Anatomy Test 3 Flashcards
5 special senses (and cranial nerves)
olfaction, taste, vision, hearing, equilibrium and balance
Olfactory Pathway
- odors are sensed by olfactory receptors (at the nasal mucosa), whose axons pass through cribiform plate of ethmoid bone, forming CN I called olfactory nerve
- CN I synapse on neurons in the olfactory bulb whose axons from olfactory tract, which send info to the olfactory in the____
Gustatory Pathway (1)
- taste buds: on the dorsal surface (top) of tongue
- taste receptors: clustered deep in the grooves of taste buds
- there are 6 primary taste sensations: sweet, salty, sour, bitter, umami, water
- when swallowing thats when you will taste water
Umami
characteristic of chicken broths and parmesan cheese (one of the 6 primary taste sensations)
Gustatory Pathway
Taste-> taste Rs-> CNs-> (medulla)-> Gustatory cortex
- CNs: facial N (CN VII): anterior 2/3 tongue
- Glossopharyngeal (CN IX): posterior 1/3 tongue
-taste and smell are linked together because they share the same orphis
Three layers of the Eyeball (1) outer layer
Outer layer: dense C.T. layer
- The Sclera: white sheath that protects the eyeball
- The Cornea: transparent anterior continuation of the sclera that protects the lens, avascular and therefore it can be transplanted and not rejected
Three layers of the Eyeball (2) middle layer
Middle layer: loose connective tissue layer
1) Choroid: contains blood vessels that supply oxygen and nutrients to the tissues of eye
2) Ciliary Body: anterior continuation of the choroid, contains smooth muscle called ciliary muscles to control the shape of eye for focusing on an object
3) Iris: gives the eye color composed of smooth muscles which change the size of pupil to regulate the amount of light entering the eye
How the Iris controls the size of the pupil
- decreased light intensity, increased sympathetic stimulation: fight or flight
- increased light intensity and increased parasympathetic stimulation: rest and digest
The Layers of the Eyeball (3) Inner Layer
Inner layer: nervous tissue layer called: retina contains photoreceptors associated with optic nerve CN II
Rods
- receptors activated by dim light
- used for night vision
- black and white vision
- used for peripheral vision
Cones
- receptors activated by bright light
- used for daylight vision
- color vision
- used for central vision
Posterior Cavity of Eye
Contains vitreous humor:
- transparent gel (99% H2O)
- fills most (80%) of eyeball
- helps keep the retina in place!
- not produced until you are 4-5 years old
- only 1/2 full by the time you are 70 years old
- it is not replaced
- can lead to floaters
Posterior vitreous detachment: seeing floaters
The visual pathway to consciousness
Information travels from
- the optic nerves (CN II)
- via the optic chasm
- to the optic tract
- via the thalamus
- to the visual cortex (that is, consciousness) in the occipital lobe
light-> optics Rs-> optic Ns-> optic chiasm-> optic tracts-> thalamus-> visual cortex (0)
Eye Muscles are what kind of muscles?
these are skeletal muscles
6 Eye Muscles
Inferior rectus, medial rectus, superior rectus, lateral rectus, inferior oblique, superior oblique
Inferior rectus eye muscle
Action: eye looks down
Innervation: oculomotor nerve (III)
Medial rectus eye muscle
Action: eye looks medially that is, IN
Innervation: oculomotor nerve (III)
Superior rectus eye muscle
Action: eye looks up
Innervation: oculomotor nerve (III)
Lateral rectus eye muscle
Action: eye looks laterally that is, OUT
Innervation: Abducens nerve (VI)
Inferior oblique eye muscle
Action: eye rolls, looks up, and laterally OUT
Innervation: Oculomotor nerve (III)
Superior oblique eye muscle
Action: eye rolls, looks down and laterally OUT
Innervation: trochlear nerve (IV)
The Ear
external, middle, and inner ear, and vestibulocochlear
external and middle ear: involved with hearing
internal: hearing and equilibrium
The Hearing Process (1) parts 1-3
Sound waves
1) travel along the external ear canal
2) arrive at tympanic membrane
3) vibration of tympanic membrane causes little bones move (called ossicles: malleus, incus, stapes in the middle ear)
The Hearing Process (2) parts 4-5
4) movement of stapes at oval window generates pressure waves in the fluid-filled cochlea of the inner ear
5) pressure waves in the inner ear finally travel to the round window
The Hearing Process (3) cochlea
The cochlea contains 3 circular chambers
-this creates vibrators alone the floor of the middle chamber called basilar membrane
- when the basilar membrane moves, hair cells (receptors for hearing) embedded in the membrane move
- However, the tops of the hair cells embedded in the tectorial membrane do not move. This bends the hair cells
The Hearing Process (4) bending hair cells
Bending the hair cells:
- opens ion channels in hair cell membranes
- this causes ions to rush into hair cells
- this activates hair cells
- this stimulates CN VII
The Hearing Process (5) info travels
Information now travels from CN VIII
- via the thalamus
- to the auditory cortex
- in the temporal lobe
- where it reaches consciousness
Summary of hearing process
1) sound waves arrive at tympanic membrane
2) movement of tympanic membrane causes displacement of the auditory ossicles
3) movement of the stapes at the oval window establishes pressure waves in the perilymph of the vestibular duct
4) the pressure waves distort the basilar membrane on their way to the round window of the tympanic duct
5) vibration of the basilar membrane causes vibration of hair cells against the tectorial membrane
6) information about the region and the intensity of stimulation is relayed to the CNS over the cochlear branch of cranial nerve VIII
Vestibular Apparatus
- The vestibular apparatus is also in the inner ear and also connected to CN VIII
- Associated with equilibrium and balance
- It is composed of the: semicircular canals, saccule and utricle
The Vestibular Apparatus (1) semicircular canals
Semicircular canals contains a structure called a cupola filled with a gelatinous substance
-receptors called hair cells embedded in it, are stimulated by head rotators
The hair cells bends, which opens ion channels:
- this activates the hair cells
- this stimulates CN VIII
- this helps you maintain your balance during head rotation
Sensory Pathway
Sensory Pathway: conscious sensory info
1) originates at receptors in the peripheral
2) ascends on axons of sensory neuron in the white matter (CNS) of spinal cord
3) is relayed to cell bodies of sensory neuron in the gray matter of cerebral cortex (CNS), where it becomes conscious
Motor Pathway
Motor Pathway: conscious motor commands
1) originate in cell bodies of motor neuron in the gray matter (CNS) of the cerebral cortex (conscious)
2) descend on axons of motor neuron through the white matter (CNS) of the spinal cord
3) are relayed to cell bodies of spinal cord motor neuron whose axons (Sp. N, PNS) carry the info to skeletal muscles
However, a reflex…..
