Unit 3 Flashcards by Latisha De'Bose

Two functional types of smooth muscle

Multi-unit

2. Unitary

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True or False:
Multi-unit smooth muscle fibers are independent of other fibers. Each fiber is innervated by its own nerve ending and are insulated by collagen and glycoproteins

True

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What is the type of muscle found in ciliary muscle of the eye, iris, pilo-erector muscles

Multi unit Smooth muscle

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What is the AKA for unitary smooth muscle

Syncytial smooth muscle

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Unitary smooth muscle multiple muscle fibers function as a ___ unit.

Single

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This type of muscle fibers are arranged in sheets or bundles

Unitary smooth muscle

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Membranes interconnected by gap junctions and found in most viscera (gut, blood vessels, uterus, ureters, bile ducts)

Unitary smooth muscle

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What structure is Actin attached to?

Dense bodies

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Adjacent smooth muscle cell’s dense bodies are attached to each other by

Intercellular proteins

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Smooth muscle myosin interspersed amongst the

Actin

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Name the Smooth Muscle Contraction properties

Slow cycling of myosin cross bridges
Force of contraction
Latch mechanism
Stress-relaxation

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Smooth muscle Contraction properties slow cycling of myosin cross bridges. Frequently is much less than ____ muscle and cross bridges ___ for longer time.
Lower energy requirement of smooth muscle problem due to ___ ___ of cross b

Skeletal, hold

Slow cycling

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Contraction properties:

Lower energy requirement of smooth muscle due to

Slow cycling of cross bridges

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contraction properties: Smooth muscles ______ of contraction is as much or greater than _______ muscle

Force

Skeletal

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Developed tension, cross-bridges are maintained for a period of time with ______. This is a ________ way to maintain tone.

Name this mechanism

Little additional energy
Energy efficient

Latch mechanism

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Stress-relaxation is a response seen principally in

visceral unitary muscle

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This type of contraction property response is principally seen visceral unitary muscle (gut, blood vessels, uterus, ureters, bile ducts).

Stress-relations

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Smooth muscle exhibits a phenomenon called

Stress-relaxation

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Smooth muscles responds to stretch only _____, then adapts to its new length.
New length retains ability to ______; which enables organs like the ____ & ____ to temporarily store contents.

Briefly
Contract
Stomach and bladder

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Contraction mechanism:
Stimulus causes increase in \_\_\_
Ca binds to \_\_\_
Ca/Calmodulin binds to &amp; activates \_\_\_
Myosin is capable of binding to \_\_\_

Intracellular Ca
Calmodulin
Myosin light chain kinase (MLCK)
Actin

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The myosin kinase _____ is the light chains of the _______ heads.

Phosphorylates

Myosin

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Relaxation mechanism: Contraction is stopped by ______ ______

Myosin phosphatase

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Adding phosphate to myosin

Actives it for muscle contraction

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Ca+2 Sources for muscle contraction
Almost all from _______
Poorly developed in smooth muscle _____
Rudimentary ______

Cell membrane, channels, ECF
Sarcoplasmic Recticulum
T-tubules called caveolae

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Control of contraction

Smooth muscle can be stimulated by the Nervous system, hormones, local tissue factors and stretch

Autonomic fibers end in varicosities making _______ neuromuscular junctions. Nerve endings are closer to ______ smooth muscle cells as compared to visceral muscle. Typical neurotransmitters are _____ and _____

Diffuse Multi-unit Ach, NE

Hormonal effects on smooth muscle stimulated by

Nervous system Hormones Local tissue factors Stretch

Hormones can cause ______ or ______ based on the receptor type they bind to. Some receptors are themselves ion channels that cause _____ or _____ depending on which ion the are specific to. Some use 2nd messenger systems such as _____.

