Equine Anatomy ANS 110

What are the basic components of life?

Organic compounds: carbon, oxygen, and hydrogen are the basic building blocks

Carbohydrates, lipids, and proteins

What's a tissue?

group of similar cells

What's an organ?

group of similar tissues functioning together

What is a system?

A group of organs with similar functions working together

What does the digestive system do?

breaks down food and absorbs nutrients from food

What does the skin and coat aid in?

protection from weather, sharp objects, etc. Vitamin D synthesis, temperature regulation (sweating), and sensation

What is anhydrosis?

The inability to sweat; can be fatal

What does the urinary system do?

removes wastes from the blood

What does the urinary system include?

kidneys, ureter, bladder, and urethra

What expels wastes as urine?

the urethra

What regulates pH?

kidneys

What shape are the horse's kidneys?

heart-shaped

What does the respiratory system do?

It exchanges oxygen and carbon dioxide

External respiration is done by...?

breathing

Internal respiration is done by....?

Cells using oxygen

What does the upper airway include?

nostrils, nasal cavity (divided in two) and pharynx

What does the nasal cavity do?

Many different sinuses help warm cold air before getting inside horses body, helping cool blood. Has scrolled tissues with blood vessels surrounding all of that.

When a horse is hot, what does blood do? How do horses combat this?

hot blood tries to go to the brain (not good), so when horses breathe, there is cooling of the blood since they are going through the nasal passages (sinuses with blood vessels- have tons of blood that is then cooled as the air passes by)

Where is the soft palate?

it is very long and at the top of the horses mouth

Can horses breathe out of their nostrils, mouth, or both, and why?

Only the nostrils because of the long soft palate

Can horses breathe while swallowing?

No, the soft palate and other similar structures block off the airway as food travels down the esophagus

What is roaring caused by?

Laryngeal Hemiplegia

Where is Laryngeal hemiplegia usually seen?

on the left side

What does laryngeal hemiplegia cause?

The left arytenoid cartilage becomes paralyzed and is unable to pull back, which blocks the airway, causes roaring noise and making the horse be unable to breath as effectively

What are some ways to treat laryngeal hemiplegia?

tie back surgery to pull open the left arytenoid cartilage, you scope the horses upper airway (endoscopy) to see the issue

What is the dorsal displacement of the soft palate?

it is where the soft palate displaces and sits on the top of the epiglottis and obstructs the airway, usually occurring at irregular intervals

What are some treatments of dorsal displacement of the soft palate?

nosebands and surgery

What breaks down to what in the lower respiratory tract?

The trachea breaks down into bronchi, bronchi into bronchioles, and bronchioles into alveoli

What is breathing controlled by?

The respiratory center, aka the medulla oblongata

When do horses control their breathing?

phonation (vocalizations), parturition (giving birth), and defecation

What does locomotion-respiratory coupling entail?

When cantering or galloping, horses can only inhale in the suspension phase (can only breathe as fast as the rate they are running), and exhale when their legs are on the ground

EIPH

What does EIPH stand for?

Exercise-induced pulmonary hemorrhage

What kind of horses is EIPH seen in?

Performance animals

What is EIPH?

intense exercise causes increased pressure in pulmonary capillaries which casuses capillary walls rupture, blood leaks into alveolar sac, exits via nostrils

Fancy name for a nosebleed.

existaxis

What does laxis cause in horses? How is this related to EIPH?

causes horses to urinate 20 pounds of water, which decreases blood pressure, and decreases the likelihood that the horse is going to bleed

What are heaves also known as?

Chronic obstructive pulmonary disorder (COPD) and equine asthma

What does COPD cause in the abdominal area?

a heaves line which is essentially a six pack causes by having to overwork the abdominal muscles since they are working so hard to breathe

What causes COPD/heaves?

respiratory irritants

What are some treatments for COPD?

Treatments: remove irritant (can be difficult if irritant is very common, such as dust or something in hay- soak bedding and hay to prevent this), increase turnout, and bronchodilators, injectable steroids to reduce inflammation

COPD is sometimes only ________.

seasonal

What does the circulatory system do?

supplies the body with nutrients and removes wastes via the heart, arteries, veins, and capillaries

Arteries carry blood....?

away from the heart

Veins carry blood....?

to the heart

Capillaries facilitate what?

gas and nutrient exchange at the tissues and lungs

How big is the average horse's heart?