This means that:
1) A spinal cord motor neuron can be told what to do by a spinal nerve sensory neuron
2) Sensory info does not all go directly to consciousness
- sensory to motor
- A sample of this info does also usually ascend to consciousness. It just takes longer to get there.
- You usually become conscious of a reflex after it has occurred
A spinal reflex is…
- a motor response (muscle contraction) produced when a sensory neuron synapses on a spinal cord motor neuron
- very fast: occurs before the information has reached the brain
- unconscious and therefore involuntary: occurs before the information has reached the brain
Types of Spinal Reflexes
monosynaptic reflexes and polysynaptic reflexes
Name the different kinds of skin receptors
- pain, temperature, touch
- pressure, vibration
______ also contain receptors. What do you think ______ receptors sense?
- muscles, muscles
- stretch, tension
What do you think muscle receptors sense?
stretch, tension
Skin receptors and muscle receptors, one thing in common
all these sensations travel to the spinal cord on spinal nerves and can also be involved in spinal reflexes
Monosynaptic Reflexes
An example is stretch reflex:
- a sensory neurons synapses directly on cell body of a spinal cord motor neuron
- that is, only 1 synapse has occurred
The stretch reflex occurs constantly to help you maintain an upright posture
Steps in a Stretch Reflex
1) a stretch stimulates muscle spindle
2) axons in dorsal root send info to sensory neurons in DRG
3) sensory neuron synapses with motor neuron
4) axons in ventral root send info out from activated motor neurons
5) contraction of muscles
The patellar tendon stretch reflex
- AKA knee jerk reflex
- patellar ligament stretched when knee is bent
- quads contract when knee extends
- look at PG 69
After the knee “jerks” you become aware of what happened, don’t you?
the info does reach the cerebral cortex. It just takes longer
Polysynaptic Reflexes
An example is the withdrawal reflex:
- this is an unconscious reaction to a painful stimulus
- a sensory neuron synapses on interneurons which synapse on motor neurons (more than 1 synapse occurs!)
Polysnaptic reflexes help you respond quickly to unexpected stimuli
Polysynaptic Reflex (1): Stimulated Side
Example: stepping on a thumb tack
- Quad relax, extensors inhibited
- Sensory neuron carrying pain information
- Flexors stimulated, hamstrings contract, extensors inhibited
- Final result: flex knee
Polysynaptic Reflex (2): the opposite side
- extensor stimulated
- flexors inhibited
- final result: knee extend
- ipsilateral
- contralateral
The Autonomic Nervous System (ANS)
- AKA the visceral motor system
- Coordinates the functions of the:
- cardiovascular system
- respiratory system
- digestive system
- urinary system
- reproductive system
Similarities between the somatomotor and autonomic NSs
-both are motor systems to innervate muscles
Differences between the Somatomotor and Autonomic NSs
Somatic Nervous System
- innervates skeletal muscles
- is a voluntary system (conscious)
- initiates skeletal muscle contraction
- initiates skeletal muscle contraction
- is a 1-neuron system
Autonomic Nervous System
- innervates smooth and cardiac muscle
- is involuntary (unconscious)
- coordinates smooth or cardiac muscle contraction (it does NOT initiate it!)
- is a 2-neuron system
The Somatomotor System is a ________ system
1-neuron
The Somatomotor System
- somatomotor neuron cell bodies are located in the CNS
- their axons synapse directly on skeletal muscles in the periphery
The ANS: a 2-neuron system (1)
- Neuron #1 is called the preganglionic neuron whose cell bodies in the CNS synapse on neurons #2
- Neuron #2 is called the postganglionic neuron, whose cell bodies located in ganglia in the PNS, synapse on smooth or cardiac muscles in the periphery
- This allows the signal to be amplified or weakened or otherwise modified b/w its source and its targets!
Remember, there are also 2 divisions of the ANS
Sympathetic division:
- has a stimulating effect on the body
- “fight or flight” (heart rate (up), digestion (down)
Parasympathetic division:
- has a relaxing effect on the body
- “rest and digest” (heart rate (down), digestion (up)
- Point: these 2 divisions do not compete, they take turns***
- when 1 is up-regulated, the other is down regulated
Another important differences between 2 divisions: Sympathetics and Parasympathetics
Sympathetics innervate mainly vascular smooth muscle
- blood vessels are everywhere
- so sympathetic are everywhere involving the whole body
Parasympathetics innervate only visceral smooth muscle (that is, of the gut, for example)
- visceral organs are only in the trunk (thorax, abdomen, and pelvis) or head (glands, for ex.)