Contraction, dilation Depolarization, hyperpolarization -cAMP

Smooth muscle naturally maintain ____ in arterioles, metarterioles & pre-capillary sphincters

Tone

local tissue chemical factors: Vasodilation results from

``` Lack O2 Increased CO2 H+ Lactic acid Adenosine Increased body temp ```

Muscle stretch _____ the negativity of smooth muscle membrane _____ leading to more ______ at the _____ of slow waves.

Reduces Potential Depolarization Peaks

Depolarization of multi-unit smooth muscle

No true action potentials (AP) occur Cells - individually innervated 2 small for AP Depolarizations = “junctional potentials”

_______ channels more responsible for action potentials than ______.

V-gated Ca+2 | Na+2

Action potential patterns

Spike potentials Slow-waves with spike potentials Action potentials with plateaus

Slow waves means ______ fluctuations in membrane potentials. Slow waves are _______

“Pacemaker-like” | spontaneous

Smooth muscle spike potential elicited by

External stimulus

Slow waves with spike potentials from

Intestinal smooth muscle

Action potential with plateau from

Uterus or ureter

Electrical activity of Gastrointestinal smooth muscle: | Depolarizing factors-

Stretching Acetylcholine/parasympathetic Gastrointestinal hormones

Electrical activity of Gastrointestinal smooth muscle: | Hyperpolarizing factors-

Norepinephrine/epinephrine/sympathetics

membrane potential (hyperpolarization) Stimulated by

Norepinephrine | Sympathetics

Spikes stimulated by

Stretch Acetylcholine Parasympathetics

membrane potential Slow waves

Resting

Principles of GI physiology | Propulsion

Food through GI tract

principles of GI physiology | Secretion

Digestive juices

Principles of GI physiology | Digestion

Chemical and mechanical digestion

Principles of GI physiology | Absorption

Digestive products

Principles of GI physiology | Circulation

Blood through the GI tract to circulate absorbed digestive products

Local, nervous, and hormonal __________ propulsion, secretion, digestion, absorption and circulation functions.

Control

Histology of GI tract wall | most external/exterior/outside part is called

Serosa

Histology: | Adventitious layer=Serosa

Loose areolar CT with Blood vessels Lymph vessels or Adipose tissue

GI Histology: Longitudinal smooth muscle Can be found in what organs? Muscularis externa Muscularis mucosa

Esophagus, stomach, jejunoileum and large intestine Made up of an inner circular and outer longitudinal layer of smooth muscle Longitudinal smooth muscle with electric fibers

GI Histology Circular smooth muscle Found in which organs?

Stomach: in muscularis mucosa inner layer | Large intestine: in muscularis Externa, complete layer circular + incomplete longitudinal layer = forms Tania Coli

GI tract Histology Submucosa Submucosal meissner’s located in the and is the ________

Dense CT made of collagen, elastic & reticular fibers Submucosa, Nerve plexus

Propulsion

Of food through the GI tract

Secretion

Of digestive juices

Propulsion is broken down into two parts. What are they?

Swallowing (oropharynx) Peristalsis (esophagus, stomach, small intestine, large intestine)

Mechanical digestion

Chewing (mouth) Churning (stomach) Segmentation (small intestine)

Absorption

Nutrients and water to blood vessels & lymph vessels (small intestine) Water to blood vessels (large intestine)

Digestion:

Chemical and mechanical digestion

Absorption

Of digestive products

Circulation

Of the blood through the GI tract ( to circulate absorbed digestive products)

Order of GI tract

``` Mouth Esophagus Stomach Duodenum Jejunum Ileum Ascending Colon Transverse Colon Descending Colon Anus ```

Accessory organs

Salivary glands Pancreas Liver, gallbladder

This is also known as the “Brain of the Gut”

Enteric Nervous system

Name the two plexi for Enteric nervous system has

Myenteric | Submucosal

Myenteric plexus is defined as

Between the longitudinal and circular muscle layers

Submucosal plexus is defined as

Within the submucosa

Myenteric nerve plexus, Meissner’s nerve plexus and submucosal glands are located within the

Submucosal layer

Myenteric ganglia is within which layer?

Muscularis externa

Muscularis contains

Circular & longitudinal muscle

Mucosa contains what?

Epithelium Lamina propria Muscularis mucosae

What does MALT stand for (mean)?