9 pounds (pretty large)

What pushes blood from the heart to the rest of the body?

The contraction of the ventricles

How does blood get back to the heart?

Valves in our veins are one-way, meaning they can only go up and close behind them, so the blood cannot go backwards. Vesicles surrounded by muscles push blood back up to the next level, and no back flow, so it pushes it all the way up

Horses have no ____ below their knee/hock. So...?

muscles; so tendons move their feet and therefore the walls of the horses feet are elastic and expand when weight is applied, this expansion causes blood to pull while contracting sends blood back up (no muscles on vesicles)

What can stall rest/limited movement cause regarding blood?

fluid buildup in horse feet due to limited walking (not as many contractions/expansions)

Blood makes up __ of the body weight. How many liters is this?

9%, 45 liters

Horses have ____ of blood.

LOTS

High amounts of blood makes blood samples ____ to obtain.

easy

20% of the blood is?

pulmonary

80% of the blood is..?

systemic (flowing through body to transport oxygen)

60% of the blood is?

in the veins

40% of the blood is..?

in the arteries

What are the components of blood?

red blood cells (carry oxygen), white blood cells (immune responses), platelets (clotting), plasma (liquid proportion)

Where is blood sampling taken?

from the jugular vein

Where is blood sampling collected into?

tubes

What are the two types of blood sampling?

Anticoagulant - mostly plasma (purple tube) no clotting (RBC at bottom, then WBC, then plasma is the rest)

No anticoagulant - serum (red tube) has clotting, the left over stuff is the serum (no clotting, no WBC, no RBC)

What color is horse plasma?

very yellow

Serum vs plasma formula

Serum = plasma - clotting factors

What is the hematocrit (PCV)?

the percentage of RBCs in a sample

What is the normal percentage of hematocrit?

30-45%

Why would hematocrit levels decrease? Increase?

Decreases if anemic

Increases in stress, dehydration - meaning less plasma

What does the spleen do?

stores and releases RBCs during exercise for increased oxygen delivery

More RBCs cause blood consistency to be....

extra thick

What are the two control systems?

The nervous and endocrine systems

What is the main purpose of the control systems?

To maintain homeostasis by responding to external stimuli and changing

The endocrine systems include?

glands

What are the senses?

Sight

Hearing

Smell

Taste

Touch

How many eyelids does a horse have?

3

Should you be able to see the third eyelid?

No

What is the iris?

the color part

What is the schlera?

the white part, and can only be seen in Appaloosas

What shape is the pupil?

horizontal shape

What is the copora nigra?

acts as a visor over the pupil

Horses have a wide range of _____.

vision

Horses' vision is mostly what?

monocular, some binocular

Where are the horses' blind spots?

immediately in front of and behind them

What gives a horse night vision by acting as a reflector?

the tapetum lucidum

A horses eye is flattened so..

The retina is closer to the lens at the bottom, which causes a visual streak, which is an area where horses can detect things exceptionally well

What kind of color vision do horses have?

Dichromatic vision: see blue and yellow-green, not red

Is a horse's or a human's hearing better?

horse

How much can a horse's ears rotate?

180 degrees

How many muscles allow a horse's ears to rotate?

16 muscles

How does a sound wave affect a horse's hearing?

It makes the eardrum vibrate, which sends electrical impulses.

How does a horse's hearing change over time?

It deteriorates with age.

What is horse taste highly linked to?

Smell

Where are taste buds located in horses?

In papillae on the tongue

What type of tastes do horses prefer?

Sweet tastes

How sensitive are horses to taste?

Very sensitive

What is a horse's ability regarding food selection?

Very good at avoiding poisonous plants

What can horses smell detect?

Predator detection

How do horses communicate via smell?

social and reproductively

What do horses smell to learn about other horses?

Droppings to see what other horses have been there

What is the vomeronasal organ also known as?

Organ of Jacobson

What type of cells are found in the vomeronasal organ?

Specialized olfactory (scent) cells

What chemicals can horses detect with their vomeronasal organ?

Pheromones