- so parasympathetics are more localized responses are restricted to a single organ
The Sympathetic Nervous System
- Preganglionic neuron cell bodies are located in the spinal cord
- Post ganglionic neuron cell bodies are located in ganglia; located mainly in the sympathetic trunk (a chain of ganglia)
Many sympathetic axons (N) travel with _______ ________ to reach their targets
spinal nerves
Sympathetics: Fight or Flight
-The sympathetic division readies the body for crisis
-An increase in sympathetic activity:
UP: respiratory rate, heart rate, blood pressure, metabolism, alertness, sweating
Down: digestive and urinary functions
-if you workout too soon after eating, you might get cramps or feel food bouncing around, you interrupt digestion
The Parasympathetic Nervous System (1) pre and postganglionic neurons
Preganglionic neuron cell bodies are located in the
- brain stem
- spinal cord (sacral)
Postganglionic neuron cell bodies are located in ganglia
- in the head
- or in the walls of the viscera
Parasympathetic nerves (axons)
- From the brainstem travels with cranial nerves to reach their targets in the head, thorax, abdomen
- From the spinal cord travel with spinal nerves to reach their targets in the pelvis
Parasympathetic: Rest and Digest
The Parasympathetic division:
-stimulates visceral activity
-conserves energy reserves
-An increase in parasympathetic activity:
Down: heart rate, blood pressure, metabolic rate
Up: glandular secretions, digestive tract motility, the urge to urinate and defecate
Summary: Central control of ANS
1) cerebral cortex
2) Hypothalamus ANS center
3) Brainstem ANS center
4) Preganglionic neurons in BS and Sp. C
5) Postganglionic neurons in autonomic ganglia
6) end organs smooth muscle, cardiac muscles
Epithelial Tissue: Functions
- Lines all boyd surfaces including cavities and tubes (most organs are tubes)
- Serves as a barrier
- Provides protection for the deeper tissue layers (connective tissue, muscle and nerve)
- Regulates exchange of substances for these deeper tissue layers
- Performs absorption and secretion (because glands come from epithelium and this is what glands do)
Epithelial Tissue: Characteristics
- composed only of epithelial cells
- forms a continuous sheet of cells
- therefore there is almost NO extracellular space between adjacent cells
- therefore it is avascular (NO place for blood vessels to travel)
Epithelial Tissue: Characteristics
-receives its nutrients via diffusion
- it is connected to the underlying connective tissue layer by a basement membrane (AKA basal lamina) that enable epithelial cells to:
- attach to the connective tissue
- divide when necessary
- migrate to close a wound
Epithelial cells: characteristics
They exhibit polarity that is, each surface has a unique function
- each cell has an apical surface: furthest from the basement membrane, may contain microvilli or cilia
- each cell has a lateral surface: contains specializations such as “junctions”
- each cell has a basal surface: closest to the basement membrane
-they undergo frequent mitosis
Epithelial Cells: Classification
Based on the shape and size of the cell:
- Squamous cells
- small flat, slightly active cells (think 3D, looks like a fried egg)
- Cuboidal cells
- slightly larger moderately active cells (cube-shaped)
- Columnar cells
- much larger cells that are very active (and shaped like a column)
- microvila are usually on columnar cells, because they do more absorption
-the more active, means they have more absorption to complete
Epithelial tissue: Classification: Simple Epithelium
- one layer of cells
- all cells are in contact with the basement membrane
Type 1a: Simple Squamous
- Location: lines blood vessels, body cavities
- Function: regulates diffusion across this layer
Epithelial Tissue: Classification: simple cubodial
- location: lines ducts
- function: provide moderate amounts of recreation and absorption
-pancreatic duct, mammary duct
Epithelial Tissue: Classification: simple columnar
- location: lines the intestines
- Function: provides vast amounts of secretion and absorption
Epithelial Tissue: Classification: pseudostratified
- AKA respiratory epithelium
- location: lines the respiratory tract
- function: provide secretion and movement along the surface
-most cells are columnar and ciliated LOOKS like it is composed of multiple layers of cells But EVERY cell’s basal surface touches the basement membrane
Epithelial Tissue: Classification: stratified epithelium
- composed of more than 1 layer of cells
- function: protection
Type 2a: stratified unkeratinized
- location: lines internal surfaces of tubes such as the esophagus
- must remain moist superficial most layers of cells are alive but flat hence the name “squamous”
- stratified layered
Epithelial Tissue: Classification: Stratified keratinized epithelium
- location: lines the skin
- superficial-most layers of cells are: flat, dead, filled with keratin (a waxy hydrophobic protein which reduces water loss)
Keratin repels water, so we won’t lose any water
Epithelial Tissue: Classification: transitional epithelium
- a type of stratified
- AKA urothelium
- Location: lines urinary bladder and ureters
- many layers of cells, the layers can rearrange themselves and spread out as the bladder fills! Compare empty and full bladder
Glandular Epithelium
- from the invagination of surface epithelium
- exocrine glands: releases saliva, sweat onto a surface through ducts
- endocrine glands: release hormones into the surrounding connective tissue and blood stream, no ducts
Endo means
inside, within
Crinin means
something that stimulates glandular secretion
Endocrine and Nervous Systems are similar
- both nervous and endocrine systems release chemicals
- share many chemical messengers
Endocrine and Nervous Systems however:
The nervous system releases neurotransmitters
- at a synapse
- very close to its target
- the action is fast and short
The endocrine system releases hormones
- into connective tissue
- relies on the blood stream to distribute its secretions
- far from its target cells
- the action is slower but lasts longer
-These 2 systems are linked through the hypotriglamus and pituitary gland
The Endocrine System
- regulates long term processes:
- development
- growth
- reproduction
- regulated by negative feedback
- goal: to preserve homeostasis
Endocrine Glands
Secretory units composed of endocrine cells
1) begin as invaginations of surface epithelium, LOSE their duct
2) release hormones secretory products into the blood stream for distribution
Hormones
Chemicals that:
- are released from endocrine system
- are distributed by the blood
- change rate of activity performed by the body:
