdown of FAs, Carbs, and proteins (Aerobic)
Phase 3 of Energy Utilization
Return to glycolysis of remaining glycogen (Anaerobic)
Muscle Spindles
In m. belly, monitors changes in m. length
Structure of M. Spindles
Intrafusal fibers enclosed in a connective tissue capsule. Contains Nuclear bag and chain fibers
Ratio of Nuclear Bag to Nuclear Chain fibers
2:1 ratio of Chain to Bag fibers
Sensory N. fibers have what 2 types of endings
Primary and Secondary
What are Primary sensory n. endings
Type Ia and wrapped around center of both bag and chain fibers
What are Secondary sensory n. endings
Type II and wrapped around ONLY CHAIN fibers
What do Gamma-Dynamic motor nerves innervate
Primarily Bag intrafusal fibers
What do Gamma-Static motor nerves innervate
Primarily Chain intrafusal fibers
Slow prolonged stretch “Static” response
Primary and Secondary sensory endings fire continuously and in proportion to degree of stretch. Gamma-static motor fire proportionate to inc or dec in stretch
Sudden stretch “Dynamic” response
Primary fire only while length is changing. Gamma-dynamic fire maintaining spindle fiber length proportions, and thereby maintaining receptor sensitivity
What is the Tendon organ (GTO)
Stretch receptor located at the myotendinous junction
How do GTOs work
Small bundle of tendon collagen fibers surrounded by a connective tissue sheath, one end connected to muscle fibers, the other end merging into the tendon
What kind of fiber wraps around the collagen fibers of the GTO
A single type Ib sensory fiber
When/Why does the GTO fire
In response to tension on the organ. Can be either contraction or stretch
T/F: The Tendon organ/GTO has both dynamic and static response levels
True
What kind of reflex is the muscle stretch reflex
Mono-synaptic, 2 neuron pathway
First half of Reflex Cycle (M. Stretch)
Stretch leads to primary sensory activated “dynamic response”. AP to spinal cord direct synapse with alpha motor neurons associated with homonymous m.
Second Half of Reflex Cycle (M. Stretch)
Alpha motor neurons of homonymous m. cause m. to contract decreasing the stretch on the m. returning the m. spindles to original length and returns firing rate of primary sensory fibers to baseline “static” levels
During the reflex cycle, what motor commands are sent from the spinal cord
Contract synergistic m. AND relax antagonistic m.
What does the stretch reflex also allow
During voluntary m. contraction, prevents antagonistic m. from contracting. Stabilize posture, and make m. action smooth
What kind of reflex it the Golgi Tendon reflex
Di-synaptic, 3 neuron pathway
First half of Reflex Cycle (Golgi Tendon)
M. contracts, shorten extrafusal fibers and inc tension on GTOs, activating type Ib sensory afferent fibers;action potentials to spinal cord, synapse directly with inhibitory interneurons; they synapse with alpha motor neurons of the homonymous muscle
Second half of Reflex Cycle (Golgi Tendon)
Alpha motor neurons of homonymous m. inhibited from firing. leads to relaxing of homonymous m.
What does the GTO reflex also allow
Relax synergistic m. and contract antagonistic m.
Functions of GTO
Prevent too much tension in m. protecting it from damage. also equalizes contraction strength of m. fibers w/in a m.
What is the flexor-withdrawal reflex
Stimulation of a body part causes contraction of flexor m. Withdrawing body part away from stimulus
What spreads the flexor-withdrawal reflex to other associated m.
Diverging Neural Circuits
What inhibits contraction of associated antagonist m.
Reciprocal inhibition
Diverging Neural Circuits produce an after discharge which does what
Prolongs the contraction of the flexor m. after the stimulus has stopped
What is the Crossed-extensor reflex
Ext. of contralateral limb .2-.5 sec after start of flexor-withdrawal reflex. Initial stimulus is moderate or strong
What do the cells in Cardiac m. tissue look like
Short and branched with a single nucleus. Striated with actin and myosin arranged into sarcomeres.
What is larger and more plentiful in cardiac m. than it is in skeletal m.
Mitochondria
What are larger (in diameter) and more numerous in cardiac m. than they are in skeletal m.
Transverse Tubules
What is less well developed in cardiac m. than it is in skeletal m.
