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NE binds to the beta-1 receptor. Some cardiac medications (for example, beta blockers) work by blocking these receptors, thereby slowing HR and are one possible treatment for hypertension. Overprescription of these drugs may lead to bradycardia and even stoppage of the heart.

Autonomic innervation of the heart

This figure shows the brain and the nerves connecting the brain to the heart.
Cardioaccelerator and cardioinhibitory areas are components of the paired cardiac centers located in the medulla oblongata of the brain. They innervate the heart via sympathetic cardiac nerves that increase cardiac activity and vagus (parasympathetic) nerves that slow cardiac activity.

Parasympathetic stimulation originates from the cardioinhibitory region with impulses traveling via the vagus nerve (cranial nerve X). The vagus nerve sends branches to both the SA and AV nodes, and to portions of both the atria and ventricles. Parasympathetic stimulation releases the neurotransmitter acetylcholine (ACh) at the neuromuscular junction. ACh slows HR by opening chemical- or ligand-gated potassium ion channels to slow the rate of spontaneous depolarization, which extends repolarization and increases the time before the next spontaneous depolarization occurs. Without any nervous stimulation, the SA node would establish a sinus rhythm of approximately 100 bpm. Since resting rates are considerably less than this, it becomes evident that parasympathetic stimulation normally slows HR. This is similar to an individual driving a car with one foot on the brake pedal. To speed up, one need merely remove one’s foot from the break and let the engine increase speed. In the case of the heart, decreasing parasympathetic stimulation decreases the release of ACh, which allows HR to increase up to approximately 100 bpm. Any increases beyond this rate would require sympathetic stimulation. [link] illustrates the effects of parasympathetic and sympathetic stimulation on the normal sinus rhythm.

Effects of parasympathetic and sympathetic stimulation on normal sinus rhythm

This figure shows three graphs. The top panel shows the normal or resting potential with time. The middle panel shows membrane potential with time in a parasympathetic stimulation where the heart rate is decreased. The bottom panel shows membrane potential with time in a sympathetic stimulation with increased heart rate.
The wave of depolarization in a normal sinus rhythm shows a stable resting HR. Following parasympathetic stimulation, HR slows. Following sympathetic stimulation, HR increases.

Input to the cardiovascular center

The cardiovascular center receives input from a series of visceral receptors with impulses traveling through visceral sensory fibers within the vagus and sympathetic nerves via the cardiac plexus. Among these receptors are various proprioreceptors, baroreceptors, and chemoreceptors, plus stimuli from the limbic system. Collectively, these inputs normally enable the cardiovascular centers to regulate heart function precisely, a process known as cardiac reflexes    . Increased physical activity results in increased rates of firing by various proprioreceptors located in muscles, joint capsules, and tendons. Any such increase in physical activity would logically warrant increased blood flow. The cardiac centers monitor these increased rates of firing, and suppress parasympathetic stimulation and increase sympathetic stimulation as needed in order to increase blood flow.