- smooth muscle cells up or down activity
- epithelial cells secretory product
Homeostasis
- defined as stable internal environment
- all body systems work together to maintain homeostasis, and to prevent potentially dangerous changes
- body systems must function within a normal range body temperature, fluid balance
- failure to function within a normal range results in disease or death
- homeostasis is necessary for your survival (so it is kind of important)
How your body maintains Homeostasis:
- it has receptors that sense 2 stimulus (change)
- it has a control center that receives and processes this information from receptors
- it has effectors that respond commands by the control center
Physiological example of homeostasis
This is called Negative feedback
-not that the response of the effector negates the stimulus and restores normal function
Hypothalamus****
Has 3 roles:
-as nervous tissue: controls the ANS (autonomic nervous system)
- as the integrator between the nervous and endocrine systems:
- secretes regulatory hormones: that control endocrine cell secretion in the pituitary gland
-as an endocrine organ: secretes the hormones ADH and oxytocin
The Pituitary Gland: anterior and posterior lobe
Anterior lobe:
- grandular
- developed from epithelium
- composed of endocrine cells
Posterior lobe:
- developed from nervous tissue
- part of the CNS
- composed of axons whose cells bodies are in the hypothalamus
Pituitary Gland
- major endocrine gland (hormone producer)
- connects nervous and endocrine systems
- connected to hypothalamus via infundibulum (stalk)
How the hypothalamus communicates with the anterior lobe of the pituitary gland (1)
Releasing hormone (RH) and inhibitory hormones (IH)
- from neurons in the hypothalamus
- enter blood vessels called a portal system
- and are released onto endocrine cells in the anterior lobe of the pituitary gland
- Instant message system
- Pituitary gland can’t communicate with hypothalamus unless go through whole body
How the hypothalamus communicates with the anterior lobe of the pituitary gland (2)
- Releasing hormones: stimulate secretor of hormones from the anterior pituitary GHRH (makes that hormone)
- Inhibiting hormones: prevent secretion hormones from the anterior pituitary PIH (inhibits prolactin secretion) (does not make that hormone)
The Pituitary Portal System
This portal system is composed of:
- capillaries in both the hypothalamus and the anterior pituitary gland
- portal veins in the infundibulum (stalk) (this is rare)
Portal meaning
entrance, gateway
The advantage of the Portal System
The portal system:
-allows cell sin the hypothalamus:
to secrete very small amounts of hormones into the 1st set of capillaries
- allows these hormones to:
- reach their target cells in the anterior pituitary via the 2nd set of capillaries
- very rapidly
- without being diluted in the general circulation
F(L)AT PIG
- The anterior lobe of the pituitary gland releases 6 hormones
- These hormones in turn stimulate other endocrine glands in the body
- FSH: follicle-stimulating hormone, sex (releasing hormones)
- LH: luteinizing hormone, sex (releasing hormone)
- ACTH: adrenocorticotropic hormone
- TSH: thyroid stimulating hormone
- PRL: prolactin, will be produced until told to stop (include inhibiting hormones)
- GH: growth hormone, will be produced until told to stop
Anterior Pituitary Hormones (F(L)AT) (1) Gonadotropins category
The gonadotropins (sex related)
- FSH: follicle-stimulating
- stimulates follicle development in female ovaries
- stimulates maturation of sperm in male testes
- LH: luteinizing
- stimulates progesterone production in females
- stimulates testosterone production in males
Stimulated by GNRH gonadotropin-releasing hormone from the hypothalamus
Regulates activities of gonads (testes, ovaries)
Anterior Pituitary Hormones (F(L)AT) (2) ACTH and TSH
ACTH: adrenocorticotropic
- stimulates the release of steroid hormones by the adrenal cortex
- stimulated by CRH (corticotropin releasing hormone) from the hypothalamus
TSH: thyroid-stimulating
- also called thyrotropin
- stimulates the release of thyroid hormones from thyroid gland
- stimulated by TRH (thyrotropin releasing hormone) from the hypothalamus
Hypothalamic Regulatory Hormones for (F(L)AT) **
- Hypothalamus secretes ONLY releasing (+) hormones for 4 pituitary hormones
- secretion is controlled by negative feedback
-releasing hormone (RH): GnRH, CRH, TRH
-hormones from pituitary: FSH, LH, ACTH, TSH
-Endocrine target organs:
FSH to testes (inhibin) and ovaries (inhibin, estrogen),
LH to ovaries (progestins, estrogens) and testes (androgens),
ACTH to adrenal cortex (glucocorticoids),
and TSH to thyroid gland (thyroid hormones)
Anterior Pituitary Hormones (P(I)G)
PRL
-stimulates mammry gland development in females (will in males as well)
-may regulate androgen production in males
-production regulated by the hypothalamic hormones:
prolactin-releasing hormone (PRH) and prolactin- inhibiting hormone (PIH)
GH
- stimulates growth
- production regulated by by the hypothalamic hormones: growth hormone-releasing hormone (GHRH) and growth hormone- inhibiting hormone (GHIH)
Hypothalamic Regulatory Hormones for (P(I)G)
-Hypothalamus secretes both releasing (+) and inhibiting (-) hormones for these 2 pituitary hormones
Posterior Pituitary Hormones
Posterior lobe of pituitary gland contains 2 hormones that are:
- synthesized in nerve cell bodies located in the hypothalamus and
- released from axon terminals to the posterior pituitary
- taken up by the blood stream so “hormones”
Posterior Pituitary Hormones include:
ADH (antidiuretic hormone)
-restricts H2O loss from the kidneys and promotes thirst
Oxytocin
- stimulates smooth muscle contractions in the:
- mammary glands
- uterus
- prostate gland
Adrenal Glands
(AKA “suprarenal glands” guess why?)
- located along the superior border of each kidney
- are subdivided into an outer cortex and an inner medulla
Adrenal Cortex
Synthesizes (cortico) steroid hormones:
- mineral ocorticoids for the kidneys which increase Na+ (and H2O) retention (kidneys)
- glucocorticoids (ex. cortisol) which increases blood glucose
- sex steroids which stimulate the onset of puberty
CRH release form the hypothalamus stimulates ACTH release from the pituitary which stimulates release of these steroids from the adrenal gland (too much)
- Cushing’s syndrome: high BP, hyperglycemia weight gain
- Addison’s disease: fatigue, weight loss
Adrenal Medull
- its secretory activities are controlled by the sympathetic nervous system
- its cells produce epinephrine (adrenaline) and norepinephrine (just like the post ganglionic sympathetics!)