Sarcoplasmic Reticulum
What are the sources of Ca++ during cell contraction
Extracellular Fluid (via T tubules and diffuse across cell membrane to interior) and Released from Cisternae of the SR
What do cardiac cells originate from
A Single myoblast
How are cells interconnected to each other
Intercalated discs
What do Intercalated discs consist of
Numerous adherent and gap junctions
What do Desmosomes do
Keep the cells from pulling apart as they contract
What do Gap junctions act as
Electrical Synapses passing the contraction signal directly from one cell to all the others within the interconnected network
How are the cells in the L/R atria and L/R ventricles connected
Atria are interconnected into single network and Ventricles are interconnected into a single network
What is Functional Syncytium
All the cells within each network contract simultaneously as if they were a single cell
What is the structure of smooth m.
Short and fusiform (spindle) with a single centrally located nucleus
What is different about smooth m. cells compared to skeletal and cardiac cells
Cells are not striated and actin and myosin are arranged differently
Membrane Dense Bodies
Some bonded to membrane dense bodies of adjacent cells
What are attached to dense bodies in smooth m.
Actin/thin filaments
What is different about actin and Ca++ binding in smooth m.
Actin lacks troponin, Ca++ binds to regulatory protein Calmodulin of myosin filaments
What are intermediate filaments in smooth m.
Structural proteins forming a framework for the actin and myosin filaments
What is different about Sidepolar cross-bridges in smooth m.
Myosin heads on one side bend in one direction, while heads on opp. side hinge/bend in the opp. direction
What kind of contraction occurs due to Sidepolar cross-bridges
Spiral, Corkscrew-like contraction
What is different about the SR in smooth m.
Sparse and no T Tubules
Where does the Ca++ come from in smooth m.
Little in SR, Most from extracellular fluid, and enters via calcium channels in sarcolemma
Other names for Visceral smooth m.
Unitary, Syncytial, Single-unit
How are cells arranged in Visceral smooth m.
Single sheet interconnected via gap junctions which all contract simultaneously. Can transmit APs
Where is Visceral smooth m. typically found
Hollow organs. (stomach, intestines, uterus, bile duct, bladder, blood vessels)
Most organs have 2 layers of m. running in what 2 directions
Longitudinally and transversely
The stomach has a 3rd layer that runs in what direction
Obliquely
How is multi-unit smooth m. composed
Individual smooth m. cells unconnected to nearby cells
Characteristics of multi-unit smooth m. cells
Thin collagen & glycoprotein membrane for insulation, own innervation, and found in iris constrictors/dialtors, arrector pili, pulmonary air passages, and walls of largest arteries
Smooth m. cell contraction process
Ca++ enters and binds to calmdulin, this binds to MLCK which phosphorylates one of light chains within a mysoin head allowing it to bind to actin.
T/F: Myosin-actin cross-bridge cycle in smooth m. cell contractoin is slower that in skeletal m.
True
MLCK is de-phosphorylated by what
Action of Myosin phosphatase
Why is the cycle slower in smooth m.
Ca++ channels open slower, and stay open longer. slow removal of Ca++ by Ca++ pumps
Because the cycle is slower in smooth m. what does it allow for
Prolonged m. tone w/o excessive energy expenditure
What regulates smooth m. contraction
Nervous, Hormonal, M. cell stretch, and Nearby chemical environment of m. cell
The skin is aka
The integument, an organ within the integumentary system
What makes up the integumentary system
Skin and accessory organs (nails, hair, glands, sensory receptors)
Functions of the integumentary system
Protection, Regulates body temp, Houses sensory receptors, Vit D synthesis, and Excrete waste materials via perspiration
How does the integumentary system regulate body temps
Retains via subcutaneous layer, and eliminates via radiation (dilate blood vessels), convection and conduction, and evaporation of perspiration`
What is the most superficial layer of the skin
Epidermis
What makes up the Epidermis
Keratinized stratified squamous epithelium
What 4 types of cells make up the Keratinized stratified squamous epithelium
Keratinocytes, Melanocytes, Dendritic cells, and Merkel cells
What are keratinocytes
Predominate cell type of Keratinized stratified squamous epithelium. Manufacture keratin
What is Keratin
Structural protein which toughens and waterproofs the surface of the epidermis
What do melanocytes do
Manufacture melanin, a brown-pigment
What are Dendritic cells (Langerhans, histocytes) do
Immune cells
What are Merkel cells (aka discs)
Type I tactile mechanoreceptors
Histologically, how many layers make up the Epidermis
Thin skin (4) vs. Thick skin (5)
What is the deepest layer of the Epidermis, and is highly mitotic
Stratum Basale
What layer of the Epidermis is mitotic only in its deeper layers and begins the synthesis of keratin
Stratum spinosum
What is the Stratum Germinativum and Function
The Stratum basale + Stratum Spinosum. Primary site of cholecalciferol manufacture
What layer of the Epidermis is composed of flattened cells, filled up with keratin
Stratum Granulosum
What layer of the Epidermis is present only in thick skin (palms and soles)
Stratum Lucidum
What layer of the Epidermis is 20-30 layers of flattened keratinized dead cells
Stratum Corneum
Characteristics of the Dermis
Connective tissue housing m. fibers, blood vessels, hair follicles, exocrine glands, and nerve fibers
What are the 2 layers of the Dermis
Papillary layer and Reticular layer
Where is the Papillary layer located and what is it made of
Loose connective tissue directly underlying the epidermis.