Mucosa-associated lymphatic tissue

Ducts of glands are outside tract of

Pancreas

What is contained within the serosa?

Areolar connective tissue | Epithelium

Characteristics of the myenteric plexus

Mostly responsible for GI movement | Made of linear chain of interconnecting neurons, extends the GI tract

Excitation increases

Tonic (tone) contractions Intensity of rhythmic contractions Velocity of wave conduction Release of vasoactive intestinal polypeptide (which relaxes pyloric and ileocecal sphincters)

Submucosal plexus function

Control local intestinal secretion & absorption | Controls local contraction of submucosal muscles (unfolding of the mucosa)

Parasympathetic Innervation: | Cranial parasympathetic N. (Mainly Vagus)

Esophagus, 1st half of Lg intestine | Pancreas

Parasympathetic Innervation: | Sacral parasympathetic N (pelvic N.)

Distal Lg intestine, anus

Parasympathetic Innervation | Postganglionic parasympathetic neurons and _____ are within the _____ _____.

Ganglia | Enteric plexus

Parasympathetic Innervation: | _____is largely _____ to the GI tract

Acetylcholine | Excitatory

Parasympathetic Innervation: | Vagus N. Innervates

``` Esophagus Stomach Duodenum Small intestine Ilium ```

Parasympathetic Innervation: | Pelvic N. Innervates

Defending colon | Sigmoid

Sympathetic innervation: | _______ Neurons to the GI tract originate from T5-L2.

Preganglionic

Sympathetic innervation: | _____ neurons originate from the prevertebral ganglia.

Postganglionic

Sympathetic innervation: Norepinephrine _____ intestinal tract smooth muscle mainly via the enteric plexus (except the _____ mucosa which it excites).

Inhibits | Muscularis

Sympathetic system is mainly

Postganglionic

Parasympathetic system is

Preganglionic

Only sympathetic innervates

Epithelium

Afferents from the Gut: Sensory fibers from the gut | Feedback to the ____ ____ for local control

Enteric plexus

Afferents from the Gut: Sensory fibers from the gut | To the prevertebral ganglia, cord and brain stem to ____ ____ ____.

Mediate broader reflexes

Afferents from the Gut: Sensory fibers from the gut | ____ of Nerve limbers in the ______ nerves are _______

80% Vagus Sensory

Afferents from the Gut: Sensory fibers from the gut | Afferents are sensitive to what 3 things?

Irritation of the mucosa Distinction of the gut Chemicals in the gut

GI Reflexes: The 3 types of GI reflexes include

Enteric reflexes Automatic reflexes Higher level reflexes

GI Reflexes: The 3 types of GI reflexes include Enteric reflexes are ____ within the ____ wall ____ nervous system. Control local gastrointestinal _____, ____, _____, and local ____ effects.

Entirely, Gut, Enteric | Secretions, peristalsis, mixing, inhibitory

GI Reflexes: The 3 types of GI reflexes include | Autonomic reflexes _____ signals originate in the ____, prevertebral ganglia, then ____ back to the gut.

Sensory, gut, motor

GI Reflexes: The 3 types of GI reflexes include Example of Autonomic reflexes Gastronomic reflex-

Promotes evacuation of colon

GI Reflexes: The 3 types of GI reflexes include Examples of Autonomic reflexes Enterogastric reflex-

Inhibits stomach motility and secretions

GI Reflexes: The 3 types of GI reflexes include Examples of Autonomic reflexes Colonoileal reflex-

Inhibits emptying of ideal contents into the colon

Movements of the Colon: | Longitudinal layer of muscles are clustered in ___ bands called ____ ____.

3 | Teniae coli

Movements of the Colon: | 3 bands of longitudinal layers is an arrangement forms _______.

Haustrations

Movements of the Colon: Repeating haustrations cause movement of _____ to improve ___ & ___ absorption.

Feces Water Electrolyte

How long does it take material to transverse the colon?

8-15 hours to trav

___ motility causes _____ absorption, and hard ____ in transverse colon cause ____.

Poor Greater Feces Constipation

____ motility causes less ____ and ____ (loose feces)

Excess Absorption Diarrhea

Mass movements Occurs a few times a day, contractile ring forms at ___ point, then ____ to that the colon ____ as a unit, flattening the ___.

One Distal Contracts Haustrations

Mass movements: | The effect is to move ____ ____ in bulk.

Fecal material in bulk

Mass movements of colon: | When ___ moves into rectum, the desire to ____ is felt.

Feces | Defecate

Food residue is also called

Feces

Defecation: | Rectum is normally ____. It is a weak ____ between the ___ colon and the ____.

Empty Sphincter Sigmoid Rectum

Defecation: | Mass movements ___ feces past sigmoid colon and rectum. These are called what?

Push Internal anal sphincter External anal sphincter

Internal anal sphincter is controlled by ____ and ____ reflexes as peristaltic waves reach it.

Myenteric | Parasympathetic

External anal sphincter is a ____ control; innervated by ____.

Voluntary | Pudendal N.

List Types of Glands

Goblet (mucus) cells Pits (crypts of Lieberkuhn in small intestine) Tubular and complex glands

Goblet (mucus) cells ◦ ___ celled gland located in GI tract. ◦ ___ mucus directly into lumen as a protective lubricant from physical and chemical damage. ◦ Respond to local ___ ___

◦ Single ◦ Secrete ◦ Mucosal irritation

Goblet cells have these fingerlike projections.

Microvilli

This part of the goblet cell contains mucin

Secretory vesicles

Define the following type of gland: Pits AKA They contain

crypts of Lieberkühn in the small intestine Secretory cells

Intro to GI Hormones: Gastrin is secreted by ___ cells of the stomach. It stimulates ___ acid secretion and gastric ____ growth.

“G” Gastric Mucosal

Intro to GI hormones: Cholecystokinin (CCK) Is secreted by by “_” cells of the ____ mucosa. It stimulates ___ ___ contraction, ____ gastric emptying, and ___ appetite