- Causes: heart rate and blood pressure to rise
- unlike the immediate changes produced by these chemicals when released by nerves, these metabolic changes persist for several minutes
The Thyroid Gand
- lies inferior to the thyroid cartilage of the larynx and superficial to the trachea
- consists of 2 lobes
Thyroid follicles and thyroid hormones
The thyroid gland is composed of follicles
- hollow balls lined by epithelial cells
- synthesizes the hormones: T3 (triiodothyronine) and T4 (thyroxine)
- the hormones are stored in the cavities of the follicles until needed
Thyroid Gland Function
Thyroid hormones increase your basal metabolic rate (BMR) by:
- increasing oxygen and energy consumption (which increase temperature)
- increase heart rate and contraction strength (which increase blood pressure (BP)
Remember: TRH release from the hypothalamus stimulates TSH release from the pituitary which stimulates thyroxin release from the thyroid gland
Hyperthyroidism
- high BP
- excessive sweating
- increase in appetite
- increase in heat intollerance
Hypothyroidism
- fatigue
- weight gain
- cold intolerance
The Thyroid gland also contains ________ cells
C (clear) cells
The thyroid gland also contains C (clear) cells
- C cells produce hormone calcitonin
- causes a decrease in blood Ca2+
- controlled by the thalamus
The Parathyroid Glands
- its cells produce parathyroid hormone (PTH)
- causes an increase in blood ca+
Where must parathyroid Glands be located?
on the thyroid
Summary (Ca2+ regulation): Calcitonin
Calcitonin
- produced by thyroid gland
- high BP Ca2+ leads to
- increase calcitonin release which decreases Ca2+ by
- increasing Ca2+ excretion
- decreasing osteoclast activity (bone breakdown)
Summary (Ca2+ regulation): Parathyroid hormone (parathormone)
- produced by parathyroid gland
- low blood Ca2+ leads to
- increase in parathormone release which increases blood Ca2+ by
- decreasing Ca2+ excretion
- increasing osteoclast activity
-Calcium does NOT rely on info from hypothalamus and pituitary
The Pancreas
- lies between: the spleen and the small intestine
- contains exocrine and endocrine cells
- the endocrine cells form clusters:
- called islets of langerhans or pancreatic islets
The 2 major types of endocrine cells in Pancreatic Islets
Alpha Cells
- secrete hormone glucagon which increase blood glucose
- increase the rates of glycogen breakdown and glucose manufactured by the liver
Beta Cells
- secrete hormone insulin which decreases blood glucose
- increase the rate of glucose uptake and utilization
Note: glucose regulation does not rely on info from the hypothalamus and pituitary
Metabolism (esp. glucose) regulation: Insulin vs. Thyroxin, Cortisol, and Adrenaline
- Insulin is known as the BUILDING HORMONE
- Thyroxin, Cortisol, and Adrenaline are known as the BREAKDOWN OR USING UP HORMONES (released when you are stressed)
- A proper balance between these vital hormones is CRUCIAL for proper metabolism, which affects every aspect of your conscious and unconscious life!
- regulated by pancreas
- cortisol puts on weight because of stress
- cortisol and insulin will fight each other, and eventually stress wins
Stress
Stress= any condition that threatens homeostasis
GAS stands for what?
general adaptation syndrome
General Adaptation Syndrome (GAS)
is our bodies response to stress-causing factors, and is also called stress response
General Adaptation Syndrome (GAS) Three Phases
- Alarm Phase:
- immediate, fight or flight, directed by the sympathetic nervous system - Resistance phase: dominated by glucocorticoids (hormone)
- Exhaustion phase: breakdown of homeostatic regulation failure of one or more organ systems
- if we were to finish all phases, we would all be dead
- anything with the word syndrome is bad
GAS Alarm Phase
- is an immediate response to stress
- directed by ANS
- energy reserves mobilized (glucose)
- fight or flight responses (only for a few hours)
- dominant hormone is epinephrine
- energy demands are so high that this phase cannot be maintained for any extended period of time
- can’t stay in this phase for longer than an hour
GAS Resistance Phase
- entered if stress lasts longer than a few hours
- dominant hormones are glucocorticoids
- conserve salts, water, and loss of K+, H+
- Energy demands remain high (glucose is very important to maintain neural tissues and needs to be conserved)
1) glycogen reserves: nearly exhausted after several hours of stress
2) lipid reserves: mobilized to support body systems for years
3) protein reserves: mobilized to support body systems for years, e.g. muscles, and other structural proteins
-fat burning stage, longer period of time
GAS Exhaustion Phase
- begins when homeostatic regulation breakdown
- failure of 1 or more organ systems will prove fatal
- mineral imbalance
- if stress/stressor is stopped at beginning of this phase, they can survive. But could have some damage still.
- electrolyte imbalance happens
- possible coma
Example of Resistance Phase
- when prisoners of war are released, they are boney because of lipid reserves and protein reserves are depleated. But they survive because, they are trained for this and they survive the resistance phase.