What causes dermal ridges
(Finger and toe prints) Pulling of elastic fibers in the papillary layer
Where is the Reticular layer located, and what is it made of
Dense irregular connective tissue underlying the papillary layer
What is significant about the reticular layer
Quite distensible and resilient. When over-stretched it tears producing striae distensae “stretch marks”
What is the Subcutaneous layer aka
Hypodermis or superficial fascia
Although not officially part of the skin, what is the Subcutaneous layer made up of
Adipose, loose connective tissue, and blood vessels
Function of Adipose tissue in Subcutaneous layer
Heat insulator and energy resevoir. Conserves internal body hear or impedes entrance of external heat. Also binds skin to underlying structures
How much thicker generally is body fat in women than in men
8% thicker
Thickness of the subcutaneous layer can be indicative of what
Nutritional Status
Cause of Pink skin color
Blood flow in dermis and subcutaneous layers
Cause of Yellow skin color
Carotene and having a thicker stratum corneum with increased amounts of structural protein keratin. East Asia
What is Carotene
Yellowish pigment acquired through diet
Cause of Brown Skin color
Due to melanin, a brown-black pigment produced by melanocytes in stratum basale
What are human skin color differences primarily due to
Amount of melanin produced and its distribution. Everybody has approx. same number of melanocytes
What are freckles
Small, isolated patches of highly concentrated melanin secretion
Geographical distribution of skin colors
Darkest in areas with greatest amount of sunlight. Lightest in areas with least amount of sunlight
How does dark skin help
They protect against cell damage due to excessive UV radiation
How does melanin help with UV light
It absorbs UV radiation and prevents excessive amounts from reaching the mitotic cells of stratum germinativum and dermis
What else can help prevent excessive UVR from reaching the lower mitotic cell layers
Thicker stratum corneum
How does tanning work
Melanocytes respond to increased amounts of UVR by producing more melanin
Light skin tones and Vit. D
Allow for the synthesis of Vit. D
What will happen to darker skin tones in areas of lower UVR exposure
Decreased production of Vit. D
What is Vit. D needed for
Proper bone growth and maintenance. Rickets in kids and Osteomalacia in adults
T/F: Lighter skin is more susceptible to damage by extreme cold than dark skin
FALSE Dark skin is more susceptible
These structures reside in the dermis and subcutaneous layer, but originate from epidermal tissue
Hair and the hair follicle
What is a follicle
Tube-like structure which protrudes down into the dermis, houses an individual hair
3 Parts of the hair
Bulb, Root, and Shaft
What is the bulb
Zone of actively dividing cells at the base of the hair
What is the root
Column of flattened, dead keratinized cells within the follicle
What is the shaft
Column of flattened, dead keratinized cells external to the skin’s surface
What makes up the root and shaft of hair
Medulla, cortex, and outer cuticle
Goosebumps are caused by these smooth m.
Arrector pili m.
