A&P Exam 4 Flashcards
5 characteristics of cells
- Irritability (stimulated by environment)
- Growth
- Spontaneous movement
- Metabolism (use food/oxygen to build/repair tissue)
- Reproduction
Cells consist of highly organized masses of __________.
protoplasm
Landmarks of the nucleus
- Endoplasmic reticulum
- Chromatin (DNA & chromosomes)
- Nucleolus & ribosomes
- synthesis of protein
Landmarks of cytoplasm
- Made up of 70-80% water. Incudes:
- Mitochondria
- ATP
- Golgi Apparatus
- Lysosomes
- digestive organ of the cell
- Mitochondria
Intracellular vs. extracellular fluid
- Intracellular: inside the cell
- Extracellular: cells float in this
Mitosis
- Cell division for growth & development
- One cell produces 2 identical, diploid cells
Meiosis
- Cell division for the formation of sperm/eggs
- Produces identical, haploid information
- 1 cell → 4 cells w/ half of the information
Blastocyst & trophoblasts
- Blastocyst: fluid-filled sphere created after successful fertilization (meiosis) and cell division (mitosis).
- forms embryonic tissue
- Trophoblasts: outer layer of cells surrounding inner mass
- attaches to uterine wall & becomes placenta
Endoderm
Inner cell mass of blastocyst begins to differentiate & proliferate to form endoderm early in development.
- layers become yolk sack & amniotic cavity
Yolk sack
Formed from one layer of endodermal cells early in development.
Amniotic cavity
Fluid-filled cavity that develops from inner cell mass cells of endoderm early in development.
Embryonic Disc
Inner cell mass including yolk sac and amniotic cavity early in development.
Primitive streak
Formed from ectodermal cells at the caudal end of the embryonic disc early in development.
Henson’s Node
Formed from layer of mesodermal cells that grow laterally from the primitive streak early in development.
Notochord
Primitive axial skeleton that grows from Henson’s node along the midline axis of the embryo early in development.
Prochordal plate
Found at rostral end of embryonic disc early in development.
Procardiac area
Found at rostral end of embryonic disc early in development.
Neural plate
Thickening of the ectoderm over the neural plate early in development. Lateral margins grow upward to form neural tube, which will develop into the entire CNS.
Flexion
Occurs during week 3. Intraembryonic structures grow rapidly and cannot maintain platelike position, so embryo is thrown in a series of folds.
Cephalic fold
Formed from rapid growth at cephalic end (toward the head) during week 3.
- Prochordal plate (now called buccopharyngeal membrane) folded under embryonic head
- Procardiac area also carried under developing head
3 primary layers of tissue during the flexion stage
- Ectoderm: outermost tissue. Forms epidermis of skin, teeth, nervous system, hair, nails & epithelial tissue
- Mesoderm: forms most of connective tissue
- Endoderm: forms lining of digestive and respiratory tract
Prosencephalon
Forebrain
Stomedium
Primitive mouth. Deepens at week 4 to communicate with foregut.
Branchial arches (general)
- Lateral walls of anterior part of foregut differentiate into bilateral branchial grooves
- As these depressions grow, they meet at the midline and form branchial arches (bumps)
- 4 of the 6 are visible externally:
- mandibular
- hyoid
- third
- fourth
- fifth
Branchial arch 1
Mandibular arch. Forms lower lip, muscles of mastication, mandible, anterior tongue, and some middle ear structures.
Branchial arch 2
Hyoid arch. Forms hyoid bone, stapes, muscles of facial expression.
Branchial arch 3
Third arch. Forms hyoid bone, posterior tongue.
Branchial arches 4 & 5
Fourth/fifth arches. Form cricoid, arytenoid & tracheal cartilages.
Development of face: week 3
- ventral aspect of forebrain develops into frontonasal process
- nasal placodes develop on either side
- give rise to nasal pits that divide frontonasal process into medial & 2 lateral segments
- mandibular arch gives rise to maxillary process on each side
Development of face: week 5
Face divided into 4 primordial areas:
- frontonasal proess: lateral nasal processes grow slower than medial
- maxillary process:
- still can’t be differentiated from mandibular arch.
- Frontonasal & maxillary processes fuse & constrict opening of nasal pits.
- mandibular arch
- hyoid arch
Development of face: week 6
Embryo is 9 mm long
- Eye begins to develop laterally (starts on side & moves to front)
- Medial nasal process narrows & anterior growth begins
- Maxillary & medial nasal processes fuse, creating shelf called primary palate
Development of face: week 7
- Nasal area more prominent
- Eyes move anteriorly
- Not much change in mandible
Development of face: week 8
- Mouth opening narrows, forming cheeks
- Head grows vertically, increasing height of oral cavity
- Palate still incomplete
Primary palate vs. secondary palate
- Primary palate: will develop into upper lip & anterior portion of alveolar ridge
- Secondary palate: remaining hard palate and all of soft palate
Development of palate
- Primary palate fuses in front first.
- Tongue has to drop with growth of mandibular arch before palate can fuse.
- Should be complete by 12 weeks.
Development of tongue
- Arises from branchial arches.
- Base of tongue, apex, & body evident by wk 7.