- this phase can last for years like for prisoners of war
The Respiratory System
Consists of a conducting portion:
- from nasal cavity
- through the bronchioles
Consists of a respiratory portion:
- alveoli in the lungs
- where O2/CO2 exchange occurs
The Pleural Sacs and Gross Anatomy
- Each lung becomes surrounded by a pleural sac
- 2 of 3 sacs within the thoracic cavity (the 3rd is for the heart)
- Each lung extends from the diaphragm to the clavicle
Functions of the Respiratory System
1) move air to and from alveoli in the lungs
2) provide a gas exchange surface between air and blood
- O2 is obtained from the air during breathing by diffusion across membranes in the lungs
- O2 is carried to the cells of the body by the cardiovascular system
- the cardiovascular system also returns CO2 to the lungs to be eliminated
1) produce sounds
2) contribute to olfaction
The amazing tasks of the Respiratory System
The respiratory system must:
- prevent contaminants in the air from plugging the airway or getting into the blood
- get enough air close enough to the blood for O2/CO2 exchange without substantial water loss
- accomplish these tasks in a fairly compact space
- (if the lining of the lungs were to spread out flat it would cover an entire tennis court)
Respiratory Tract Lining
Composed of:
-a surface layer of epithelium: “respiratory epithelium” AKA “pseudostratified epithelium”
- a deeper layer of connective tissue:
- loose and dense connective tissue called “lamina propria” also contains:
- cartilage, smooth muscle, elastic fibers, and mucous glands that secrete mucus onto the epithelial surface
-Lines most of the respiratory tract
Respiratory Epithelium (AKA “pseudo stratified epithelium”)
Composed of:
- goblet mucus cells
- ciliate cells (movement)
- stem cells (regeneration)
-stem cells give it a stratified look, but it is not actually stratified
Functions of the Respiratory Epithelium
- mucus from goblet cells catches inhaled debris
- cilia of ciliated cells move mucus towards oropharynx
- stem cells divide and replace old goblet and ciliated cells
- you produce about a cup of mucus everyday, if healthy
- goblet cells produce mucus
- smokers must cough to attempt to rid their airways and lungs of debris
The Nasal Cavity: Conchae
Conchae (looks like conch shells)
- AKA “turbinates”
- produce air turbulence
- warm the air
- associated with paranasal sinuses
- nasal hair filters the air of particulate matter
The Nasal Cavity: mucous glands
- moisten the air with mucus secretions
- breathing through mouth bypasses these important steps
-popsicles help with nose bleeds
The Pharynx (AKA throat)
- A chamber shared by the digestive and respiratory systems
- Extends from nasal cavity to entrances of larynx and esophagus
-to check if a feeding tube is installed correctly, push air through and if stomach rises, it is correct
The Pharynx: Divisions of the pharynx
Nasopharynx
- posterior to the nasal cavity
- contains pharyngeal tonsils and openings to the auditory tubes
Oropharynx
- posterior to the oral cavity
- contains palatine tonsils
Laryngopharynx
- posterior to the larynx
- extends to the opening of the esophagus
The larynx (AKA voice box) thyroid and cricoid cartilage
Thyroid cartilage ("shield", hyaline cartilage) for protection
-attachment site for vocal cords
Cricoid cartilage ("signet ring," hyaline cartilage) for protection
-a complete ring of cartilage
The larynx (AKA voice box) arytenoid cartilage and epiglottis
Arytenoid cartilage (2;”jug,” hyaline cartilage)
- attached to the cricoid cartilage
- attachment site for the vocal cord
Epiglottis (“above the glottis,” glottis=floor of the larynx), elastic cartilage
- folds over glottis during swallowing
- Prevents entry of food and liquids into respiratory tract
The glottis
- the floor of the larynx
- the entrance to the trachea
Composition: the vocal cords
- ligaments attached to the arytenoid and thyroid cartilages
- skeletal muscles (their contraction opens/closes the glottis)
- must be open to breathe
- must be closed to speak
- the cartilage protects the vocal cords
The Trachea (AKA windpipe)
- used for breathing
- extends from the cricoid cartilage of 1 bronchi
- contains 15-20 cartilage rings (hyaline cartilage):
- strengthen and protect airway
The Bronchi a series of tubes of decreasing diameter (1)
1 Bronchi (primary)
- right and left
- each 1 bronchus supplies 1 lung
- 1 Bronchi branch into 2 bronchi (secondary)
- each 2 bronchus supplies 1 lobe of a lung
The Bronchi (2) (tertiary)
- 2 bronchi branch into 3 bronchi
- each 3 bronchus supplies a broncho pulmonary segment of a lobe
- each lung has about 10 of these segments
The Bronchi (3)
The walls of 1, 2, and 3 bronchi:
- contain progressively
- less cartilage and more smooth muscle and elastic fibers
-this means that smooth muscle has more control over airway constriction in a 3 bronchus than in a 1 bronchus
Bronchodilation
- dilation of bronchial airways
- caused by the sympathetic nervous system: allows smooth muscle to relax
- reduces resistance of airflow
Bronchoconstriction
- constriction of bronchial airways
- caused by the parasympathetic nervous system
- causes smooth muscle to contract
- increases resistance of airflow
Asthma
- excessive bronchoconstritction: due to an allergic reaction and inflammation
- results in severely restricted airflow
The Bronchioles
Each 3 bronchus branches into multiple bronchioles:
- are lined by a simple epithelium (1 cell layer)
- no longer respiratory epithelium
- have NO cartilage in the lamina propria
- ONLY smooth muscle and elastic fibers control diameter of bronchioles and control airflow in lungs
Gross Anatomy of the Lungs: right lung
The RIGHT lung has: 3 lobes: -superior, middle, and inferior Separated by 2 fissures: -horizontal and oblique
3/2 right
Gross Anatomy of the Lungs: left
The LEFT lung has: 2 lobes: -superior and inferior Separated by 1 fissure: -oblique
2/1 left
Microscopic Anatomy of the lungs: Bronchioles
Bronchioles give rise to alveoli where:
- gas exchange takes place
- air filled balls make up most of the lungs
- give lung its spongy quality
500 MILLION alveoli/lung
The Alveolus: its epithelial lining
- Simple lining epithelium
- type 1 cells
- O2/CO2 exchange
- type 2 cells
- produce surfactant
- an oily secretion (like soap)
Surfactant
-coats alveolar surfaces
Reduces surface tension
- surface tension is the attraction between water molecules
- if surface tension is too high, the alveoli collapse
Respiratory Distress Syndrome
- difficult respiration:
- due to alveolar collapse
- caused when Type II cells do not produce enough surfactant
- surfactant is not synthesized until 8 months of fetal development
- premature babies born prior to this have difficulty breathing
The Aveolus (2)
Its connective tissue layer contains:
- capillaries
- elastic fibers
- NO MORE smooth muscle
3 Components of the Respiratory membrane
1) Epithelial cell (type 1 cell) lining the alveolus
2) thin layer of connective tissue in between
3) endothelial cell lining a capillary
GAS EXCHANGE
Pneumonia
- aveolar walls become inflamed
- alveoli become full of fluid
- O2 from the air cannot reach the bloodstream
- mucus
- wheezing on inhalation
Pneumothorax
-From knife wound, broken rib, spontaneous in some individuals
The “vacuum” between the 2 layers of the pleural sac is compromised
- 1 layer is attached to the lungs
- 1 layer is attached to the thoracic wall (rib cage)
- This is what holds the lungs against the thoracic wall
- Air enters the pleural sac.