What does the arrector pili m. attach to
Hair follicle surface and the dermis
High concentration of melanin in hair
Dark hair
Moderate concentration of melanin in hair
Light brown
Little concentration of melanin in hair
Blonde hair
No melanin concentration of melanin in hair
White hair
Mix of pigmented and unpigmented hairs
Gray hair
Red coloration of hair
Pigment contains iron
How is texture of hair determined
Shape and size of hair follicle
What is the function of hair
Protection and identification
Most human hair is…
Short, fine, and faintly pigmented. Dense is scalp, face, axilla and pubic areas
In adults, men are more likely than women to have noticeable hair on…
Back, abdomen, chest, limbs, and face
Those of European descent are the hairiest aka
Hirsute
Thos of East Asian and Amerinidians are the least hairy aka
Glabrous
What makes up the Nail plate
Modified hardened stratum corneum, divisible into nail root, nail body, and free edge
What makes up the Nail bed
Underlying nail plate. Continuous with stratum basale and stratum spinosum of surrounding epidermis
What makes up the Lunula
Part of nail plate, light half-moon region at the proximal end of the nail plate, coloration due to extreme thickness of underlying nail bed
Function of nails
Protection and facilitation of digital dexterity
Glands of the integumentary of what kind of glands in function and structure
Exocrine
Sebaceous Gland
Branched and acinar/alveolar in shape. connected to hair follicle. Holocrine secretion (sebum), which lubricates and waterproofs hair and stratum corneum
Overproduction of sebum may lead to what
Clogged sebaceous ducts, leading to acne
Apocrine gland
Tubular in shape and connected to hair follicle. Sudoriferous (sweat) glands concentrated in axillary and pubic regions
What does the Apocrine gland produce
An odoriferous merocrine secretion in response to emotonial stress.
Eccrine gland
Sudoriferous (sweat) gland found all over body esp. in forehead, back, palms, and soles. Tubular and exit directly onto the surface of the skin
What does the Eccrine gland produce
A thin merocrine secretion
The thin merocrine secretion functions
Evaporative cooling of the body and elimination of some chemical wastes (lactic and uric acid)
Corpuscle of touch aka
Meissner’s corpuscle, tactile corpuscle. located in dermal papillae, discriminate touch
Hair root plexus
Sensory nerve endings wrapped around the base of the hair follicle, discriminate touch
Merkel cell/disc
Type 1 mechanoreceptor located in the stratum basale. discriminate touch
Ruffini’s endings/corpuscles
Type II mechanoreceptor located deep in the dermis. NON-discriminate touch (crude touch)
Pacinian Corpuscles
Pressure: lamellated, responds to sustained pressure. deep in dermis and subcutaneous layer
Thermal receptors
Free nerve endings responding to hot or cold. located in epidermis
Nociceptors
Pain receptors. free nerve endings, responding to tissue trauma or extreme tissue deformation. located in epidermis
Healing of wounds involving just the epidermis
Greater mitotic activity in the stratum basale and stratum spinosum
Deep wounds causing rupture of blood vessels within the dermis and subcutaneous layer
Will result in bleeding. blood platelets and fibrinogen protein form a clot which stops bleeding. scab forms
What may be seen as a sign of damaged cells and foreign microorganisms are destroyed by immune cells
Inflammation
What binds wound edges together within the dermis
Fibroblasts form collagen fibers
When does the scab slough off
When healing is nearly complete
First degree burn
Superficial partial-thickness. only epidermis. warm and reddened. possible peeling
Second degree burn
Deep partial-thickness. epidermis and dermis. skin blisters and healing process will involve epithelial cells from the accessory organs within the damaged area
Third degree burn
Destroys epidermis, dermis, and accessory organs. epithelial healing can occur only at margins of injury
Fourth degree burn
Destruction of epidermis, dermis, and subcutaneous layer. epithelial healing only at margins
Benign neoplasm
Non life threatening
Mole aka nevus
Benign abnormal growth of melanocytes
Wart aka verruca
abnormal growth of skin tissue caused by viral infection
Malignant
Life threatening
Cutaneous carcinoma
Long-term exposure to UVR. Malignant. can be divisible into basal cell carcinoma and squamous cell carcinoma
Cutaneous melanoma
Due to short but intense exposure to UVR. HIGHLY Malignant.
ABCD rule
Asymmetry, Border, Color, Diameter, Evolution
What can the integumentary system indicate clinically
Dietary deficiencies, Heavy metal exposure, Allergic rxns, and specific diseases
Results of aging on the Integumentary system
Loss of elasticity in the dermis
Decrease in amount of adipose tissue in subcutaneous layer
Decreased activity of hair follicles and exocrine glands (especially, eccrine and sebaceous glands)
Changesin pigmentation (of skin andhair)
Increase in number of moles