``` “I” Duodenum Gall bladder Slows Inhibits ```

Intro to GI hormones: Secretin is secreted by “_” cells of the duodenum mucosa. It stimulates ___ secretion of ____, and some effect on GI motility.

S Pancreatic Bicarbonate

Intro to GI hormones: Gastric inhibitory peptide (GIP) Is also known as __________

Glucose-dependent insulinotropic peptide

Intro to GI hormones: Gastric inhibitory peptide (GIP) aka glucose-dependent insulinotropic peptide Is secreted by mucosa of the upper ____ ____. It also stimulates ___ secretion, and ____ stomach motility.

Small intestine Insulin Decreases

Intro to GI hormones: | Motilin is secreted by the ____ and ____ duodenum during fasting. Increases ____ motility “___ ___”

Stomach Upper Gastrointestinal “Growling stomach”

What type of GI movement is described as propulsive movement is ___.

Peristalsis

Propulsive Movements – Peristalsis ◦ Contractile ring progresses along ___ propelling contents ◦ Generally stimulated by ____, also by ___ and ___ to the epithelium ◦ Requires the ___ plexus ◦ Always moves toward the anus.

Tube Distention Parasympathetics and irritation Myenteric

Peristalsis is towards a ___ sphincter causes a ___ effect. Local intermittent constrictive contractions create a ___ or ___ effect.

Closed, churning | Chopping or shearing

Splanchnic circulation: | Blood supply to the stomach is ___. Arterial supplies are ___, Superior and inferior ___ arteries.

Causally Celiac Mesenteric

The following are branches of the inferior mesenteric artery

L. Colic a. - transverse colon, descending colon, sigmoid colon Sigmoid a.- sigmoid colon Sup. Rectal a. - sup. Part of rectum

``` Valvulae conniventes (folds of Kerckring) Villi Microvilli (brush border) Is found where in ```

Absorptive Gut

What mechanism is a tension cross bridge which creates an efficient way to maintain tone?

Latch

This type of smooth muscle is found in most viscera (gut, blood vessels, uterus, bile ducts)

Unitary smooth muscle