- The elastic component of the lungs causes them to collapse
- With each attempt to take a breath, more air fills the space between the lungs and the thoracic wall, further collapsing the lungs
- (Ribs expand chest cavity with each breath but lungs no longer follow)
The Abdominal Cavity
- Bordered superiorly by the diaphragm (above)
- bordered inferiorly by the pelvic cavity (below)
- lined by the perineum (serous membrane)
Functions of the Digestive System 1-3
1) Ingestion
- occurs when materials enter digestive tract via the mouth
2) Mechanical processing:
- chewing, churning
- makes materials easier to propel along digestive tract
3) Secretors
- the release of water, acids, enzymes and buffers by cells of epithelial lining and by glandular organs
Functions of the Digestive System 4-6
4) Digestion
- the chemical breakdown of food into small fragments
5) Absorption
- movement of organic substrates, ions, vitamins, and water
- from the lumen
- across the cells of the epithelial lining
- into interstitial fluid (and blood vessels)
6) Excretion
- removal of waste products (feces) from body
The impressive lining of the digestive tract
- The epithelial lining of the digestive tract is CONTINUOUS at the mouth and at the anus, with the external environment
- It must accommodate these TRANSITIONS at either end while remaining MOIST
- It must also be VERY THIN to accomplish both digestion and absorption
- It must handle the RAPID TURNOVER of its epithelial cells due to mechanical and chemical insults while protecting the deeper tissues against:
- chemical stresses (corrosive effects of digestive acids and enzymes)
- mechanical stresses, such ad abrasion
- pathogenic bacteria
General Organization of the Digestive Tract
The 4 major layers o the digestive tract from inside to outside:
- mucosa
- submucosa
- muscularis
- serosa
Mucosa
- the inner lining of the digestive tract
- consists of its own 3 layers: epithelium, lamina propria (loose connective tissue), muscular mucosae (thin smooth muscle layer)
Surface Epithelium (1) Epithelium is either______ or _____ depending on….
The epithelium is either stratified or simple columnar depending on location, function, and stresses
Surface Epithelium (2)
-oral cavity, pharynx, esophagus, and anus:
Function: ingestion, transport along the length of the tube
-lined with stratified epithelium for protection
Surface Epithelium (3)
-Stomach, S. intestine, and L. intestine
Function: digestion and absorption
-are lined with simple columnar epithelium
-for rapid transport across the epithelial lining
Lamina Propria
-DEEP to the epithelial layer
-loose connective tissue
Contains:
-small blood vessels
-small lymphatic vessels and lymphoid tissue
-small sensory and motor nerves
Muscularis Mucosae means
Muscular movement
Muscularis Mucosae
- deep to the lamina propr.
- a thin layer of smooth muscle cells
- muscle contraction causes movement of the mucosa
- Submucosa
- deep (“sub”) to the mucosa
- dense irregular connective tissue
Contains:
- large blood vessels
- large lymphatic vessels
- large nerves
Submucosal nerve plexus
Contains:
- sensory neurons: sense chemical changes in the lumen
- motor neurons (sympathetic and parasympathetic)
- innervate the muscular mucosae
Plexus means
complex network
- Muscularis
- 2 thick layers of smooth muscles: inner circular and outer longitudinal (opposites)
- involved in peristalsis: wave like muscular contractions that move materials along digestive tract
- contains a nerve plexus
Myenteric nerve plexus
Contains:
- sensory neurons: sense muscle stretch
- motor nuerons (sympathetic and parasympathetic) coordinate peristalsis
- innervates this muscular layer
Interesting Facts! (digestive system)
- there are more neurons in the gut than in the spina l cord (over 1 hundred million!)
- the only organ with more neurons is the brain (which contains about 10 billion neurons!)
- Many neurotransmitters found int eh brain are also used by the neurons in the gut
- this is one reason why stress, for example, leads to GI complications (20% of Americans suffer from bowel diseases)
- Many causes are unknown, quite a few are autoimmune diseases!
Peristalsis
- waves of muscular contractions
- moves a bolus along the length of the digestive tract
1) Circular smooth muscle layer contracts behind bolus
2) longitudinal smooth muscle layer ahead of bolus contracts: shortening adjacent segments
3) Wave of contraction in circular muscles: forces bolus forward
- Serosa
- The outer lining of the digestive tract
- composed of simple squamous epithelium and loose connective tissue
Functions of the oral cavity
Mechanical Processing:
-through actions of teeth and tongue
Lubrication:
-mixing with salivary gland secretions
Some Digestion:
-saliva contains amylase (enzyme that breaks down starches) and lipase (enzyme that breaks down lipids)
The pharynx
A common passage way for solid food, liquids, and air
-shared by digestive and respiratory systems
Food passes through the pharynx to the esophagus
The esophagus
- A hollow muscular tube
- transports solid food and liquids to the stomach
- passes through he diaphragm muscle to get from the thorax to the abdomen, acts like a sphincter
Functions of the Stomach
- storage of ingestive food
- sterilization of ingested food
Some digestion:
- mechanical breakdown of ingested food by churning
- chemical breakdown of food material: by acids and enzymes
Some absorption:
- alcohol
- aspirin
The lining of the Stomach
- simple columnar epithelium
- invaginates to form gastric glands
Epithelial Cells lining the Stomach
Epithelial cells of the gastric glands
- mucous cells: secrete mucus for protection
- parietal cells: secrete HCI (hydrochloric acid). gastric acid
- chief cells: secrete pepsinogen, converted to pepsin (a protease enzyme) that breaks down proteins by gastric acid
Epithelial Cells lining the stomach
Epithelial cells of the gastric glands (continued)
- Endocrine cells: G cells: release the hormone gastrin which stimulates secretions by parietal and chief cells
- stem cells
Functions of the small intestine
-plays a key role in digestion and absorption of nutrients
90% of nutrient absorption occurs in the small intestines
Regions of the small intestine: duodenum
The duodenum
- the first segment of small intestine
- begins at the pyloric sphincter and controls flow from the stomach into the duodenum