- Mucous membrane develops first, followed by striated muscle fibers.
Development of respiratory system
- Develops from the pharyngeal pouches which arise from the foregut
- Laryngotracheal groove appears around 4 wks
- deepens & fuses to form laryngeotracheal tube
- lined with endoderm which becomes epithelial tissue
- In wks 8-10, cranial end becomes trachea & larynx; caudal end becomes bronchi & lungs
Development of external ear
- Around wks 8-10
- Formed from 1st & 2nd arches & 1st branchial groove
- EAM from 1st branchial groove
- Final development of EAM & middle ear around 7th month
Neuromuscular junction
Point where neuron and muscle communicate.
Innervation ratio
of muscle fibers innervated by one motor neuron
- muscles used for crude movements will have more muscle fibers innervated by one motor neuron
- muscles used for finer movements will have fewer muscle fibers innervated by one motor neuron.
Motor unit
Array of one motor neuron & its muscle fibers.
Motor endplate
Junction of final motor neuron & muscle fiber.
Muscle Action Potential (MAP)
Action potential from brain that spreads along muscle fiber.
Sarcomere
1 segment of mibrofybril in a striated muscle fiber.
Myofibril & muscle fiber
Muscle fiber is one strand of a striated muscle. Made up of myofibril.
Myosin & Actin
- Myosin: thick filaments of myofibril
- Actin: thin filaments of myofibril
Sliding filament hypothesis
When a motor action potential stimulates the release of calcium, the binding site on the actin is uncovered, and cross-bridges from the myosin swing up and attach to these binding sites. These cross bridges then pull the actin filaments toward the center of the sarcomere (segment of muscle), causing the actin and myosin to slide over one another and the muscle to contract.
Force generation by muscles
When muscle contracts, contractile components shorten & elastic portion stretches
- isometric contraction: muscle tendon is held rigid & tension is built up (holding books)
- isotonic shortening: tendon is released, muscle shortens & load is moved (lifting books)
2 ways to build up muscle force
- A faster firing rate, or a faster rate of action potentials and subsequent contractions.
- Recruitment of more motor units―recruiting additional motor neurons causes a greater number of muscle fibers to contract, resulting in more force generated.
Pyriform sinuses
Spaces formed between the lateral insertion of the inferior constrictor & the lateral walls of the thyroid cartilage.
Esophagus
- empty tube about 20 cm long
- has two layers of muscle - inner and outer
- proximal 1/4 composed of striated muscle
- next 1/4 composed of a mixture of striated and smooth muscle
- distal 1/2 composed of smooth muscle
Role of larynx & trachea during swallow.
During swallowing the larynx moves up and forward to protect the opening to the trachea and keep food or liquid from entering it.
Phase 1 of swallowing: oral prep
- voluntary phase that involves what you do to get the food or liquid into your mouth
- can involve the teeth, tongue, lip, or jaw, depending on the substance being taken in
- influenced by the taste or environment and the individual’s thirst, hunger, or motivation.
Phase 2 of swallowing: oral
- voluntary phase that includes the formation of the bolus and the transport of the bolus through the mouth
- after the bolus is formed it is put on the tongue, which forms a groove by raising the sides of the tongue and tilting it back.
- the lip and buccal muscles contract, the posterior tongue depresses, and the soft palate elevates, all of which push the bolus to the back of the mouth.
Phase 3 of swallowing: pharyngeal
- involuntary phase that involves coordinated movements that propel the bolus into the esophagus
- movements are triggered when the bolus passes through the faucial arches
- lips and velopharyngeal port close, the arytenoids approximate and close the vocal folds, and the epiglottis covers the aditus laryngus to protect the airway
Phase 4 of swallowing: esophageal
- involuntary phase that begins after the bolus enters the esophagus
- peristaltic contractions push the bolus toward the stomach in 8-20 seconds.
- at the bottom, the lower esophageal sphincter relaxes to allow passage of the bolus into the stomach
3 levels of safety for the larynx during swallowing
- epiglottis
- false vocal folds
- true vocal folds
3 biomechanical valves involved in swallowing
- soft palate & superior constrictor to close velopharyngeal port
- laryngeal airway (closed by epiglottis)
- upper esophageal sphincter & cricopharyngeus muscle (opens to allow bolus in)
Dysphagia
Difficulty in swallowing. Caused by:
- neuromuscular/neuromotor disorders
- congenital disorders (e.g., cerebral palsy)
- stroke
- TBI
- head & neck cancer
Aspiration
Food/drink goes past true VFs into airway. Causes aspiration pneumonia.
Swallowing assessment: clinical
- pros: can be done at bedside so the patient does not have to be transported
- cons: the SLP can’t detect silent aspiration or pocketing in the valleculae or pyriform sinuses.
Swallowing assessment: Modified barium swallow
- pros: gives a better view of what is going on
- cons: exposes patient to radiation and requires that they be transported to radiology.
Swallowing assessment: FEES
- pros: gives a clearer view of the airway and is easier to do at bedside
- cons: you lose visual when the velum raises and therefore see only what happens before and after the swallow.
Swallowing assessment: ultrasound
- pros: gives a good idea of timing
- cons: doesn’t give a clear visual (not used often)