Questions & Answers

send me a cytoplasm arganles anatomy and thire physology
Hayat Reply
the organelles r found within the cytoplasm e.g. mitochondria etc.
Patrick
one by one detail
Hayat
the cell contains the cytoplasm, organelles, cytoskeleton, inclusions(foreign material), cytosol. of course the cell membrane. the nucleus. the nucleus is inside the nucleus. the rough endoplasmic reticulum is usually next to the smooth er
Patrick
nucleolus inside nucleus
Patrick
the mitochondria is in there and the Golgi apparatus, lysosomes, ribosomes, peroxisomes and centrioles
Patrick
everything I mentioned after the nucleus kinda the nucleolus: r organelles
Patrick
Bones that are bind together by inelastic tissue connective tissue are called
Augustina Reply
vertebrae
KWAKU
the skull too can be part
KWAKU
the skull is 22 bones
Amiebo
vertebral bones
Drs
what are the body plains
Sanjana Reply
median plane,transverse or horizontal plane and coronal or frontal plane
ASIMENU
How do I summarize the whole of muscular system
Mary Reply
briefly explain the similarities between transcription and DNA replication
Emmanuel Reply
transcription copies DNA into RNA while replication makes another copy of DNA
Goode
A general explanation: Replication occurs when a copy of DNA is made. Transcription is the first step in the process of protein synthesis. Messenger RNA is made using a portion of the DNA molecule as a template.
Lessa
please what group is this?
Winifred
hello guys
PRINCE
Relationship between essential amino acids and immune response
Eunice
transcription from DNA to rna involves the matching of the nucleotides represented by c,g, t and A, but where there is a t, it is replaced by a u- uracil
Patrick
what is the main function of the pcn?
DAVID Reply
career in the health professions, respond appropriately to signs of illness, help you in your roles as a parent, spouse
Coach Reply
student would have an appreciation of the heart anatomy to give understanding of anatomy while opening ideas of function and physiology
Coach
study of the parts of the body
Coach
macro anatomy, study of big structures of the body that can be viewed with the naked eye
Coach
that is called gross anatomy
Patrick
what is integumentry
Amiebo Reply
chemical level cell level tissue level organs level organ system organism
sam Reply
when you sitting close to a campfire your sense smell adapts the smell but when the trace of smoke is introduced into your environments it becomes unsual for you
sam
I need to know mechanism of body fluid
johnson
OK but I need to know where are you coming from
johnson
ask how
Amiebo
oh ft, help out with integumentary system now
Amiebo
Pls give me a brief description of vetebra
Deborah Reply
7 cervical (c1 atlas and c2 axis help the neck rotate) 12 thoracic 5 lumbar 1 sacral and 2 coccyx
Anna
breakfast at 7, lunch at 12, and dinner at 5. sacrum holds 5, coccyx holds 4
Patrick
really there's just one coccyx and sacrum
Patrick
atlas like the Greek God holds the weight of the world on top of him
Patrick
elasticity of the vagina
Mariam Reply
The vagina is an elastic muscular wall
antouman
*organ
antouman
It has I think squamous cuboidal or maybe columnar epithelium designed for secretion, expansion and friction.
Patrick
how can you remember the integumentary system
Naomi Reply
integumentary system is the skin the skin is protection all the body and contain deid cells
Drs
how can you remember the formation of bone?
Maame
the largest organ of the body
Toni
skin is largest organ
Zara
what is the best way to remember the cranial bones or any other bones ?
Savannah
skeletal system?
Savannah
look at the diagram structure and then remember it considering it your own body i memorise like that
Zara
hi guys! do you have to remember ALL the structures of the bones- I mean every single hole, depression or tuberosity?
Kristina
tuborisity
Zara
hey guz i hv to remember Immune antibodies and antigens how? i found it difficult
Zara
well, they are all grouped, aren't they? I mean they all come in series like H1, H2A, H2B and so on. In this case I learn the common part first and then that what's different
Kristina
nd what about IgG , IgE etc.
Zara
the majors
Toni
the thin skin does not have stratum lucidium I believe
Patrick
acronyms
Patrick
if u know the bones, the muscle has part of the name of the bone in it
Patrick
epidermis, I believe epi means on top. dermis in the middle and hypodermis, hypo meaning below. the hypodermis is actually considered not part of the skin or int system
Patrick
big sweet guys love candy = basale, spinosum, granulosum, lucidum ( only in thick skin), corneum
Anna
I love it ☝🏾
Savannah
thank you Zara !
Savannah
can anyone send diet plan for asthma patients
waseem
is
Drs
hey
Daud
jam how are you
Daud
Hey guys l am Matrin
Matrin
blood is a connective tissue which transport oxygen and other nutrients to body
Zara Reply
which type of protein is blood?
Zara
what is blood?
Masthan Reply
blood is a connective tissue which transport oxygen and nutrients to body
Zara
which type of protein is blood?
Zara
haemoglobin
Rashid
and what about its structure i think its Quartenary structure 🤔💭
Zara
yes it is
Rashid
it is globular
Rashid
a vascular structure compose of vessels.
Toni
what is the functions of lymph
moula Reply

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Source:  OpenStax, Anatomy & Physiology. OpenStax CNX. Feb 04, 2016 Download for free at http://legacy.cnx.org/content/col11496/1.8
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