- about 1 foot long
- it receives: chyme from stomach, digestive enzymes and buffers from pancreas and liver
Regions of the small intestine: jujenum
- the middle segment of the small intestine
- about 8 feet long
- site of most digestion and absorption
Regions of the Small Intestine
The ileum
- the last segment of small intestine
- about 12 feet long
- ends at the ileocecal valve: controls the flow from the small intestines into the large intestine
How the Small Intestine increases surface area: plica and vii
Plica
- folds in the intestinal lining
- increase surface area
- are covered with
Vili (villus singular)
- fingerlike projections
- increase surface area
How the small intestine increases surface area (2)
the columnar epithelial cells lining the villi contain microvilli, increase surface area
Epithelial Cells lining the small intestine (1)
Absorptive cells
-contain microvilli to increase surface area for absorption
Goblet cells
-secrete mucus for protection
Epithelial cells lining the small intestine
Endocrine cells
- CCK cells: secrete CholeCystoKinin
- S cells: secrete Secretin
- GIP cells: secrete Gastric Inhibitory Peptide (stomach)
- stem cells
Endocrine Cells of the Small Intestine*****
CCK cells secrete cholecystokinin:
- stimulates secretion of
- pancreatic enzymes from the pancreas
- bile (for lipid digestion) from the liver via the gall bladder
- into the small intestines
S cells secret secretin:
-stimulates secretion of buffers from the pancreas into the small intestines to neutralize the acidic chyme
GIP cells secrete gastric inhibitory peptide: inhibits gastric secretion (stomach)
Functions of the large intestine
- extends from end of ileum to anus
- is about 5 feet long
- compaction of feces
- storage of feces prior to defecation
Functions:
- absorption of water
- vitamins produced by bacteria
- bile
Regions of the large intestine
1) Cecum:
- the expanded pouch like first portion
- receives material arriving form the ileum
2) Colon:
- the largest portion
- its wall forms a series of pouches (haustra)
3) rectum
- the last 6 inches of digestive tract
The appendix
- attached to the posterior surface of the cecum
- a slender, hollow, vestigial appendage (3-4 inches long)
Regions of the colon (1) ascending colon and transverse colon
Ascending colon:
- begins at the cecum
- ascends along the right side of the abdomen
Transverse colon
-crosses abdomen from right to left
Regions of the Colon (2)
Descending colon
-descends along the left side of the abdomen
Sigmoid colon
- S shaped segment, about 6 inches long
- empties into the rectum
Epithelial Cells lining the colon
The main cell type of its simple columnar epithelial lining is the goblet cell:
- which produces vast amounts of mucus for lubrication of the feces
- it also contains absorptive cells which absorb water, vitamins and bile
- the colon (like the stomach) has NO VILI, does not need as much surface area for absorption
The Anus
- inferior to the rectum
- lined by stratified squamous keratinized epithelium
The Glandular components of the digestive system
liver, gall bladder, pancreas
The location of the Pancreas
- inferior and posterior to stomach
- extends from the duodenum to the spleen
The exocrine pancreas
Exocrine cells:
- 99% of the pancreatic cells
- secrete pancreatic enzymes into duct
Secretions:
- reach duodenum via pancreatic duct
- enter the duodenum at duodenal papilla
- release is controlled by hormones from the duodenum
Pancreatic Enzymes
pancreatic anylase, pancreatic lipase, pancreatic protease
Pancreatic lipase
breaks down complex lipids into fatty acids
Pancreatic analyse
breaks down carbohydrates into di- and trip-saccharides
Pancreatic protease
breaks down proteins into peptides
The liver
- the largest visceral organ (about 3 pounds)
- divided into lobes: right, left, caudate, quadrate
- performs many essential functions
Some of the Functions of the Liver
- removes and stores nutrients and toxins from the blood
- synthesizes nutrients when necessary
- regulates blood glucose, lipid, amino acid levels
- phagocytizes of old or damaged RBC’s
Synthesizes bile
- bile breaks lipid droplets apart (“emulsification”):
- creates tiny droplets
- this increases surface area for lipid digestion by pancreatic lipase which is itself water-soluble
Liver Disease
-You CANNOT live without your liver
Liver cirrhosis:
- hepatocytes die
- are replaced by scar tissue
- cannot be reversed
- one ultimately dies if a liver transplant is not available
- causes are from alcoholism, chronic hepatitis
Liver Histology #1
- liver lobule: the functional unit of the liver
- composition of the lobule:
1) hepatocytes - liver cells form walls of cells (radiate out from central being like spokes on a wheel)
Liver Histology #2
- composition of lobule:
2) bile canaliculi - spaces between heptocytes within a wall
- drain bile: synthesized by hepatocytes into the bile duct
Liver Histology #3
-Composition of lobule:
3) Sinusoids
-capillary-like vessels
-spaces between hepatocytes between walls
-drain blood from the hepatic portal and hepatic artery
and into the central vein
Hepatic Blood Supply (1)
- 1/3 of the blood supplied to the liver is O2 rich blood from the hepatic artery
- 2/3 is nutrient rich but O2 poor blood from the hepatic portal vein (another portal system)
- carries blood from the: stomach, small intestine, and large intestine
Liver histology 1-3
hepatocytes, bile canaliculi, sinusoids
Hepatic Blood Supply (2)
Sinusoids (capillary like vessels) in the liver drain blood
-from both hepatic A and hepatic portal V
to the central beings of the hepatic lobules
-then via the hepatic vein and then inferior vena cava
-back to the heart and general circulation
Liver drainage
- blood drains out of the liver via the hepatic veins into the inferior vena cava an on to the heart
- bile drains out of the liver via the hepatic ducts and on to the gall bladder
The gallbladder and bile ducts
Bile travels from
- the hepatic duct
- via the cystic duct
- to the gallbladder (a pear-shaped muscular sac)
-Where it is stored and concentrated (H2O is removed)
The gallbladder and bile duct system
- in response to CCK, a hormone released by the duodenum
- the gallbladder:
- contracts
- releases bile via the common bile duct
- into the duodenum though the duodenal papilla
